小川　美香子 (オガワ　ミカコ)

薬学研究院　医療薬学部門　医療薬学分野教授
Last Updated :2024/12/05

■研究者基本情報

学位

  • 博士（薬学）, 京都大学

Researchmap個人ページ

ホームページURL

研究者番号

  • 20344351

J-Global ID

研究分野

  • ライフサイエンス, 薬系分析、物理化学

■研究活動情報

論文

  • Piperazine based pH-responsive cyanine dyes for cancer cell photoacoustic imaging
    Koki Tsuchiya, Hideo Takakura, Kohei Nakajima, Naoya Ieda, Takashi Kaneko, Takeshi Hirasawa, Masato Kobayashi, Yoshihisa Yamaoka, Miya Ishihara, Tetsuya Taketsugu, Mikako Ogawa
    Journal of Photochemistry and Photobiology A: Chemistry, 453, 115634, 115634, Elsevier BV, 2024年08月
    研究論文（学術雑誌）
  • Investigation of the substituent effect of indocyanine green derivatives for lymph imaging
    Naoya Ieda, Hideo Takakura, Hirotaka Maeta, Takayuki Ohira, Koki Tsuchiya, Kohei Nakajima, Mikako Ogawa
    Bioorganic & Medicinal Chemistry, 117824, 117824, Elsevier BV, 2024年06月
    研究論文（学術雑誌）
  • Attenuated polyethylene glycol immunogenicity and overcoming accelerated blood clearance of a fully PEGylated dendrimer
    Chie Kojima, Junjie Yao, Kohei Nakajima, Motofumi Suzuki, Ayako Tsujimoto, Yuji Kuge, Mikako Ogawa, Akikazu Matsumoto
    International Journal of Pharmaceutics, 659, 124193, 124193, Elsevier BV, 2024年06月
    研究論文（学術雑誌）
  • Development of small molecule–drug conjugates based on derivatives of natural proteasome inhibitors that exhibit selectivity for PSMA-expressing cancer cells
    Takahiro Obara, Nanami Kawano, Kengo Tatsumi, Akira Katsuyama, Kohei Nakajima, Mikako Ogawa, Satoshi Ichikawa
    Bioorganic & Medicinal Chemistry, 108, 117773, 117773, Elsevier BV, 2024年06月
    研究論文（学術雑誌）
  • Development of a red-shifted photosensitizer for near-infrared photoimmunotherapy of cancer
    Yuto Goto, Kanta Ando, Hideo Takakura, Kohei Nakajima, Masato Kobayashi, Osamu Inanami, Tetsuya Taketsugu, Mikako Ogawa
    Journal of Photochemistry and Photobiology, 20, 100230, 100230, Elsevier BV, 2024年04月
    研究論文（学術雑誌）
  • Theoretical Design and Synthesis of Caged Compounds Using X‐Ray‐Triggered Azo Bond Cleavage
    Koki Ogawara, Osamu Inanami, Hideo Takakura, Kenichiro Saita, Kohei Nakajima, Sonu Kumar, Naoya Ieda, Masato Kobayashi, Tetsuya Taketsugu, Mikako Ogawa
    Advanced Science, Wiley, 2024年01月15日
    研究論文（学術雑誌）, Abstract

    Caged compounds are frequently used in life science research. However, the light used to activate them is commonly absorbed and scattered by biological materials, limiting their use to basic research in cells or small animals. In contrast, hard X‐rays exhibit high bio‐permeability due to the difficulty of interacting with biological molecules. With the main goal of developing X‐ray activatable caged compounds, azo compounds are designed and synthesized with a positive charge and long π‐conjugated system to increase the reaction efficiency with hydrated electrons. The azo bonds in the designed compounds are selectively cleaved by X‐ray, and the fluorescent substance Diethyl Rhodamine is released. Based on the results of experiments and quantum chemical calculations, azo bond cleavage is assumed to occur via a two‐step process: a two‐electron reduction of the azo bond followed by N─N bond cleavage. Cellular experiments also demonstrate that the azo bonds can be cleaved intracellularly. Thus, caged compounds that can be activated by an azo bond cleavage reaction promoted by X‐ray are successfully generated.
  • Novel Auger-Electron-Emitting 191Pt-Labeled Pyrrole-Imidazole Polyamide Targeting MYCN Increases Cytotoxicity and Cytosolic dsDNA Granules in MYCN-Amplified Neuroblastoma.
    Honoka Obata, Atsushi B Tsuji, Hitomi Sudo, Aya Sugyo, Kaori Hashiya, Hayato Ikeda, Masatoshi Itoh, Katsuyuki Minegishi, Kotaro Nagatsu, Mikako Ogawa, Toshikazu Bando, Hiroshi Sugiyama, Ming-Rong Zhang
    Pharmaceuticals (Basel, Switzerland), 16, 11, 2023年10月27日, ［国際誌］
    英語, 研究論文（学術雑誌）, Auger electrons can cause nanoscale physiochemical damage to specific DNA sites that play a key role in cancer cell survival. Radio-Pt is a promising Auger-electron source for damaging DNA efficiently because of its ability to bind to DNA. Considering that the cancer genome is maintained under abnormal gene amplification and expression, here, we developed a novel 191Pt-labeled agent based on pyrrole-imidazole polyamide (PIP), targeting the oncogene MYCN amplified in human neuroblastoma, and investigated its targeting ability and damaging effects. A conjugate of MYCN-targeting PIP and Cys-(Arg)3-coumarin was labeled with 191Pt via Cys (191Pt-MYCN-PIP) with a radiochemical purity of >99%. The binding potential of 191Pt-MYCN-PIP was evaluated via the gel electrophoretic mobility shift assay, suggesting that the radioagent bound to the DNA including the target sequence of the MYCN gene. In vitro assays using human neuroblastoma cells showed that 191Pt-MYCN-PIP bound to DNA efficiently and caused DNA damage, decreasing MYCN gene expression and MYCN signals in in situ hybridization analysis, as well as cell viability, especially in MYCN-amplified Kelly cells. 191Pt-MYCN-PIP also induced a substantial increase in cytosolic dsDNA granules and generated proinflammatory cytokines, IFN-α/β, in Kelly cells. Tumor uptake of intravenously injected 191Pt-MYCN-PIP was low and its delivery to tumors should be improved for therapeutic application. The present results provided a potential strategy, targeting the key oncogenes for cancer survival for Auger electron therapy.
  • Near-infrared photoimmunotherapy and anti-cancer immunity
    Kohei Nakajima, Mikako Ogawa
    International Immunology, Oxford University Press (OUP), 2023年10月16日
    研究論文（学術雑誌）, Abstract

    The activation of the anti-cancer immune system is an important strategy to control cancer. A new form of cancer phototherapy, near-infrared photoimmunotherapy (NIR-PIT), was approved for clinical use in 2020 and uses IRDye® 700DX (IR700)-conjugated antibodies and NIR light. After irradiation with NIR light, the antibody–IR700 conjugate forms water-insoluble aggregations on the plasma membrane of target cells. This aggregation causes lethal damage to the plasma membrane, and effectively leads to immunogenic cell death (ICD). Subsequently, ICD activates anti-cancer immune cells such as dendritic cells and cytotoxic T cells. Combination therapy with immune-checkpoint blockade has synergistically improved the anti-cancer effects of NIR-PIT. Additionally, NIR-PIT can eliminate immunosuppressive immune cells in light-irradiated tumors by using specific antibodies against regulatory T cells and myeloid-derived suppressor cells. In addition to cancer-cell-targeted NIR-PIT, such immune-cell-targeted NIR-PIT has shown promising results by activating the anti-cancer immune system. Furthermore, NIR-PIT can be used to manipulate the tumor microenvironment by eliminating only targeted cells in the tumor, and thus it also can be used to gain insight into immunity in basic research.
  • In vivo imaging of acute physiological responses after treatment of cancer with near-infrared photoimmunotherapy
    Kohei Nakajima, Akiyo Sugikawa, Hironobu Yasui, Kei Higashikawa, Chie Suzuki, Takahiro Natsume, Motofumi Suzuki, Hideo Takakura, Mayu Tomita, Sachi Takahashi, Kenji Hirata, Yasuhiro Magata, Yuji Kuge, Mikako Ogawa
    Molecular Imaging and Biology, Springer Science and Business Media LLC, 2023年05月16日
    研究論文（学術雑誌）
  • X線によるアゾ結合の開裂により活性化されるケージド化合物の開発　　　　　　　　　　　　　　　
    小河原 浩輝, 高倉 栄男, 中島 孝平, 斉田 謙一郎, Kumar Sonu, 小林 正人, 武次 徹也, 稲波 修, 小川 美香子
    JSMI Report, 16, 2, 64, 64, 日本分子イメージング学会, 2023年05月
    日本語
  • 潰瘍性大腸炎におけるニコチンの抗炎症作用に関する[18F]FDGを用いた検討　　　　　　　　　　　　　　　
    吉野 元貴, 中島 孝平, 高倉 栄男, 小川 美香子
    JSMI Report, 16, 1, 21, 25, 2023年02月, ［査読有り］
    日本語
  • Application of Imaging for Antibody-Based Cancer Therapies : Photoimmunotherapy and Immune Checkpoint Blockade Therapy
    Kohei NAKAJIMA, Mikako OGAWA
    Journal of the Imaging Society of Japan, 61, 6, 643, 651, 2022年12月10日, ［査読有り］
    英語, 研究論文（学術雑誌）
  • Dynamic imaging analysis reveals Auger electron-emitting radio-cisplatin induces DNA damage depending on the cell cycle
    Honoka Obata, Akihiro Kurimasa, Tadanori Muraoka, Atsushi B. Tsuji, Katsuya Kondo, Yoshikazu Kuwahara, Katsuyuki Minegishi, Kotaro Nagatsu, Mikako Ogawa, Ming-Rong Zhang
    Biochemical and Biophysical Research Communications, 637, 286, 293, Elsevier BV, 2022年12月
    研究論文（学術雑誌）
  • Precise quantitative evaluation of pharmacokinetics of cisplatin using a radio-platinum tracer in tumor-bearing mice.
    Honoka Obata, Atsushi B Tsuji, Hitomi Sudo, Aya Sugyo, Katsuyuki Minegishi, Kotaro Nagatsu, Mikako Ogawa, Ming-Rong Zhang
    Nuclear medicine communications, 43, 11, 1121, 1127, 2022年11月01日, ［国際誌］
    英語, 研究論文（学術雑誌）, OBJECTIVE: The platinum-based antineoplastic drug cisplatin is commonly used for chemotherapy in clinics. This work aims to demonstrate a radio-platinum tracer is useful for precisely quantifying small amounts of platinum in pharmacokinetics studies. METHODS: A cisplatin radiotracer (radio-cisplatin) was synthesized, and a comprehensive evaluation of cisplatin over 7 days after its intravenous injection into nude mice bearing a subcutaneous lung tumor (H460) was conducted. RESULTS: A biphasic retention curve in the whole body and blood was observed [ T1/2 (α) = 1.14 h, T1/2 (β) = 5.33 days for the whole body, and T1/2 (α) = 23.9 min, T1/2 (β) = 4.72 days for blood]. The blood concentration decreased within 1 day after injection. Most of the intact cisplatin was excreted via the kidneys in the early time points, and a small part was distributed in tissues including tumors. The plasma protein binding rate of cisplatin increased rapidly after injection, and the protein-bound cisplatin remained in the blood longer than intact cisplatin. The peak uptake in H460 tumors was 4.7% injected dose per gram at 15 min after injection, and the area under the curve (AUC 0-7 days ) was approximately one-half to one-third of the AUC 0-7 days in the kidneys, liver, and bone, where some toxicity is observed in humans. CONCLUSION: The radio-platinum tracer revealed the highly quantitative biodistribution of cisplatin, providing insights into the properties of cisplatin, including its adverse effects. The tracer enables a precise evaluation of pharmacokinetics for platinum-based drugs with high sensitivity.
  • 低酸素条件下のがん細胞に対する光免疫療法(PIT)の有効性の評価　　　　　　　　　　　　　　　
    白川 晴香, 後藤 悠人, 中島 孝平, 高倉 栄男, 安井 博宣, 小川 美香子, 稲波 修
    日本獣医学会学術集会講演要旨集, 165回, [I1A, 12], (公社)日本獣医学会, 2022年09月
    日本語
  • 腫瘍内の低酸素状態に抗PD-1療法が及ぼす影響に関する検討(Reduction of tumor hypoxia during anti-PD-1 therapy in a CT26 colon cancer model)　　　　　　　　　　　　　　　
    中島 孝平, 鈴木 基史, 高倉 栄男, 久下 裕司, 小川 美香子
    日本癌学会総会記事, 81回, P, 2194, (一社)日本癌学会, 2022年09月
    英語
  • Ligand release from silicon phthalocyanine dyes triggered by X-ray irradiation.
    Hideo Takakura, Shino Matsuhiro, Osamu Inanami, Masato Kobayashi, Kenichiro Saita, Masaki Yamashita, Kohei Nakajima, Motofumi Suzuki, Naoki Miyamoto, Tetsuya Taketsugu, Mikako Ogawa
    Organic & biomolecular chemistry, 2022年08月16日, ［国際誌］
    英語, 研究論文（学術雑誌）, Ligand release from silicon phthalocyanine (SiPc) dyes triggered by near-infrared (NIR) light is a key photochemical reaction involving caged compounds based on SiPc. Although NIR light is relatively permeable compared with visible light, this light can be attenuated by tissue absorption and scattering; therefore, using light to induce photochemical reactions deep inside the body is difficult. Herein, because X-rays are highly permeable and can produce radicals through the radiolysis of water, we investigated whether the axial ligands of SiPcs can be cleaved using X-ray irradiation. SiPcs with different axial ligands (alkoxy, siloxy, oxycarbonyl, and phenoxy groups) were irradiated with X-rays under hypoxic conditions. We found that the axial ligands were cleaved via reactions with hydrated electrons (e-aq), not OH radicals, generated from water in response to X-ray irradiation, and SiPc with alkoxy groups exhibited the highest cleavage efficiency. A quantitative investigation revealed that X-ray-induced axial ligand cleavage proceeds via a radical chain reaction. The reaction is expected to be applicable to the molecular design of X-ray-activatable functional molecules in the future.
  • PD1 blockade alters cell-cycle distribution and affects 3'-deoxy-3'-[18F]fluorothymidine uptake in a mouse CT26 tumor model.
    Motofumi Suzuki, Takuma Matsuda, Kohei Nakajima, Yuta Yokouchi, Yuji Kuge, Mikako Ogawa
    Annals of nuclear medicine, 2022年08月15日, ［国内誌］
    英語, 研究論文（学術雑誌）, OBJECTIVE: We previously reported that alterations of the tumor microenvironment (TME) by programmed death receptor-1 (PD1) blockade affected tumor glucose metabolism and tumor 2-deoxy-2-[18F]fluoro-D-glucose ([18F]FDG) uptake. In cancer cells, high glycolysis allows cells to sustain rapid proliferation since glycolysis is closely related to the proliferation of cancer cells. Therefore, imaging of cellular proliferation may provide more detail of TME alterations. In this study, we investigated how TME alterations by PD1 blockade affects the uptake of 3'-deoxy-3'-[18F]fluorothymidine ([18F]FLT), which is a 18F-radiolabeled thymidine derivative and is taken up by proliferating cells. METHODS: Mice inoculated with murine colon carcinoma CT26 cells were intraperitoneally administered an anti-PD1 antibody on Day 0, when the tumor volume exceeded 50 mm3, and Day 5. [18F]FLT-PET imaging was performed pre-treatment (Day 0) and post treatment (Day 7). Tumor infiltrating lymphocytes (TILs) were identified by flow cytometry. [18F]FLT accumulation and localization in tumor tissue was evaluated by autoradiography and immunohistochemistry. The cell-cycle distribution of tumors and CT26 cells exposed to cytokines (interleukin-2, interferon [INF]-γ, and tumor necrosis factor [TNF]-α) was analyzed by flow cytometry. RESULTS: PD1 blockade increased CD8+ and CD4+ T cells in tumor tissue and significantly suppressed tumor proliferation; however, tumor [18F]FLT uptake remained unchanged. Autoradiography and immunohistochemistry showed that [18F]FLT was mainly taken up by cancer cells, but not TILs. Flow cytometric analysis demonstrated that the population of cells in G2/M phase increased after PD1 blockade. Moreover, INF-γ and TNF-α significantly increased cells in G2/M phase in vitro. CONCLUSION: PD1 blockade-induced alteration of the TME increased CT26 tumor cells in the G2/M phase, which have high thymidine kinase 1 activity. Therefore, [18F]FLT is taken up by tumor cells even if tumor proliferation is suppressed. This observation may be useful for evaluating the response to immunotherapy.
  • Reduction of tumor hypoxia by anti-PD-1 therapy assessed using pimonidazole and [18F]FMISO
    Kohei Nakajima, Mitsunori Homma, Motofumi Suzuki, Yuta Yokouchi, Takuma Matsuda, Hideo Takakura, Kenji Hirata, Yuji Kuge, Mikako Ogawa
    Nuclear Medicine and Biology, 108-109, 85, 92, Elsevier BV, 2022年05月
    研究論文（学術雑誌）
  • Development of Novel 191Pt-Labeled Hoechst33258: 191Pt Is More Suitable than 111In for Targeting DNA.
    Honoka Obata, Atsushi B Tsuji, Katsushi Kumata, Hitomi Sudo, Katsuyuki Minegishi, Kotaro Nagatsu, Hideo Takakura, Mikako Ogawa, Akihiro Kurimasa, Ming-Rong Zhang
    Journal of medicinal chemistry, 65, 7, 5690, 5700, 2022年04月14日, ［国際誌］
    英語, 研究論文（学術雑誌）, This study aims to establish new labeling methods for no-carrier-added radio-Pt (191Pt) and to evaluate the in vitro properties of 191Pt-labeled agents compared with those of agents labeled with the common emitter 111In. 191Pt was complexed with the DNA-targeting dye Hoechst33258 via diethylenetriaminepentaacetic acid (DTPA) or the sulfur-containing amino acid cysteine (Cys). The intranuclear fractions of 191Pt- and 111In-labeled Hoechst33258 were comparable, indicating that the labeling for 191Pt via DTPA or Cys and the labeling for 111In via DTPA worked equally well. 191Pt showed a DNA-binding/cellular uptake ratio of more than 1 order of magnitude greater than that of 111In. [191Pt]Pt-Hoechst33258 labeled via Cys showed a higher cellular uptake than that labeled via DTPA, resulting in a very high DNA-binding fraction of [191Pt]Pt-Cys-Hoechst33258 and extensive DNA damage. Our labeling methods of radio-Pt, especially via Cys, promote the development of radio-Pt-based agents for use in Auger electron therapy targeting DNA.
  • Axial-ligand-cleavable silicon phthalocyanines triggered by near-infrared light toward design of photosensitizers for photoimmunotherapy
    Hideo Takakura, Shino Matsuhiro, Masato Kobayashi, Yuto Goto, Mei Harada, Tetsuya Taketsugu, Mikako Ogawa
    Journal of Photochemistry and Photobiology A: Chemistry, 426, 113749, 113749, Elsevier BV, 2022年04月
    研究論文（学術雑誌）
  • 免疫チェックポイント阻害剤が腫瘍内の低酸素状態に及ぼす影響に関する検討　　　　　　　　　　　　　　　
    本間 充憲, 中島 孝平, 鈴木 基史, 横内 勇太, 松田 拓真, 高倉 栄男, 平田 健司, 久下 裕司, 小川 美香子
    日本薬学会年会要旨集, 142年会, 26H, pm06S, (公社)日本薬学会, 2022年03月
    日本語
  • New cancer therapy with Illuminox<sup>Ⓡ</sup> platform
    Kohei Nakajima, Mikako Ogawa
    Drug Delivery System, 37, 1, 72, 77, Japan Society of Drug Delivery System, 2022年01月25日
    研究論文（学術雑誌）
  • Correction: In Vitro and In Vivo Cell Uptake of a Cell-Penetrating Peptide Conjugated with Fluorescent Dyes Having Different Chemical Properties (Cancers, (2021), 13, 2245, 10.3390/cancers13092245)
    Takakura, H., Sato, H., Nakajima, K., Suzuki, M., Ogawa, M.
    Cancers, 14, 8, 2022年
    研究論文（学術雑誌）
  • EPR Characterisation of Phthalocyanine Radical Anions in Near‐Infrared Photocleavage of the Hydrophilic Axial Ligand of a Photoimmunotherapeutic Reagent, IR700
    Osamu Inanami, Wakako Hiraoka, Yuto Goto, Hideo Takakura, Mikako Ogawa
    ChemPhotoChem, Wiley, 2021年11月15日
    研究論文（学術雑誌）
  • Electron Donors Rather Than Reactive Oxygen Species Needed for Therapeutic Photochemical Reaction of Near-Infrared Photoimmunotherapy.
    Takuya Kato, Ryuhei Okada, Yuto Goto, Aki Furusawa, Fuyuki Inagaki, Hiroaki Wakiyama, Hideyuki Furumoto, Dagane Daar, Baris Turkbey, Peter L Choyke, Hideo Takakura, Osamu Inanami, Mikako Ogawa, Hisataka Kobayashi
    ACS pharmacology & translational science, 4, 5, 1689, 1701, 2021年10月08日, ［国際誌］
    英語, 研究論文（学術雑誌）, Near-infrared photoimmunotherapy (NIR-PIT) employs molecularly targeted antibodies conjugated with a photoabsorbing silicon-phthalocyanine dye derivative which binds to cancer cells. Application of NIR light following binding of the antibody-photoabsorber conjugates (APCs) results in ligand release on the dye, dramatic changes in solubility of the APC-antigen complex, and rapid, irreversible cell membrane damage of cancer cells in a highly selective manner, resulting in a highly immunogenic cell death. Clinically, this process results in edema after treatment mediated by reactive oxygen species (ROS). Based on the chemical and biological mechanism of NIR-PIT cytotoxicity and edema formation, in order to minimize acute inflammatory edema without compromising therapeutic effects, l-sodium ascorbate (l-NaAA) was administered to quench harmful ROS and accelerate the ligand release reaction. l-NaAA suppressed acute edema by reducing ROS after NIR-PIT yet did not alter the therapeutic effects. NIR-PIT could be performed safely under existence of l-NaAA without side effects caused by unnecessary ROS production.
  • PETイメージング剤を用いた動脈硬化プラークにおけるニコチン受容体の発現に関する検討　　　　　　　　　　　　　　　
    鈴木 基史, 片山 竜樹, 鈴木 千恵, 中島 孝平, 間賀田 泰寛, 小川 美香子
    日本動脈硬化学会総会プログラム・抄録集, 53回, 195, 195, (一社)日本動脈硬化学会, 2021年10月
    日本語
  • Uptake of nicotinic acetylcholine receptor imaging agent is reduced in the pro-inflammatory macrophage.
    Motofumi Suzuki, Tatsuki Katayama, Chie Suzuki, Kohei Nakajima, Yasuhiro Magata, Mikako Ogawa
    Nuclear medicine and biology, 102-103, 45, 55, 2021年09月29日, ［国際誌］
    英語, 研究論文（学術雑誌）, INTRODUCTION: Macrophages play a vital role in the development of atherosclerotic cardiovascular disease. Macrophages are functionally and phenotypically heterogeneous immune cells and commonly exist in two distinct or polarized subsets: pro-inflammatory M1 and anti-inflammatory M2 phenotypes. Previous reports suggest that stimulation of α7 or α4β2 nicotinic acetylcholine receptors (nAChRs) in macrophages leads to an anti-inflammatory response. However, the biological link between nAChR expression on macrophages and the polarization state is unknown. Therefore, we evaluated the relationship between nAChRs and polarized macrophages in peritoneal macrophages and atherosclerotic plaques of apolipoprotein E knockout (ApoE-/-) mice. METHODS: Peritoneal macrophages isolated from mice were polarized into M1 and M2 macrophages, and the uptake of the nAChR-imaging agents, (R)-2-[11C]methylamino-benzoic acid 1-aza-bicyclo[2.2.2]oct-3-yl ester ([11C]MeQAA) or 2-[18F]fluoro-3-(2(S)-azetidinylmethoxy) pyridine ([18F]2FA), and 2-deoxy-2-[18F]fluoro-D-glucose ([18F]FDG) was assessed. We also evaluated the accumulation of imaging agents in atherosclerotic plaques of ApoE-/- mice by autoradiography. After an autoradiogram was obtained, the same aortic tissue was used for immunohistochemical staining of CD68, inducible nitric oxide synthase (iNOS), and arginine-1. RESULTS: In an in vitro assay, the uptake of [11C]MeQAA or [18F]2FA was lower in M1 than in M0 and M2 macrophages. In comparison, the uptake of [18F]FDG was higher in M1 macrophages. Ex vivo autoradiography showed that [11C]MeQAA was localized to the extensive plaque area. By contrast, the accumulation of [18F]2FA and [18F]FDG was heterogeneous and found only in some plaques. Moreover, the expression of CD68 and iNOS was higher in [18F]2FA non-uptake than [18F]2FA uptake plaques. CONCLUSION: Macrophage polarization was related to nAChR expression, and α4β2 nAChR expression was suppressed in the M1 macrophage. These findings suggest that nAChR imaging has the potential to identify the inflammatory status of atherosclerotic plaque.
  • Comparison of low-molecular-weight ligand and whole antibody in prostate-specific membrane antigen targeted near-infrared photoimmunotherapy.
    Kohei Nakajima, Fuka Miyazaki, Kazuki Terada, Hideo Takakura, Motofumi Suzuki, Mikako Ogawa
    International journal of pharmaceutics, 609, 121135, 121135, 2021年09月24日, ［国際誌］
    英語, 研究論文（学術雑誌）, Near-infrared photoimmunotherapy (NIR-PIT) is a cancer phototherapy that uses antibody-IR700 conjugate (Ab-IR700) and NIR light. Ab-IR700 forms aggregates on the plasma membranes of targeted cancer cells after light exposure, inducing lethal physical damage within the membrane. Low-molecular-weight (LMW) ligands are candidate targeting moieties instead of antibodies, but whether LMW-IR700 conjugates induce cell death by aggregation, the same mechanism as Ab-IR700, is unknown. Thus, we investigated differences in cytotoxicity and mechanisms between LMW-IR700 and Ab-IR700 targeting prostate-specific membrane antigen (PSMA). Both conjugates decreased cell viability to the same degree after light irradiation, but different morphological changes were observed in PSMA-positive LNCaP cells by microscopy. Cell swelling and bleb formation were induced by Ab-IR700, but only swelling was observed in cells treated with LMW-IR700, suggesting the cells were damaged via different cytotoxic mechanisms. However, LMW-IR700 induced bleb formation, a hallmark of NIR-PIT with Ab-IR700, when singlet oxygen was quenched or LMW-IR700 was localized only on the plasma membrane. Moreover, the water-soluble axial ligands of LMW-IR700 were cleaved, consistent with previous reports on Ab-IR700. Thus, the main cytotoxic mechanisms of Ab-IR700 and LMW-IR700 differ, although LMW-IR700 on the plasma membrane can cause aggregation-mediated cytotoxicity as well as Ab-IR700.
  • Photoimmunotherapy: A new cancer treatment using photochemical reactions.
    Mikako Ogawa, Hideo Takakura
    Bioorganic & medicinal chemistry, 43, 116274, 116274, 2021年08月01日, ［国際誌］
    英語, 研究論文（学術雑誌）, Photoimmunotherapy (PIT) is a new molecular-targeted phototherapy in which administration of an antibody conjugated to IR700 (Ab-IR700, a phthalocyanine derivative) is followed by irradiation with near-infrared light. PIT induces cell death due to cell membrane damage, and the formation of IR700 aggregates on the cell membrane triggered by photochemical reactions is an important mechanism of cell killing. Specifically, water-soluble axial ligands of IR700 are cleaved by the photochemical reaction, and the phthalocyanine stacks up due to the π-π interaction, resulting in the formation of aggregates. In addition, the formation of IR700 radical anions and their protonation are essential for the progress of this photochemical reaction. The elucidation of these mechanisms may lead to the development of more effective compounds in the future. In addition, the optical properties of phthalocyanine are expected to expand the medical application of phthalocyanine derivatives in the future.
  • Transition-metal-free nucleophilic 211At-astatination of spirocyclic aryliodonium ylides.
    Keitaro Matsuoka, Honoka Obata, Kotaro Nagatsu, Masahiro Kojima, Tatsuhiko Yoshino, Mikako Ogawa, Shigeki Matsunaga
    Organic & biomolecular chemistry, 19, 25, 5525, 5528, 2021年06月30日, ［国際誌］
    英語, 研究論文（学術雑誌）, The transition-metal-free 211At-astatination of spirocyclic aryliodonium ylides via a nucleophilic aromatic substitution reaction is described. This method enables the preparation of 211At-radiolabeled compounds derived from multi-functionalized molecules and heteroarenes in good to excellent radiochemical yields.
  • In Vitro and In Vivo Cell Uptake of a Cell-Penetrating Peptide Conjugated with Fluorescent Dyes Having Different Chemical Properties.
    Hideo Takakura, Honoka Sato, Kohei Nakajima, Motofumi Suzuki, Mikako Ogawa
    Cancers, 13, 9, 2021年05月07日, ［国際誌］
    英語, 研究論文（学術雑誌）, In molecular imaging, a targeting strategy with ligands is widely used because specificity can be significantly improved. In fluorescence imaging based on a targeting strategy, the fluorescent dyes conjugated with ligands may affect the targeting efficiency depending on the chemical properties. Herein, we used a cell-penetrating peptide (CPP) as a ligand with a variety of fluorescent cyanine dye. We investigated in vitro and in vivo cell uptake of the dye-CPP conjugates when cyanine dyes with differing charge and hydrophilicity/lipophilicity were used. The results showed that the conjugates with positively charged and lipophilic cyanine dyes accumulated in cancer cells in vitro, but there was almost no accumulation in tumors in vivo. On the other hand, the conjugates with negatively charged and hydrophilic cyanine dyes did not accumulate in cancer cells in vitro, but fluorescence was observed in tumors in vivo. These results show that there are some cases in which the cell uptake of the dye-peptide conjugates may differ significantly between in vitro and in vivo experiments due to the chemical properties of the fluorescent dyes. This suggests that attention should be paid to the chemical properties of fluorescent dyes in fluorescence imaging based on a targeting strategy.
  • PETイメージング剤を用いた動脈硬化病変におけるニコチン受容体の機能解明　　　　　　　　　　　　　　　
    鈴木 基史, 片山 竜樹, 鈴木 千恵, 中島 孝平, 間賀田 泰寛, 小川 美香子
    JSMI Report, 14, 2, 125, 125, 日本分子イメージング学会, 2021年05月
    日本語
  • PETイメージング剤を用いた動脈硬化病変におけるニコチン受容体の機能解明　　　　　　　　　　　　　　　
    鈴木 基史, 片山 竜樹, 鈴木 千恵, 中島 孝平, 間賀田 泰寛, 小川 美香子
    JSMI Report, 14, 2, 125, 125, 日本分子イメージング学会, 2021年05月
    日本語
  • In Vitro Evaluation of No-Carrier-Added Radiolabeled Cisplatin ([189, 191Pt]cisplatin) Emitting Auger Electrons.
    Honoka Obata, Atsushi B Tsuji, Hitomi Sudo, Aya Sugyo, Katsuyuki Minegishi, Kotaro Nagatsu, Mikako Ogawa, Ming-Rong Zhang
    International journal of molecular sciences, 22, 9, 2021年04月28日, ［国際誌］
    英語, 研究論文（学術雑誌）, Due to their short-range (2-500 nm), Auger electrons (Auger e-) have the potential to induce nano-scale physiochemical damage to biomolecules. Although DNA is the primary target of Auger e-, it remains challenging to maximize the interaction between Auger e- and DNA. To assess the DNA-damaging effect of Auger e- released as close as possible to DNA without chemical damage, we radio-synthesized no-carrier-added (n.c.a.) [189, 191Pt]cisplatin and evaluated both its in vitro properties and DNA-damaging effect. Cellular uptake, intracellular distribution, and DNA binding were investigated, and DNA double-strand breaks (DSBs) were evaluated by immunofluorescence staining of γH2AX and gel electrophoresis of plasmid DNA. Approximately 20% of intracellular radio-Pt was in a nucleus, and about 2% of intra-nucleus radio-Pt bound to DNA, although uptake of n.c.a. radio-cisplatin was low (0.6% incubated dose after 25-h incubation), resulting in the frequency of cells with γH2AX foci was low (1%). Nevertheless, some cells treated with radio-cisplatin had γH2AX aggregates unlike non-radioactive cisplatin. These findings suggest n.c.a. radio-cisplatin binding to DNA causes severe DSBs by the release of Auger e- very close to DNA without chemical damage by carriers. Efficient radio-drug delivery to DNA is necessary for successful clinical application of Auger e-.
  • Synthesis of no-carrier-added [188, 189, 191Pt]cisplatin from a cyclotron produced 188, 189, 191PtCl42- complex.
    Honoka Obata, Katsuyuki Minegishi, Kotaro Nagatsu, Mikako Ogawa, Ming-Rong Zhang
    Scientific reports, 11, 1, 8140, 8140, 2021年04月14日, ［国際誌］
    英語, 研究論文（学術雑誌）, We developed a novel method for production of no-carrier-added (n.c.a.) [188, 189, 191Pt]PtIICl42- from an Ir target material, and then synthesized n.c.a. [*Pt]cis-[PtIICl2(NH3)2] ([*Pt]cisplatin) from [*Pt]PtIICl42-. [*Pt]PtIICl42- was prepared as a synthetic precursor of n.c.a. *Pt complex by a combination of resin extraction and anion-exchange chromatography after the selective reduction of IrIVCl62- with ascorbic acid. The ligand-substitution reaction of Cl with NH3 was promoted by treating n.c.a. [*Pt]PtIICl42- with excess NH3 and heating the reaction mixture, and n.c.a. [*Pt]cisplatin was successfully produced without employing precipitation routes. After this treatment, [*Pt]cisplatin was isolated through preparative HPLC with a radiochemical purity of 99 + % at the end of synthesis (EOS).
  • Nothing seek, nothing find.-分子イメージングの先に見えるもの- 光音響イメージングのための機能性シアニン色素の開発　　　　　　　　　　　　　　　
    土屋 光輝, 高倉 栄男, 小川 美香子
    日本薬学会年会要旨集, 141年会, GS05, 2, (公社)日本薬学会, 2021年03月
    日本語
  • Nothing seek, nothing find.-分子イメージングの先に見えるもの- 光免疫療法における分子イメージングの利用　　　　　　　　　　　　　　　
    中島 孝平, 高倉 栄男, 小川 美香子
    日本薬学会年会要旨集, 141年会, GS05, 3, (公社)日本薬学会, 2021年03月
    日本語
  • Analysis of the triplet-state kinetics of a photosensitizer for photoimmunotherapy by fluorescence correlation spectroscopy
    Hideo Takakura, Yuto Goto, Akira Kitamura, Toshitada Yoshihara, Seiji Tobita, Masataka Kinjo, Mikako Ogawa
    Journal of Photochemistry and Photobiology A: Chemistry, 408, 2021年03月01日
    研究論文（学術雑誌）, © 2020 Elsevier B.V. Herein, we evaluated the intersystem crossing quantum yield (ΦISC) of a silicon phthalocyanine derivatized from IRDye700DX (IR700) which is used as a photosensitizer for photoimmunotherapy (PIT), using fluorescence correlation spectroscopy (FCS). The calculated ΦISC was 0.019 ± 0.002. The FCS measurement was validated by experiment in the presence of potassium iodide, which can change the kinetics of the relaxation process in the excited state.
  • Near-infrared photoimmunotherapy (NIR-PIT) on cholangiocarcinoma using a novel catheter device with light emitting diodes.
    Hajime Hirata, Masaki Kuwatani, Kohei Nakajima, Yuki Kodama, Yasuo Yoshikawa, Mikako Ogawa, Naoya Sakamoto
    Cancer science, 112, 2, 828, 838, 2021年02月, ［国際誌］
    英語, 研究論文（学術雑誌）, Near-infrared photoimmunotherapy (NIR-PIT) is a novel therapy for cancers that uses NIR light and antibody-photosensitizer (IR700) conjugates. However, it is difficult to deliver NIR light into the bile duct for cholangiocarcinoma (CCA) from the conventional extracorporeal apparatus. Thus, in this study, we developed a dedicated catheter with light emitting diodes (LEDs) that supersedes conventional external irradiation devices; we investigated the therapeutic effect of NIR-PIT for CCA using the novel catheter. The new catheter was designed to be placed in the bile duct and a temperature sensor was attached to the tip of the catheter to avoid thermal burn. An anti-epidermal growth factor receptor (EGFR) antibody, Panitumumab-IR700 conjugate or anti-human epidermal growth factor receptor type 2 (HER2) antibody, Trastuzumab-IR700 conjugate, was used with EGFR- or HER2-expressing cell lines, respectively. The in vitro efficacy of NIR-PIT was confirmed in cultured cells; the capability of the new catheter for NIR-PIT was then tested in a mouse tumor model. NIR-PIT via the developed catheter treated CCA xenografts in mice. NIR-PIT had an effect in Panitumumab-IR700 conjugate- and Trastuzumab-IR700 conjugate-treated CCA cells that depended on the receptor expression level. Tumor growth was significantly suppressed in mice treated with NIR-PIT using the novel catheter compared with controls (P < .01). NIR-PIT was an effective treatment for EGFR- and HER2-expressing CCA cells, and the novel catheter with mounted LEDs was useful for NIR-PIT of CCA.
  • An imaging approach for determining the mechanism of enhancement of intestinal absorption of an L-theanine supplement.
    Yuki Sato, Kazuki Yamaguchi, Mikako Ogawa, Yoh Takekuma, Mitsuru Sugawara
    PloS one, 16, 6, e0253066, 2021年, ［国際誌］
    英語, 研究論文（学術雑誌）, BACKGROUND & OBJECTIVE: Theanine (L-glutamylethylamide) contained in green tea is a functional food component that has been attracting attention due to its relaxation effect. It was shown that the ingredients added to the theanine formulations increased the absorption of theanine. If this mechanism can be elucidated, it would be possible to contribute to development of evidence-based formulations. In this study, we investigated the effect of ingredients in the formulations on the absorption of theanine in detail. MAIN METHODS: After oral administration of a mixture of theanine and additional components to Wistar rats the plasma concentration was determined by an HPLC and the pharmacokinetic parameters were calculated. In addition, a new system for evaluating intestinal blood flow was developed since the involvement of intestinal blood flow was considered as a factor that increased absorption of theanine. KEY FINDINGS: Plasma concentration of theanine increased significantly in the combined use group with eight ingredients containing piperine as compared with theanine only group. Piperine would increase theanine absorption by increased blood flow, not an inhibition of metabolism. We succeeded to develop a visual and quantitative system to evaluate the effect of these ingredients directly including piperine on the intestinal blood flow using indocyanine green while maintaining physiological conditions. SIGNIFICANCE: Increased intestinal blood flow by these ingredients including piperine enhanced the absorption of theanine. Other mechanisms may also be considered as the mechanism by which theanine absorption is increased in addition to increased blood flow.
  • PETイメージング剤を用いた動脈硬化病変におけるニコチン受容体の機能解明　　　　　　　　　　　　　　　
    鈴木 基史, 片山 竜樹, 鈴木 千恵, 中島 孝平, 間賀田 泰寛, 小川 美香子
    核医学, 57, Suppl., S149, S149, (一社)日本核医学会, 2020年10月
    日本語
  • 免疫賦活マウス腫瘍における抗PD-1治療後の[18F]FDG取り込みに関する検討　　　　　　　　　　　　　　　
    富田 真由, 鈴木 基史, 河野 裕允, 中島 孝平, 松田 拓真, 久下 裕二, 小川 美香子
    核医学, 57, Suppl., S150, S150, (一社)日本核医学会, 2020年10月
    日本語
  • インテグリンαvβ3標的RGDペプチドを用いた光免疫療法のメカニズム解明　　　　　　　　　　　　　　　
    寺田 一貴, 中島 孝平, 高倉 栄男, 小川 美香子
    日本癌学会総会記事, 79回, OJ16, 5, (一社)日本癌学会, 2020年10月
    英語
  • Phototoxicity in near-infrared photoimmunotherapy is influenced by the subcellular localization of antibody-IR700.
    Kohei Nakajima, Mikako Ogawa
    Photodiagnosis and photodynamic therapy, 31, 101926, 101926, 2020年09月, ［国際誌］
    英語, 研究論文（学術雑誌）, BACKGROUND: Near-infrared photoimmunotherapy (NIR-PIT) is a newly developed cancer phototherapy that utilizes monoclonal antibody-IRDye700DX conjugates (mAb-IR700) and NIR light. We previously reported that mAb-IR700 aggregated on the plasma membrane and induced physical damage within the membrane, leading to necrotic/immunogenic cancer cell death. However, cytotoxic effects caused by internalized mAb-IR700, which is localized in lysosomes after endocytosis, remain unclear. Thus, in this study, we investigated how internalized mAb-IR700 influences phototoxicity. METHODS: Cytotoxicity depending on the subcellular localization of mAb-IR700 was examined by varying the incubation time after washing. The influence of a singlet oxygen (1O2) was examined by cell viability assay in the presence of 1O2 quencher. The type of cell death was analyzed by flow cytometry with Annexin V/propidium iodide. Furthermore, IR700 fluorescence in cells was observed by fluorescence microscopy. RESULTS: mAb-IR700 in lysosomes induced cytotoxicity, which was weaker than that induced by mAb-IR700 on plasma membranes. Cellular damage caused by mAb-IR700 in lysosomes was completely inhibited by an 1O2 quencher. mAb-IR700 on plasma membranes and in lysosomes induced necrotic, but not apoptotic, cell death. IR700 was localized in lysosomes before light irradiation but then diffused into the cytosol immediately after irradiation. CONCLUSIONS: Although the main cytotoxic trigger in NIR-PIT is plasma membrane damage as previously reported, mAb-IR700 in lysosomes also induces necrotic cell death. The internalized mAb-IR700 caused 1O2-mediated damage, leading to the marked leakage of lysosomal contents into the cytosol. The mechanism of NIR-PIT depends on the subcellular localization of mAb-IR700.
  • DDSとの融合による分子イメージングの新展開 標的化DDSの利用による動脈硬化巣の非侵襲的光イメージング　　　　　　　　　　　　　　　
    清水 広介, 成田 雄大, 浅井 知浩, 奥 直人, 小川 美香子, 間賀田 泰寛
    日本DDS学会学術集会プログラム予稿集, 36回, 95, 95, 日本DDS学会, 2020年08月
    日本語
  • Association of Hydrophobic Carboxyl-Terminal Dendrimers with Lymph Node-Resident Lymphocytes.
    Yutaka Nishimoto, Misaki Nishio, Shu Nagashima, Kohei Nakajima, Takayuki Ohira, Shinya Nakai, Ikuhiko Nakase, Kei Higashikawa, Yuji Kuge, Akikazu Matsumoto, Mikako Ogawa, Chie Kojima
    Polymers, 12, 7, 2020年06月30日, ［査読有り］, ［国際誌］
    英語, 研究論文（学術雑誌）, Delivery systems to lymph node-resident T cells around tumor tissues are essential for cancer immunotherapy, in order to boost the immune responses. We previously reported that anionic dendrimers, such as carboxyl-, sulfonyl-, and phosphate-terminal dendrimers, were efficiently accumulated in lymph nodes via the intradermal injection. Depending on the terminal structure, their cell association properties were different, and the carboxyl-terminal dendrimers did not associate with any immune cells majorly. In this study, we investigated the delivery of carboxyl-terminal dendrimers with different hydrophobicity to lymph node-resident lymphocytes. Four types of carboxyl-terminal dendrimers-succinylated (C) and 2-carboxy-cyclohexanoylated (Chex) dendrimers with and without phenylalanine (Phe)-were synthesized and named C-den, C-Phe-den, Chex-den, and Chex-Phe-den, respectively. Chex-Phe-den was well associated with lymphocytes, but others were not. Chex-Phe-den, intradermally injected at the footpads of mice, was accumulated in the lymph node, and was highly associated with the lymphocytes, including T cells. Our results suggest that Chex-Phe-den has the potential for delivery to the lymph node-resident T cells, without any specific T cell-targeted ligands.
  • Theoretical and Experimental Studies on the Near‐Infrared Photoreaction Mechanism of a Silicon Phthalocyanine Photoimmunotherapy Dye: Photoinduced Hydrolysis by Radical Anion Generation
    Masato Kobayashi, Mei Harada, Hideo Takakura, Kanta Ando, Yuto Goto, Takao Tsuneda, Mikako Ogawa, Tetsuya Taketsugu
    ChemPlusChem, 85, 9, 1953, 1953, Wiley, 2020年05月25日, ［査読有り］, ［国際誌］
    英語, 研究論文（学術雑誌）, Invited for this month's cover are the collaborating groups of Dr. Masato Kobayashi and Prof. Mikako Ogawa, both from Hokkaido University, Sapporo, Japan. The cover picture shows the photochemical reaction process of the near-infrared (NIR) photoimmunotherapy dye IR700, and subsequent cancer cell death. A computational study predicted that ligand dissociation, which is known to initiate cancer cell death, proceeds by the hydrolysis of the IR700 radical anion, rather than as a direct result of NIR irradiation. This mechanism has also been supported by experimental work. Read the full text of the Communication at 10.1002/cplu.202000338.
  • Potential role of transforming growth factor-beta 1/Smad signaling in secondary lymphedema after cancer surgery.
    Masaki Sano, Satoshi Hirakawa, Minoru Suzuki, Jun-Ichi Sakabe, Mikako Ogawa, Seiji Yamamoto, Takanori Hiraide, Takeshi Sasaki, Naoto Yamamoto, Kazunori Inuzuka, Hiroki Tanaka, Takaaki Saito, Ryota Sugisawa, Kazuto Katahashi, Tatsuro Yata, Takafumi Kayama, Tetsumei Urano, Yoshiki Tokura, Kohji Sato, Mitsutoshi Setou, Hiroya Takeuchi, Hiroyuki Konno, Naoki Unno
    Cancer science, 111, 7, 2620, 2634, 2020年05月15日, ［査読有り］, ［国際誌］
    英語, 研究論文（学術雑誌）, Secondary lymphedema often develops after cancer surgery, and over 250 million patients suffer from this complication. A major symptom of secondary lymphedema is swelling with fibrosis, which lowers the patient's quality of life, even if cancer does not recur. Nonetheless, the pathophysiology of secondary lymphedema remains unclear, with therapeutic approaches limited to physical or surgical therapy. There is no effective pharmacological therapy for secondary lymphedema. Notably, the lack of animal models that accurately mimic human secondary lymphedema has hindered pathophysiological investigations of the disease. Here, we developed a novel rat hindlimb model of secondary lymphedema and showed that our rat model mimics human secondary lymphedema from early to late stages in terms of cell proliferation, lymphatic fluid accumulation, and skin fibrosis. Using our animal model, we investigated the disease progression and found that transforming growth factor-beta 1 (TGFB1) was produced by macrophages in the acute phase and by fibroblasts in the chronic phase of the disease. TGFB1 promoted the transition of fibroblasts into myofibroblasts and accelerated collagen synthesis, resulting in fibrosis, which further indicates that myofibroblasts and TGFB1/Smad signaling play key roles in fibrotic diseases. Furthermore, the presence of myofibroblasts in skin samples from lymphedema patients after cancer surgery emphasizes the role of these cells in promoting fibrosis. Suppression of myofibroblast-dependent TGFB1 production may therefore represent an effective pharmacological treatment for inhibiting skin fibrosis in human secondary lymphedema after cancer surgery.
  • Influence on [18F]FDG uptake by cancer cells after anti-PD-1 therapy in an enforced-immune activated mouse tumor.
    Mayu Tomita, Motofumi Suzuki, Yusuke Kono, Kohei Nakajima, Takuma Matsuda, Yuji Kuge, Mikako Ogawa
    EJNMMI research, 10, 1, 24, 24, 2020年03月19日, ［査読有り］, ［国際誌］
    英語, 研究論文（学術雑誌）, BACKGROUND: Anti-programmed cell death 1 (PD-1) antibody is an immune checkpoint inhibitor, and anti-PD-1 therapy improves the anti-tumor functions of T cells and affects tumor microenvironment. We previously reported that anti-PD-1 treatment affected tumor glycolysis by using 2-deoxy-2-[18F]fluoro-D-glucose ([18F]FDG) positron emission tomography (PET). That study showed that anti-PD-1 therapy in a mouse B16F10 melanoma model increased glucose metabolism in cancer cells at the point where anti-PD-1 therapy did not cause a significant inhibition of tumor growth. However, the B16F10 melanoma model is poorly immunogenic, so it is not clear how anti-PD-1 treatment affects glucose metabolism in highly immunogenic cancer models. In this study, we used a cyclic dinucleotide GMP-AMP (cGAMP)-injected B16F10 melanoma model to investigate the effect of anti-PD-1 therapy on [18F]FDG uptake in a highly immune activated tumor in mice. RESULTS: To compare the cGAMP-injected B16F10 model with the B16F10 model, experiments were performed as described in our previous manuscript. [18F]FDG-PET was measured before treatment and 7 days after the start of treatment. In this study, [18F]FDG uptake in tumors in the cGAMP/anti-PD-1 combination group was lower than that in the anti-PD-1 treatment group tumors on day 7, as shown by PET and ex vivo validation. Flow-cytometry was performed to assess immune cell populations and glucose metabolism. Anti-PD-1 and/or cGAMP treatment increased the infiltration level of immune cells into tumors. The cGAMP/anti-PD-1 combination group had significantly lower levels of GLUT1high cells/hexokinase IIhigh cells in CD45- cancer cells compared with tumors in the anti-PD-1 treated group. These results suggested that if immune responses in tumors are higher than a certain level, glucose uptake in cancer cells is reduced depending on that level. Such a change of glucose uptake might be caused by the difference in infiltration or activation level of immune cells between the anti-PD-1 treated group and the cGAMP/anti-PD-1 combination group. CONCLUSIONS: [18F]FDG uptake in cancer cells after anti-PD-1 treatment might be affected by the tumor immune microenvironment including immune cell infiltration, composition, and activation status.
  • PSMAを標的とする小分子リガンドを利用した新規光免疫療法薬剤の開発　　　　　　　　　　　　　　　
    宮崎 風香, 中島 孝平, 寺田 一貴, 高倉 栄男, 小川 美香子
    日本薬学会年会要旨集, 140年会, 28M, pm03S, (公社)日本薬学会, 2020年03月
    日本語
  • Theoretical and Experimental Studies on the Near-Infrared Photoreaction Mechanism of a Silicon Phthalocyanine Photoimmunotherapy Dye: Photoinduced Hydrolysis by Radical Anion Generation
    Masato Kobayashi, Mei Harada, Hideo Takakura, Kanta Ando, Yuto Goto, Takao Tsuneda, Mikako Ogawa, Tetsuya Taketsugu
    ChemPlusChem, Wiley-VCH Verlag, 2020年
    英語, 研究論文（学術雑誌）, Ligand release from IR700, a silicon phthalocyanine dye used in near-infrared (NIR) photoimmunotherapy, initiates cancer cell death after NIR absorption, although its photochemical mechanism has remained unclear. This theoretical study reveals that the direct Si-ligand dissociation by NIR light is difficult to activate because of the high dissociation energy even in excited states, i. e., >
    1.30 eV. Instead, irradiation generates the IR700 radical anion, leading to acid-base reactions with nearby water molecules (i. e., calculated pKb for the radical anion is 7.7) to produce hydrophobic ligand-released dyes. This suggests two possibilities: (1) water molecules participate in ligand release and (2) light is not required for Si–ligand dissociation as formation of the IR700 radical anion is sufficient. Experimental evidence confirmed possibility (1) by using 18O-labeled water as the solvent, while (2) is supported by the pH dependence of ligand exchange, providing a complete description of the Si-ligand bond dissociation mechanism.
  • Surface Modification of Liposomes Using IR700 Enables Efficient Controlled Contents Release Triggered by Near-IR Light.
    Yusuke Kono, Kazuha Yokoyama, Motofumi Suzuki, Hideo Takakura, Mikako Ogawa
    Biological & pharmaceutical bulletin, 43, 4, 736, 741, 2020年, ［査読有り］, ［国内誌］
    英語, 研究論文（学術雑誌）, Stimuli-responsive liposomes are promising drug carriers for cancer treatment because they enable controlled drug release and the maintenance of desired drug concentrations in tumor tissue. In particular, near-IR (NIR) light is a useful stimulus for triggering drug release from liposomes based on its advantages such as deep tissue penetration and safety. Previously, we found that a silicon phthalocyanine derivative, IR700, conjugated to antibodies, can induce the rupture of the cell membrane following irradiation by NIR light. Based on this finding, we constructed IR700-modified liposomes (IR700 liposomes) and evaluated their drug release properties triggered by NIR light. IR700 liposomes released substantial amounts of encapsulated calcein following irradiation by NIR light. Drug release was substantially suppressed by the addition of sodium azide, suggesting that liposomal membrane permeabilization was mediated by singlet oxygen generated from IR700. Moreover, calcein release from IR700 liposomes triggered by NIR light was promoted under conditions of deoxygenation and the presence of electron donors. Thus, membrane disruption should be induced by the physical change of IR700 from highly hydrophilic to hydrophobic as we previously described, although singlet oxygen can cause a certain level of membrane disruption under normoxia. We also observed that doxorubicin-encapsulated IR700 liposomes exhibited significant cytotoxic effects against CT-26 murine colon carcinoma cells following NIR light exposure. These results indicate that IR700 liposomes can efficiently release anti-cancer drugs following NIR light irradiation even under hypoxic conditions and, therefore, they would be useful for cancer treatment.
  • From the respective expert viewpoints of the ANM specialty editors.
    Masayuki Inubushi, Miho Shidahara, Yasuyuki Takahashi, Mikako Ogawa, Yasushi Kiyono
    Annals of nuclear medicine, 33, 12, 877, 880, 2019年12月, ［国内誌］
    英語, 研究論文（学術雑誌）, Although it may not be well known, the Annals of Nuclear Medicine (ANM) Editorial Committee includes one specialty editor of nuclear medicine physics, one of nuclear medicine technology, one of molecular imaging, and two of radiopharmacology. In addition, a statistics editor and a language editor are also on the committee. Manuscripts submitted to ANM can be peer-reviewed by such specialty editors similar to those submitted to highly ranked journals, which is a great pride and joy to us. To offer our readers a condensed global view on the high-quality research work in the field of nuclear medicine, we have published a mini-review article every year under the joint authorship of the ANM associate editors since 2016. This is our fourth serial review article written by the ANM specialty editors from their respective expert viewpoints.
  • 深部がんを検出可能なpH応答性光音響イメージング剤の開発(pH-activatable photoacoustic imaging agents for detecting deep tumors)　　　　　　　　　　　　　　　
    土屋 光輝, 高倉 栄男, 小川 美香子
    日本癌学会総会記事, 78回, J, 1047, (一社)日本癌学会, 2019年09月
    英語
  • 光免疫療法が腫瘍に及ぼす変化に関する[18F]FDGと[18F]FMISOを用いた検討(Evaluation of changes in biological characteristics after photoimmunotherapy using [18F]FDG and [18F]FMISO)　　　　　　　　　　　　　　　
    中島 孝平, 安井 博宣, 東川 桂, 高倉 栄男, 久下 裕司, 小川 美香子
    日本癌学会総会記事, 78回, P, 3146, (一社)日本癌学会, 2019年09月
    英語
  • Accumulation of hypoxia imaging probe "18F-FMISO" in macrophages depends on macrophage polarization in addition to hypoxic state.
    Shimizu Y, Motomura A, Takakura H, Tamaki N, Kuge Y, Ogawa M
    Annals of nuclear medicine, 33, 5, 362, 367, 2019年05月, ［査読有り］, ［国内誌］
    英語, 研究論文（学術雑誌）, OBJECTIVE: Macrophages play an essential role in immune response, and are closely related to the progression of diseases such as cancer and atherosclerosis. Macrophages polarize to M1 or M2 type, which is related to the environmental hypoxic state. Previously, we found that 18F-FMISO uptake varied according to expression levels of biomolecules such as glutathione S-transferase P1 (GST-P1), which catalyzes the conjugation of glutathione to 18F-FMISO metabolites, and multidrug resistance-associated protein 1 (MRP1), which exports glutathione-18F-FMISO metabolite conjugates out of cells. However, the relationship between macrophage polarization and 18F-FMISO accumulation remains unclear. METHODS: Mouse peritoneal macrophages were polarized to either the M1 or M2 type, and were treated with 18F-FMISO. Then, their radioactivity after a 4 h incubation period under normoxic (21% O2) or hypoxic (1% O2) condition was measured. GST-P1 and MRP1 expression levels were measured by qRT-PCR. RESULTS: M2 macrophages exhibited a significantly higher uptake of 18F-FMISO than non-polarized (M0) macrophages, whereas M1 macrophages had a significantly lower uptake than M0 macrophages (M0: 1.05 ± 0.22, M1: 0.34 ± 0.02, M2: 4.17 ± 0.36 %dose/mg protein). The GST-P1 expression level in M1 macrophages was higher than that in M2 and M0 macrophages [GST-P1/β-actin normalized by M0: 9.0 ± 3.7 (M1), 1.2 ± 0.2 (M2)]. The MRP1 expression level in M1 macrophages was significantly higher than that in M2 and M0 macrophages [MRP1/β-actin normalized by M0 macrophages: 5.1 ± 2.1 (M1), 2.8 ± 1.0 (M2)]. CONCLUSIONS: 18F-FMISO accumulation in macrophages may depend on the polarization state in addition to hypoxic condition.
  • Macrophage-targeted, enzyme-triggered fluorescence switch-on system for detection of embolism-vulnerable atherosclerotic plaques.
    Narita Y, Shimizu K, Ikemoto K, Uchino R, Kosugi M, Maess MB, Magata Y, Oku N, Ogawa M
    Journal of controlled release : official journal of the Controlled Release Society, 302, 105, 115, 2019年05月, ［査読有り］, ［国際誌］
    英語, 研究論文（学術雑誌）, The development of atherosclerotic plaques is a critical step that can result in an arterial embolism. Therefore, detection of these vulnerable plaques is of clinical significance for the diagnosis of atherosclerosis. However, there are few imaging systems able to detect such plaques easily. In this study, we designed a new platform for near-infrared fluorescence (NIRF) imaging of macrophages in atherosclerotic plaques, one using both a liposomal DDS and an activatable fluorescent probe, and evaluated the utility of this imaging for the diagnosis of atherosclerosis. We first synthesized a fluorescent switch-on probe, Peptide-ICG2, which is optically silent under normal conditions but activated in the presence of the lysosomal enzyme, cathepsin B. To achieve macrophage-specific fluorescence activation, we encapsulated Peptide-ICG2 into phosphatidylserine-containing liposome (P-ICG2-PS-Lip), since the accumulation of phosphatidylserine receptor-bearing macrophages is characteristic of embolism-vulnerable plaques. The experiments using macrophage-like RAW264 cells in culture showed that P-ICG2-PS-Lip was selectively taken up into the cells and that significant fluorescence of the probe was observed. For NIRF imaging of the atherosclerotic plaques, P-ICG2-PS-Lip was intravenously injected into ApoE-knockout atherosclerotic model mice or WHHL rabbits, and the fluorescence at the aortae was imaged. The results indicated that ICG fluorescence could be successfully observed at the plaques on the artery walls. The results of the present study thus suggest that NIRF imaging using P-ICG2-PS-Lip would be useful for detecting embolism-vulnerable atherosclerotic plaques.
  • 小分子ペプチドを利用した光免疫療法のメカニズム解明　　　　　　　　　　　　　　　
    寺田 一貴, 中島 孝平, 高倉 栄男, 小川 美香子
    JSMI Report, 12, 2, 118, 118, 日本分子イメージング学会, 2019年05月
    日本語
  • 光免疫療法による腫瘍環境の変化に関する[18F]FDGと[18F]FMISOを用いた検討　　　　　　　　　　　　　　　
    中島 孝平, 杉川 晃代, 安井 博宣, 東川 桂, 高倉 栄男, 志賀 哲, 久下 裕司, 小川 美香子
    JSMI Report, 12, 2, 131, 131, 日本分子イメージング学会, 2019年05月
    日本語
  • 量子化学計算を用いた光免疫療法における細胞障害メカニズムの検討　　　　　　　　　　　　　　　
    原田 芽生, 小林 正人, 安藤 完太, 高倉 栄男, 武次 徹也, 小川 美香子
    日本薬学会年会要旨集, 139年会, 2, 80, 80, (公社)日本薬学会, 2019年03月
    日本語
  • 光免疫療法の細胞障害メカニズム　　　　　　　　　　　　　　　
    小川 美香子, 佐藤 和秀, 安藤 完太, 奥山 修平, 森口 志穂, 小倉 泰郎, 十時 慎一郎, 花岡 宏史, 長屋 匡信, 粉川 良平, 高倉 栄男, 西村 雅之, 長谷川 好規, Choyke Peter, 小林 久隆
    日本薬学会年会要旨集, 139年会, 2, 80, 80, (公社)日本薬学会, 2019年03月
    日本語
  • A Novel PET Probe "[18F]DiFA" Accumulates in Hypoxic Region via Glutathione Conjugation Following Reductive Metabolism.
    Yoichi Shimizu, Songji Zhao, Hironobu Yasui, Ken-Ichi Nishijima, Hiroki Matsumoto, Tohru Shiga, Nagara Tamaki, Mikako Ogawa, Yuji Kuge
    Molecular imaging and biology, 21, 1, 122, 129, 2019年02月, ［査読有り］, ［国際誌］
    英語, 研究論文（学術雑誌）, PURPOSE: Hypoxia in tumor has close relationship with angiogenesis and tumor progression. Previously, we developed 2,2-dihydroxymethyl-3-[18F]fluoropropyl-2-nitroimidazole ([18F]DiFA) as a novel positron emission tomography (PET) probe for diagnosis of hypoxia. In this study, we elucidated whether the accumulation of [18F]DiFA in cells is dependent on the hypoxic state and revealed how [18F]DiFA accumulates in hypoxic cells in combination with imaging mass spectrometry (IMS). PROCEDURES: FaDu human head and neck cancer cells were treated with [18F]DiFA and then incubated under normoxia (21% O2) or hypoxia (1% O2) for 2 h. The cells were extracted using methanol, and the radioactivities of the precipitates (macromolecule fraction) and supernatants (low-molecular-weight fraction) were measured. FaDu-bearing mice were injected intravenously with [18F]DiFA and with pimonidazole 1 h later. The tumors were excised 2 h after the injection of [18F]DiFA. Autoradiography, IMS, and immunohistochemical (IHC) staining for pimonidazole were performed with serial tumor sections. RESULTS: In the in vitro study, the radioactivity of FaDu cells was significantly higher under hypoxia than that under normoxia (0.53 ± 0.02 vs. 0.27 ± 0.02 %dose/mg protein, p < 0.05). The radioactivity of the low-molecular-weight fraction was 66.3 ± 0.6% in the hypoxic cell. In the in vivo study, [18F]DiFA accumulated in the tumor tissues existed mainly as low-molecular-weight compounds (90.4 ± 0.9%). In addition, the glutathione conjugate of reductive DiFA metabolite (amino-DiFA-GS) existed in tumor tissues revealed by the IMS study, and the distribution pattern of amino-DiFA-GS was very similar to that of the radioactivity and the positive staining area of pimonidazole. CONCLUSIONS: Our results suggest that [18F]DiFA undergoes the glutathione conjugation reaction following reductive metabolism in hypoxic cells, which leads hypoxia-specific PET imaging with [18F]DiFA.
  • Photoinduced Ligand Release from a Silicon Phthalocyanine Dye Conjugated with Monoclonal Antibodies: A Mechanism of Cancer Cell Cytotoxicity after Near-Infrared Photoimmunotherapy.
    Sato K, Ando K, Okuyama S, Moriguchi S, Ogura T, Totoki S, Hanaoka H, Nagaya T, Kokawa R, Takakura H, Nishimura M, Hasegawa Y, Choyke PL, Ogawa M, Kobayashi H
    ACS central science, 4, 11, 1559, 1569, 2018年11月, ［査読有り］, ［国際誌］
    英語, 研究論文（学術雑誌）, Photochemical reactions can dramatically alter physical characteristics of reacted molecules. In this study, we demonstrate that near-infrared (NIR) light induces an axial ligand-releasing reaction, which dramatically alters hydrophilicity of a silicon phthalocyanine derivative (IR700) dye leading to a change in the shape of the conjugate and its propensity to aggregate in aqueous solution. This photochemical reaction is proposed as a major mechanism of cell death induced by NIR photoimmunotherapy (NIR-PIT), which was recently developed as a molecularly targeted cancer therapy. Once the antibody-IR700 conjugate is bound to its target, activation by NIR light causes physical changes in the shape of antibody antigen complexes that are thought to induce physical stress within the cellular membrane leading to increases in transmembrane water flow that eventually lead to cell bursting and necrotic cell death.
  • PD-1治療が[18F]FDGのがん組織への集積に与える影響についてのマウスを用いた検討　　　　　　　　　　　　　　　
    富田 真由, 安井 博宣, 東川 桂, 中島 孝平, 高倉 栄男, 志賀 哲, 久下 裕司, 小川 美香子
    核医学, 55, Suppl., S173, S173, (一社)日本核医学会, 2018年11月
    英語
  • 光免疫療法による[18F]FDGおよび[18F]FMISOの集積変化に関する検討　　　　　　　　　　　　　　　
    中島 孝平, 杉川 晃代, 安井 博宣, 東川 桂, 高倉 栄男, 志賀 哲, 久下 裕司, 小川 美香子
    核医学, 55, Suppl., S174, S174, (一社)日本核医学会, 2018年11月
    英語
  • 小分子ペプチドをリガンドとして用いた光免疫療法新規治療薬の開発(Development of a new therapeutic agent for photoimmunotherapy with small peptides as a targeting ligand)　　　　　　　　　　　　　　　
    寺田 一貴, 高倉 栄男, 中島 孝平, 小川 美香子
    日本癌学会総会記事, 77回, 132, 132, (一社)日本癌学会, 2018年09月
    英語
  • 深部腫瘍の治療を可能とするワイヤレス給電LEDを用いた光免疫療法(Near-infrared photoimmunotherapy(NIR-PIT) using wireless light-emitting diode system to treat tumors in deep tissue)　　　　　　　　　　　　　　　
    中島 孝平, 高倉 栄男, 小川 美香子
    日本癌学会総会記事, 77回, 133, 133, (一社)日本癌学会, 2018年09月
    英語
  • Evaluation of drug effects on cerebral blood flow and glucose uptake in un-anesthetized and un-stimulated rats: application of free-moving apparatus enabling to keep rats free during PET/SPECT tracer injection and uptake.
    Sugita T, Kondo Y, Ishino S, Mori I, Horiguchi T, Ogawa M, Magata Y
    Nuclear medicine communications, 39, 8, 753, 760, 2018年08月, ［査読有り］
  • Anti PD-1 treatment increases [18F]FDG uptake by cancer cells in a mouse B16F10 melanoma model.
    Tomita M, Yasui H, Higashikawa K, Nakajima K, Takakura H, Shiga T, Kuge Y, Ogawa M
    EJNMMI research, 8, 1, 82, Springer Science and Business Media LLC, 2018年08月, ［査読有り］
    研究論文（学術雑誌）
  • Changes in plasma membrane damage inducing cell death after treatment with near-infrared photoimmunotherapy.
    Nakajima K, Takakura H, Shimizu Y, Ogawa M
    Cancer science, 109, 9, 2889, 2896, Wiley, 2018年06月, ［査読有り］
    研究論文（学術雑誌）
  • 近赤外光線免疫療法への利用を目指した埋め込み型ワイヤレス給電LEDの開発　　　　　　　　　　　　　　　
    中島 孝平, 木村 俊広, 高倉 栄男, 吉川 恭央, 亀田 篤志, 進藤 崇之, 佐藤 和秀, 小林 久隆, 小川 美香子
    JSMI Report, 11, 2, 96, 96, 日本分子イメージング学会, 2018年05月
    日本語
  • 小分子ペプチドを利用した新規光線免疫療法薬剤の開発　　　　　　　　　　　　　　　
    寺田 一貴, 高倉 栄男, 中島 孝平, 安藤 完太, 小川 美香子
    JSMI Report, 11, 2, 139, 139, 日本分子イメージング学会, 2018年05月
    日本語
  • 薬剤の構造変化に着目した光線免疫療法のメカニズム解明　　　　　　　　　　　　　　　
    高倉 栄男, 安藤 完太, 中島 孝平, 小川 美香子
    JSMI Report, 11, 2, 75, 75, 日本分子イメージング学会, 2018年05月
    日本語
  • Implantable wireless powered light emitting diode (LED) for near-infrared photoimmunotherapy: Device development and experimental assessment in vitro and in vivo
    Kohei Nakajima, Toshihiro Kimura, Hideo Takakura, Yasuo Yoshikawa, Atsushi Kameda, Takayuki Shindo, Kazuhide Sato, Hisataka Kobayashi, Mikako Ogawa
    Oncotarget, 9, 28, 20048, 20057, Impact Journals LLC, 2018年04月13日, ［査読有り］
    英語, 研究論文（学術雑誌）, Purpose: The aim of this study was to develop and assess a novel implantable, wireless-powered, light-emitting diode (LED) for near-infrared photoimmunotherapy (NIR-PIT). NIR-PIT is a recently developed cancer therapy that uses NIR light and antibody-photosensitizer conjugates and is able to induce cancer-specific cell death. Due to limited light penetration depth it is currently unable to treat tumors in deep tissues. Use of implanted LED might potentially overcome this limitation. Results: The wireless LED system was able to emit NIR light up to a distance of 20 cm from the transmitter coil by using low magnetic fields as compliant with limits for use in humans. Results indicated that the LED system was able to kill tumor cells in vitro and to suppress tumor growth in implanted tumor-bearing mice. Conclusions: Results indicated that the proposed implantable wireless LED system was able to suppress tumor growth in vivo. These results are encouraging as wireless LED systems such as the one here developed might be a possible solution to treat tumors in deep regions in humans. Further research in this area would be important. Materials and Methods: An implantable LED system was developed. It consisted of a LED capsule including two LED sources and a receiver coil coupled with an external coil and power source. Wireless power transmission was guaranteed by using electromagnetic induction. The system was tested in vitro by using EGFR-expressing cells and HER2-expressing cells. The system was also tested in vivo in tumor-bearing mice.
  • [18F]FDG PETを用いたPD-1治療効果の早期予測に関するin vivoでの検討　　　　　　　　　　　　　　　
    富田 真由, 高倉 栄男, 安井 博宣, 東川 桂, 久下 裕司, 小川 美香子
    日本薬学会年会要旨集, 138年会, 4, 66, 66, (公社)日本薬学会, 2018年03月
    日本語
  • 光線免疫療法におけるメカニズム解明に向けた薬剤の光応答性に関する検討　　　　　　　　　　　　　　　
    安藤 完太, 中島 孝平, 高倉 栄男, 小川 美香子
    日本薬学会年会要旨集, 138年会, 4, 66, 66, (公社)日本薬学会, 2018年03月
    日本語
  • 光線免疫療法によるがん細胞死誘発過程における細胞膜の変化に関する検討　　　　　　　　　　　　　　　
    中島 孝平, 高倉 栄男, 志水 陽一, 浅沼 大祐, 上野 匡, 浦野 泰照, 小川 美香子
    日本薬学会年会要旨集, 138年会, 4, 66, 66, (公社)日本薬学会, 2018年03月
    日本語
  • In vivo molecular imaging for biomedical analysis and therapies
    Mikako Ogawa, Hideo Takakura
    Analytical Sciences, 34, 3, 273, 281, Japan Society for Analytical Chemistry, 2018年, ［査読有り］
    英語, In vivo molecular imaging is a powerful tool to analyze the human body. Precision medicine is receiving high attention these days, and molecular imaging plays an important role as companion diagnostics in precision medicine. Nuclear imaging with PET or SPECT and optical imaging technologies are used for in vivo molecular imaging. Nuclear imaging is superior for quantitative imaging, and whole-body analysis is possible even for humans. Optical imaging is superior due to its ease of use, and highly targeted specific imaging is possible with activatable agents. However, with optical imaging using fluorescence, it is difficult to obtain a signal from deep tissue and quantitation is difficult due to the attenuation and scattering of the fluorescent signal. Recently, to overcome these issues, optoacoustic imaging has been used in in vivo imaging. In this article, we review in vivo molecular imaging with nuclear and optical imaging and discuss their utility for precision medicine.
  • Immunoglobulin G (IgG)-Based Imaging Probe Accumulates in M1 Macrophage-Infiltrated Atherosclerotic Plaques Independent of IgG Target Molecule Expression
    Yoichi Shimizu, Hiroko Hanzawa, Yan Zhao, Sagiri Fukura, Ken-ichi Nishijima, Takeshi Sakamoto, Songji Zhao, Nagara Tamaki, Mikako Ogawa, Yuji Kuge
    MOLECULAR IMAGING AND BIOLOGY, 19, 4, 531, 539, SPRINGER, 2017年08月, ［査読有り］
    英語, 研究論文（学術雑誌）, Vulnerable plaques are key factors for ischemic diseases. Thus, their precise detection is necessary for the diagnosis of such diseases. Immunoglobulin G (IgG)-based imaging probes have been developed for imaging biomolecules related to plaque formation for the diagnosis of atherosclerosis. However, IgG accumulates nonspecifically in atherosclerotic regions, and its accumulation mechanisms have not yet been clarified in detail. Therefore, we explored IgG accumulation mechanisms in atherosclerotic lesions and examined images of radiolabeled IgG for the diagnosis of atherosclerosis.
    Mouse IgG without specificity to biomolecules was labeled with technetium-99m via 6-hydrazinonicotinate to yield [Tc-99m]IgG. ApoE(-/-) or C57BL/6J mice were injected intravenously with [Tc-99m]IgG, and their aortas were excised 24 h after injection. After radioactivity measurement, serial aortic sections were autoradiographically and histopathologically examined. RAW264.7 macrophages were polarized into M1 or M2 and then treated with [Tc-99m]IgG. The radioactivities in the cells were measured after 1 h of incubation. [Tc-99m]IgG uptake in M1 macrophages was also evaluated after the pretreatment with an anti-Fc gamma receptor (Fc gamma R) antibody. The expression levels of Fc gamma Rs in the cells were measured by western blot analysis.
    [Tc-99m]IgG accumulation levels in the aortas were significantly higher in apoE(-/-) mice than in C57BL/6J mice (5.1 +/- A 1.4 vs 2.8 +/- A 0.5 %ID/g, p < 0.05). Autoradiographic images showed that the accumulation areas highly correlated with the macrophage-infiltrated areas. M1 macrophages showed significantly higher levels of [Tc-99m]IgG than M2 or M0 (nonpolarized) macrophages [2.2 +/- A 0.3 (M1) vs 0.5 +/- A 0.1 (M2), 0.4 +/- A 0.1 (M0) %dose/mg protein, p < 0.01] and higher expression levels of Fc gamma RI and Fc gamma RII. [Tc-99m]IgG accumulation in M1 macrophages was suppressed by pretreatment with the anti-Fc gamma R antibody [2.2 +/- A 0.3 (nonpretreatment) vs 1.2 +/- A 0.2 (pretreatment) %ID/mg protein, p < 0.01].
    IgG accumulated in pro-inflammatory M1 macrophages via Fc gamma Rs in atherosclerotic lesions. Thus, the target biomolecule-independent imaging of active inflammation should be taken into account in the diagnosis of atherosclerosis using IgG-based probes.
  • Immunogenic cancer cell death selectively induced by near infrared photoimmunotherapy initiates host tumor immunity
    Mikako Ogawa, Yusuke Tomita, Yuko Nakamura, Min-Jung Lee, Sunmin Lee, Saori Tomita, Tadanobu Nagaya, Kazuhide Sato, Toyohiko Yamauchi, Hidenao Iwai, Abhishek Kumar, Timothy Haystead, Hari Shroff, Peter L. Choyke, Jane B. Trepel, Hisataka Kobayashi
    ONCOTARGET, 8, 6, 10425, 10436, IMPACT JOURNALS LLC, 2017年02月, ［査読有り］
    英語, 研究論文（学術雑誌）, Immunogenic cell death (ICD) is a form of cell death that activates an adaptive immune response against dead-cell-associated antigens. Cancer cells killed via ICD can elicit antitumor immunity. ICD is efficiently induced by near-infrared photo-immunotherapy (NIR-PIT) that selectively kills target-cells on which antibody-photoabsorber conjugates bind and are activated by NIR light exposure. Advanced live cell microscopies showed that NIR-PIT caused rapid and irreversible damage to the cell membrane function leading to swelling and bursting, releasing intracellular components due to the influx of water into the cell. The process also induces relocation of ICD bio markers including calreticulin, Hsp70 and Hsp90 to the cell surface and the rapid release of immunogenic signals including ATP and HMGB1 followed by maturation of immature dendritic cells. Thus, NIR-PIT is a therapy that kills tumor cells by ICD, eliciting a host immune response against tumor.
  • Peptide-based tumor inhibitor encoding mitochondrial p14(ARF) is highly efficacious to diverse tumors
    Ken Saito, Hidekazu Iioka, Chie Kojima, Mikako Ogawa, Eisaku Kondo
    CANCER SCIENCE, 107, 9, 1290, 1301, WILEY-BLACKWELL, 2016年09月, ［査読有り］
    英語, 研究論文（学術雑誌）, p14(ARF) is one of the major tumor suppressors conventionally identified both as the mdm2-binding molecule restoring p53 function in the nucleus, and as a nucleophosmin-binding partner inside the nucleolous to stabilize ribosomal RNA. However, its recently reported mitochondrial localization has pointed to novel properties as a tumor suppressor. At the same time, functional peptides are gaining much attention in nanomedicine for their in vivo utility as non-invasive biologics. We previously reported the p14(ARF)-specific peptide that restored the sensitivity to gefitinib on the gefitinib-resistant lung cancer cells. Based on the information of this prototype peptide, here we generated the more powerful anti-tumor peptide "r9-CatB-p14 MIS," which comprises the minimal inhibitory sequence of the mitochondrial targeting p14(ARF) protein in combination with the proteolytic cleavage site for cathepsin B, which is activated in various tumor cells, fused with the nine-polyarginine-domain for cell penetration, and demonstrated its novel action of regulating mitochondrial function in accordance with localization of endogenous p14(ARF). The p14 MIS peptide showed a potent tumor inhibiton in vitro and in vivo against not only lung cancer cells but also tumor cells of diverse lineages, via modulating mitochondrial membrane potential, with minimal cytotoxicity to non-neoplastic cells and tissues. Hence, this mitochondrially targeted p14 peptide agent provides a novel basis for non-invasive peptide-based antitumor therapeutics.
  • Monoclonal antibody-based optical molecular imaging probes; considerations and caveats in chemistry, biology and pharmacology
    Hisataka Kobayashi, Peter L. Choyke, Mikako Ogawa
    CURRENT OPINION IN CHEMICAL BIOLOGY, 33, 32, 38, ELSEVIER SCI LTD, 2016年08月, ［査読有り］
    英語, The monoclonal antibody (mAb) has proven to be a good platform for designing specific molecular imaging probes due to its superior binding specificity. Several optical imaging probes have been developed for surgical navigation in patients and are in early phase clinical trials. However, an inherent limitation of using the mAb is its pharmacokinetics which result in a prolonged circulating half-life and slow clearance from the body. This results in undesirable target to background ratios during imaging. In this review, we first describe the mAb as a platform material for optical probe design and then discuss optimizing the design of monoclonal antibody-based optical molecular imaging probes by focusing on chemistry, biology and pharmacology.
  • 病態メカニズムに迫るイメージング技術 DDSへの期待 動脈硬化のマルチモダル生体イメージングを目指したDDS製剤の開発　　　　　　　　　　　　　　　
    小川 美香子, 清水 広介, 成田 雄大, Maess Marten, 梅田 泉, 奥 直人, 間賀田 泰寛
    日本DDS学会学術集会プログラム予稿集, 32回, 95, 95, 日本DDS学会, 2016年06月
    日本語
  • Optimization of dendrimer structure for sentinel lymph node imaging: Effects of generation and terminal group
    Yuichiro Niki, Mikako Ogawa, Rie Makiura, Yasuhiro Magata, Chie Kojima
    NANOMEDICINE-NANOTECHNOLOGY BIOLOGY AND MEDICINE, 11, 8, 2119, 2127, ELSEVIER SCIENCE BV, 2015年11月, ［査読有り］
    英語, 研究論文（学術雑誌）, The detection of the sentinel lymph node (SLN), the first lymph node draining tumor cells, is important in cancer diagnosis and therapy. Dendrimers are synthetic macromolecules with highly controllable structures, and are potent multifunctional imaging agents. In this study, 12 types of dendrimer of different generations (G2, G4, G6, and G8) and different terminal groups (amino, carboxyl, and acetyl) were prepared to determine the optimal dendrimer structure for SLN imaging. Radiolabeled dendrimers were intradermally administrated to the right footpads of rats. All G2 dendrimers were predominantly accumulated in the kidney. Amino-terminal, acetyl-terminal, and carboxyl-terminal dendrimers of greater than G4 were mostly located at the injection site, in the blood, and in the SLN, respectively. The carboxyl-terminal dendrimers were largely unrecognized by macrophages and T-cells in the SLN. Finally, SLN detection was successfully performed by single photon emission computed tomography imaging using carboxyl-terminal dendrimers of greater than G4.
    From the Clinical Editor: The early detection of tumor cells in the sentinel draining lymph nodes (SLN) is of utmost importance in terms of determining cancer prognosis and devising treatment. In this article, the authors investigated various formulations of dendrimers to determine the optimal one for tumor detection. The data generated from this study would help clinicians to fight the cancer battle in the near future. (C) 2015 Elsevier Inc. All rights reserved.
  • A handy camera for near-infrared fluorescence imaging
    Mikako Ogawa
    Drug Delivery System, 30, 2, 145, 148, Japan Society of Drug Delivery System, 2015年06月25日, ［査読有り］
    日本語, 研究論文（学術雑誌）
  • Radiosynthesis and in vivo evaluation of two imidazopyridineacetamides, [ (11)C]CB184 and [ (11)C]CB190, as a PET tracer for 18 kDa translocator protein: direct comparison with [ (11)C](R)-PK11195.
    Hatano K, Sekimata K, Yamada T, Abe J, Ito K, Ogawa M, Magata Y, Toyohara J, Ishiwata K, Biggio G, Serra M, Laquintana V, Denora N, Latrofa A, Trapani G, Liso G, Suzuki H, Sawada M, Nomura M, Toyama H
    Annals of nuclear medicine, 29, 4, 325, 335, SPRINGER, 2015年05月, ［査読有り］
    英語, 研究論文（学術雑誌）, We report synthesis of two carbon-11 labeled imidazopyridines TSPO ligands, [C-11]CB184 and [C-11]CB190, for PET imaging of inflammatory process along with neurodegeneration, ischemia or brain tumor. Biodistribution of these compounds was compared with that of [C-11]CB148 and [C-11](R)-PK11195.
    Both [C-11]CB184 and [C-11]CB190 having C-11-methoxyl group on an aromatic ring were readily prepared using [C-11]methyl triflate. Biodistribution and metabolism of the compounds were examined with normal mice. An animal PET study using 6-hydroxydopamine treated rats as a model of neurodegeneration was pursued for proper estimation of feasibility of the radioligands to determine neuroinflammation process.
    [C-11]CB184 and [C-11]CB190 were obtained via O-methylation of corresponding desmethyl precursor using [C-11]methyl triflate in radiochemical yield of 73 % (decay-corrected). In vivo validation as a TSPO radioligand was carried out using normal mice and lesioned rats. In mice, [C-11]CB184 showed more uptake and specific binding than [C-11]CB190. Metabolism studies showed that 36 % and 25 % of radioactivity in plasma remained unchanged 30 min after intravenous injection of [C-11]CB184 and [C-11]CB190, respectively. In the PET study using rats, lesioned side of the brain showed significantly higher uptake than contralateral side after i.v. injection of either [C-11]CB184 or [C-11](R)-PK11195. Indirect Logan plot analysis revealed distribution volume ratio (DVR) between the two sides which might indicate lesion-related elevation of TSPO binding. The DVR was 1.15 +/- A 0.10 for [C-11](R)-PK11195 and was 1.15 +/- A 0.09 for [C-11]CB184.
    The sensitivity to detect neuroinflammation activity was similar for [C-11]CB184 and [C-11](R)-PK11195.
  • Development of radioiodinated lipophilic cationic compounds for myocardial imaging
    Toshihiro Sakai, Yuriko Saito, Misato Takashima, Mikako Ogawa, Yasuhiro Magata
    NUCLEAR MEDICINE AND BIOLOGY, 42, 5, 482, 487, ELSEVIER SCIENCE INC, 2015年05月, ［査読有り］
    英語, 研究論文（学術雑誌）, Introduction: Tc-99m compounds are mainly used in myocardial blood flow studies. These compounds, however, are produced by a generator and alternate single photon emission computed tomography (SPECT) radiopharmaceuticals are therefore required to avoid the risks posed by generator failure. Three radiolabeled compounds, including [I-125]p-iodobenzyl triphenylphosphonium ([I-125]ITPP), [I-125]p-lodobenzyl dipropylphenylphosphonium ([I-125]IDPP) and [I-125]p-iodobenzyl methyldiphenylphosphonium ([I-125]IMPP), have been synthesized in the current study. All three of these compounds contain a lipophilic cation, which enhances their cell permeability properties and allows them to accumulate in the myocardium as SPECT probes.
    Methods: 4-(2-Tributylstannyl) benzyl alcohol was mixed with [I-125]NaI in the presence of aqueous hydrogen peroxide and hydrochloric acid to allow for the synthesis of 4-[I-125]iodobenzyl alcohol. Bromination of the alcohol under standard conditions gave 4-[I-125]iodo benzyl bromide, which was treated with triphenylphosphine, dipropylphenylphosphine or methyldiphenylphosphine to give [I-125]ITPP, [I-125]IDPP and [I-125]IMPP, respectively. These compounds were evaluated in biodistribution and SPECT studies in normal ddY mice.
    Results: All three of the radiolabeled compounds were synthesized in approximately 60% yield with radiochemical purities greater than 99%. The specific activity of each compound was 74 GBq/mu mol. The results of the biodistribution and SPECT studies showed that all compounds accumulated preferentially in the heart in vivo, especially [I-125]IDPP.
    Conclusion: [I-123] IDPP could be used in clinical practice as a novel myocardial imaging agent. (C) 2015 Elsevier Inc. All rights reserved.
  • PEG modification on In-111-labeled phosphatidyl serine liposomes for imaging of atherosclerotic plaques
    Mikako Ogawa, Ryuji Uchino, Ayumi Kawai, Mutsumi Kosugi, Yasuhiro Magata
    NUCLEAR MEDICINE AND BIOLOGY, 42, 3, 299, 304, ELSEVIER SCIENCE INC, 2015年03月, ［査読有り］
    英語, 研究論文（学術雑誌）, Introduction: Previously, we reported a probe for imaging of atherosclerotic plaques: In-111-labeled liposomes. Liposomes were modified with phosphatidylserine (PS) because macrophages recognize PS and phagocytize apoptotic cells in plaques. PS modification was successful and we could visualize atherosclerotic plaques by single-photon emission computed tomography (SPECT). However, too-rapid blood clearance reduced accumulation of PS-liposomes in plaques in vivo. Therefore, in the present study, PS-liposomes were modified with polyethylene glycol (PEG) to retard the rate of blood clearance.
    Methods: PS-liposomes (size, 100 nm or 200 nm) were PEGylated with PEG2000 or PEG5000 at 1 or 5 mol%, and radiolabeled with In-111. For the study of uptake in vitro, liposomes were incubated with mouse peritoneal macrophages. Biodistribution studies in vivo were carried out in ddY mice. Enlace autoradiograms were obtained with apoE(-/-) mice upon intravenous injection of In-111-liposomes.
    Results: Uptake was decreased significantly at 5 mol%PEGylation in 100-nm PS-liposomes (*P < 0.05 vs. 0 mol%). All the PEGylated liposomes tested showed significantly lower uptake than the non-PEGylated control in 200-nm liposomes. In vivo results showed slower blood clearance in PEGylated liposomes. Autoradiograms in apoE(-/-) mice were well matched with Oil Red O staining. Additionally, 200-nm PS-liposomes modified with 5% PEG2000 (In-[111]5PEG2000PS200) showed the highest uptake to the region in vivo.
    Conclusions: As expected, PEGylation retarded the rate of blood clearance. In addition, it affected liposome uptake by macrophages in vitro. These results suggest that the balance between the rate of blood clearance and macrophage recognition is important, and [In-111]5%PEG2000PS200 showed the best results in our investigation. (C) 2014 Elsevier Inc. All rights reserved.
  • Sensitive β-galactosidase-targeting fluorescence probe for visualizing small peritoneal metastatic tumours in vivo.
    Asanuma D, Sakabe M, Kamiya M, Yamamoto K, Hiratake J, Ogawa M, Kosaka N, Choyke PL, Nagano T, Kobayashi H, Urano Y
    Nature communications, 6, 6463, NATURE PUBLISHING GROUP, 2015年03月, ［査読有り］
    英語, 研究論文（学術雑誌）, Fluorescence-guided diagnostics is one of the most promising approaches for facile detection of cancer in situ. Here we focus on beta-galactosidase, which is overexpressed in primary ovarian cancers, as a molecular target for visualizing peritoneal metastases from ovarian cancers. As existing fluorescence probes are unsuitable, we have designed membrane-permeable HMRef-beta Gal, in which the optimized intramolecular spirocyclic function affords > 1,400-fold fluorescence enhancement on activation. We confirm that HMRef-bGal sensitively detects intracellular beta-galactosidase activity in several ovarian cancer lines. In vivo, this probe visualizes metastases as small as < 1 mm in diameter in seven mouse models of disseminated human peritoneal ovarian cancer (SHIN3, SKOV3, OVK18, OVCAR3, OVCAR4, OVCAR5 and OVCAR8). Because of its high brightness, real-time detection of metastases with the naked eye is possible. Endoscopic fluorescence detection of metastases is also demonstrated. The results clearly indicate preclinical potential value of the probe for fluorescence-guided diagnosis of peritoneal metastases from ovarian cancers.
  • Prolonged local retention of subcutaneously injected polymers monitored by noninvasive SPECT imaging
    Chie Kojima, Yuichiro Niki, Mikako Ogawa, Yasuhiro Magata
    INTERNATIONAL JOURNAL OF PHARMACEUTICS, 476, 1-2, 164, 168, ELSEVIER SCIENCE BV, 2014年12月, ［査読有り］
    英語, 研究論文（学術雑誌）, Polymers are widely applied to drug delivery systems because polymers are generally excreted from the body more slowly than small molecules. Subcutaneous injection is one plausible means of administration. In this study, the in vivo behaviors of subcutaneously injected polymers, linear poly (glutamic acid) (Poly-Glu), acetylated dendrimer (Ac-den) and collagen peptide-conjugated dendrimer (CP-den), were investigated. Single photon emission computed tomography (SPECT) imaging was used to noninvasively monitor the in vivo behaviors. Diethylenetriaminepentaacetic acid (DTPA) was conjugated to these polymers, which were labeled with radioactive In-111. These In-111-DTPA-bearing polymers (Poly-Glu- DTPA, Ac-den-DTPA and CP-den-DTPA) and unconjugated DTPA were subcutaneously injected into tumor-bearing mice, which were subjected to SPECT imaging. These In-111-DTPA-bearing polymers were largely retained at the injection site for at least 1 day, whereas the unconjugated DTPA was rapidly cleared from the whole body through excretion. Poly-Glu-DTPA and Ac-den-DTPA were partly accumulated in the kidney (and the liver), but the CP-den-DTPA was not. However, these In-111-DTPA-bearing polymers were accumulated in the liver and the kidney following intravenous administration. These results indicate that the subcutaneously injected polymers did not largely gain substantial access to the systemic circulation, which is useful for a depot of drug around the injection site. (C) 2014 Elsevier B.V. All rights reserved.
  • Radiolabeled γ-polyglutamic acid complex as a nano-platform for sentinel lymph node imaging.
    Sano K, Iwamiya Y, Kurosaki T, Ogawa M, Magata Y, Sasaki H, Ohshima T, Maeda M, Mukai T
    Journal of controlled release : official journal of the Controlled Release Society, 194, 310, 315, ELSEVIER SCIENCE BV, 2014年11月, ［査読有り］
    英語, 研究論文（学術雑誌）, We established a ternary anionic complex constructed with polyamidoamine dendrimer (4th generation; G4) modified with chelating agents (diethylenetriamine pentaacetic acid (DTPA) derivative), polyethyleneimine (PEI), and gamma-polyglutamic acid (PGA) as a safe nano-platform for molecular imaging. We prepared indium-111-labeled DTPA-G4/PEI/gamma-PGA, and evaluated the effectiveness as a nuclear imaging probe for sentinel lymph node (LN), the first LN that drains the primary tumor. In-111-DTPA-G4/PEI with strong cationic charge agglutinated with erythrocytes and showed extremely high cytotoxicity. By contrast, the anionic In-111-DTPA-G4/PEI/gamma-PGA had little agglutination activity with erythrocytes and no cytotoxicity, indicating their high biocompatibility. In-111-DTPA-G4/PEI/gamma-PGA was highly taken up by macrophage cells (high populations in LNs) comparable to In-111-DTPA-G4/PEI. The uptake mechanisms of In-111-DTPA-G4/PEI/gamma-PGA were suggested to be both phagocytosis and gamma-PGA-specific pathway. Upon administration of each In-111-labeled nano-platform into rat footpads intradermally, significantly higher radioactivity of In-111-DTPA-G4/PEI/gamma-PGA was observed in the first draining popliteal LN when compared with that of In-111-DTPA-G4/PEI. Moreover, In-111-DTPA-G4/PEI/gamma-PGA clearly visualized the sentinel LN with single photon emission computed tomography (SPECT) compared with In-111-DTPA-G4/PEI. Thus, In-111-DTPA-G4/PEI/gamma-PGA can be useful as a nano-platform for molecular imaging including sentinel LN imaging. (C) 2014 Elsevier B.V. All rights reserved.
  • Application of nano-particles for in vivo molecular imaging
    Mikako Ogawa
    Transactions of Japanese Society for Medical and Biological Engineering, 52, 35, SY-36, Japan Soc. of Med. Electronics and Biol. Engineering, 2014年08月17日, ［査読有り］
    英語, 研究論文（学術雑誌）, In vivo molecular imaging has great possibility to monitor the molecular process in diagnostic or therapeutic applications noninvasively. Several kinds of imaging tools are used in clinical situations, such as positron emission tomography (PET), single photon emission computed tomography (SPECT), optical imaging, magnetic resonance imaging (MRI), computed tomography (CT), and ultrasound imaging (US). Among these, CT, MRI and ultrasound are categorized as morphological imaging technologies, although some molecular imaging trials are undertaken these days. PET, SPECT and optical imaging can be used for molecular imaging. Molecular imaging probes are composed of signal molecules and targeting molecules. Nano-particles can be applied for the targeting molecules. Especially, nano-particles have great advantages in making multimodal imaging probes, since multiple signal molecules can be combined to them. Herein, we discuss advances and disadvantages of the imaging techniques, and in vivo molecular imaging with nano-particles would be discussed by showing our practical examples.
  • In vivo molecular imaging techniques for non-invasive atherosclerotic plaque detection
    Mikako Ogawa, Kosuke Shimizu, Huijun Zhu, Yasuhiro Magata, Naoto Oku
    Transactions of Japanese Society for Medical and Biological Engineering, 52, 60, SY-61, Japan Soc. of Med. Electronics and Biol. Engineering, 2014年08月17日, ［査読有り］
    英語, 研究論文（学術雑誌）, Vulnerable plaques in atherosclerotic lesions cause acute myocardial infarction and stroke. Therefore, detection of high-risk, vulnerable plaque is important for risk stratification and to provide early treatment. Plaque vulnerability is characterized by the large size of the lipid-rich atheromatous core, the thin fibrous cap, and the infiltration of inflammatory cells such as macrophages, although intimal thickening is observed in both vulnerable and stable plaques. Several imaging approaches have been applied to detect vulnerable plaques
    however, quantification of plaque inflammation is necessary to predict the risk of plaque rupture. Recently, clinical trials to detect atherosclerotic lesions with molecular imaging technologies have been settled out. Among them, optical imaging probes are promising candidate for vulnerable plaque detection due to its easy-to-use properties. Herein, several examples of the atherosclerotic plaque imaging methods would be shown, and the capability of optical imaging for vulnerable plaque detection would be discussed.
  • 動脈硬化不安定プラークイメージングのためのリポソーム製剤の開発　　　　　　　　　　　　　　　
    小川 美香子, 内納 隆治, 梅田 泉, 間賀田 泰寛
    日本動脈硬化学会総会プログラム・抄録集, 46回, 220, 220, (一社)日本動脈硬化学会, 2014年06月
    日本語
  • 動脈硬化不安定プラークマルチモダルイメージングのためのリポソーム製剤の開発　　　　　　　　　　　　　　　
    小川 美香子, 内納 隆治, 梅田 泉, 間賀田 泰寛
    JSMI Report, 7, 2, 79, 79, 日本分子イメージング学会, 2014年05月
    日本語
  • F-18-FDG PET and intravascular ultrasonography (IVUS) images compared with histology of atherosclerotic plaques: F-18-FDG accumulates in foamy macrophages
    Seigo Ishino, Mikako Ogawa, Ikuo Mori, Satoshi Nishimura, Shota Ikeda, Taku Sugita, Tatsuo Oikawa, Takashi Horiguchi, Yasuhiro Magata
    EUROPEAN JOURNAL OF NUCLEAR MEDICINE AND MOLECULAR IMAGING, 41, 4, 624, 633, SPRINGER, 2014年04月, ［査読有り］
    英語, 研究論文（学術雑誌）, Purpose Intravascular ultrasonography (IVUS) and F-18-FDG PET have been used to evaluate the efficacy of antiatherosclerosis drugs. These two modalities image different characteristics of atherosclerotic plaques, and a comparison of IVUS and PET images with histology has not been performed. The aim of this study was to align IVUS and PET images using anatomic landmarks in Watanabe heritable hyperlipidaemic (WHHL) rabbits, enabling comparison of their depiction of aortic atherosclerosis. Cellular F-18-FDG localization was evaluated by H-3-FDG microautoradiography (micro-ARG).
    Methods A total of 19 WHHL rabbits (7 months of age) were divided into three groups: baseline (n = 6), 3 months (n = 4), and 6 months (n = 9). PET, IVUS and histological images of the same aortic segments were analysed. Infiltration by foamy macrophages was scored from 0 to IV using haematoxylin and eosin (H&E) and antimacrophage immunohistochemical staining, and compared with H-3-FDG micro-ARG findings in two additional WHHL rabbits.
    Results IVUS images did not identify foamy macrophage deposition but revealed the area of intimal lesions (r = 0.87). F-18-FDG PET revealed foamy macrophage distribution in the plaques. The intensity of F-18-FDG uptake was correlated positively with the degree of foamy macrophage infiltration. Micro-ARG showed identical H-3-FDG accumulation in the foamy macrophages surrounding the lipid core of the plaques.
    Conclusion F-FDG PET localized and quantified the degree of infiltration of foamy macrophages in atherosclerotic lesions. IVUS defined the size of lesions. F-18-FDG PET is a promising imaging technique for evaluating atherosclerosis and for monitoring changes in the composition of atherosclerotic plaques affecting their stability.
  • MRI-蛍光デュアルイメージングプローブ2BDP3Gdによる動脈硬化巣の可視化　　　　　　　　　　　　　　　
    岩木 慎平, 花岡 健二郎, 外村 和也, 小川 美香子, 竹原 康雄, 萩沢 康介, 守本 祐司, 梅村 和夫, 長野 哲雄, 浦野 泰照
    日本薬学会年会要旨集, 134年会, 2, 300, 300, (公社)日本薬学会, 2014年03月
    日本語
  • Dendrimers as high relaxivity MR contrast agents
    Michelle R. Longmire, Mikako Ogawa, Peter L. Choyke, Hisataka Kobayashi
    WILEY INTERDISCIPLINARY REVIEWS-NANOMEDICINE AND NANOBIOTECHNOLOGY, 6, 2, 155, 162, WILEY, 2014年03月, ［査読有り］
    英語, Dendrimers are versatile macromolecules with tremendous potential as magnetic resonance imaging (MRI) contrast agents. Dendrimer-based agents provide distinct advantages over low-molecular-weight gadolinium chelates, including enhanced r1 relaxivity due to slow rotational dynamics, tunable pharmacokinetics that can be adapted for blood pool, liver, kidney, and lymphatic imaging, the ability to be a drug carrier, and flexibility for labeling due to their inherent multivalency. Clinical applications are increasingly being developed, particularly in lymphatic imaging. Herein we present a broad overview of dendrimer-based MRI contrast agents with attention to the unique chemistry and physical properties as well as emerging clinical applications. For further resources related to this article, please visit the . (C) 2013 Wiley Periodicals, Inc.
  • Lymphangiogenesis and Angiogenesis in Abdominal Aortic Aneurysm
    Masaki Sano, Takeshi Sasaki, Satoshi Hirakawa, Junichi Sakabe, Mikako Ogawa, Satoshi Baba, Nobuhiro Zaima, Hiroki Tanaka, Kazunori Inuzuka, Naoto Yamamoto, Mitsutoshi Setou, Kohji Sato, Hiroyuki Konno, Naoki Unno
    PLOS ONE, 9, 3, e89830, PUBLIC LIBRARY SCIENCE, 2014年03月, ［査読有り］
    英語, 研究論文（学術雑誌）, The pathogenesis of abdominal aortic aneurysm (AAA) is characterized to be inflammation-associated degeneration of vascular wall. Neovascularization is regularly found in human AAA and considered to play critical roles in the development and rupture of AAA. However, little is known about lymphangiogenesis in AAA. The purpose of this study was to demonstrate both angiogenesis and lymphangiogenesis in AAA. Abdominal aortic tissue was harvested either from autopsy (control group) and during open-repair surgery for AAA (AAA group). Adventitial lymphatic vasa vasorum was observed in both groups, but seemed to be no significant morphological changes in AAA. Immunohistochemical studies identified infiltration of lymphatic vessel endothelial hyaluronan receptor (LYVE) -1, vascular endothelial growth factor (VEGF)-C, and matrix metalloproteinase (MMP)-9-positive macrophages and podoplanin and Prox-1-positive microvessels in the intima/media in AAA wall, where hypoxia-inducible factors (HIF)-1 alpha was expressed. VEGF-C and MMP-9 were not expressed in macrophages infiltrating in the adventitia. Intraoperative indocyanine green fluorescence lymphography revealed lymph stasis in intima/medial in AAA. Fluorescence microscopy of the collected samples also confirmed the accumulation of lymph in the intima/media but not in adventitia. These results demonstrate that infiltration of macrophages in intima/media is associated with lymphangiogenesis and angiogenesis in AAA. Lymph-drainage appeared to be insufficient in the AAA wall.
  • Investigation of dynamic morphological changes of cancer cells during photoimmuno therapy (PIT) by low-coherence quantitative phase microscopy
    Mikako Ogawa, Toyohiko Yamauchi, Hidenao Iwai, Yasuhiro Magata, Peter L. Choyke, Hisataka Kobayashi
    Progress in Biomedical Optics and Imaging - Proceedings of SPIE, 8931, SPIE, 2014年, ［査読有り］
    英語, 研究論文（国際会議プロシーディングス）, We have reported a new molecular-targeted cancer phototherapy, photoimmunotherapy (PIT), which killed implanted tumors in mice without side-effects. To understand the mechanism of cell killing with PIT, three-dimentional dynamic low-coherence quantitative phase microscopy (3D LC-QPM), a device developed by Hamamatsu Photonics K.K, was used to detect morphologic changes in cancer cells during PIT. 3T3/HER2 cells were incubated with anti-HER2 trastuzumab-IR700 (10 μg/mL, 0.1 μM as IR700) for 24 hours, then, three-dimensionally imaged with the LC-QPM during the exposure of two different optically filtered lights for excitation of IR700 (500-780 nm) and imaging (780-950 nm). For comparison with traditional PDT, the same experiments were performed with Photofrin (10 and 1 μM). Serial changes in the cell membrane were readily visualized on 3D LC-QPM. 3T3/HER2 cells began to swell rapidly after exposure to 500-780 nm light excitation. The cell volume reached a maximum within 1 min after continuous exposure, and then the cells appeared to burst. This finding suggests that PIT damages the cell membrane by photo-reaction inducing an influx of water into the cell causing swelling and bursting of the cells. Interestingly, even after only 5 seconds of light exposure, the cells demonstrated swelling and bursting albeit more slowly, implying that sufficient cumulative damage occurs on the cell membrane to induce lethal damage to cells even at minimal light exposure. Similar but non-selective membrane damage was shown in PDT-treated cells Photofrin. Thus, PIT induces sufficient damage to the cell membrane within 5 seconds to induce rapid necrotic cell death which can be observed directly with 3D LC-QPM. Further investigation is needed to evaluate the biochemical mechanisms underlying PIT-induced cellular membrane damage. © 2014 SPIE.
  • Investigation of dynamic morphological changes of cancer cells during photoimmuno therapy (PIT) by low-coherence quantitative phase microscopy
    Mikako Ogawa, Toyohiko Yamauchi, Hidenao Iwai, Yasuhiro Magata, Peter L. Choyke, Hisataka Kobayashi
    OPTICAL METHODS FOR TUMOR TREATMENT AND DETECTION: MECHANISMS AND TECHNIQUES IN PHOTODYNAMIC THERAPY XXIII, 8931, SPIE-INT SOC OPTICAL ENGINEERING, 2014年, ［査読有り］
    英語, 研究論文（国際会議プロシーディングス）, We have reported a new molecular-targeted cancer phototherapy, photoimmunotherapy (PIT), which killed implanted tumors in mice without side-effects. To understand the mechanism of cell killing with PIT, three-dimentional dynamic low-coherence quantitative phase microscopy (3D LC-QPM), a device developed by Hamamatsu Photonics K. K, was used to detect morphologic changes in cancer cells during PIT. 3T3/HER2 cells were incubated with anti-HER2 trastuzumab-IR700 (10 mu g/mL, 0.1 mu M as IR700) for 24 hours, then, three-dimensionally imaged with the LC-QPM during the exposure of two different optically filtered lights for excitation of IR700 (500-780 nm) and imaging (780-950 nm). For comparison with traditional PDT, the same experiments were performed with Photofrin (10 and 1 mu M).
    Serial changes in the cell membrane were readily visualized on 3D LC-QPM. 3T3/HER2 cells began to swell rapidly after exposure to 500-780 nm light excitation. The cell volume reached a maximum within 1 min after continuous exposure, and then the cells appeared to burst. This finding suggests that PIT damages the cell membrane by photo-reaction inducing an influx of water into the cell causing swelling and bursting of the cells. Interestingly, even after only 5 seconds of light exposure, the cells demonstrated swelling and bursting albeit more slowly, implying that sufficient cumulative damage occurs on the cell membrane to induce lethal damage to cells even at minimal light exposure. Similar but non-selective membrane damage was shown in PDT-treated cells Photofrin.
    Thus, PIT induces sufficient damage to the cell membrane within 5 seconds to induce rapid necrotic cell death which can be observed directly with 3D LC-QPM. Further investigation is needed to evaluate the biochemical mechanisms underlying PIT-induced cellular membrane damage.
  • Development of In-111-Labeled Liposomes for Vulnerable Atherosclerotic Plaque Imaging
    Mikako Ogawa, Izumi O. Umeda, Mutsumi Kosugi, Ayumi Kawai, Yuka Hamaya, Misato Takashima, Hongxia Yin, Takayuki Kudoh, Masaharu Seno, Yasuhiro Magata
    JOURNAL OF NUCLEAR MEDICINE, 55, 1, 115, 120, SOC NUCLEAR MEDICINE INC, 2014年01月, ［査読有り］
    英語, 研究論文（学術雑誌）, Macrophage infiltration is a common characteristic feature of atherosclerotic-vulnerable plaques. Macrophages recognize phosphatidylserine (PS) exposed on the surface of apoptotic cells, which triggers the engulfment of the apoptotic cells by macrophages through phagocytosis. In this study, we prepared radiolabeled PS liposomes for detection of vulnerable plaques. Methods: PS liposomes were prepared by lipid film hydration. Phosphatidylcholine (PC) liposomes were prepared as controls. Liposomes (100 or 200 nm) were generated by an extruder to produce PS100, PS200, PC100, and PC200 liposomes. These were then radiolabeled by encapsulating In-111-nitrilotriacetic acid using an active-loading method. In-111 liposomes were incubated with cultured macrophages for 2 h, and the uptake level was measured. For biodistribution studies, the In-111 liposomes were injected intravenously into ddY mice. In addition, the In-111 liposomes were injected into apolipoprotein E-deficient (apoE-/-) mice, and the aortas were harvested for autoradiography and oil red O staining. For SPECT imaging, In-111 liposomes were injected intravenously into Watanabe heritable hyperlipidemic rabbits and scanned 48 h after injection. Results: The radiochemical yields were greater than 95% for all the prepared In-111 liposomes. The level of in vitro uptake by macrophages was 60.5, 14.7, 32.0, and 14.4 percentage injected dose per milligram of protein for In-111-PS100, In-111-PC100, In-111-PS200, and In-111-PC200, respectively. In biodistribution studies, high spleen uptake was seen with PC liposomes. Liver uptake was high for all liposomes but was lowest with In-111-PS200. The blood half-lives were 3.2, 22.0, 3.6, and 7.4 min for In-111-PS100, In-111-PC100, In-111-PS200, and In-111-PC200, respectively. The distribution of In-111-labeled PS liposomes into atherosclerotic regions determined by autoradiography was well matched with the results of oil red O staining in apoE-/- mice. The target-to-nontarget ratios were 2.62, 2.23, 3.27, and 2.51 for In-111-PS100, In-111-PC100, In-111-PS200, and In-111-PC200, respectively. The aorta was successfully visualized by SPECT at 48 h after In-111-labeled PS liposome injection; however, high liver uptake was also observed. Discussion: From the in vitro uptake study, it has been demonstrated that macrophage targeting was accomplished by PS modification. Also, an atherosclerotic region was successfully detected by In-111-PS200 in apoE-/- mice and Watanabe heritable hyperlipidemic rabbits in vivo. Liposome modification to obtain slower blood clearance and lower liver uptake would be required to improve the SPECT images.
  • Relationship between uptake of a radioiodinated quinazoline derivative and radiosensitivity in non-small cell lung cancer.
    Zhu HJ, Ogawa M, Magata Y, Hirata M, Ohmomo Y, Sakahara H
    American journal of nuclear medicine and molecular imaging, 4, 4, 293, 302, 2014年, ［査読有り］
  • A design strategy for small molecule-based targeted MRI contrast agents: their application for detection of atherosclerotic plaques
    Shimpei Iwaki, Kazuya Hokamura, Mikako Ogawa, Yasuo Takehara, Yasuaki Muramatsu, Takehiro Yamane, Kazuhisa Hirabayashi, Yuji Morimoto, Kohsuke Hagisawa, Kazuhide Nakahara, Tomoko Mineno, Takuya Terai, Toru Komatsu, Tasuku Ueno, Keita Tamura, Yusuke Adachi, Yasunobu Hirata, Makoto Arita, Hiroyuki Arai, Kazuo Umemura, Tetsuo Nagano, Kenjiro Hanaoka
    ORGANIC & BIOMOLECULAR CHEMISTRY, 12, 43, 8611, 8618, ROYAL SOC CHEMISTRY, 2014年, ［査読有り］
    英語, 研究論文（学術雑誌）, Gadolinium(III) ion (Gd3+) complexes are widely used as contrast agents in magnetic resonance imaging (MRI), and many attempts have been made to couple them to sensor moieties in order to visualize biological phenomena of interest inside the body. However, the low sensitivity of MRI has made it difficult to develop practical MRI contrast agents for in vivo imaging. We hypothesized that practical MRI contrast agents could be designed by targeting a specific biological environment, rather than a specific protein such as a receptor. To test this idea, we designed and synthesized a Gd3+-based MRI contrast agent, 2BDP3Gd, for visualizing atherosclerotic plaques by linking the Gd3+-complex to the lipophilic fluorophore BODIPY to stain lipid-rich environments. We found that 2BDP3Gd was selectively accumulated into lipid droplets of adipocytes at the cellular level. Atherosclerotic plaques in the aorta of Watanabe heritable hyperlipidemic (WHHL) rabbits were clearly visualized in T-1-weighted MR images after intravenous injection of 2BDP3Gd in vivo.
  • Accumulated phosphatidylcholine (16:0/16:1) in human colorectal cancer; possible involvement of LPCAT4
    Nobuya Kurabe, Takahiro Hayasaka, Mikako Ogawa, Noritaka Masaki, Yoshimi Ide, Michihiko Waki, Toshio Nakamura, Kiyotaka Kurachi, Tomoaki Kahyo, Kazuya Shinmura, Yutaka Midorikawa, Yasuyuki Sugiyama, Mitsutoshi Setou, Haruhiko Sugimura
    CANCER SCIENCE, 104, 10, 1295, 1302, WILEY-BLACKWELL, 2013年10月, ［査読有り］
    英語, 研究論文（学術雑誌）, The identification of cancer biomarkers is critical for target-linked cancer therapy. The overall level of phosphatidylcholine (PC) is elevated in colorectal cancer (CRC). To investigate which species of PC is overexpressed in colorectal cancer, an imaging mass spectrometry was performed using a panel of non-neoplastic mucosal and CRC tissues. In the present study, we identified a novel biomarker, PC(16:0/16:1), in CRC using imaging mass spectrometry. Specifically, elevated levels of PC(16:0/16:1) expression were observed in the more advanced stage of CRC. Our data further showed that PC(16:0/16:1) was specifically localized in the cancer region when examined using imaging mass spectrometry. Notably, because the ratio of PC(16:0/16:1) to lyso-PC(16:0) was higher in CRC, we postulated that lyso-PC acyltransferase (LPCAT) activity is elevated in CRC. In an in vitro analysis, we showed that LPCAT4 is involved in the deregulation of PC(16:0/16:1) in CRC. In an immunohistochemical analysis, LPCAT4 was shown to be overexpressed in CRC. These data indicate the potential usefulness of PC(16:0/16:1) for the clinical diagnosis of CRC and implicate LPCAT4 in the elevated expression of PC(16:0/16:1) in CRC.
  • Accumulated phosphatidylcholine (16:0/16:1) in human colorectal cancer; possible involvement of LPCAT4
    Nobuya Kurabe, Takahiro Hayasaka, Mikako Ogawa, Noritaka Masaki, Yoshimi Ide, Michihiko Waki, Toshio Nakamura, Kiyotaka Kurachi, Tomoaki Kahyo, Kazuya Shinmura, Yutaka Midorikawa, Yasuyuki Sugiyama, Mitsutoshi Setou, Haruhiko Sugimura
    Cancer Science, 104, 10, 1295, 1302, 2013年10月, ［査読有り］
    英語, 研究論文（学術雑誌）, The identification of cancer biomarkers is critical for target-linked cancer therapy. The overall level of phosphatidylcholine (PC) is elevated in colorectal cancer (CRC). To investigate which species of PC is overexpressed in colorectal cancer, an imaging mass spectrometry was performed using a panel of non-neoplastic mucosal and CRC tissues. In the present study, we identified a novel biomarker, PC(16:0/16:1), in CRC using imaging mass spectrometry. Specifically, elevated levels of PC(16:0/16:1) expression were observed in the more advanced stage of CRC. Our data further showed that PC(16:0/16:1) was specifically localized in the cancer region when examined using imaging mass spectrometry. Notably, because the ratio of PC(16:0/16:1) to lyso-PC(16:0) was higher in CRC, we postulated that lyso-PC acyltransferase (LPCAT) activity is elevated in CRC. In an in vitro analysis, we showed that LPCAT4 is involved in the deregulation of PC(16:0/16:1) in CRC. In an immunohistochemical analysis, LPCAT4 was shown to be overexpressed in CRC. These data indicate the potential usefulness of PC(16:0/16:1) for the clinical diagnosis of CRC and implicate LPCAT4 in the elevated expression of PC(16:0/16:1) in CRC. © 2013 Japanese Cancer Association.
  • Alterations in α4β2 nicotinic receptors in cognitive decline in Alzheimer's aetiopathology.
    Okada H, Ouchi Y, Ogawa M, Futatsubashi M, Saito Y, Yoshikawa E, Terada T, Oboshi Y, Tsukada H, Ueki T, Watanabe M, Yamashita T, Magata Y
    Brain : a journal of neurology, 136, Pt 10, 3004, 3017, OXFORD UNIV PRESS, 2013年10月, ［査読有り］
    英語, 研究論文（学術雑誌）, Nicotinic acetylcholine receptor subtype alpha 4 beta 2 is considered important in the regulation of attention and memory, and cholinergic degeneration is known as one pathophysiology of Alzheimer's disease. Brain amyloid-beta protein deposition is also a key pathological marker of Alzheimer's disease. Recent amyloid-beta imaging has shown many cognitively normal subjects with amyloid-beta deposits, indicating a missing link between amyloid-beta deposition and cognitive decline. To date, the relationship between the alpha 4 beta 2 nicotinic acetylcholine receptor and amyloid-beta burden has not been elucidated in vivo. In this study we investigated the relation between alpha 4 beta 2 nicotinic acetylcholine receptor availability in the brain, cognitive functions and amyloid-beta burden in 20 non-smoking patients with Alzheimer's disease at an early stage and 25 age-matched non-smoking healthy elderly adults by measuring levels of alpha 4 beta 2 nicotinic acetylcholine receptor binding estimated from a simplified ratio method (BPRI) and Logan plot-based amyloid-beta accumulation (BPND) using positron emission tomography with alpha 4 beta 2 nicotinic acetylcholine receptor tracer F-18-2FA-85380 and C-11-Pittsburgh compound B. The levels of tracer binding were compared with clinical measures for various brain functions (general cognition, episodic and spatial memory, execution, judgement, emotion) using regions of interest and statistical parametric mapping analyses. Between-group statistical parametric mapping analysis showed a significant reduction in F-18-2FA-85380 BPRI in the cholinergic projection region in patients with Alzheimer's disease with a variety of C-11-Pittsburgh compound B accumulation. Spearman rank correlation analyses showed positive correlations of F-18-2FA-85380 BPRI values in the medial frontal cortex and nucleus basalis magnocellularis region with scores of the Frontal Assessment Battery (a test battery for executive functions and judgement) in the Alzheimer's disease group (P < 0.05 corrected for multiple comparison), and also positive correlations of the prefrontal and superior parietal F-18-2FA-85380 BPRI values with the Frontal Assessment Battery score in the normal group (P < 0.05 corrected for multiple comparison). These positive correlations indicated an in vivo alpha 4 beta 2 nicotinic acetylcholine receptor role in those specific functions that may be different from memory. Both region of interest-based and voxelwise regression analyses showed a negative correlation between frontal C-11-Pittsburgh compound B BPND and F-18-2FA-85380 BPRI values in the medial frontal cortex and nucleus basalis magnocellularis region in patients with Alzheimer's disease (P < 0.05 corrected for multiple comparison). These findings suggest that an impairment of the cholinergic alpha 4 beta 2 nicotinic acetylcholine receptor system with the greater amount of amyloid deposition in the system plays an important role in the pathophysiology of Alzheimer's disease.
  • 動脈硬化不安定プラークイメージングのためのリポソーム製剤の開発
    小川 美香子, 内納 隆治, 梅田 泉, 間賀田 泰寛
    核医学, 50, 3, S188, S188, (一社)日本核医学会, 2013年09月
    日本語
  • Differentiation of tumor sensitivity to photodynamic therapy and early evaluation of treatment effect by nuclear medicine techniques
    Jie Liu, Mikako Ogawa, Toshihiro Sakai, Misato Takashima, Shigetoshi Okazaki, Yasuhiro Magata
    ANNALS OF NUCLEAR MEDICINE, 27, 7, 669, 675, SPRINGER, 2013年08月, ［査読有り］
    英語, 研究論文（学術雑誌）, Our final goal is to develop an appropriate method using nuclear medicine technique for monitoring the effect and prediction of Photodynamic Therapy (PDT) on tumors. The aim of this study is to evaluate the effect of PDT on tumor cells in vitro using F-18-FDG and Tc-99m-MIBI as tracers.
    Five tumor cell lines (A431, DU145, H1650, LS180, SHIN3) with varied characteristics were irradiated after incubating for 24 h with several doses of Photofrin (PF). Singlet oxygen was monitored by the near-IR emission detection system during irradiation and generated O-1(2) was calculated. PDT effects were rapidly evaluated by nuclear medicine techniques (uptake of F-18-FDG and Tc-99m-MIBI) and traditional methods for cell viability (MTT and trypan blue assays) at 3 h after PDT. Intracellular PF concentration was measured by absorption spectrometer and cell protein content was measured by the Lowry method. F-18-FDG uptake, Tc-99m-MIBI uptake, singlet oxygen, and intracellular PF concentration were standardized by protein content. Decrease % of F-18-FDG and Tc-99m-MIBI, MTT, and trypan blue was normalized to the control group.
    Decrease % of F-18-FDG was exponentially related to decrease % of MTT (R (2) = 0.650, P < 0.01) while decrease % of Tc-99m-MIBI was linearly related to that of MTT (R (2) = 0.719, P < 0.01). The decrease % of MTT was more sensitive than that of trypan blue. However, neither O-1(2) nor PF uptake was correlated with sensitivity to PDT. In addition, F-18-FDG uptake before PDT was linearly related to decrease % of MTT (R (2) = 0.800, P < 0.05).
    Our findings in in vitro studies suggest that Tc-99m-MIBI is better than F-18-FDG for early evaluation of PDT effect, but F-18-FDG uptake may be used to predict PDT sensitivity before therapy.
  • Comparison of Contrast Agents for Atherosclerosis Imaging Using Cultured Macrophages: FDG Versus Ultrasmall Superparamagnetic Iron Oxide
    Tomoko Satomi, Mikako Ogawa, Ikuo Mori, Seigo Ishino, Kazuki Kubo, Yasuhiro Magata, Tomoyuki Nishimoto
    JOURNAL OF NUCLEAR MEDICINE, 54, 6, 999, 1004, SOC NUCLEAR MEDICINE INC, 2013年06月, ［査読有り］
    英語, 研究論文（学術雑誌）, Various noninvasive imaging methods have been developed to evaluate atherosclerotic plaques. Among them, F-18-FDG PET and MR imaging with ultrasmall superparamagnetic iron oxide particles (USPIO) have been used to quantify plaque inflammation. Both methods are based on the efficient uptake of FDG and USPIO by macrophages in atherosclerotic lesions. Differently polarized macrophages have been reported to have different characteristics that are involved in the pathologic development of atherosclerosis. M1 polarized macrophages are considered the more proatherogenic phenotype than M2 polarized macrophages. However, little is known regarding the association between macrophage polarization and FDG or USPIO accumulation. In this study, we investigated intracellular FDG and USPIO accumulation in M1 and M2 polarized macrophages. Methods: THP-1 macrophages were differentiated into M1 and M2 polarized macrophages. Under optimal glucose conditions, we investigated the 3H-labeled FDG uptake in M1 and M2 polarized macrophages. We then investigated intracellular USPIO uptake by M1 and M2 macrophages. Results: We found that M1 polarization, compared with M2 polarization, results in increased intracellular accumulation of FDG. To elucidate the mechanism by which FDG was preferentially accumulated in M1 macrophages, we examined messenger RNA expressions of glucose transporters (GLUTs) and hexokinases, which have pivotal roles in glucose uptake, and glucose-6-phosphatase (G6Pase), which catalyzes the reverse reaction of hexokinase. In M1 macrophages, GLUT-1, GLUT-3, hexokinase 1, and hexokinase 2 were upregulated and G6Pase was downregulated. In contrast to FDG, M1 polarization resulted in decreased intracellular accumulation of USPIO. We found that scavenger receptor A and CD11b, which are involved in USPIO binding and uptake, were significantly downregulated by M1 polarization. Conclusion: Compared with M2, proatherogenic M1 macrophages preferentially accumulated FDG but not USPIO, suggesting that FDG PET is a useful method for the detection of proinflammatory M1 macrophages.
  • 動脈硬化巣の可視化を目指したMRI造影剤の開発とその応用　　　　　　　　　　　　　　　
    岩木 慎平, 外村 和也, 小川 美香子, 竹原 康雄, 梅村 和夫, 長野 哲雄, 花岡 健二郎
    JSMI Report, 6, 2, 121, 121, 日本分子イメージング学会, 2013年05月
    日本語
  • 浜松医科大学イメージングコンプレックスの形成 第三世代PET施設の構築　　　　　　　　　　　　　　　
    間賀田 泰寛, 小川 美香子, 高島 好聖, 外村 和也, 竹原 康雄, 夏目 貴弘, 阿部 紀里子, 小野寺 雄一郎, 尾内 康臣, 阪原 晴海, 梅村 和夫, 山本 清二
    JSMI Report, 6, 2, 114, 114, 日本分子イメージング学会, 2013年05月, ［査読有り］
    日本語
  • 動脈硬化の可視化を目指したMRIプローブの開発とその応用　　　　　　　　　　　　　　　
    岩木 慎平, 花岡 健二郎, 外村 和也, 小川 美香子, 竹原 康雄, 梅村 和夫, 長野 哲雄
    日本薬学会年会要旨集, 133年会, 2, 311, 311, (公社)日本薬学会, 2013年03月
    日本語
  • Doxorubicin-conjugated dendrimer/collagen hybrid gels for metastasis-associated drug delivery systems
    Chie Kojima, Tomoyuki Suehiro, Kenji Watanabe, Mikako Ogawa, Ayano Fukuhara, Eiko Nishisaka, Atsushi Harada, Kenji Kono, Takashi Inui, Yasuhiro Magata
    ACTA BIOMATERIALIA, 9, 3, 5673, 5680, ELSEVIER SCI LTD, 2013年03月, ［査読有り］
    英語, 研究論文（学術雑誌）, Metastasis is a characteristic property of cancer cells, which degrade extracellular matrix containing collagen. We prepared a polymer prodrug-embedded collagen gel for metastasis-associated drug delivery. A collagen peptide-modified dendrimer that attached doxorubicin (Dox) via a pH-degradable linkage was synthesized as a polymer prodrug. Compared with free Dox, the diffusion of the dendrimer prodrug from the collagen gel was suppressed. Highly invasive MDA-MB-231 cells were more sensitive to the pro-drughybrid collagen gel than poorly invasive MCF-7 cells, even though the cytotoxicity of the dendrimer prodrug by itself against these cells was almost identical. The cytotoxicity against MDA-MB-231 cells decreased in the presence of a matrix metalloproteinase (MMP) inhibitor, suggesting that the dendrimer prodrug/collagen hybrid gel was affected by MMP activity. The dendrimer prodrug/collagen hybrid gel not only suppressed tumor growth but also attenuated metastatic activity in vivo. Therefore, the dendrimer prodrug-embedded collagen gel is useful for cancer chemotherapy. (C) 2012 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.
  • One-pot sequential reactions for the synthesis of versatile C-11-labeled olefin frameworks
    Misato Takashima, Koichi Kato, Mikako Ogawa, Yasuhiro Magata
    RSC ADVANCES, 3, 44, 21275, 21279, ROYAL SOC CHEMISTRY, 2013年, ［査読有り］
    英語, 研究論文（学術雑誌）, A simple and efficient methodology to construct C-11-labeled olefins (5) was developed. The method involves two different C-C bond-forming reactions: C-11-methylation of a phosphonate (2) using [C-11] methyl iodide (1) and subsequent HWE reaction of C-11-methylated phosphonate (3) with aldehydes (4). Tetrabutylammonium fluoride promoted both C-C bond-forming reactions efficiently as a base. This sequential reaction was conducted in one pot. A wide variety of alpha-[C-11] methyl-alpha,beta-unsaturated compounds were prepared by changing the substituents on the phosphonate and the aldehyde.
  • Assessment of epidermal growth factor receptor status in glioblastomas.
    Zhu HJ, Ogawa M, Magata Y, Hirata M, Ohmomo Y, Namba H, Sakahara H
    Asia Oceania journal of nuclear medicine & biology, 1, 2, 47, 52, 2013年, ［査読有り］
  • 動脈硬化不安定プラークのイメージングを目的とした、111In標識リポソームの開発
    小川 美香子, 梅田 泉, 小杉 睦, 河合 亜由美, 間賀田 泰寛
    核医学, 49, 3, S248, S248, (一社)日本核医学会, 2012年08月
    日本語
  • Sentinel lymph node imaging with a novel radiolabeled gamma-polyglutamic acid complex
    Sano Kohei, Iwamiya Yuriko, Kurosaki Tomoaki, Ogawa Mikako, Magata Yasuhiro, Sasaki Hitoshi, Ohshima Takashi, Maeda Minoru, Mukai Takahiro
    JOURNAL OF NUCLEAR MEDICINE, 53, SOC NUCLEAR MEDICINE INC, 2012年05月01日, ［査読有り］
    英語
  • What Can Be Seen by F-18-FDG PET in Atherosclerosis Imaging? The Effect of Foam Cell Formation on F-18-FDG Uptake to Macrophages In Vitro
    Mikako Ogawa, Satoki Nakamura, Yuriko Saito, Mutsumi Kosugi, Yasuhiro Magata
    JOURNAL OF NUCLEAR MEDICINE, 53, 1, 55, 58, SOC NUCLEAR MEDICINE INC, 2012年01月, ［査読有り］
    英語, 研究論文（学術雑誌）, F-18-FDG PET is a promising tool for detecting vulnerable plaques, depending on the extent of macrophage infiltration; however, it is still not clear which stage of the lesion can be detected by F-18-FDG PET. Methods: In this study, we investigated the effect of foam cell formation on F-18-FDG uptake using cultured mouse peritoneal macrophages. Results: F-18-FDG accumulation was increased by foam cell formation, but the uptake was decreased to the control level after complete differentiation to foam cells. Changes in hexokinase activity tended to accompany changes in F-18-FDG uptake. In contrast, changes in glucose-6-phosphatase activity and glucose transporter 1 expression did not parallel F-18-FDG uptake. Conclusion: Our results suggest that F-18-FDG PET detects the early stage of foam cell formation in atherosclerosis.
  • Dendrimer-based MRI contrast agents: the effects of PEGylation on relaxivity and pharmacokinetics
    Chie Kojima, Baris Turkbey, Mikako Ogawa, Marcelino Bernardo, Celeste A. S. Regino, L. Henry Bryant, Peter L. Choyke, Kenji Kono, Hisataka Kobayashi
    NANOMEDICINE-NANOTECHNOLOGY BIOLOGY AND MEDICINE, 7, 6, 1001, 1008, ELSEVIER SCIENCE BV, 2011年12月, ［査読有り］
    英語, 研究論文（学術雑誌）, Polyethylene glycol (PEG) surface modification can make nanomaterials highly hydrophilic, reducing their sequestration in the reticuloendothelial system. In this study, polyamidoamine (PAMAM) dendrimers bearing gadolinium (Gd) chelates were PEGylated with different PEG-chain lengths, and the effects on paramagnetic and pharmacokinetic properties were evaluated. Specifically, Gd chelate-bearing PAMAM dendrimers (generations 4 and 5; G4 and G5) were conjugated with two different PEG chains (2 kDa and 5 kDa; 2k and 5k). Long PEG chains (5k) on the smaller (G4) dendrimer resulted in reduced relaxivity compared to non-PEGylated dendrimers, whereas short PEG chains (2k) on a larger (G5) dendrimer produced relaxivities comparable to non-PEGylated G4 dendrimers. The relaxivity of all PEGylated or lysine-conjugated dendrimers increased at higher temperature, whereas that of intact G4 Gd-PAMAM dendrimer decreased. All PEGylated dendrimers had minimal liver and kidney uptake and remained in circulation for at least 1 hour. Thus, surface-PEGylated Gd-PAMAM dendrimers showed decreased plasma clearance and prolonged retention in the blood pool. Shorter PEG, higher generation conjugates led to higher relaxivity.
    From the Clinical Editor: In this study, polyamidoamine dendrimers bearing gadolinium (Gd) chelates were PEGylated with different PEG-chain lengths, and the effects on paramagnetic and pharmacokinetic properties were evaluated. (C) 2011 Elsevier Inc. All rights reserved.
  • Cancer cell-selective in vivo near infrared photoimmunotherapy targeting specific membrane molecules
    Makoto Mitsunaga, Mikako Ogawa, Nobuyuki Kosaka, Lauren T. Rosenblum, Peter L. Choyke, Hisataka Kobayashi
    NATURE MEDICINE, 17, 12, 1685, U210, NATURE PUBLISHING GROUP, 2011年12月, ［査読有り］
    英語, 研究論文（学術雑誌）, Three major modes of cancer therapy (surgery, radiation and chemotherapy) are the mainstay of modern oncologic therapy. To minimize the side effects of these therapies, molecular-targeted cancer therapies, including armed antibody therapy, have been developed with limited success. In this study, we have developed a new type of molecular-targeted cancer therapy, photoimmunotherapy (PIT), that uses a target-specific photosensitizer based on a near-infrared (NIR) phthalocyanine dye, IR700, conjugated to monoclonal antibodies (mAbs) targeting epidermal growth factor receptors. Cell death was induced immediately after irradiating mAbIR-700-bound target cells with NIR light. We observed in vivo tumor shrinkage after irradiation with NIR light in target cells expressing the epidermal growth factor receptor. The mAb-IR700 conjugates were most effective when bound to the cell membrane and produced no phototoxicity when not bound, suggesting a different mechanism for PIT as compared to conventional photodynamic therapies. Target-selective PIT enables treatment of cancer based on mAb binding to the cell membrane.
  • Rapid cancer detection by topically spraying a γ-glutamyltranspeptidase-activated fluorescent probe.
    Urano Y, Sakabe M, Kosaka N, Ogawa M, Mitsunaga M, Asanuma D, Kamiya M, Young MR, Nagano T, Choyke PL, Kobayashi H
    Science translational medicine, 3, 110, 110ra119, AMER ASSOC ADVANCEMENT SCIENCE, 2011年11月, ［査読有り］
    英語, 研究論文（学術雑誌）, The ability of the unaided human eye to detect small cancer foci or accurate borders between cancer and normal tissue during surgery or endoscopy is limited. Fluorescent probes are useful for enhancing visualization of small tumors but are typically limited by either high background signal or the requirement for administration hours to days before use. We synthesized a rapidly activatable, cancer-selective fluorescence imaging probe, gamma-glutamyl hydroxymethyl rhodamine green (gGlu-HMRG), with intramolecular spirocyclic caging for complete quenching. Activation occurs by rapid one-step cleavage of glutamate with gamma-glutamyltranspeptidase (GGT), which is not expressed in normal tissue, but is overexpressed on the cell membrane of various cancer cells, thus leading to complete uncaging and dequenching of the fluorescence probe. In vitro activation of gGlu-HMRG was evident in 11 human ovarian cancer cell lines tested. In vivo in mouse models of disseminated human peritoneal ovarian cancer, activation of gGlu-HMRG occurred within 1 min of topically spraying the tumor, creating high signal contrast between the tumor and the background. The gGlu-HMRG probe is practical for clinical application during surgical or endoscopic procedures because of its rapid and strong activation upon contact with GGT on the surface of cancer cells.
  • Biologically Optimized Nanosized Molecules and Particles: More than Just Size
    Michelle R. Longmire, Mikako Ogawa, Peter L. Choyke, Hisataka Kobayashi
    BIOCONJUGATE CHEMISTRY, 22, 6, 993, 1000, AMER CHEMICAL SOC, 2011年06月, ［査読有り］
    英語, The expanded biological and medical applications of nanomaterials place a premium on better understanding of the chemical and physical determinants of in vivo particles. Nanotechnology allows us to design a vast array of molecules with distinct chemical and biological characteristics, each with a specific size, charge, hydrophilicity, shape, and flexibility. To date, much research has focused on the role of particle size as a determinant of biodistribution and clearance. Additionally, much of what we know about the relationship between nanoparticle traits and pharmacokinetics has involved research limited to the gross average hydrodynamic size. Yet, other features such as particle shape and flexibility affect in vivo behavior and become increasingly important for designing and synthesizing nanosized molecules. Herein, we discuss determinants of in vivo behavior of nanosized molecules used as imaging agents with a focus on dendrimer-based contrast agents. We aim to discuss often overlooked or, yet to be considered, factors that affect in vivo behavior of synthetic nanosized molecules, as well as aim to highlight important gaps in current understanding.
  • In Vivo Relationship Between Thalamic Nicotinic Acetylcholine Receptor Occupancy Rates and Antiallodynic Effects in a Rat Model of Neuropathic Pain: Persistent Agonist Binding Inhibits the Expression of Antiallodynic Effects
    Masashi Ueda, Yasuhiko Iida, Tomoki Yoneyama, Tomoki Kawai, Mikako Ogawa, Yasuhiro Magata, Hideo Saji
    SYNAPSE, 65, 1, 77, 83, WILEY-LISS, 2011年01月, ［査読有り］
    英語, 研究論文（学術雑誌）, We have recently clarified that nicotinic acetylcholine receptors (nAChRs) expressed in the thalamus play an important role in antiallodynic effects produced by the nAChR agonist, 5-iodo-3-(2(S)-azetidinylmethoxy) pyridine (5IA). This study aimed to reveal the in vivo relationship between thalamic nAChR occupancy rates and antiallodynic effects using 5IA and [ (125)I] 5IA. We partially ligated the sciatic nerve of a rat to induce neuropathic pain. Antiallodynic effects were evaluated at 15, 30, 60, and 90 min after intracerebroventricular (i.c.v.) administration of multiple doses (1-100 nmol) of 5IA by the von Frey filament test. Receptor occupancy rates were measured by autoradiography at 15 and 90 min after administration. Antiallodynic effects of repetitive treatment of 5IA (5 and 50 nmol) were also examined. A significant and dose-dependent antiallodynic effect was observed 15 min after administration. It showed a good correlation with receptor occupancy rates (r = 0.97), indicating the binding of 5IA to nAChRs expressed in the thalamus involved in the antiallodynic effect. Five, 50, and 100 nmol of 5IA occupied the thalamic nAChRs until 90 min after administration, while the antiallodynic effect diminished. Five nanomoles of 5IA (which occupied 40% of thalamic nAChRs) showed a significant antiallodynic effect (percentage of the maximal possible effect (%MPE): 35 +/- 7) after the second administration, while 50 nmol of 5IA (which occupied 80% of thalamic nAChRs) did not (%MPE: 7 +/- 1). These findings suggest that not clearance of 5IA but desensitization of nAChRs caused by persistent binding of 5IA is responsible for the disappearance of antiallodynic effects. Synapse 65:77-83, 2011. (C) 2010 Wiley-Liss, Inc.
  • Rational chemical design of the next generation of molecular imaging probes based on physics and biology: mixing modalities, colors and signals
    Hisataka Kobayashi, Michelle R. Longmire, Mikako Ogawa, Peter L. Choyke
    CHEMICAL SOCIETY REVIEWS, 40, 9, 4626, 4648, ROYAL SOC CHEMISTRY, 2011年, ［査読有り］
    英語, In recent years, numerous in vivo molecular imaging probes have been developed. As a consequence, much has been published on the design and synthesis of molecular imaging probes focusing on each modality, each type of material, or each target disease. More recently, second generation molecular imaging probes with unique, multi-functional, or multiplexed characteristics have been designed. This critical review focuses on (i) molecular imaging using combinations of modalities and signals that employ the full range of the electromagnetic spectra, (ii) optimized chemical design of molecular imaging probes for in vivo kinetics based on biology and physiology across a range of physical sizes, (iii) practical examples of second generation molecular imaging probes designed to extract complementary data from targets using multiple modalities, color, and comprehensive signals (277 references).
  • Synthesis and biological evaluation of radio-iodinated benzimidazoles as SPECT imaging agents for NR2B subtype of NMDA receptor
    Takeshi Fuchigami, Hiroshi Yamaguchi, Mikako Ogawa, Le Biao, Morio Nakayama, Mamoru Haratake, Yasuhiro Magata
    BIOORGANIC & MEDICINAL CHEMISTRY, 18, 21, 7497, 7506, PERGAMON-ELSEVIER SCIENCE LTD, 2010年11月, ［査読有り］
    英語, 研究論文（学術雑誌）, In this study, the benzimidazole derivatives were synthesized and evaluated as imaging agents for the NR2B subtype of NMDA receptor. Among these ligands, 2-{[4-(4-iodobenzyl)piperidin-1-yl]methyl}benzimidazol-5-ol (8) and N-{2-[4-(4-iodobenzyl)-piperidin-1-ylmethyl]benzoimidazol-5-yl}-methanesulfonamide (9) exhibited high affinity for the NR2B subunit (K-i values; 7.28 nM for 8 and 5.75 nM for 9). In vitro autoradiography experiments demonstrated high accumulation in the forebrain regions but low in the cerebellum for both [I-125]8 and [I-125]9. These regional distributions of the radioligands correlated with the expression of the NR2B subunit. The in vitro binding of these ligands was inhibited by NR2B antagonist but not by other site ligands, which suggested the high selectivity of [I-125]8 and [I-125]9 for the NR2B subunit. In mice, the regional brain uptakes of [I-125]8 and [I-125]9 at 5-180 min after administration were 0.42-0.56% and 0.44-0.67% dose/g, respectively. The brain-to-blood ratio of [I-125]8 at 180 min was reduced by 34% in the presence of non-radioactive ligands and by 59% in the presence of the NR2B ligand Ro-25,6981. These results indicated that [I-125]8 could be partially bound to the NR2B subunit in vivo. Although the brain uptake of these benzimidazole derivatives was too low to allow for in vivo SPECT imaging, these compounds might be useful scaffolds for the development of imaging probes specific for the NMDA receptors. (C) 2010 Elsevier Ltd. All rights reserved.
  • Multiplexed imaging in cancer diagnosis: applications and future advances
    Hisataka Kobayashi, Michelle R. Longmire, Mikako Ogawa, Peter L. Choyke, Satomi Kawamoto
    LANCET ONCOLOGY, 11, 6, 589, 595, ELSEVIER SCIENCE INC, 2010年06月, ［査読有り］
    英語, The development of imaging technologies that have sufficient specificity and sensitivity to enable early, accurate detection of cancer and response to therapy has long been a goal in oncology. Various radiological techniques have been used for diagnosis and surveillance of disease recurrence and imaging has revolutionised oncology. However, despite the widespread use of technologies, the ability of currently available imaging methods to facilitate early detection, precise characterisation, and accurate localisation of maligant disease could be improved. The simultaneous use of two or more techniques, contrast reagents, signalling methods, or the coupling of agent and tissue properties to achieve so-called multiplexed imaging is a promising approach. In this review, we provide a broad overview of current and emerging multiplexed, imaging technologies.
  • X-ray computed tomography contrast agents prepared by seeded growth of gold nanoparticles in PEGylated dendrimer
    Chie Kojima, Yasuhito Umeda, Mikako Ogawa, Atsushi Harada, Yasuhiro Magata, Kenji Kono
    NANOTECHNOLOGY, 21, 24, 245104, IOP PUBLISHING LTD, 2010年06月, ［査読有り］
    英語, 研究論文（学術雑誌）, Gold nanoparticles (Au NPs) are a potential x-ray computed tomography (CT) contrast agent. A biocompatible and bioinactive surface is necessary for application of gold nanoparticle to CT imaging. Polyethylene glycol (PEG)-attached dendrimers have been used as a drug carrier with long blood circulation. In this study, the Au NPs were grown in the PEGylated dendrimer to produce a CT contrast agent. The Au NPs were grown by adding gold ions and ascorbic acid at various equivalents to the Au NP-encapsulated dendrimer solution. Both size and surface plasmon absorption of the grown Au NPs increased with adding a large number of gold ions. The x-ray attenuation of the Au NPs also increased after the seeded growth. The Au NPs grown in the PEG-attached dendrimer at the maximum under our conditions exhibited a similar CT value to a commercial iodine agent, iopamidol, in vitro. The Au NP-loaded PEGylated dendrimer and iopamidol were injected into mice and CT images were obtained at different times. The Au NP-loaded PEGylated dendrimer achieved a blood pool imaging, which was greater than a commercial iodine agent. Even though iopamidol was excreted rapidly, the PEGylated dendrimer loading the grown Au NP was accumulated in the liver.
  • New Strategies for Fluorescent Probe Design in Medical Diagnostic Imaging
    Hisataka Kobayashi, Mikako Ogawa, Raphael Alford, Peter L. Choyke, Yasuteru Urano
    CHEMICAL REVIEWS, 110, 5, 2620, 2640, AMER CHEMICAL SOC, 2010年05月, ［査読有り］
    英語
  • New Nanosized Biocompatible MR Contrast Agents Based on Lysine-Dendri-Graft Macromolecules
    Mikako Ogawa, Celeste A. S. Regino, Bernardo Marcelino, Mark Williams, Nobuyuki Kosaka, L. Henry Bryant, Peter L. Choyke, Hisataka Kobayashi
    BIOCONJUGATE CHEMISTRY, 21, 5, 955, 960, AMER CHEMICAL SOC, 2010年05月, ［査読有り］
    英語, 研究論文（学術雑誌）, Paramagnetic nanomaterials for use as magnetic resonance imaging (MRI) contrast agents have higher relaxivity than conventional low molecular weight MRI agents. However, the biocompatibility and pharmacokinetics of such nanomaterials will strongly affect the likelihood of clinical approval. We synthesized MRI contrast agents based on biocompatible lysine-dendri-grafts: Gd-BzDTPA-lysineG2 and Gd-BzDTPA-lysineG3. The relaxivity of Gd-BzDTPA-lysineG2 and Gd-BzDTPA-lysineG3 increased with sample temperature, while the relaxivity of Gd-BzDTPA-PAMAMG4 decreased with increasing sample temperature. The increase in relaxivity with increasing temperature may be attributed to accessibility of water to the internal Gd chelates with lysine-dendri-grafts, which does not occur with PAMAM dendrimers. Gd-BzDTPA-lysineG3 had a long intravascular half-life but were largely excreted by the kidneys. Therefore, Gd-BzDTPA-lysineG3 enhanced the blood vessels for longer periods than Gd-BzDTPA-PAMAMG4, but was still excreted through the kidney. Because of their biocompatibility, desirable magneto-physical characteristics and favorable pharmacokinetics, which are derived from different interior structures rather than the physical size, lysine-dendri-graft MRI contrast agents may be feasible for clinical use.
  • High sensitivity detection of cancer in vivo using a dual-controlled activation fluorescent imaging probe based on H-dimer formation and pH activation
    Mikako Ogawa, Nobuyuki Kosaka, Celeste A. S. Regino, Makoto Mitsunaga, Peter L. Choyke, Hisataka Kobayashi
    MOLECULAR BIOSYSTEMS, 6, 5, 888, 893, ROYAL SOC CHEMISTRY, 2010年05月, ［査読有り］
    英語, 研究論文（学術雑誌）, The key to improving the sensitivity of in vivo molecular imaging is to increase the target-to-background signal ratio (TBR). Optical imaging has a distinct advantage over other molecular imaging methods in that the fluorescent signal can be activated at the target thus reducing background signal. Previously, we found that H-dimer formation quenches fluorescence of xanthene fluorophores, and among these, TAMRA had the highest quenching ratio. Another approach to lowering background signal is to employ pH activation based on the photon-induced electron transfer (PeT) theory. We hypothesized that combining these two strategies could lead to greater quenching capacity than was possible with either probe alone. A pH-sensitive fluorophore, pHrodo or TAMRA was conjugated to the cancer targeting molecules, avidin (Av) and trastuzumab (Tra). As expected, both pHrodo and TAMRA formed H-dimers when conjugated to avidin or antibody and the dimerization resulted in efficient fluorescence quenching. In addition, pHrodo conjugated probes showed pH-dependent fluorescence activation. When the probes were used in an in vivo animal model, fluorescence endoscopy with Av-pHrodo depicted tumors with high TBR 1 h and 2 h after injection. Av-TAMRA also visualized tumors 1 h and h after the injection, however. TBR was lower due to the background signal from non-specific binding 1 h after the injection as well as background fluorescence from the unbound agent. Thus, we demonstrate that a dual-controlled activatable optical probe based on the combination of H-dimer formation and pH activation can achieve high TBR at early time points during in vivo molecular imaging.
  • Synthesis and evaluation of new imaging agent for central nicotinic acetylcholine receptor α7 subtype.
    Ogawa M, Nishiyama S, Tsukada H, Hatano K, Fuchigami T, Yamaguchi H, Matsushima Y, Ito K, Magata Y
    Nuclear medicine and biology, 37, 3, 347, 355, ELSEVIER SCIENCE INC, 2010年04月, ［査読有り］
    英語, 研究論文（学術雑誌）, Introduction: The nicotinic acetylcholine receptor (nAChR) alpha 7 subtype (alpha(7) nAChR) is one of the major nAChR subtypes in the brain. We synthesized C-11 labeled alpha(7) nAChR ligands, (R)-2-[C-11]methylamino-benzoic acid 1-aza-bicyclo[2.2.2]oct-3-yl ester ([C-11](R)-MeQAA) and its isomer (S)-[C-11]MeQAA, for in vivo investigation with positron emission tomography (PET). Then, the potential of (R)- and (S)-[C-11] MeQAA for in vivo imaging of alpha(7) nAChR in the brain was evaluated in mice and monkeys.
    Methods: The binding affinity for alpha(7) nAChR was measured using rat brain. Biodistribution and in vivo receptor blocking studies were undertaken in mice. Dynamic PET scans were performed in conscious monkeys.
    Results: The affinity for alpha(7) nAChR was 41 and 182 nM for (R)- and (S)-MeQAA, respectively. The initial uptake in the mouse brain was high ([C-11](R)-MeQAA: 7.68 and [C-11](S)-MeQAA: 6.65 %dose/g at 5 min). The clearance of [C-11](R)-MeQAA was slow in the hippocampus (alpha(7) nAChR-rich region) but was rapid in the cerebellum (alpha(7) nAChR-poor region). On the other hand, the clearance was fast for [C-11](S)-MeQAA in all regions. The brain uptake of [C-11](R)-MeQAA was decreased by methyllycaconitine (alpha(7) nAChR antagonist) treatment. In monkeys, alpha(7) nAChRs were highly distributed in the thalamus and cortex but poorly distributed in the cerebellum. The high accumulation was observed in the cortex and thalamus for [C-11](R)-MeQAA, while the uptake was rather homogeneous for [C-11](S)-MeQAA.
    Conclusions: [C-11](R)-MeQAA was successfully synthesized and showed high uptake to the brain. However, since the in vivo selectivity for alpha(7) nAChR was not enough, further PET kinetic analysis or structure optimization is needed for specific visualization of brain alpha(7) nAChRs in vivo. (C) 2010 Elsevier Inc. All rights reserved.
  • 125I標識ベンズイミダゾール誘導体のNMDA受容体NR2Bサブタイプ機能診断薬剤としての基礎的評価　　　　　　　　　　　　　　　
    淵上 剛志, 山口 博司, 小川 美香子, 楽 豹, 中山 守雄, 間賀田 泰寛
    日本薬学会年会要旨集, 130年会, 4, 124, 124, (公社)日本薬学会, 2010年03月, ［査読有り］
    日本語
  • Nicotinic acetylcholine receptors expressed in the ventralposterolateral thalamic nucleus play an important role in anti-allodynic effects
    M. Ueda, Y. Iida, A. Tominaga, T. Yoneyama, M. Ogawa, Y. Magata, H. Nishimura, Y. Kuge, H. Saji
    British Journal of Pharmacology, 159, 6, 1201, 1210, 2010年03月, ［査読有り］
    英語, 研究論文（学術雑誌）, Background and purpose: Much interest is currently being focused on the anti-nociceptive effects mediated by nicotinic acetylcholine (nACh) receptors, including their location and mechanism of action. The purpose of this study was to elucidate these issues using 5-iodo-3-(2(S)-azetidinylmethoxy)pyridine (5IA), a nACh receptor agonist, and [ 125I]5IA. Experimental approach: We partially ligated the sciatic nerve of Sprague-Dawley rat to induce neuropathic pain [Seltzer's partial sciatic nerve ligation (PSL) model]. We then examined the changes in nACh receptor density in the CNS using [ 125I]5IA autoradiography and the involvement of nACh receptors in anti-nociceptive effects in the region where changes occurred. Key results: Autoradiographic studies showed that the accumulation of [ 125I]5IA and the number of nACh receptors in the thalamus of PSL rats were increased about twofold compared with those in the sham-operated rats. No change was observed in other brain regions. Rats injected in the ventral posterolateral thalamic nucleus (VPL) with 5IA demonstrated a significant and dose-dependent anti-allodynic effect and this effect was completely antagonized by mecamylamine, injected with 5IA, into the VPL. The blockade of nACh receptors in the VPL by mecamylamine decreased by 70% the anti-allodynic effect of 5IA, given i.c.v. Moreover, mecamylamine given intra-VPL by itself, induced significant hyperalgesia. Conclusions and implications: Our findings suggest that the nACh receptors expressed in the VPL play an important role in the anti-allodynic effects produced by exogenous and endogenous agonists. © 2010 The Authors.
  • Semiquantitative assessment of the microdistribution of fluorescence-labeled monoclonal antibody in small peritoneal disseminations of ovarian cancer
    Nobuyuki Kosaka, Mikako Ogawa, David S. Paik, Chang H. Paik, Peter L. Choyke, Hisataka Kobayashi
    CANCER SCIENCE, 101, 3, 820, 825, WILEY-BLACKWELL PUBLISHING, INC, 2010年03月, ［査読有り］
    英語, 研究論文（学術雑誌）, Uniform antibody microdistribution throughout tumor nodules is crucial for antibody-targeted therapy, because non-uniform microdistribution leads to suboptimal therapeutic effect, a commonly observed limitation of therapeutic antibodies. Herein, we evaluated the microdistribution of different doses of intraperitoneally injected fluorescence-labeled full-antibody trastuzumab (15, 50, and 150 mu g) and its Fab fragment (trastuzumab-Fab: 15 and 50 mu g) in a mouse model of ovarian cancer with peritoneal disseminated tumor. A semiquantitative approach (central/peripheral accumulation ratio; C/P ratio) was developed using in situ fluorescence microscopy. Furthermore, we compared the microdistribution of intact trastuzumab with a mixed injection of trastuzumab and trastuzumab-Fab or serial injections of trastuzumab using in situ multicolor fluorescence microscopy. Fluorescence images after the administration of 15 or 50 mu g trastuzumab and 15 mu g trastuzumab-Fab demonstrated antibody accumulation in the tumor periphery, whereas administration of 150 mu g trastuzumab and 50 mu g trastuzumab-Fab showed relatively uniform accumulation throughout the tumor nodule. Using serial injections (19-h interval) of trastuzumab-rhodamine green and carboxytetramethylrhodamine (TAMRA), it was observed that the latterly injected trastuzumab-TAMRA was distributed more centrally than trastuzumab-rhodamine green injected first, whereas no difference was observed in the control mixed-injection group. Moreover, the mixed injection of trastuzumab and trastuzumab-Fab showed that trastuzumab-Fab distributed more centrally than the same amount of co-injected trastuzumab. Our results suggest that the strategies of increasing dose and using Fab fragments can be used to achieve a uniform antibody distribution within peritoneal disseminated nodules after intraperitoneal injection. Furthermore, serial-injection and mixed-injection strategies can modify antibody microdistribution within tumors and have the potential for preferential delivery of anticancer drugs to either the tumor periphery or its center. (Cancer Sci 2010; 101: 820-825)
  • Two-Step Synthesis of Galactosylated Human Serum Albumin as a Targeted Optical Imaging Agent for Peritoneal Carcinomatosis
    Celeste Aida S. Regino, Mikako Ogawa, Raphael Alford, Karen J. Wong, Noboyuki Kosaka, Mark Williams, Brian J. Feild, Masatoshi Takahashi, Peter L. Choyke, Hisataka Kobayashi
    JOURNAL OF MEDICINAL CHEMISTRY, 53, 4, 1579, 1586, AMER CHEMICAL SOC, 2010年02月, ［査読有り］
    英語, 研究論文（学術雑誌）, An optical probe, RG-(gal)(28)GSA, was synthesized to improve the detection of peritoneal implants by targeting the beta-D-galactose receptors highly expressed oil the cell surface of a wide variety of cancers arising from the ovary, pancreas, colon, and stomach. Evaluation of RG-(gal)(28)GSA, RG-(gal)(20)GSA, glucose-analogue RG-(glu)(28)GSA, and control RG-HSA demonstrates specificity for the galactose, binding to several human adenocarcinoma cell lines, and cellular internalization. Studies using peritoneally disseminated SHIN3 xenografts in mice also confirmed a preference for galactose with the ability to detect submillimeter size lesions. Preliminary toxicity study for RG-(gal)(28)GSA using Balb/c mice reveal 110 toxic effects up to 100x of the standard imaging dose of 1 mg/kg administered either intraperitoneally or intravenously. These data Indicate that RG-(gal)(28)GSA can selectively target a variety of human adenocarcinomas, can Improve intraoperative or endoscopic tumor detection and resection, and may have little or no toxic in vivo effects hence, it may be clinically translatable.
  • Microdistribution of Fluorescently-labeled Monoclonal Antibody in a Peritoneal Dissemination model of Ovarian Cancer
    Nobuyuki Kosaka, Mikako Ogawa, David S. Paik, Chang H. Paik, Peter L. Choyke, Hisataka Kobayashi
    REPORTERS, MARKERS, DYES, NANOPARTICLES, AND MOLECULAR PROBES FOR BIOMEDICAL APPLICATIONS II, 7576, SPIE-INT SOC OPTICAL ENGINEERING, 2010年, ［査読有り］
    英語, 研究論文（国際会議プロシーディングス）, The microdistribution of therapeutic monoclonal antibodies within a tumor is important for determining clinical response. Nonuniform microdistribution predicts therapy failure. Herein, we developed a semiquantitative method for measuring microdistribution of an antibody within a tumor using in situ fluorescence microscopy and sought to modulate the microdistribution by altering the route and timing of antibody dosing. The microdistribution of a fluorescently-labeled antibody, trastuzumab (50-mu g and 150-mu g intraperitoneal injection (i.p.), and 100-mu g intravenous injection (i.v.)) was evaluated in a peritoneal dissemination mouse model of ovarian cancer. In addition, we evaluated the microdistribution of concurrently-injected (30-mu g i.p. and 100-mu g i.v.) or serial (two doses of 30-mu g i.p.) trastuzumab using in situ multicolor fluorescence microscopy. After the administration of 50-mu g i.p. and 100-mu g i.v. trastuzumab fluorescence imaging showed no significant difference in the central to peripheral signal ratio (C/P ratio) and demonstrated a peripheral-dominant accumulation, whereas administration of 150-mu g i.p. trastuzumab showed relatively uniform, central dominant accumulation. With concurrent-i.p.-i.v. injections trastuzumab showed slightly higher C/P ratio than concurrently-injected i.p. trastuzumab. Moreover, in the serial injection study, the second injection of trastuzumab distributed more centrally than the first injection, while no difference was observed in the control group. Our results suggest that injection routes do not affect the microdistribution pattern of antibody in small peritoneal disseminations. However, increasing the dose results in a more uniform antibody distribution within peritoneal nodules. Furthermore, the serial i.p. injection of antibody can modify the microdistribution within tumor nodules. This work has implications for the optimal delivery of antibody based cancer therapies.
  • Fluorescence lifetime imaging of activatable target specific molecular probes
    Raphael Alford, Mikako Ogawa, Moinuddin Hassan, Amir H. Gandjbakhche, Peter L. Choyke, Hisataka Kobayashi
    CONTRAST MEDIA & MOLECULAR IMAGING, 5, 1, 1, 8, WILEY-HINDAWI, 2010年01月, ［査読有り］
    英語, 研究論文（学術雑誌）, In vivo optical imaging using fluorescently labeled self-quenched monoclonal antibodies, activated through binding and internalization within target cells, results in excellent target-to-background ratios. We hypothesized that these molecular probes could be utilized to accurately report on cellular internalization with fluorescence lifetime imaging (FLI). Two imaging probes were synthesized, consisting of the antibody trastuzumab (targeting HER2/neu) conjugated to Alexa Fluor750 in ratios of either 1:8 or 1:1. Fluorescence intensity and lifetime of each conjugate were initially determined at endosomal pHs. Since the 1:8 conjugate is self-quenched, the fluorescence lifetime of each probe was also determined after exposure to the known dequencher SDS. In vitro imaging experiments were performed using 3T3/HER2(+) and BALB/3T3 (HER2(-)) cell lines. Changes in fluorescence lifetime correlated with temperature- and time-dependent cellular internalization. In vivo imaging studies in mice with dual flank tumors [3T3/HER2(+) and BALB/3T3 (HER2(-))] detected a minimal difference in FLI. In conclusion, fluorescence lifetime imaging monitors the internalization of target-specific activatable antibody-fluorophore conjugates in vitro. Challenges remain in adapting this methodology to in vivo imaging. Copyright (C) 2010 John Wiley & Sons, Ltd.
  • In Vivo Real-Time, Multicolor, Quantum Dot Lymphatic Imaging
    Nobuyuki Kosaka, Mikako Ogawa, Noriko Sato, Peter L. Choyke, Hisataka Kobayashi
    JOURNAL OF INVESTIGATIVE DERMATOLOGY, 129, 12, 2818, 2822, NATURE PUBLISHING GROUP, 2009年12月, ［査読有り］
    英語, 研究論文（学術雑誌）, The lymphatic network is complex and difficult to visualize in real-time in vivo. Moreover, the direction of flow within lymphatic networks is often unpredictable especially in areas with well-developed "watershed'' or overlapping lymphatics. Herein, we report a method of in vivo real-time multicolor lymphatic imaging using cadmium-selenium quantum dots (Qdots) with a fluorescence imaging system that enables the simultaneous visualization of up to five distinct lymphatic basins in real-time. Five visually well-distinguishable carboxyl-Qdots (Qdot 545, 565, 585, 605, and 655) were selected and injected subdermally into mice at five different sites, and serially imaged in vivo or in situ under surgery with real-time multicolor lymphatic imaging. In all seven mice, in vivo lymphatic images successfully distinguished all five lymphatic basins with different colors in real-time. These visualizations of lymph node lasted up to at least 7 days. This method could have a considerable potential in lymphatic research for studying the anatomy and flow within the lymphatic system as well as in some limited clinical settings where real-time visible fluorescence could facilitate procedures under surgery or endoscopy.
  • New approaches to lymphatic imaging.
    Lucarelli RT, Ogawa M, Kosaka N, Turkbey B, Kobayashi H, Choyke PL
    Lymphatic research and biology, 7, 4, 205, 214, 2009年12月, ［査読有り］
  • Clinical implications of near-infrared fluorescence imaging in cancer
    Nobuyuki Kosaka, Mikako Ogawa, Peter L. Choyke, Hisataka Kobayashi
    FUTURE ONCOLOGY, 5, 9, 1501, 1511, FUTURE MEDICINE LTD, 2009年11月, ［査読有り］
    英語, Near-infrared (NIR) fluorescence cancer imaging is a growing field for both preclinical and clinical application to the clinical management for cancer patients due to its advantageous features, including a high spatial resolution, portability, real-time display and detailed molecular profiling with the multiplexed use of fluorescent probes. In this review, we present a basic concept of NIR fluorescence imaging and overview its potential clinical applications for in vivo cancer imaging, including cancer detection/characterization, lymphatic imaging (sentinel lymph node detection) and surgical/endoscopic guidance. NIR fluorescence imaging can compensate some limitations of conventional imaging modalities, and thus it could play an important role for cancer imaging combined with other modalities in clinical practice.
  • Dual-Modality Molecular Imaging Using Antibodies Labeled with Activatable Fluorescence and a Radionuclide for Specific and Quantitative Targeted Cancer Detection
    Mikako Ogawa, Celeste A. S. Regino, Jurgen Seidel, Michael V. Green, Wenze Xi, Mark Williams, Nobuyuki Kosaka, Peter L. Choyke, Hisataka Kobayashi
    BIOCONJUGATE CHEMISTRY, 20, 11, 2177, 2184, AMER CHEMICAL SOC, 2009年11月, ［査読有り］
    英語, 研究論文（学術雑誌）, Multimodality molecular imaging should have potential for compensating the disadvantages and enhancing the advantages of each modality. Nuclear imaging is superior to optical imaging in whole body imaging and in quantification due to good tissue penetration of gamma rays. However, target specificity can be compromised by high background signal due to the always signal ON feature of nuclear probes. In contrast, optical imaging can be superior in target-specific imaging by employing target-specific signal activation systems, although it is not quantitative because of signal attenuation. In this study, to take advantage of the mutual cooperation of each modality, multimodality imaging was performed by a combination of quantitative radiolabeled probe and an activatable optical probe. The monoclonal antibodies, panitumumab (anti-HER1) and trastuzumab (anti-HER2), were labeled with In-111 and ICG and tested. in both HER1 and HER2 tumor bearing mice by the cocktail injection of radiolabeled and optical probes and by the single injection of a dual-labeled probe. The optical and nuclear images were obtained over 6 days after the conjugates injection. The fluorescence activation properties of ICG labeled antibodies were also investigated by in vitro microscopy. In vitro microscopy demonstrated that there was no fluorescence signal with either panitumumab-ICG or trastuzumab-ICG, when the probes were bound to cell surface antigens but were not yet internalized. After the conjugates were internalized into the cells, both conjugates showed bright fluorescence signal only in the target cells. These results show that both conjugates work as activatable probes. In in vivo multimodality imaging by injection of a cocktail of radio-optical probes, only the target specific tumor was visualized by optical imaging. Meanwhile, the biodistribution profile of the injected antibody was provided by nuclear imaging. Similar results were obtained with radio and optical dual-labeled probes, and it is confirmed that pharmacokinetic properties did not affect the results above. Here, we could characterize the molecular targets by activatable optical probes and visualize the delivery of targeting molecules quantitatively by radioactive probes. Multimodality molecular imaging combining activatable optical and radioactive probes has great potential for simultaneous visualization, characterization, and measurement of biological processes.
  • Toxicity of Organic Fluorophores Used in Molecular Imaging: Literature Review
    Raphael Alford, Haley M. Simpson, Josh Duberman, G. Craig Hill, Mikako Ogawa, Celeste Regino, Hisataka Kobayashi, Peter L. Choyke
    MOLECULAR IMAGING, 8, 6, 341, 354, B C DECKER INC, 2009年11月, ［査読有り］
    英語, Fluorophores are potentially useful for in vivo cancer diagnosis. Using relatively inexpensive and portable equipment, optical imaging with fluorophores permits real-time detection of cancer. However, fluorophores can be toxic and must be investigated before they can be administered safely to patients. A review of published literature on the toxicity of 19 widely used fluorophores was conducted by searching 26 comprehensive biomedical and chemical literature databases and analyzing the retrieved material. These fluorophores included Alexa Fluor 488 and 514, BODIPY FL, BODIPY R6G, Cy 5.5, Cy 7, cypate, fluorescein, indocyanine green, Oregon green, 8-phenyl BODIPY, rhodamine 110, rhodamine 6G, rhodamine X, rhodol, TAMRA, Texas red, and Tokyo green. Information regarding cytotoxicity, tissue toxicity, in vivo toxicity, and mutagenicity was included. Considerable toxicity-related information was available for the Food and Drug Administration (FDA)-approved compounds indocyanine green and fluorescein, but published information on many of the non-FDA-approved fluorophores was limited. The information located was encouraging because the amounts of fluorophore used in molecular imaging probes are typically much lower than the toxic doses described in the literature. Ultimately, the most effective and appropriate probes for use in patients will be determined by their fluorescent characteristics and the safety of the conjugates.
  • ニコチン慢性投与中における脳循環代謝変化の小動物PETによる追跡　　　　　　　　　　　　　　　
    山口 博司, 二ツ橋 昌実, 尾内 康臣, 鳥塚 達郎, 小杉 睦, 小川 美香子, 淵上 剛志, 間賀田 泰寛
    核医学, 46, 3, 327, 327, (一社)日本核医学会, 2009年09月, ［査読有り］
    日本語
  • Development of N-[C-11]methylamino 4-hydroxy-2(1H)-quinolone derivatives as PET radioligands for the glycine-binding site of NMDA receptors
    Takeshi Fuchigami, Terushi Haradahira, Noriko Fujimoto, Yumiko Nojiri, Takahiro Mukai, Fumihiko Yamamoto, Takashi Okauchi, Jun Maeda, Kazutoshi Suzuki, Tetsuya Suhara, Hiroshi Yamaguchi, Mikako Ogawa, Yasuhiro Magata, Minoru Maeda
    BIOORGANIC & MEDICINAL CHEMISTRY, 17, 15, 5665, 5675, PERGAMON-ELSEVIER SCIENCE LTD, 2009年08月, ［査読有り］
    英語, 研究論文（学術雑誌）, In this study, we synthesized and evaluated several amino 4-hydroxy-2(1H)-quinolone (4HQ) derivatives as new PET radioligand candidates for the glycine site of the NMDA receptors. Among these ligands, we discovered that 7-chloro-4-hydroxy-3-{3-(4-methylaminobenzyl) phenyl}-2-(1H)-quinolone (12) and 5-ethyl-7-chloro-4-hydroxy-3-(3-methylaminophenyl)-2(1H)-quinolone (32) have high affinity for the glycine site (K-i values; 11.7 nM for 12 and 11.8 nM for 32). In vitro autoradiography experiments indicated that [C-11]12 and [C-11]32 showed high specific binding in the brain slices, which were strongly inhibited by both glycine agonists and antagonists. In vivo brain uptake of these C-11-labeled 4HQs were examined in normal mice. Cerebellum to blood ratio of accumulation, of both [C-11]12 and [C-11]32 at 30 min were 0.058, which were slightly higher than those of cerebrum to blood ratio (0.043 and 0.042, respectively). These results indicated that [C-11]12 and [C-11]32 have poor blood brain barrier permeability. Although the plasma protein-binding ratio of [C-11]32 was much lower than methoxy analogs (71% vs 94-98%, respectively), [C-11]32 still binds with plasma protein strongly. It is conjectured that still acidic moiety and high affinity with plasma protein of [C-11]32 may prevent in vivo brain uptake. In conclusion, [C-11]12 and [C-11]32 are unsuitable for imaging cerebral NMDA receptors. (C) 2009 Elsevier Ltd. All rights reserved.
  • Imaging of Tumor Angiogenesis: Functional or Targeted?
    Baris Turkbey, Hisataka Kobayashi, Mikako Ogawa, Marcelino Bernardo, Peter L. Choyke
    AMERICAN JOURNAL OF ROENTGENOLOGY, 193, 2, 304, 313, AMER ROENTGEN RAY SOC, 2009年08月, ［査読有り］
    英語, OBJECTIVE. Angiogenesis-the growth of new vessels-is both a normal physiologic response and a critical step in many pathologic processes, particularly cancer. Imaging has long relied on the different enhancement characteristics of cancer compared with normal tissue; the information generated is often primarily morphologic and qualitative. However, more quantitative methods based on functional and targeted imaging have recently emerged.
    CONCLUSION. In this article, we review both functional and targeted imaging techniques for assessing tumor angiogenesis.
  • H-Type Dimer Formation of Fluorophores: A Mechanism for Activatable, in Vivo Optical Molecular Imaging
    Mikako Ogawa, Nobuyuki Kosaka, Peter L. Choyke, Hisataka Kobayashi
    ACS CHEMICAL BIOLOGY, 4, 7, 535, 546, AMER CHEMICAL SOC, 2009年07月, ［査読有り］
    英語, 研究論文（学術雑誌）, In vivo molecular imaging with target-specific activatable "smart" probes, which yield fluorescence only at the intended target, enables sensitive and specific cancer detection. Dimerization and fluorescence quenching has been shown to occur in concentrated aqueous solutions of various fluorophores. Here, we hypothesized that fluorophore dimerization and quenching after conjugation to targeting proteins can occur at low concentration. This dimerization can be exploited as a mechanism for fluorescence activation. Rhodamine derivatives were conjugated to avidin and trastuzumab, which target D-galactose receptor and HER2/neu antigen, respectively. After conjugation, a large proportion of R6G and TAMRA formed H-type dinners, even at low concentrations, but could be fully dequenched upon dissociation of the dinners to monomers. To demonstrate the fluorescence activation effect during in vivo fluorescence endoscopic molecular imaging, a highly quenched probe, avidin-TAMRA, or a minimally quenched probe, avidin-Alexa488, was administered into mice with ovarian metastases to the peritoneum. The tumors were clearly visualized with avidin-TAMRA, with low background fluorescence; in contrast, the background fluorescence was high for avidin-Alexa488. Thus, H-dimer formation as a mechanism of fluorescence quenching could be used to develop fluorescence activatable probes for in vivo molecular imaging.
  • In Vivo Stable Tumor-Specific Painting in Various Colors Using Dehalogenase-Based Protein-Tag Fluorescent Ligands
    Nobuyuki Kosaka, Mikako Ogawa, Peter L. Choyke, Natasha Karassina, Cesear Corona, Mark McDougall, David T. Lynch, Clifford C. Hoyt, Richard M. Levenson, Georgyi V. Los, Hisataka Kobayashi
    BIOCONJUGATE CHEMISTRY, 20, 7, 1367, 1374, AMER CHEMICAL SOC, 2009年07月, ［査読有り］
    英語, 研究論文（学術雑誌）, In vivo fluorescence cancer imaging is an important tool in understanding tumor growth and therapeutic monitoring and can be performed either with endogenously produced fluorescent proteins or with exogenously introduced fluorescent probes bound to targeting molecules. However, endogenous fluorescence proteins cannot be altered after transfection, thus requiring rederivation of cell lines for each desired color, while exogenously targeted fluorescence probes are limited by the heterogeneous expression of naturally occurring cellular targets. In this study, we adapted the dehalogenase-based protein-Tag (HaloTag) system to in vivo cancer imaging, by introducing highly expressed HaloTag receptors (HaloTagR) in cancer cells coupled with a range of externally injected fluorophore-conjugated dehalogenase-reactive reactive linkers. Tumor nodules arising from a single transfected cell line were stably labeled with fluorescence varying in emission spectra front green to near-infrared. After establishing and validating a SHIN3 cell line stably transfected with HaloTagR (HaloTagR-SHIN3), in vivo spectral fluorescence imaging Studies were performed in live animals using a peritoneal dissemination model. The tumor nodules arising from HaloTagR-SHIN3 could be successfully labeled by four different fluorophore-conjugated HaloTag-ligands each emitting light at different wavelengths. These fluorophores could be alternated on serial imaging sessions permitting assessment of interval growth. Fluorescence was retained in histological specimens after fixation. Thus, this tagging system proves versatile both for in vivo and in vitro imaging without requiring modification of the underlying cell line. Thus, this strategy can overcome some of the limitations associated with the use of endogenous fluorescent proteins and exogenous targeted optical agents in current use.
  • Multicolor in vivo targeted imaging to guide real-time surgery of HER2-positive micrometastases in a two-tumor coincident model of ovarian cancer
    Michelle Longmire, Nobuyuki Kosaka, Mikako Ogawa, Peter L. Choyke, Hisataka Kobayashi
    CANCER SCIENCE, 100, 6, 1099, 1104, WILEY-BLACKWELL PUBLISHING, INC, 2009年06月, ［査読有り］
    英語, 研究論文（学術雑誌）, One of the primary goals of oncological molecular imaging is to accurately identify and characterize malignant tissues in vivo. Currently, molecular imaging relies on targeting a single molecule that while overexpressed in malignancy, is often also expressed at lower levels in normal tissue, resulting in reduced tumor to background ratios. One approach to increasing the specificity of molecular imaging in cancer is to use multiple probes each with distinct fluorescence to target several surface antigens simultaneously, in order to identify tissue expression profiles, rather than relying on the expression of a single target. This next step forward in molecular imaging will rely on characterization of tissue based on fluorescence and therefore will require the ability to simultaneously identify several optical probes each attached to different targeting ligands. We created a novel 'coincident' ovarian cancer mouse model by coinjecting each animal with two distinct cell lines, HER2(+)/red fluorescent protein (RFP)(-) SKOV3 and HER2(-)/RFP(+) SHIN3-RFP, in order to establish a model of disease in which animals simultaneously bore tumors with two distinct phenotypes (HER2(+)/RFP(-), HER2(-)/RFP(+)), which could be utilized for multicolor imaging. The HER2 receptor of the SKOV3 cell line was targeted with a trastuzumab-rhodamine green conjugate to create green tumor implants, whereas the RFP plasmid of the SHIN3 cells created red tumor implants. We demonstrate that real-time in vivo multicolor imaging is feasible and that fluorescence characteristics can then serve to guide the surgical removal of disease. (Cancer Sci 2009; 100: 1099-1104).
  • Multicolor imaging of lymphatic function with two nanomaterials: quantum dot-labeled cancer cells and dendrimer-based optical agents
    Hisataka Kobayashi, Mikako Ogawa, Nobuyuki Kosaka, Petet L. Choyke, Yasuteru Urano
    NANOMEDICINE, 4, 4, 411, 419, FUTURE MEDICINE LTD, 2009年06月, ［査読有り］
    英語, 研究論文（学術雑誌）, Aim: The lymphatics, critical conduits of metastases, are difficult to study because of their size and location. Two approaches to lymphatic imaging have been employed; cancer cell labeling provides information on cell migration and metastasis and macromolecular contrast agents enable visualization of the lymphatic drainage and identification of sentinel lymph node. Only one of these approaches is typically employed during an imaging examination. Here, we demonstrate the combined use of both approaches. Method: In this study, we simultaneously visualize migration of quantum dot-labeled melanoma cells and the lymphatics using optically labeled dendrimers in vivo. Results: The appropriate use of two nanomaterials, quantum dots and dendrimers, enabled the simultaneous tracking of cancer cells within draining lymphatics. Conclusion: This technique could enable better understanding of lymph node metastasis.
  • Central in Vivo Nicotinic Acetylcholine Receptor Imaging Agents for Positron Emission Tomography (PET) and Single Photon Emission Computed Tomography (SPECT)
    Mikako Ogawa, Hideo Tsukada, Kentaro Hatano, Yasuomi Ouchi, Hideo Saji, Yasuhiro Magata
    BIOLOGICAL & PHARMACEUTICAL BULLETIN, 32, 3, 337, 340, PHARMACEUTICAL SOC JAPAN, 2009年03月, ［査読有り］
    英語, 研究論文（学術雑誌）, Positron emission tomography (PET) and single photon emission computed tomography (SPECT) are useful for non-invasive investigation of brain receptors. With these imaging techniques, changes in brain receptor densities and distributions during chronic drug treatments and disease progressions can be tracked for a long period. Appropriate radiolabeled imaging agents are necessary for PET and SPECT molecular imaging. Nicotinic acetylcholine receptors (nAChRs) play important roles in brain functions. The alpha 4 beta 2 find alpha 7 are the major nAChR subtypes in the brain. To date, several subtype selective radiolabeled ligands for nAChR have been reported. For the alpha 4 beta 2 subtype, some agents are already applied for human studies, but only a few agents are developed for the alpha 7 subtype. Here, we overview our results of [I-125/123]5-iodo-3-(2(S)-azetidinylmethoxy)pyridine and 5-[C-11]methyl-3-(2-(S)-azetidinylmethoxy)pyridine ([C-11]5MA) for alpha 4 beta 2 subtype imaging, and [C-11](R)-2-methylamino-benzoic acid 1-aza-bicyclo[2.2.2]oct-3-yl ester ([C-11](R)-McQAA) for alpha 7 subtype imaging.
  • Fluorophore-Quencher Based Activatable Targeted Optical Probes for Detecting in Vivo Cancer Metastases
    Mikako Ogawa, Nobuyuki Kosaka, Michelle R. Longmire, Yasuteru Urano, Peter L. Choyke, Hisataka Kobayashi
    MOLECULAR PHARMACEUTICS, 6, 2, 386, 395, AMER CHEMICAL SOC, 2009年03月, ［査読有り］
    英語, 研究論文（学術雑誌）, In vivo molecularly targeted fluorescence imaging of tumors has been proposed as a strategy for improving cancer detection and management. Activatable fluorophores, which increased their fluorescence by 10-fold after binding tumor cells, result in much higher target to background ratios than conventional fluorophores. We developed an in vivo targeted activatable optical imaging probe based on a fluorophore-quencher pair, bound to a targeting moiety. With this system, fluorescence is quenched by the fluorophore-quencher interaction outside cancer cells, but is activated within the target cells by dissociation of the fluorophore-quencher pair. We selected the TAMRA (fluorophore)-QSY7 (quencher) pair and conjugated it to either avidin (targeting the D-galactose receptor) or trastuzumab (a monoclonal antibody against the human epithelial growth factor receptor type2 (HER2/neu)) and evaluated their performance in mouse models of cancer. Two probes, TAMRA-QSY7 conjugated avidin (Av-TM-Q7) and trastuzumab (Traz-TM-07) were synthesized. Both demonstrated better than similar self-quenching probes. In vitro fluorescence microscopic studies of SHIN3 and NIH/3T3/HER2+ cells demonstrated that Av-TM-Q7 and Traz-TM-Q7 produced high intracellular fluorescent signal. In vivo imaging with Av-TM-Q7 and Traz-TM-07 in mice enabled the detection of small tumors. This molecular imaging probe, based on a fluorophore-quencher pair conjugated to a targeting ligand, successfully detected tumors in vivo due to its high activation ratio and low background signal. Thus, these activatable probes, based on the fluorophore-quencher system, hold promise clinically for "see and treat" strategies of cancer management.
  • In vivo Molecular Imaging of Cancer with a Quenching Near-Infrared Fluorescent Probe Using Conjugates of Monoclonal Antibodies and Indocyanine Green
    Mikako Ogawa, Nobuyuki Kosaka, Peter L. Choyke, Hisataka Kobayashi
    CANCER RESEARCH, 69, 4, 1268, 1272, AMER ASSOC CANCER RESEARCH, 2009年02月, ［査読有り］
    英語, 研究論文（学術雑誌）, Near-infrared (NIR) fluorophores have several advantages over visible fluorophores, including improved tissue penetration and lower autofluorescence; however, only indocyanine green (ICG) is clinically approved. Its use in molecular imaging probes is limited because it loses its fluorescence after protein binding. This property can be harnessed to create an activatable NIR probe. After cell binding and internalization, ICG dissociates from the targeting antibody, thus activating fluorescence. ICG was conjugated to the antibodies daclizumab (Dac), trastuzumab (Tra), or panitumumab (pan). The conjugates had almost no fluorescence in PBS but became fluorescent after SDS and 2-mercaptoethanol, with a quenching capacity of 10-fold for 1:1 conjugates and 40- to 50-fold for 1:5 conjugates. In vitro microscopy showed activation within the endolysosomes in target cells. In vivo imaging in mice showed that CD25-expressing tumors were specifically visualized with Dac-ICG. Furthermore, tumors overexpressing HER1 and HER2 were successfully characterized in vivo by using Pan-ICG(1:5) and Tra-ICG(1:5), respectively. Thus, we have developed an activatable NIR optical probe that "switches on" only in target cells. Because both the antibody and the fluorophore are Food and Drug Administration approved, the likelihood of clinical translation is improved. [Cancer lies 2009;69(4):1268-72]
  • Activatable optical imaging probes with various fluorophore-quencher combinations
    Mikako Ogawa, Nobuyuki Kosaka, Yasuteru Urano, Peter L. Choyke, Hisataka Kobayashi
    Progress in Biomedical Optics and Imaging - Proceedings of SPIE, 7190, 2009年, ［査読有り］
    英語, 研究論文（国際会議プロシーディングス）, Molecular imaging probes rely on high target-to-background ratios (TBR) to achieve maximum sensitivity and specificity. We utilized "quenchers" to turn off the background signal from the unbound probe and investigated the ability of specific fluorophore-quencher pairs to activate at target tissues. Both fluorophore and quencher were conjugated to a single cancer targeting molecule, either avidin or antibody. Fluorescence signal from these targeting molecules was "turned off" by the quencher in the unbound state, but was "turned on" only when the molecules bound to the cell surface target and was internalized. We tested the following fluorophore-quencher combinations based on fluorescence resonance energy transfer (FRET) pairs
    OregonG-BHQ1, RhodG-BHQ1/ATTO540Q, TAMRA-QSY7/QSY21, TexRed-QSY21, Alexa647-QSY21, Cy5.5-QSY21/BHQ3 and Alexa680-QSY21/BHQ3. Among these, only RhodGATTO540Q and TAMRA-QSY7/21 pair showed activation upon cell binding/internalization. Among these combinations, TAMRA-QSY7 pair showed the highest activation (40-fold and 13-fold for avidin and antibody conjugate, respectively) as measured with an in vitro dissociation assay. The activation was dependent on the method used to conjugate fluorophores and quenchers to the targeting molecule. In vitro microscopic studies with TAMRA-QSY7 pair conjugated to avidin or antibody showed high fluorescent signal inside the target cancer cells, indicating activation after internalization. In vivo imaging studies in tumor bearing mice demonstrated that tumors could be clearly detected with low background. Although the precise quenching mechanism remains to be determined, this activation system can achieve high TBR in vivo molecular imaging. © 2009 SPIE.
  • Activatable optical imaging probes with various fluorophore-quencher combinations
    Mikako Ogawa, Nobuyuki Kosaka, Yasuteru Urano, Peter L. Choyke, Hisataka Kobayashi
    REPORTERS, MARKERS, DYES, NANOPARTICLES, AND MOLECULAR PROBES FOR BIOMEDICAL APPLICATIONS, 7190, SPIE-INT SOC OPTICAL ENGINEERING, 2009年, ［査読有り］
    英語, 研究論文（国際会議プロシーディングス）, Molecular imaging probes rely on high target-to-background ratios (TBR) to achieve maximum sensitivity and specificity. We utilized "quenchers" to turn off the background signal from the unbound probe and investigated the ability of specific fluorophore-quencher pairs to activate at target tissues. Both fluorophore and quencher were conjugated to a single cancer targeting molecule, either avidin or antibody. Fluorescence signal from these targeting molecules was "turned off" by the quencher in the unbound state, but was "turned on" only when the molecules bound to the cell surface target and was internalized.
    We tested the following fluorophore-quencher combinations based on fluorescence resonance energy transfer (FRET) pairs; OregonG-BHQ1, RhodG-BHQ1/ATTO540Q, TAMRA-QSY7/QSY21, TexRed-QSY21, Alexa647-QSY21, Cy5.5-QSY21/BHQ3 and Alexa680-QSY21/BHQ3. Among these, only RhodG-ATTO540Q and TAMRA-QSY7/21 pair showed activation upon cell binding/internalization. Among these combinations, TAMRA-QSY7 pair showed the highest activation (40-fold and 13-fold for avidin and antibody conjugate, respectively) as measured with an in vitro dissociation assay. The activation was dependent on the method used to conjugate fluorophores and quenchers to the targeting molecule. In vitro microscopic studies with TAMRA-QSY7 pair conjugated to avidin or antibody showed high fluorescent signal inside the target cancer cells, indicating activation after internalization. In vivo imaging studies in tumor bearing mice demonstrated that tumors could be clearly detected with low background.
    Although the precise quenching mechanism remains to be determined, this activation system can achieve high TBR in vivo molecular imaging.
  • Tumor-Specific Detection of an Optically Targeted Antibody Combined with a Quencher-Conjugated Neutravidin "Quencher-Chaser": A Dual "Quench and Chase" Strategy to Improve Target to Nontarget Ratios for Molecular Imaging of Cancer
    Mikako Ogawa, Nobuyuki Kosaka, Peter L. Choyke, Hisataka Kobayashi
    BIOCONJUGATE CHEMISTRY, 20, 1, 147, 154, AMER CHEMICAL SOC, 2009年01月, ［査読有り］
    英語, 研究論文（学術雑誌）, In vivo molecular cancer imaging with monoclonal antibodies has great potential not only for cancer detection, but also for cancer characterization. However, the prolonged retention of intravenously injected antibody in the blood causes low target tumor-to-background ratio (TBR). Avidin has been used as a "chase" to clear the unbound, circulating biotinylated antibody and decrease the background signal. Here, we utilize a combined approach of a fluorescence resonance energy transfer (FRET) quenched antibody with an "avidin chase" to increase TBR. Trastuzumab, a humanized monoclonal antibody against human epidermal growth factor receptor type 2 (HER2), was biotinylated and conjugated with the near-infrared (NIR) fluorophore Alexa680 to synthesize Tra-Alexa680-biotin. Next, the FRET quencher, QSY-21, was conjugated to avidin, neutravidin (nAv), or streptavidin (sAv), thus creating Av-QSY21, nAv-QSY21, or sAv-QSY21 as "chasers". The fluorescence was quenched in vitro by binding Tra-Alexa680-biotin to Av-QSY21, nAv-QSY21, or sAv-QSY21. To evaluate if the injection of quencher-conjugated avidin derivatives can improve target TBR by using a dual "quench and chase" strategy, both target (3T3/HER2+) and nontarget (Balb3T3/ZsGreen) tumor-bearing mice were employed. The "FRET quench" effect induced by all the QSY21 avidin-based conjugates reduced but did not totally eliminate background signal from the blood pool. The addition of nAv-QSY21 administration increased target TBR mainly because of the "chase" effect where unbound conjugated antibody was preferentially cleared to the liver. The relatively slow clearance of unbound nAv-QSY21 leads to further reductions in background signal by leaking out of the vascular space and binding to unbound antibodies in the extravascular space of tumors, resulting in decreased nontarget tumor-to-background ratios but increased target TBR due to the "FRET quench" effect, because target-bound antibodies were internalized and could not bind to nAv-QSY21. In conclusion, the proposed "quench-and-chase" system combines two strategies, fluorescent quenching and avidin chasing, to improve target TBR and reduce nontarget TBR, which should result in both improved tumor sensitivity and improved specificity.
  • In vivo target-specific activatable near-infrared optical labeling of humanized monoclonal antibodies
    Mikako Ogawa, Celeste A. S. Regino, Peter L. Choyke, Hisataka Kobayashi
    MOLECULAR CANCER THERAPEUTICS, 8, 1, 232, 239, AMER ASSOC CANCER RESEARCH, 2009年01月, ［査読有り］
    英語, 研究論文（学術雑誌）, Imaging with labeled monoclonal antibodies may be useful in detecting, staging, and monitoring tumors. Despite their high affinity and specificity, a critical limitation of antibody imaging is the high background signal due to prolonged clearance from the blood, which reduces the tumor-to-background ratio. To address this problem, we developed a molecular imaging probe consisting of multiple self-quenching fluorophores [Cy5.5 or Alexa Fluor 680 (Alexa680)] conjugated to a monoclonal antibody (trastuzumab) to synthesize Tra-Cy5.5(SQ) or Tra-Alexa680(SQ), respectively. This agent only becomes fluorescently "active" after cellular internalization but is quenched in the unbound state leading to high tumor-to-background ratios. The in vitro quenching capacity for both conjugates was similar to 9-fold. In vivo imaging experiments were done in mice bearing both 3T3/HER-2(+) and BALB/3T3/ZsGreen/HER-2(-) xenografts. Tra-Alexa680(SQ) produced specific enhancement in the 3T3/HER-2(+) tumors but not in the HER-2(-) control tumors. However, Tra-Cy5.5(SQ) produced nonspecific enhancement in both 3T3/HER-2(+) and control tumors. In conclusion, whereas Cy5.5-conjugates produced nonspecific results as well as rapid liver accumulation, conjugating multiple Alexa680 molecules to a single monoclonal antibody resulted in a near-infrared optical agent that activated within specific target tumors with high tumor-to-background ratio with considerable potential for clinical translation. [Mol Cancer Ther 2009;8(1):232-9]
  • Multi-targeted multi-color in vivo optical imaging in a model of disseminated peritoneal ovarian cancer
    Nobuyuki Kosaka, Mikako Ogawa, Michelle R. Longmire, Peter L. Choyke, Hisataka Kobayashi
    JOURNAL OF BIOMEDICAL OPTICS, 14, 1, 014023, SPIE-SOC PHOTOPTICAL INSTRUMENTATION ENGINEERS, 2009年01月, ［査読有り］
    英語, 研究論文（学術雑誌）, Commonly used in flow cytometry, multiplexed optical probes can diagnose multiple types of cell surface marker, potentially leading to improved diagnosis accuracy in vivo. Herein, we demonstrate the targeting of two different tumor markers in models of disseminated ovarian cancer. Two ovarian cancer cell lines (SKOV3 and SHIN3) were employed; both overexpress D-galactose receptor (D-galR), but only SKOV3 overexpresses HER2/neu. Additionally, fusion tumors composed of SKOV3 and SHIN3/RFP were evaluated. Both galactosyl serum albumin-rhodamine green (GSA-RhodG), which binds D-galR, and trastuzumab-Alexa680, which binds HER2/neu, were administered to tumor-bearing mice for in vivo fluorescence imaging and in situ fluorescence microscopy. In vivo fluorescence imaging depicted 64 of 69 SKOV3 tumors (94.2% )based on their dual spectra corresponding to both RhodG and Alexa680, while all 71 SHIN3 tumors (100%) were detected based on their single spectrum corresponding only to RhodG. All 59 SHIN3 and 36 SKOV3 tumors were correctly diagnosed with in situ microscopy. Additionally, in the mixed tumor model, all tumors could be depicted using the RhodG spectrum, but only SKOV3 components also showed the Alexa680 spectrum. In conclusion, multitargeted multicolor optical imaging enabled specific in vivo diagnosis of tumors expressing distinct patterns of receptors, leading to improved diagnostic accuracy. (C) 2009 Society of Photo-Optical Instrumentation Engineers. [DOI: 10.1117/1.3083449]
  • Molecular probes for the in vivo imaging of cancer
    Raphael Alford, Mikako Ogawa, Peter L. Choyke, Hisataka Kobayashi
    MOLECULAR BIOSYSTEMS, 5, 11, 1279, 1291, ROYAL SOC CHEMISTRY, 2009年, ［査読有り］
    英語, Advancements in medical imaging have brought about unprecedented changes in the in vivo assessment of cancer. Positron emission tomography, single photon emission computed tomography, optical imaging, and magnetic resonance imaging are the primary tools being developed for oncologic imaging. These techniques may still be in their infancy, as recently developed chemical molecular probes for each modality have improved in vivo characterization of physiologic and molecular characteristics. Herein, we discuss advances in these imaging techniques, and focus on the major design strategies with which molecular probes are being developed.
  • Targeting of Lectinlike Oxidized Low-Density Lipoprotein Receptor 1 (LOX-1) with (99m)TCLabeled Anti-LOX-1 Antibody: Potential Agent for Imaging of Vulnerable Plaque
    Seigo Ishino, Takahiro Mukai, Yuji Kuge, Noriaki Kume, Mikako Ogawa, Nozomi Takai, Junko Kamihashi, Masashi Shiomi, Manabu Minami, Toru Kita, Hideo Saji
    JOURNAL OF NUCLEAR MEDICINE, 49, 10, 1677, 1685, SOC NUCLEAR MEDICINE INC, 2008年10月, ［査読有り］
    英語, 研究論文（学術雑誌）, Lectinlike oxidized low-density lipoprotein (LDL) receptor 1 (LOX-1), a cell surface receptor for oxidized LDL, has been implicated in vascular cell dysfunction related to plaque instability, which could be a potential target for an atherosclerosis imaging tracer. In this study, we designed and prepared Tc-99m-labeled anti-LOX-1 monoclonal IgG and investigated its usefulness as an atherosclerosis imaging agent. Methods: Anti-LOX-1 monoclonal IgG and control mouse IgG2a were labeled with Tc-99m after derivatization with 6-hydrazinonicotinic acid to yield Tc-99m-LOX-1-mAb and Tc-99m-IgG2a, respectively. Myocardial infarction-prone Watanabe heritable hyperlipidemic (WHHLMI) rabbits (atherosclerosis model) and control rabbits were injected intravenously with these probes, and in vivo planar imaging was performed. At 24 h after the injection, the aortas were removed, and radioactivity was measured. Autoradiography and histologic studies were performed with serial aortic sections. Results: The level of Tc-99m-LOX-1-mAb accumulation was 2.0-fold higher than the level of Tc-99m-IgG2a accumulation in WHHLMI rabbit aortas, and the level of Tc-99m-LOX-1-mAb accumulation in WHHLMI rabbit aortas was 10.0-fold higher than the level of Tc-99m-LOX-1-mAb accumulation in control rabbit aortas. In vivo imaging clearly visualized the atherosclerotic aortas of WHHLMI rabbits. Autoradiography and histologic studies revealed that regional Tc-99m-IgG2a accumulation was independent of the histologic grade of the lesions; however, regional Tc-99m-LOX1-mAb accumulation was significantly correlated with LOX-1 expression density and the vulnerability index. The highest level of 99mTc-LOX-1-mAb accumulation, expressed as {radioactivity in region of interest (Bq/mm(2))/[injected radioactivity (Bq)/animal body weight (g)]} x 102, was found in atheromatous lesions (3.8 +/- 1.1 [mean +/- SID]), followed in decreasing order by fibroatheromatous lesions (2.0 +/- 1.0), collagen-rich lesions (1.6 +/- 0.8), and neointimal lesions (1.4 (+/-) 0.7). Conclusion: The level of Tc-99m-LOX-1-mAb accumulation in grade IV atheroma was higher than that in neointimal lesions or other, more stable lesions. Nuclear imaging of LOX-1 expression with Tc-99m-LOX-1-mAb may be a useful means for predicting atheroma at high risk for rupture.
  • 小動物イメージング装置を用いて求めるラット脳循環代謝に及ぼす体温および麻酔管理の影響に関する検討
    山口 博司, 二ツ橋 昌実, 尾内 康臣, 鳥塚 達郎, 小杉 睦, 小川 美香子, 淵上 剛志, 間賀田 泰寛
    核医学, 45, 3, S199, S199, (一社)日本核医学会, 2008年09月, ［査読有り］
    日本語
  • Determination of optimal rhodamine fluorophore for in vivo optical imaging
    Michelle R. Longmire, Mikako Ogawa, Yukihiro Hama, Nobuyuki Kosaka, Celeste A. S. Regino, Peter L. Choyke, Hisataka Kobayashi
    BIOCONJUGATE CHEMISTRY, 19, 8, 1735, 1742, AMER CHEMICAL SOC, 2008年08月, ［査読有り］
    英語, 研究論文（学術雑誌）, Optical imaging has the potential to improve the efficacy of surgical and endoscopic approaches to cancer treatment; however, the optimal type of fluorescent probe has not yet been established. It is well-known that rhodamine-core-derived fluorophores offer a combination of desirable properties such as good photostability, high extinction coefficient, and high fluorescence quantum yield. However, despite the ubiquitous use of rhodamine fluorophores for in vivo optical imaging, it remains to be determined if unique chemical properties among individual rhodamine core family members affect fluorophore parameters critical to in vivo optical imaging applications. These parameters include preserved fluorescence intensity in low pH environments, similar to that of the endolysosome; efficient fluorescence signal despite conformational changes to targeting proteins as may occur in harsh subcellular environments; persistence of fluorescence after cellular internalization; and sufficient signal-to-background ratios to permit the identification of fluorophore-targeted tumors. In the present study, we conjugated 4 common rhodamine-core based fluorescent dyes to a clinically feasible and quickly internalizing D-galactose receptor targeting reagent, galactosamine serum albumin (GmSA), and conducted a series of in vitro and in vivo experiments using a metastatic ovarian cancer mouse model to determine if differences in optical imaging properties exist among rhodamine fluorophores and if so, which rhodamine core possesses optimal characteristics for in vivo imaging applications. Herein, we demonstrate that the rhodamine-fluorophore, TAMRA, is the most robust of the 4 common rhodamine fluorophores for in vivo optical imaging of ovarian cancer metastases to the peritoneum.
  • Radiosynthesis and in vivo evaluation of N-[C-11]methylated imidazopyridineacetamides as PET tracers for peripheral benzodiazepine receptors
    Katsuhiko Sekimata, Kentaro Hatano, Mikako Ogawa, Junichiro Abe, Yasuhiro Magata, Giovanni Biggio, Mariangela Serra, Valentino Laquintana, Nunzio Denora, Andrea Latrofa, Giuseppe Trapani, Gaetano Liso, Kengo Ito
    NUCLEAR MEDICINE AND BIOLOGY, 35, 3, 327, 334, ELSEVIER SCIENCE INC, 2008年04月, ［査読有り］
    英語, 研究論文（学術雑誌）, Imidazopyridineacetoamide 5-8, a series of novel and potentially selective peripheral benzodiazepine receptor (PBR) ligands with affinities comparable to those of known PBR ligands, was investigated. Radiosyntheses of [C-11]5, 6, 7 or 8 was accomplished by N-methylation of the corresponding desmethyl precursors with [C-11]methyl iodide in the presence of NaH in dimethylformamide (DMF), resulting in 25% to 77% radiochemical yield and specific activitiy of 20 to 150 MBq/nmol. Each of the labeled compounds was injected in ddY mice, and the radioactivity and weight of dissected peripheral organs and brain regions were measured. Organ distribution of [C-11]7 was consistent with the known PBR distribution. Moreover, [C-11]7 showed the best combination of brain uptake and PBR binding, leading to its high retention in the olfactory bulb and cerebellum, areas where PBR density is high in mouse brain. Coinjection of PK11195 or unlabeled 7 significantly reduced the brain uptake of [C-11]7. These results suggest that [C-11]7 could be a useful radioligand for positron emission tomography imaging of PBRs. (C) 2008 Elsevier Inc. All rights reserved.
  • 5-Iodo-A-85380, a specific ligand for alpha A beta 2 nicotinic acetylcholine receptors, prevents glutamate neurotoxicity in rat cortical cultured neurons
    Masashi Ueda, Yasuhiko Iida, Youji Kitamura, Hidekazu Kawashima, Mikako Ogawa, Yasuhiro Mayata, Hideo Saji
    BRAIN RESEARCH, 1199, 46, 52, ELSEVIER SCIENCE BV, 2008年03月, ［査読有り］
    英語, 研究論文（学術雑誌）, 5-iodo-3-(2(S)-azetidinylmethoxy)pyridine (5-iodo-A-85380, 5IA) has very high affinity and selectivity to nicotinic acetylcholine receptor (nAChR) alpha 4 beta 2 subtype, and a relative safe profile. To assess whether 5IA has neuroprotective properties, we examined the effect of 5IA on glutamate (Glu)-induced neurotoxicity using primary cultures of rat cortical neurons. A 10-min exposure of cultures to Glu followed by 2-h incubation with drug-free medium caused a marked loss of viability, as determined by trypan blue exclusion method. Glu-induced neurotoxicity was prevented by 5IA both in a time- and concentration -dependent manner. 5IA-induced neuroprotection required pretreatment of 5IA prior to Glu exposure with an optimal concentration of 10 nM and an optimal pretreatment time of 2 h. Treatment after Glu exposure could not rescue the cultured cells. The neuroprotective effect of 5IA was antagonized by mecamylamine, a nAChR antagonist, but not by scopolamine, a muscarinic acetylcholine receptor antagonist. Dihydro-beta-erythroicline, an alpha 4 beta 2 nAChR antagonist, completely inhibited 5IA-induced neuroprotection, whereas alpha-bungarotoxin, an alpha 7 nAChR antagonist, had no effect. Furthermore, 5IA did not show neuroprotective effects in the absence of extracellular Ca2+. These results suggest that the neuroprotective effects of 5IA are produced by activation of alpha 4 beta 2 nAChRs followed by the influx of extracellular Ca2+. In conclusion, 5IA is possibly not only useful for the treatment and prevention of glutamate neurotoxicity, but also as an available tool for elucidating the mechanism of neuroprotection associated with alpha 4 beta 2 nAChRs.
  • Difference in brain distributions of carbon 11-labeled 4-hydroxy-2(1H)-quinolones as PET radioligands for the glycine-binding site of the NMDA ion channel
    Takeshi Fuchigami, Terushi Haradahira, Noriko Fujimoto, Takashi Okauchi, Jun Maeda, Kazutoshi Suzuki, Tetsuya Suhara, Futnihiko Yamamoto, Shigeki Sasaki, Takahiro Mukai, Hiroshi Yamaguchi, Mikako Ogawa, Yasuhiro Magata, Minoru Maeda
    NUCLEAR MEDICINE AND BIOLOGY, 35, 2, 203, 212, ELSEVIER SCIENCE INC, 2008年02月, ［査読有り］
    英語, High-affinity iodine- and ethyl-C-5 substituted analogs of 4-hydroxy-3-(3-[C-11]methoxyphenyl)-2(1H)-quinolone ([C-11]4HQ) were synthesized as new positron emission tomography radioligands for the glycine-binding sites of the N-methyl-D-aspartate (NMDA) ion channel. Although both radioligands showed high in vitro specific binding to rat brain slices, their binding characteristics were quite different from each other. 5-Ethyl-[C-11]4HQ (5Et-[C-11]4HQ) showed higher in vitro binding in the forebrain regions than in the cerebellum, bindings that were strongly inhibited by both glycine-site agonists and antagonists. In contrast, 5-iodo-[C-11]4HQ (5I-[C-11]4HQ) showed a homogeneous in vitro binding throughout the brain, which was inhibited by antagonists but not by agonists. This difference in in vitro binding between 5Et-[C-11]4HQ and 5I-[C-11]4HQ was quite similar to that previously observed between [C-11]L-703,717 and [C-11]4HQ, both glycine-site antagonists. In vivo brain uptakes of these C-11-labeled 4-hydroxyquinolones were examined in mice. Initial brain uptakes of 5Et- and 5I-[C-11]4HQ at 1 min after intravenous injections were comparable to that of [C-11]4HQ, but they were 1.3-2.1 times higher than that of [C-11]L-703,717. The treatment with an anticoagulant, warfarin, only slightly increased the initial uptakes of [C-11]4HQ and 5Et-[C-11]4HQ in contrast to [C-11]L-703,717. The in vivo regional brain distributions were slightly different between the two radioligands. Pretreatment with nonradioactive ligand (2 mg/kg) slightly inhibited the binding of 5Et-[C-11]4HQ (16-36% inhibition) but not that of 5I-[C-11]4HQ.
    In this study, it was found that a small structural change in [C-11]4HQ resulted in a major change in binding characteristics and distributions, suggesting the existence of two binding sites for [C-11]4-hydroxyquinolones on the NMDA ion channel-agonist-sensitive and agonist-insensitive (or antagonist-preferring) sites. (c) 2008 Elsevier Inc. All rights reserved.
  • Increased binding potential of [C-11]Raclopride during unilateral continuous microinjection of nicotine in rat striatum observed by positron emission tomography
    Toshihisa Tajima, Kentaro Hatano, Mitsuru Suzuki, Mikako Ogawa, Yojiro Sakiyama, Takashi Kato, Hidetoshi Endo, Hisayuki Miura, Michitaka Matsubara, Kengo Ito
    SYNAPSE, 61, 12, 943, 950, WILEY-LISS, 2007年12月, ［査読有り］
    英語, 研究論文（学術雑誌）, Nicotine injections and nicotine skin patches significantly improve attention, memory, and learning in Alzheimer's disease. In animal studies, nicotine improves the performance of various memory-related tasks, an effect that is thought to be mediated by the neuronal dopaminergic system as systemic administration of nicotine decreased [C-11]raclopride binding in the anesthetized state. Since high doses of systemically administered nicotine are harmful, we administrated it directly into the rat striatum via microdialysis. We then examined the acute effects of continuous central administration of high doses of nicotine on striatal dopamine concentrations by measuring [C-11]raclopride binding by positron emission tomography. The concentration of dopamine in the dialysates was significantly increased from basal levels when microdialysis with 100 mM nicotine was initiated. However, contrary to expectations, the binding potential (BP) of [C-11]raclopride in the nicotine-perfused striatum was significantly higher than that in control striatum. Preinjection of mecamylamine (3 mg/kg), a nicotinic antagonist, had no effect on either extracellular dopamine levels or on the BP of [C-11]raclopride. These findings suggest that the high dose of local nicotine administration induced mecamylamine-insensitive local increases in extracellular dopamine, but might have decreased the total amount of extracellular dopamine in the striatum.
  • Lectin-like oxidized LDL receptor-1 (LOX-1) expression is associated with atherosclerotic plaque instability-analysis in hypercholesterolemic rabbits
    Seigo Ishino, Takahiro Mukai, Noriaki Kume, Daigo Asano, Mikako Ogawa, Yuji Kuge, Manabu Minami, Toru Kita, Masashi Shiomi, Hideo Saji
    ATHEROSCLEROSIS, 195, 1, 48, 56, ELSEVIER IRELAND LTD, 2007年11月, ［査読有り］
    英語, 研究論文（学術雑誌）, Lectin-like oxidized LDL receptor-1 (LOX-1), a cell-surface receptor for oxidized LDL (Ox-LDL), has been implicated in vascular cell dysfunction related to atherosclerotic plaque instability, according to cell culture experiments. In the present study, we investigated the relationship between LOX-1 expression and plaque instability in hypercholesterolemic rabbits by immunohistological analyses in vivo. We prepared thirty series of cross sections of the thoracic aorta from six myocardial infarction-prone Watanabe heritable hyperlipidemic (WHHLMI) rabbits (12-24 months), in which seventy atherosclerotic plaques were observed. LOX-1, matrix metal loproteinase-9 (MMP-9), monocyte chemoattractant protein-1 (MCP-1) expression, apoptotic events, plaque instability index (an index of the morphological destabilization of atherosclerotic plaques) and fibromuscular cap thickness in each atherosclerotic plaque were determined by immunohistochemical staining, TUNEL staining and Azan-Mallory staining. LOX-1 expression was positively correlated with the plaque instability index and MMP-9 expression. LOX-1 expression was more prominent in atherosclerotic plaques with thinner fibromuscular cap (< 100 mu m). Furthermore, LOX-1 expression was shown in the macrophage-rich lipid core area where MCP-1 expression and apoptotic events were prominent. These results indicate that enhanced LOX-1 expression was associated with histologically unstable atherosclerotic plaques in hypercholesterolemic rabbits, suggesting the involvement of LOX-1 in the destabilization of atherosclerotic plaques in vivo. (c) 2006 Elsevier Ireland Ltd. All rights reserved.
  • [18F]FDG-PETを用いた乳酸の脳エネルギー源としての役割に関する検討　　　　　　　　　　　　　　　
    小川 美香子, 尾内 康臣, 鳥塚 達郎, 二ツ橋 昌実, 山口 博司, 淵上 剛志, 間賀田 泰寛
    核医学, 44, 3, 279, 279, (一社)日本核医学会, 2007年10月, ［査読有り］
    日本語
  • Application of F-18-FDG PET for monitoring the therapeutic effect of antiinflammatory drugs on stabilization of vulnerable atherosclerotic plaques
    Mikako Ogawa, Yasuhiro Magata, Takashi Kato, Kentaro Hatano, Seigo Ishino, Takahiro Mukai, Masashi Shiomi, Kengo Ito, Hideo Saji
    JOURNAL OF NUCLEAR MEDICINE, 47, 11, 1845, 1850, SOC NUCLEAR MEDICINE INC, 2006年11月, ［査読有り］
    英語, 研究論文（学術雑誌）, The rupture of atherosclerotic vulnerable plaques and subsequent formation of thrombi are the main factors responsible for myocardial and cerebral infarctions. Because macrophage infiltration plays an essential role in plaque rupturing, pharmacologic therapy that reduces macrophage infiltration is required to stabilize the vulnerable plaques. The monitoring of therapeutic effect is important in assessing the therapeutic effects of drugs for individual patients. We previously reported that F-18-FDG accumulates in macrophage-rich plaques. The present study was undertaken to investigate the usefulness of F-18-FDG PET for monitoring therapies that target vascular inflammation. Methods: Myocardial infarction-prone Watanabe heritable hyperlipidemic rabbits were used in this study. The antioxidant probucol was included in the diet fed to 4 rabbits starting at 10 mo of age (probucol group). In a control study, 4 rabbits received standard rabbit chow (control group). F-18-FDG PET experiments were performed on both groups before the study and at 1, 3, and 6 mo after treatment. After the last imaging session, the rabbits were sacrificed at 3 h after injection of F-18-FDG, and the aortas were removed. The accumulated radioactivity was then measured, and the number of macrophages was determined by examination of stained sections. Results: At the age of 10 mo, before the treatment, the aorta could be imaged by (18)FFDG PET in all rabbits. The aorta could not be imaged after 6 mo of probucol treatment, whereas intense radioactivity was observed in the control rabbits throughout the investigation. The standardized uptake values (SUVs) of the aorta were decreased significantly in the probucol group after 3 mo of intervention as compared with the pretreatment period. The SUVs of the control group were increased gradually at 6 mo. Radioactivity in the aorta was significantly lower in the probucol group than that in the control group. Macrophages were already present at the beginning of the study, and probucol treatment for 6 mo resulted in a significant reduction of macrophage infiltration. Conclusion: F-18-FDG PET was able to image the reduction of inflammation by probucol. F-18-FDG PET should be useful for evaluating the therapeutic effect of drugs clinically and for the development of new drugs that can stabilize vulnerable plaques. F-18-FDG PET should be useful for evaluating the therapeutic effect of drugs clinically and for the development of new drugs that can reduce inflammation of vulnerable plaques.
  • [2-11C]isopropyl-, [1-11C]ethyl-, and [ 11C]methyl-labeled phenoxyphenyl acetamide derivatives as positron emission tomography ligands for the peripheral benzodiazepine receptor: Radiosynthesis, uptake, and in vivo binding in brain
    Ming-Rong Zhang, Masanao Ogawa, Jun Maeda, Takehito Ito, Junko Noguchi, Katsushi Kumata, Takashi Okauchi, Tetsuya Suhara, Kazutoshi Suzuki
    Journal of Medicinal Chemistry, 49, 9, 2735, 2742, 2006年05月04日, ［査読有り］
    英語, 研究論文（学術雑誌）, The peripheral benzodiazepine receptor (PBR) is widely expressed in peripheral tissues, blood cells, and in glia cells in the brain. We have previously developed two positron emission tomography (PET) ligands, N-(2-[ 11C],5-dimethoxybenzyl)-N-(5-fluoro-2-phenoxyphenyl)acetamide ([ 11C]2) and its [18F]fluoroethyl analogue ([ 18F]6), for the current investigation of PBR in the human brain. The aim of this study was to label the potent PBR agonist N-(4-chloro-2- phenoxyphenyl)-N-(isopropoxybenzyl)acetamide (3) and its ethyl (7) and methyl (8) homologues with 11C and to evaluate them as PET ligands for PBR with mice, rats, and monkeys. Ligands [11C]3, [11C]7, and [11C]8 were synthesized by alkylation of phenol precursor 9 with 2-[2-11C]iodopropane ([11C]10), [1-11C] iodoethane ([11C]11), and [11C]iodomethane ([ 11C]11), respectively. The alkylating agent [11C]10 or [11C]11 was prepared by reacting CH3MgBr with [ 11C]CO2, followed by reduction with LiAlH4 and iodination with HI. In vitro quantitative autoradiography determined that 3, 7, and 8 had potent binding affinities (Ki = 0.07-0.19 nM) for PBR in the rat brain. These [11C]ligands could pass across the blood-brain barrier and enter the rat brain (0.17-0.32% of injected dose per gram wet tissue). Ex vivo autoradiography showed that the [11C]ligands preferably distributed in the olfactory bulb and cerebellum, two regions with richer PBR density in the rat brain. The co-injection of PBR-selective 2 reduced the [11C]ligand binding in the two regions, suggesting that binding in the rat brain was specific to PBR. PET study determined that the [ 11C]ligands preferably accumulate in the occipital cortex of the monkey brain, a region with a high density of PBR in the primate brain. Moreover, in vivo binding of the methyl homologue [11C]8 in the monkey brain could be inhibited by PBR-selective 2 or 1, indicating that some of the [11C]8 binding was due to PBR. Metabolite analysis demonstrated that these [11C]ligands were metabolized by debenzylation to polar products mainly in the plasma. © 2006 American Chemical Society.
  • A catheter-based intravascular radiation detector of vulnerable plaques
    R Hosokawa, N Kambara, M Ohba, T Mukai, M Ogawa, H Motomura, N Kume, H Saji, T Kita, R Nohara
    JOURNAL OF NUCLEAR MEDICINE, 47, 5, 863, 867, SOC NUCLEAR MEDICINE INC, 2006年05月, ［査読有り］
    英語, 研究論文（学術雑誌）, Detection of vulnerable plaques before rupture is important in preventing acute coronary events such as myocardial infarction. Although therapeutic strategies such as percutaneous transluminal coronary angioplasty appear to prevent coronary occlusion and consequently may lead to improved prognosis in these patients, a method of detecting vulnerable plaques has not been established. A nuclear method that uses an intravascular radiation detector (IVRD) with the plaque-avid tracer F-18-FDG is one of the most promising methods. The catheter-based IVRD consists of a catheter probe (a scintillator and flexible optic fibers), photomultipliers, a controller, and an automatic pullback unit and personal computer. A phantom study demonstrated that this detector was highly sensitive to F-18 and enabled the detection of F-18 point sources. However, details of the detection system in vivo remain unclear. Methods: To evaluate vulnerable plaques in vivo, we investigated a canine femoral artery and coronary artery using this detector system. Our goal was to estimate the ability of this device to navigate through these arteries and to detect F-18 point sources fixed on their adventitia. Results: In the study using a canine femoral artery, the IVRD could detect the point sources with good repeatability. In the study using an open-chest canine model, the catheter probe could easily be advanced into the left descending coronary artery, and the IVRD could detect target sources attached externally to the coronary artery (7- to 15-mm intervals) with good resolution. Conclusion: This newly developed catheter-based IVRD was able to detect, with good resolution, the slight radioactivity from F-18 point sources attached to the femoral artery and the coronary adventitia. These results show that catheter-based detection of coronary vulnerable plaques may be feasible.
  • Synthesis and evaluation of [I-125]I-TSA as a brain nicotinic acetylcholine receptor alpha(7) subtype imaging agent
    M Ogawa, R Tatsumi, M Fujio, KB Jiro, Y Magata
    NUCLEAR MEDICINE AND BIOLOGY, 33, 3, 311, 316, ELSEVIER SCIENCE INC, 2006年04月, ［査読有り］
    英語, 研究論文（学術雑誌）, Introduction: Some in vitro investigations have suggested that the nicotinic acetylcholine receptor (nAChR) alpha(7) subtype is implicated in Alzheimer's disease, schizophrenia and others. Recently, we developed (R)-3-(5-bromothiophen-2-yl)spiro[I-azabicyclo[2.2.2]octane-3,5'[1',3'1oxazolidin]-2'-one (Br-TSA), which has a high affinity and selectivity for (alpha(7) nAChRs. Therefore we synthesized (R)-3'(5-[. I-125] iodothiophen-2-yl)spiro[1-azabicyclo[2.2.2]octane-3,5'-[1',3']oxazolidin]-2'-one ([I-125]I-TSA) and evaluated its potential for the in vivo detection Of alpha(7) nAChR in brain,
    Method: In vitro binding affinity of I-TSA was measured in rat brain homogenates. Radioiodination was accomplished by a Br-I exchange reaction. Biodistribution Studies were undertaken in mice by tail vein injection of [1251] I-TSA. In vivo receptor blocking Studies were carried out by treating mice with methyllycaconitine (MLA; 5 nmol/5 mu l, i.c.v.) or nonradioactive I-TSA (50 mu mol/kg, i.v.).
    Results: I-TSA exhibited a high affinity and selectivity for the alpha 7 nAChR (K-i for alpha(7) nAChR=0.54 nM). Initial uptake in the brain was high (4.42 %dose/g at 5 min), and the clearance of radioactivity was relatively slow in the hippocampus (alpha(7) nAChR-rich region) and was rather rapid in the cerebellum ((alpha(7) nAChR poor region). The hippocampus to cerebellum uptake ratio was 0.9 at 5 min postinjection, but it was increased to 1.8 at 60 min postinjection. Although the effect was not statistically significant, administration of I-TSA and MLA decreased the accumulation of radioactivity in hippocampus.
    Conclusion: Despite its high affinity and selectivity, [I-125] I-TSA does not appear to be a Suitable tracer for in Vivo alpha(7) nAChR receptor imaging Studies due to its high nonspecific binding. Further structural optimization is needed. (c) 2006 Elsevier Inc. All rights reserved.
  • Change of central cholinergic receptors following lesions of nucleus basalis magnocellularis in rats: search for an imaging index suitable for the early detection of Alzheimer's disease
    M Ogawa, Y Iida, M Nakagawa, Y Kuge, H Kawashima, A Tominaga, M Ueda, Y Magata, H Saji
    NUCLEAR MEDICINE AND BIOLOGY, 33, 2, 249, 254, ELSEVIER SCIENCE INC, 2006年02月, ［査読有り］
    英語, 研究論文（学術雑誌）, Cholinergic system in the central nervous system is involved in the memory function. Thus, because the dysfunction of cholinerglic system that project to the cerebral cortex from nucleus basalis of Meynert (nbM) Would be implicated in the memory function deficits in Alzheimer's disease (AD), evaluating cholinergic function may be useful for the early detection of AD. In this study, because the nucleus basalis magnocellularis (NBM) in rats is equivalent to nbM ill human, We investigated the change in cholinergic receptors in the frontal cortex of rats With unilateral lesion to the NBM to find an appropriate index for the early detection of AD using techniques Of nuclear medicine. The right NBM was injected with ibotenic acid. [F-18]FDG-PET images were obtained 3 days later. Some rats were sacrificed at 1 week, whereas others were subjected to a second [F-18]FDG-PET at 4 weeks then sacrificed for membrane preparation. The prepared membranes were Subjected to radioreceptor assays to Measure the density of nicotinic and muscarinic acetylcholine receptors. Glucose metabolism had decreased oil the damaged side compared to the control side at 3 clays, but at 4 weeks, there was no difference between the sides. Nicotinic acetylcholine receptors had significantly decreased in density compared to the control side at both I and 4 weeks. However, muscarinic receptors were not affected. These results suggested that neuronal dysfunction in AD could be diagnosed at all early stage by imaging nicotinic acetylcholine receptors. (c) 2006 Elsevier Inc. All rights reserved.
  • Understanding of cerebral energy metabolism by dynamic living brain slice imaging system with [ (18)F]FDG
    M Ogawa, H Watabe, N Teramoto, Y Miyake, T Hayashi, H Iida, T Murata, Y Magata
    NEUROSCIENCE RESEARCH, 52, 4, 357, 361, ELSEVIER IRELAND LTD, 2005年08月, ［査読有り］
    英語, 研究論文（学術雑誌）, Recently, lactate has been receiving great attention as an energy substrate in the brain. In this Study, the role of lactate was evaluated by "bioradiography" system with 2-deoxy-2-[ (18)F]fluoro-D-glucose ([ (18)F]FDG), which is a positron emitting radiotracer for glucose uptake quantification. "Bioradiography" is the dynamic living tissue slice imaging system for positron-emitter labeled compounds. We investigated the brain energy metabolism under resting state and neural activated conditions induced by KCl addition. The monocarboxylate transporter inhibitor, alpha-cyano-4-hydroxycinnamate (4-CIN), had no effect on [ (18)F]FDG uptake rate in rat brain slices before KCl addition. On the other hand, addition of 4-CIN induced larger [ (18) F]FDG uptake rates under the activated condition in comparison with the control condition. Because neurons cannot utilize lactate under the 4-CIN loaded conditions, this indicates that activated neurons consume lactate as an energy substrate. The lactate concentration in the incubation medium was increased with KCl treatment in both groups and the extent was slightly greater in 4-CIN group. These results suggested that: (1) the brain mainly uses glucose, not lactate, as an energy substrate in resting state; (2) when neuron is stimulated, excess amounts of lactate might be produced in astrocytes and the lactate is mobilized as an energy substrate. (c) 2005 Elsevier Ireland Ltd and the Japan Neuroscience Society. All rights reserved.
  • A catheter-based radiation detector for endovascular detection of atheromatous plaques
    T Mukai, R Nohara, M Ogawa, S Ishino, N Kambara, K Kataoka, T Kanoi, K Saito, H Motomura, J Konishi, H Saji
    EUROPEAN JOURNAL OF NUCLEAR MEDICINE AND MOLECULAR IMAGING, 31, 9, 1299, 1303, SPRINGER, 2004年09月, ［査読有り］
    英語, 研究論文（学術雑誌）, Purpose. Although various radiopharmaceuticals have been developed for the detection of atheromas, external imaging techniques have limitations when it comes to the detection of small plaques. In this study, we developed a charged particle-sensitive detector for the endovascular detection of small plaques. Methods. The device consists of a probe, an automatic pullback unit and a controller. The probe, which consists of a plastic scintillator and flexible optical fibres, is 1.0 mm in diameter. The probe was inserted into a catheter placed on (18)F point sources, and then the radioactivity was measured as the probe was pulled out stepwise. Results. The sensitivity for (18)F was 9.3 cps/kBq, and there was a close linear correlation between the peak counts and source dose until at least 0.8 MBq. Furthermore, this device showed low background counts (<0.1 cps) and a low detection limit (0.21 kBq). To investigate the effect of background radioactivity on the measurement at the point sources, a ball phantom was prepared and five (18)F point sources were set on the ball's surface. Even though 298 MBq of (18)F-fluorodeoxyglucose was injected into the ball, the point sources located every 10 mm on the ball's surface were detectable separately. Conclusion. The data gathered suggest that a catheter-based radiation detector in combination with charged particle-emitting radiopharmaceuticals is useful for the endovascular detection of small lesions such as coronary plaques.
  • (18)F-FDG accumulation in atherosclerotic plaques: Immunohistochemical and PET imaging study
    M Ogawa, S Ishino, T Mukai, D Asano, N Teramoto, H Watabe, N Kudomi, M Shiomi, Y Magata, H Iida, H Saji
    JOURNAL OF NUCLEAR MEDICINE, 45, 7, 1245, 1250, SOC NUCLEAR MEDICINE INC, 2004年07月, ［査読有り］
    英語, 研究論文（学術雑誌）, The rupture of atherosclerotic plaques and the subsequent formation of thrombi are the main factors responsible for myocardial and cerebral infarctions. Thus, the detection of vulnerable plaques in atherosclerotic lesions is a desirable goal, and attempts to image these plaques with (18)F-FDG have been made. In the present study, the relationship between the accumulation of (18)F-FDG and the biologic characteristics of atherosclerotic lesions was investigated. Furthermore, PET imaging of vulnerable plaques was performed with an animal model of atherosclerosis, Watanabe heritable hyperlipidemic (WHHL) rabbits. Methods: WHHL (n = 11) and control (n = 3) rabbits were injected intravenously with (18)F-FDG, and the thoracic and abdominal aortas were removed 4 h after injection. The accumulated radioactivity was measured, and the number of macrophages and the intimal area were investigated by examination of stained sections. PET and CT images were also acquired at 210 min after injection of the radiotracer. Results: (18)F-FDG accumulated to a significantly higher level in the aortas of the WHHL rabbits (mean +/- SD differential uptake ratio [DUR], 1.47 +/- 0.90) than in those of the control rabbits (DUR, 0.44 +/- 0.15); DUR was calculated as (tissue activity/tissue weight)/(injected radiotracer activity/animal body weight), with activities given in becquerels and weights given in kilograms. (113)F-FDG uptake and the number of macrophages were strongly correlated in the atherosclerotic lesions of the WHHL rabbits (R = 0.81). In the PET analysis, intense (18)F-FDG radioactivity was detected in the aortas of the WHHL rabbits, whereas little radioactivity was seen in the control rabbits. Conclusion: The results suggest that macrophages are responsible for the accumulation of (18)F-FDG in atherosclerotic lesions. Because vulnerable plaques are rich in macrophages, (18)F-FDG imaging should be useful for the selective detection of such plaques.
  • 5-[I-123]iodo-A-85380: assessment of pharmacological safety, radiation dosimetry and SPECT imaging of brain nicotinic receptors in healthy human subjects
    M Ueda, Y Iida, T Mukai, M Mamede, K Ishizu, M Ogawa, Y Magata, J Konishi, H Saji
    ANNALS OF NUCLEAR MEDICINE, 18, 4, 337, 344, JAPANESE SOCIETY NUCLEAR MEDICINE, 2004年06月, ［査読有り］
    英語, 研究論文（学術雑誌）, Recently, 5-[I-123]iodo-3-(2(S)-azetidinylmethoxy)pyridine ([I-123]5IA) was developed as a ligand for imaging the nicotinic acetylcholine receptor (nAChR) in human brain using single photon emission computed tomography (SPECT). In the present study, the toxicity and radiation absorbed dose of [I-123]5IA were investigated.
    Behavior and physiological parameters were examined in mice and rats after administration of 5IA. There were no changes in these parameters in animals administered 1mug/kg of 5IA or less, indicating that the no observed effect level (NOEL) of 5IA was 1mug/kg. [I-123]5IA was then administered to healthy human subjects and serial whole-body images were acquired over 24 hr. Initially, high levels of radioactivity were observed in the liver and urinary bladder and moderate levels in the lungs, kidneys, and brain. Whole brain activity at 1 hr was 4.6 +/- 0.4% of the injected dose and this value gradually decreased with time. The majority (similar to75%) of the radioactivity was excreted in urine within 24 hr, and less than 1% remained in all organs tested. The biological half-life of [I-123]5IA averaged 7.2 +/- 4.0 hr. Based on the biodistribution data, radiation absorbed doses were estimated using MIRDOSE 3.1 software with the dynamic bladder model and the ICRP gastrointestinal (GI) tract model. Consequently, the effective dose equivalent was estimated to be 30 +/- 1.4 muSv/MBq, which is an acceptable radiation burden. Having determined the safety of this compound, we performed SPECT imaging in a healthy human subject using 171 MBq of [I-123]5IA. SPECT images clearly revealed a cerebral distribution of radioactivity that was consistent with the known distribution of central nAChRs in humans. These results suggest that [I-123]5IA is a promising ligand for imaging nAChRs in humans, with an acceptable dosimetry and pharmacological safety at the dose required for adequate SPECT imaging.
  • Evaluation of 5-(11)C-methyl-A-85380 as an imaging agent for PET invesvigations of brain nicotinic acetylcholine receptors
    Y Iida, M Ogawa, M Ueda, A Tominaga, H Kawashima, Y Magata, S Nishiyama, H Tsukada, T Mukai, H Saji
    JOURNAL OF NUCLEAR MEDICINE, 45, 5, 878, 884, SOC NUCLEAR MEDICINE INC, 2004年05月, ［査読有り］
    英語, 研究論文（学術雑誌）, Central nicotinic acetylcholine receptors (nAChRs) represent major neurotransmitter receptors responsible for various brain functions, and changes in the density of nAChRs have recently been reported in several neurodegenerative diseases. Visualization of nAChRs in human brain has thus been of great interest, and the development of radiopharmaceuticals for the imaging and quantitative assessment of central nAChRs has been desired. In this study, we synthesized 5-(11)C-methyl-3-(2-(S)-azetidinylmethoxy)pyridine (5MA), a derivative of 3-(2-(S)-azetidinylmethoxy)pyridine (A-85380) (11)C-methylated at position 5 of the pyridyl fragment, and evaluated its potential for investigating central nAChRs by PET. Methods: (11)C-5MA was synthi by the incorporation of (11)C-methyl iodide into 5-butylstannyl A-85380, using a Pd-catalyzed coupling reaction. The affinity of 5MA for central nAChRs was measured by displacement of (-)-(3)H-cytisine from binding sites in rat cortical membranes. The biodistribution of (11)C-5MA was determined with mice. PET studies were performed on rhesus monkeys with a high-resolotion PET scanner for animals. Results: The overall synthesis time was 60 min from the end of radionudide production, and the radiochemical yield, after purification by high-performance liquid chromatography, was 30%. The radiochemical purity of the product was >99%, with a specific radioactivity of >36 GBq/mumol. In vitro receptor-binding assays demonstrated that 5MA has a high, selective binding affinity for nAChRs, being approximately 1.5-fold higher than that of A-85380, 3.5-fold higher than that of (-)-cytisine, and 10-fold higher than that of (-)-nicotine. The distribution studies in mice showed that the brain uptake of (11)C-5MA was profound. Regional cerebral distribution studies in mice demonstrated that the accumulation of (11)C-5MA was consistent with the density of nAChRs, with the highest uptake observed in the thalamus, a moderate uptake in the cortex and striatum, and the lowest uptake in the cerebellum. Furthermore, preinjection of nAChR-binding ligands, (-)nicotine and (-)-cytisine, reduced the uptake of (11)C-5MA in brain regions of high uptake in the untreated experiment. PET imaging studies with (11)C-5MA in rhesus monkeys demonstrated clear images consistent with the distribution of nAChRs in the brain. Conclusion: These results suggest that (11)C-5MA is a potential PET radiopharmaceutical for nuclear medical studies of nAChRs in the brain.
  • Development of a new radioligand, N-(5-fluoro-2-phenoxyphenyl)-N-(2-[F-18]fluoroethyl-5-methoxybenzyl)acetamide, for PET imaging of peripheral benzodiazepine receptor in primate brain
    MR Zhang, J Maeda, M Ogawa, J Noguchi, T Ito, Y Yoshida, T Okauchi, S Obayashi, T Suhara, K Suzuki
    JOURNAL OF MEDICINAL CHEMISTRY, 47, 9, 2228, 2235, AMER CHEMICAL SOC, 2004年04月, ［査読有り］
    英語, 研究論文（学術雑誌）, To develop a positron emission tomography (PET) ligand for imaging the 'peripheral benzodiazepine receptor' (PBR) in brain and elucidating the relationship between PBR and brain diseases, four analogues (4-7) of N-(2,5-dimethoxybenzyl)-N-(5-fluoro-2-phenoxyphenyl)acetamide (2) were synthesized and evaluated as ligands for PBR. Of these compounds, fluoromethyl (4) and fluoroethyl (5) analogues had similar or higher affinities for PBR than the parent compound 2 (K-i = 0.16 nM for PBR in rat brain sections). Iodomethyl analogue 6 displayed a moderate affinity, whereas tosyloxyethyl analogue 7 had weak affinity. Radiolabeling was performed for the fluoroalkyl analogues 4 and 5 using fluorine-18 (F-18, beta(+); 96.7%, T-1/2 = 109.8 min). Ligands [F-18]4 and [F-18]5 were respectively synthesized by the alkylation of desmethyl precursor 3 with [F-18]fluoromethyl iodide ([F-18]8) and 2-[F-18]fluoroethyl bromide ([F-18]9). The distribution patterns of [F-18]4 and [F-18]5 in mice were consistent with the known distribution of PBR. However, compared with [F-18]5, [F-18]4 displayed a high uptake in the bone of mice. The PET image of [F-18]4 for monkey brain also showed significant radioactivity in the bone, suggesting that this ligand was unstable for in vivo defluorination and was not a useful PET ligand. Ligand [F-18]5 displayed a high uptake in monkey brain especially in the occipital cortex, a region with richer PBR than the other regions in the brain. The radioactivity level of [F-18]5 in monkey brain was 1.5 times higher than that of [C-11]2, and 6 times higher than that of (R)-(1-(2-chlorophenyl)-N-[C-11]methyl,N-(1-methylpropyl)isoquinoline ([C-11]1). Moreover, the in vivo binding of [F-18]5 was significantly inhibited by PBR-selective 2 or 1, indicating that the binding of [F-18]5 in the monkey brain was mainly due to PBR. Metabolite analysis revealed that [F-18]4 was rapidly metabolized by defluorination to [F-18]F- in the plasma and brain of mice, whereas [F-18]5 was metabolized by debenzylation to a polar product [F-18]13 only in the plasma. No radioactive metabolite of [F-18]5 was detected in the mouse brain. The biological data indicate that [F-18]5 is a useful PET ligand for PBR and is currently used for imaging PBR in human brain.
  • Endogenous dopamine release induced by repetitive transcranial magnetic stimulation over the primary motor cortex: An [11]raclopride positron emission tomography study in anesthetized macaque monkeys
    T Ohnishi, T Hayashi, S Okabe, Nonaka, I, H Matsuda, H Iida, E Imabayashi, H Watabe, Y Miyake, M Ogawa, N Teramoto, Y Ohta, N Ejima, T Sawada, Y Ugawa
    BIOLOGICAL PSYCHIATRY, 55, 5, 484, 489, ELSEVIER SCIENCE INC, 2004年03月, ［査読有り］
    英語, 研究論文（学術雑誌）, Background: Repetitive transcranial magnetic stimulation (rTMS) has been used as a treatment for neuropsychiatric disorders such as depression and Parkinson's disease (PD). Despite the growing interest in therapeutic application of rTMS, precise mechanisms of its action remain unknown. With respect to PD, activation of the mesostriatal dopaminergic pathway is likely to be a candidate mechanism underlying the therapeutic effects,. however, modulating effects of rTMS over the primary motor cortex (M1) on the dopaminergic system have not been studied.
    Methods. We used [11C]raclopride positron emission tomography to measure changes of extracellular dopamine concentration after 5Hz rTMS over the M1 in eight anesthetized monkeys.
    Results: rTMS over the right M1 induced a reduction of [11C]raclopride binding potential (BP) in the bilateral ventral striatum, including the nucleus accumbens, and a significant increase of BP in the right putamen; no significant BP reduction was found in the dorsal striatum. These data indicate that rTMS over the motor cortex induces a release of endogenous dopamine in the ventral striatum.
    Conclusions: Our results suggest that therapeutic mechanisms of rTMS may be explained in part by an activation of the mesolimbic dopaminergic pathway, which plays critical roles in rewards, reinforcement, and incentive motivation.
  • Imaging of vulnerable atherosclerotic plaque with [ (18)F]FDG-PET: an animal atherosclerosis model study
    M Ogawa, T Mukai, S Ishino, N Teramoto, H Watabe, N Kudomi, M Shiomi, Y Magata, H Iida, H Saji
    QUANTITATION IN BIOMEDICAL IMAGING WITH PET AND MRI, 1265, 266, 268, ELSEVIER SCIENCE BV, 2004年, ［査読有り］
    英語, 研究論文（国際会議プロシーディングス）, The rupture of atherosclerotic plaques and the resultant thrombus formation are mainly responsible for myocardial and cerebral infarctions. Thus, the detection of vulnerable plaques in atherosclerotic lesions has been desired, and attempts to image them with [ (18)F]FDG are ongoing. Intimal thickening can be observed both in stable and vulnerable plaques; however, in vulnerable plaque, the lesion is inflamed, and the infiltrated macrophages cause the rupture of such plaques. In this study, we investigated whether [ (18)F]FDG-PET could specifically detect the vulnerable plaque, other than stable plaque, or not using an animal model of atherosclerosis, the Watanabe heritable hyperlipidemic (WHHL) rabbit. A helical CT angiogram was acquired at 180 min postinjection of [ (18)F]FDG, and PET scanning was carried out for 15 min from 210 min postinjection of [ (18)F]FDG. At 4 h postinjection of the radiotracer, the aortas were removed, and the radioactivity was measured. Then, each arterial segment was embedded in paraffin, and consecutive 5-mum-thick slices were prepared. They were subjected to Azan-Mallory staining or immunohistochemical staining for measurement of intimal thickness and macrophage number. In the aortas of the WHHL rabbits, intense [ (18)F]FDG radioactivity was detected with PET, while little radioactivity was seen in the aortas of control rabbits. Actually, in the removed aortic segments [ (18)F]FDG accumulated significantly higher in the aortas of the WHHL rabbits than in those of the control rabbits. Furthermore, in the atherosclerotic lesions of the WHHL rabbits, the [ (18)F]FDG uptake was well correlated with macrophage number. On the other hand, the correlation between [ (18)F]FDG uptake and the area ratio of the intima to the whole cross-section was poor. These results suggest that the detected radioactivity with [ (18)F]FDG-PET in the atherosclerotic lesion is associated with macrophage density. Since macrophages are responsible for plaque vulnerability, [ (18)F]FDG imaging should be useful for selective detection of vulnerable plaques. (C) 2004 Elsevier B.V. All rights reserved.
  • Development of injectable O-15 oxygen and its application for estimation of OEF
    T Temma, Y Magata, H Iida, T Hayashi, M Ogawa, T Mukai, Y Iida, H Tsukada, J Konishi, H Saji
    QUANTITATION IN BIOMEDICAL IMAGING WITH PET AND MRI, 1265, 262, 265, ELSEVIER SCIENCE BV, 2004年, ［査読有り］
    英語, 研究論文（国際会議プロシーディングス）, In the basic research on cerebral perfusion disorders, a new method for measurement of oxygen extraction fraction (OEF) and cerebral metabolic rate for oxygen (CMRO(2)) has been desired. Although the O-15-labeled gas inhalation method is performed in clinical studies, application of the inhalation method to small animals requires too many intensive procedures. Therefore, this study investigated a new method of assessing OEF in small animals using intravenously injectable oxygen (injectable (15)O-O(2)). Additionally, it was compared with the inhalation method, using a monkey for further validation. Using injectable (15)O-O(2), 72 MBq/ml of radioactivity was obtained after (15)O-O(2) gas circulation into an artificial lung. OEF with injectable (15)O-O(2) was calculated using the same equation as that applied to the bolus inhalation method. The OEF value obtained by injectable (15)O-O(2) was well in accordance with that evaluated by the arterial-venous difference of oxygen concentration. Furthermore, the OEF and CMRO(2) images obtained with two methods using a monkey brain showed a similar distribution. These results indicate that this method is useful for the estimation of OEF and CMRO(2) in small animals using an animal positron emission tomography system and may accelerate the basic research of cerebral perfusion diseases. (C) 2004 Elsevier B.V. All rights reserved.
  • Effects of monoamine oxidase inhibitors on the diethyldithiocarbamate-induced enhancement of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine toxicity in C57BL/6 mice
    K Takahata, S Shimazu, F Yoneda, M Ogawa, Y Iida, H Saji
    JOURNAL OF NEURAL TRANSMISSION, 110, 8, 859, 869, SPRINGER-VERLAG WIEN, 2003年08月, ［査読有り］
    英語, 研究論文（学術雑誌）, Diethyldithiocarbamate (DDC) is known to potentiate the neurotoxicity of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). The aims of the present study were to provide biochemical, pathological and behavioral evidence for the degeneration of dopamine (DA) neurons in C57BL/6 strain mice treated simultaneously with DDC and MPTP, and to evaluate the effects of monoamine oxidase (MAO) inhibitors on DDC-enhanced MPTP toxicity. DDC (400 mg/kg)+MPTP (30 mg/kg) treatment decreased significantly the levels of striatal DA and its metabolites and induced bradykinesia. In mice treated with DDC+MPTP, degenerative areas were found in striatum, substantia nigra and tuberculum olfactorium by assessment of the binding of [I-125] RTI-121, a DA transporter ligand. Pretreatment with a MAO-B inhibitor selegiline prior to the administration of DDC and MPTP completely inhibited the decrease in the levels of DA and its metabolites, bradykinesia and degeneration of dopaminergic nerve terminals. In contrast, the protective action of clorgyline was not clearly observed in this model system.
  • Development of injectable O-15 oxygen and estimation of rat OEF
    Y Magata, T Temma, T Iida, M Ogawa, T Mukai, T Iida, T Morimoto, J Konishi, H Saji
    JOURNAL OF CEREBRAL BLOOD FLOW AND METABOLISM, 23, 6, 671, 676, NATURE PUBLISHING GROUP, 2003年06月, ［査読有り］
    英語, 研究論文（学術雑誌）, Cerebral metabolic rate for oxygen (CMRO(2)) and cerebral oxygen extraction fraction (OEF) are some of the most fundamental parameters to characterize the pathophysiologic status of cerebral tissue. Although O-15-labeled gases inhalation method is performed in clinical studies, application of the inhalation method on small animals requires too many intensive procedures. On this basis, the development of a new method to measure CMRO(2) and OEF in small animals is of interest. This study was aimed at developing a method to assess CMRO(2) and OEF using intravenously injectable oxygen (injectable (15)O-O(2)) for small animals such as rats. Injectable (15)O O(2), 72 MBq/mL of radioactivity, was obtained after (15)O-O(2) gas circulation into the artificial lung. OEF after injection of injectable (15)O-O(2) was calculated using the same equation as that applied to the bolus inhalation of (15)O-O(2) gas method. Values of 44 +/- 4.5 mL (.) min(-1 .) 100 g(-1) of CBF and 0.54 +/- 0.11 of OEF were obtained (n = 13). This OEF value was well accordance with OEF evaluated by arterial-venous difference of oxygen concentration (0.57 +/- 0.13). This method is useful to study the CMRO(2) and OEF in small animals using an animal positron emission tomography system. It may accelerate the basic research of several cerebral perfusion diseases.
  • Development of a GSO detector assembly for a continuous blood sampling system
    N Kudomi, E Choi, S Yamamoto, H Watabe, KM Kim, M Shidahara, M Ogawa, N Teramoto, E Sakamoto, H Iida
    IEEE TRANSACTIONS ON NUCLEAR SCIENCE, 50, 1, 70, 73, IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, 2003年02月, ［査読有り］
    英語, 研究論文（学術雑誌）, A new input function monitoring system has been developed and evaluated using a GSO detector assembly for both PET and SPECT quantitative studies. Energy resolutions were 11% for 511 keV photons, 20% for 140 keV(Tc-99m) photons and 28% for 70 keV(Tl-201) photons, enabling the use of this system in SPECT studies. The paired assembly of crystals provided an absolute sensitivity of approximately 7% for PET tracers and 70% for Tc-99m and Tl-201 (SPECT tracers). Multiple arrangement of paired detectors would make it possible to correct for the transit time of radioactivity through the catheter tube. This study demonstrates that the present system can be of use in both clinical and small animal studies using SPECT and PET tracers.
  • Absolute quantitation of regional myocardial blood flow of rats using dynamic pinhole SPECT
    T Aoi, H Watabe, HM Deloar, M Ogawa, N Teramoto, N Kudomi, T Oota, KM Kim, T Matsuda, H Iida
    2002 IEEE NUCLEAR SCIENCE SYMPOSIUM, CONFERENCE RECORD, VOLS 1-3, 1780, 1783, IEEE, 2003年, ［査読有り］
    英語, 研究論文（国際会議プロシーディングス）, PET and SPECT have been widely used to investigate the physiological function of animals in vivo. However, little efforts have been done to estimate absolute physiological parameters i.e. blood flow. of small animals. The present study was aimed at the absolute quantitation of myocardial blood flow of rats by means of the dynamic SPECT fitted with a pinhole collimator with a careful determination of the arterial input function (IF). The center-of-rotation was carefully aligned to the center of the field-of-view of a fixed gamma camera with the accuracy < 0.05 mm. A rat was placed on a rotating device that fixes the rat in a stand position. The arterial blood samples were frequently collected and their radioactivity concentration was measured using a well counter cross-calibrated to the SPECT images. Dynamic SPECT (the step-and-shoot mode) was initiated at 5 min after the injection of 201TICl into the tail vein. Acquisition period was 10 sec at each rotation angle, and 120 view projection data were obtained. The 360-degree complete data sets were obtained at approximately 20 min interval for 5 time frames. Images were reconstructed by filtered-back projection technique with Feldkamp algorithm. The cross-calibration factor was determined using a cylindrical phantom of 5 cm diameter filled with the 201TICl solution. Regions-of-Interest were placed on the left ventricular wall to generate the tissue time activity curve (TTAC). TTAC and IF were fitted to the previously validated single-tissue compartment model to estimate the regional myocardial blood flow (rMBF) and volume of distribution (Vd) of thallium. The present system provided clear images of myocardial uptake of 201TICl, and the time-dependent change of the tissue radioactivity concentration in regional basis, which was statistically sufficient for applying the compartment model analysis. The kinetic analysis yielded the rMBF of approximately 0.77 ml/min/g, which appeared to be an acceptable value with a consideration of contribution of partial volume effect and other error sources. Vd of approximately 91.9 ml/ml was also consistent with the know value of potassium potential across the cell membrane. These results strongly suggested the potential of the dynamic pinhole SPECT as a tool for absolute quantitation of physiological parameters in small animals.
  • Performance test and application of GSO detector assembly for a continuous blood sampling system
    N Kudomi, E Choi, S Yamamoto, H Watabe, KM Kim, T Hayashi, M Ogawa, N Teramoto, E Sakamoto, H Iida
    2002 IEEE NUCLEAR SCIENCE SYMPOSIUM, CONFERENCE RECORD, VOLS 1-3, 1648, 1651, IEEE, 2003年, ［査読有り］
    英語, 研究論文（国際会議プロシーディングス）, A new input function monitoring system has been developed using a GSO detector for both PET and SPECT quantitative studies. The paired assembly of crystals provided an absolute sensitivity of approximately 7 % for PET tracers and 70 % for Tc-99m and Tl-201 (SPECT tracers). This system was applied to clinical use and animal study such as monkey and rat. This study demonstrates that the present system can be of use in both clinical and small animal studies using SPECT and PET tracers.
  • Direct electrophilic radiofluorination of a cyclic RGD peptide for in vivo alpha(v)beta(3) integrin related tumor imaging
    M Ogawa, K Hatano, S Oishi, Y Kawasumi, N Fujii, M Kawaguchi, R Doi, M Imamura, M Yamamoto, K Ajito, T Mukai, H Saji, K Ito
    NUCLEAR MEDICINE AND BIOLOGY, 30, 1, 1, 9, ELSEVIER SCIENCE INC, 2003年01月, ［査読有り］
    英語, 研究論文（学術雑誌）, The association of the alpha(v)beta(3) integrin with tumor metastasis and tumor related angiogenesis has been suggested. Therefore, by imaging the alpha(v)6(3) receptor with PET. information concerning the tumor status could be obtained. Cyclic peptides including the RGD sequence. Were radiolabeled by direct electrophilic fluorination with [F-18]AcOF. In tumor-bearing mice, the labeled peptides accumulated at the tumor with a high tumor to blood ratio. These findings suggest that an assessment of tumor characteristics may be obtained by using these F-18-labeled peptides. (C) 2002 Elsevier Science Inc. All rights reserved.
  • Synthesis and evaluation of 1-[ (3R,4R)-1-cyclooctylmethyl-3-hydroxymethyl-4-piperidyl]-3-[C-11]ethyl-1,3-dihydro-2H-benzimidazol-2-one as a brain ORL1 receptor imaging agent for positron emission tomography
    M Ogawa, K Hatano, Y Kawasumi, K Ishiwata, K Kawamura, S Ozaki, K Ito
    NUCLEAR MEDICINE AND BIOLOGY, 30, 1, 51, 59, ELSEVIER SCIENCE INC, 2003年01月, ［査読有り］
    英語, 研究論文（学術雑誌）, 1-[ (3R,4R)-1-cyclooctylmethyl-3-hydroxymethyl-4-piperidyl]-3-[C-11]ethyl-1,3-dihydro-2H-benzimidazol-2-one ([C-11]CPEB) was synthesized by [C-11]N-ethylation and evaluated as a potential brain OPL1 receptor imaging agent by positron emission tomography. The uptake of [C-11]CPEB in the mouse brain was 1.9% dose/g, 2 min post-injection, and gradually decreased with time. Receptor-specific binding was observed, however, the contribution of other receptors was observed and the non-specific binding of [C-11]CPEB was too high for imaging receptors in vivo. Therefore, [C-11]CPEB is not a suitable tracer for in vivo ORL1 receptor imaging. (C) 2002 Elsevier Science Inc. All rights reserved.
  • In vivo imaging of brain dopaminergic neurotransmission system in small animals with high-resolution single photon emission computed tomography
    H Saji, Y Iida, H Kawashima, M Ogawa, Y Kitamura, T Mukai, S Shimazu, F Yoneda
    ANALYTICAL SCIENCES, 19, 1, 67, 71, JAPAN SOC ANALYTICAL CHEMISTRY, 2003年01月, ［査読有り］
    英語, 研究論文（学術雑誌）, High-resolution single photon emission computed tomography (SPELT) provides a unique capability. to image the biodistribution of radiolabeled molecules in small laboratory animals. Thus, we applied the high-resolution SPELT to in vivo imaging of the brain dopaminergic neurotransmission system in common marmosets using two radiolabeled ligands, [I-123]2beta-carbomethoxy-3beta-(4-iodophenyl)tropane (beta-CIT) as a dopamine transporter (DAT) ligand and [I-123]iodobenzamide (IBZM) as a dopamine D-2 receptor (D2R) ligand. Specific images of the striatum, a region with a high density of dopaminergic synapses, were obtained at 240 min and 60 min after injection of [I-123]beta-CIT and [I-123]IBZM, respectively. Furthermore, a significantly low accumulation of [I-123]beta-CIT in the striatum was observed in MPTP-treated animals compared with results for a control group, and a similar accumulation in the control group was observed with the pretreatment of deprenyl in the MPTP-treated animals. However, the striatal accumulation of [I-123]IBZM showed no changes among the control, MPTP-treated, and deprenyl-MPTP-treated groups. These SPELT imaging results agreed well with those of DA concentration and motor behavior. Since MPTP destroys nigrostriatal dopamine nerves and produces irreversible neurodegeneration associated with Parkinsonian syndrome, SPELT imaging data in this study demonstrated that deprenyl shows its neuroprotective effect on Parkinsonism by protecting against the destruction of presynaptic dopamine neurons.
  • Norepinephrine transporter density as a causative factor in alterations in MIBG myocardial uptake in NIDDM model rats
    Y Kiyono, Y Iida, H Kawashima, M Ogawa, N Tamaki, H Nishimura, H Saji
    EUROPEAN JOURNAL OF NUCLEAR MEDICINE AND MOLECULAR IMAGING, 29, 8, 999, 1005, SPRINGER-VERLAG, 2002年08月, ［査読有り］
    英語, 研究論文（学術雑誌）, Cardiac scintigraphic studies with iodine-123 labeled metaiodobenzylguanidine ([I-123]MIBG) have demonstrated global and regionally pronounced decreases in myocardial accumulation of radioactivity in diabetes. The aim of this study was to investigate the cause of the regional differential decrease in accumulation. To this end, we investigated the global and regional myocardial distribution of [I-125]MIBG in GK/Crj (GK) rats [a model of non-insulin-dependent diabetes mellitus (NIDDM)] and assessed the responsibility of regional myocardial blood flow, myocardial and plasma norepinephrine (NE) content, and norepinephrine transporter (NET) function for the regional variations in [I-125]MIBG accumulation. To investigate the responsibility of myocardial blood flow for the alterations in MIBG accumulation, dual-isotope autoradiographic studies with [I-125]MIBG and technetium-99m hexakis-2-methoxy-2-isobutylisonitrile (MIBI), a tracer for the measurement of myocardial blood flow, were carried out in GK rats and control rats. The results in respect of the uptake of radioactivity into various myocardial regions were expressed as distribution absorption ratios [DAR = (radioactivity of tissue/g of tissue) x (body weight/total injected dose)]. In control rats, uptake of [I-125]MIBG was significantly higher in the inferior wall than in the anterior wall (anterior wall, 6.35 +/- 0.90; inferior wall, 8.12 +/- 1.27: P<0.001). On the other hand, in GK rats, uptake of [I-125]MIBG was similar between the anterior wall and the inferior wall (anterior wall, 4.91 +/- 0.71; inferior wall, 4.81 +/- 0.69). Compared with control rats, uptake of [I-125]MIBG in GK rats was decreased in both the anterior wall and the inferior wall. Uptake of Tc-99m-MIBI was not significantly different between the anterior and inferior walls in control (anterior wall, 17.9 +/- 4.42; inferior wall, 18.1 +/- 4.52) and GK rats (anterior wall, 16.6 +/- 8.03; inferior wall, 16.7 +/- 7.90), indicating that myocardial blood flow did not change regionally in either control or GK rats, and that the blood flow was not responsible for the differential decrease in MIBG accumulation in GK rats. Cardiac and plasma NE levels were measured using an HPLC-electrochemical detection system. The cardiac and plasma NE concentrations were not significantly different between control (anterior wall, 347 +/- 56 ng/g inferior wall, 354 +/- 31 ng/g; plasma 9.38 +/- 2.10 ng/ml) and GK rats (anterior wall, 323 +/- 62 ng/g; inferior wall, 344 +/- 35 ng/g; plasma, 9.41 +/- 2.39 ng/ml). The density and affinity of NET were investigated by studying the binding of [H-3]desipramine to cardiac membranes. The B-max (fmol/mg protein) in the inferior wall was significantly higher than that in the anterior wall in the control rats (anterior wall, 364 +/- 28; inferior wall, 459 +/- 36: P<0.05). On the other hand, there was no significant difference in the B-max value between the anterior and inferior walls in GK rats (anterior wall, 263 +/- 42; inferior wall, 251 +/- 27). In conclusion, myocardial MIBG uptake was differentially reduced in GK rats, and this decrease was associated with a decrease in NET density, but the regional myocardial blood flow and the NE concentration were not responsible for the alterations in MIBG uptake. Thus, NET density was identified as the factor responsible for decreases in MIBG accumulation.
  • Age-related changes of myocardial norepinephrine transporter density in rats: implications for differential cardiac accumulation of MIBG in aging
    Y Kiyono, N Kanegawa, H Kawashima, Y Iida, T Kinoshita, N Tamaki, H Nishimura, M Ogawa, H Saji
    NUCLEAR MEDICINE AND BIOLOGY, 29, 6, 679, 684, ELSEVIER SCIENCE INC, 2002年08月, ［査読有り］
    英語, 研究論文（学術雑誌）, The myocardial regional distribution of [I-125]MIBG was examined in various aged (7-, 18-,42-,47-, and 65-week-old) rats and compared with the effects of regional myocardial blood flow and norepinephrine transporter (NET) function on regional [I-125]MIBG accumulation in aged rats. In 7- and 18-week-old rats, the accumulation of [I-125]MIBG was higher in the inferior wall than anterior wall. However, in more than 42-week-old rats, the uptake of MIBG was lower in the inferior wall than that the anterior wall. The uptake of [Tc-99m]MIBI was greater in the inferior wall than the anterior wall in 18-week-old rats, but was reduced in the inferior wall compared to the anterior wall in 42- and 47- week-old rats. Furthermore, the in vitro binding studies of [H-3]desipramine to cardiac membranes showed that the B-max value of NET was larger for the inferior wall than the anterior wall in 7-week-old rats, but was smaller for the inferior wall than the anterior wall in 47-week-old rats. The K-D values for both walls were significantly larger in 47-week-old than 7-week-old rats. These results indicated that myocardial MIBG accumulation was lower in the inferior wall than the anterior wall of older rats, and that this differential MIBG accumulation in aging was related to the regional changes in myocardial blood flow and NET functions in the inferior wall. (C) 2002 Elsevier Science Inc. All rights reserved.
  • Evaluation of radioiodinated 5-iodo-3-(2(S)-azetidinylmethoxy)pyridine as a ligand for SPECT investigations of brain nicotinic acetylcholine receptors
    H Saji, M Ogawa, M Ueda, Y Iida, Y Magata, A Tominaga, H Kawashima, Y Kitamura, M Nakagawa, Y Kiyono, T Mukai
    ANNALS OF NUCLEAR MEDICINE, 16, 3, 189, 200, JAPANESE SOCIETY NUCLEAR MEDICINE, 2002年05月, ［査読有り］
    英語, 研究論文（学術雑誌）, 5-Iodo-3-(2(S)-azetidinylmethoxy)pyridine (5IA), an A-85380 analog iodinated at the 5-position of the pyridine ring, was evaluated as a radiopharmaceutical for investigating brain nicotinic acethylcholine receptors (nAChRs) by single photon emission computed tomography (SPECT). [I-123/125]5IA was synthesized by the iododestannylation reaction under no-carrier-added conditions and purified by high-performance liquid chromatography (HPLC) with high radiochemical yield (50%), high radiochemical purity (> 98%), and high specific radioactivity (> 55 GBq/mumol). The binding affinity of 5IA for brain nAChRs was measured in terms of displacement of [H-3]Cytisine and [I-125]5IA from binding sites in rat cortical membranes. The binding data revealed that the affinity of 5IA was the same as that of A-85380 and more than seven fold higher than that of (-)-nicotine, and that 5IA bound selectively to the alpha4beta2 nAChR subtype. Biodistribution studies in rats indicated that the brain uptake of [I-125]5IA was rapid and profound. Regional cerebral distribution studies in rats demonstrated that the accumulation of [I-125]5IA was consistent with the density of high affinity nAChRs with highest uptake observed in the nAChR-rich thalamus, moderate uptake in the cortex and lowest uptake in the cerebellum. Administration of the nAChR agonists (-)-cytisine and (-)-nicotine reduced the uptake of [I-125]5IA in all regions studied with most pronounced reduction in the thalamus, and resulted in similar levels of radioactivity throughout the brain. [I-125]5IA binding sites were shown to be saturable with unlabeled 5IA. Behavioral studies in mice demonstrated that 5IA did not show signs of behavioral toxicity. Furthermore, SPECT studies with [I-123]5IA in the common marmoset demonstrated appropriate brain uptake and regional localization for a high-affinity nAChR imaging radiopharmaceutical. These results suggested that [I-123]5IA is a promising radiopharmaceutical for SPECT studies of central nAChRs in human subjects.
  • Norepinephrine transporter density as a causative factor in alterations in MIBG myocardial uptake in NIDDM model rats
    Yasushi Kiyono, Yasuhiko Iida, Hidekazu Kawashima, Mikako Ogawa, Nagara Tamaki, Hiroshi Nishimura, Hideo Saji
    European Journal of Nuclear Medicine, 29, 8, 999, 1005, 2002年, ［査読有り］
    英語, 研究論文（学術雑誌）, Cardiac scintigraphic studies with iodine-123 labeled metaiodobenzylguanidine ([123I]MIBG) have demonstrated global and regionally pronounced decreases in myocardial accumulation of radioactivity in diabetes. The aim of this study was to investigate the cause of the regional differential decrease in accumulation. To this end, we investigated the global and regional myocardial distribution of [125I]MIBG in GK/Crj (GK) rats [a model of non-insulin-dependent diabetes mellitus (NIDDM)] and assessed the responsibility of regional myocardial blood flow, myocardial and plasma norepinephrine (NE) content, and norepinephrine transporter (NET) function for the regional variations in [125I]MIBG accumulation. To investigate the responsibility of myocardial blood flow for the alterations in MIBG accumulation, dual-isotope autoradiographic studies with [125I]MIBG and technetium-99m hexakis-2-methoxy-2-isobutylisonitrile (MIBI), a tracer for the measurement of myocardial blood flow, were carried out in GK rats and control rats. The results in respect of the uptake of radioactivity into various myocardial regions were expressed as distribution absorption ratios [DAR = (radioactivity of tissue/g of tissue) x (body weight/total injected dose)]. In control rats, uptake of [125I]MIBG was significantly higher in the inferior wall than in the anterior wall (anterior wall, 6.35±0.90
    inferior wall, 8.12±1.27: P<
    0.001). On the other hand, in GK rats, uptake of [125I]MIBG was similar between the anterior wall and the inferior wall (anterior wall, 4.91±0.71
    inferior wall, 4.81±0.69). Compared with control rats, uptake of [125I]MIBG in GK rats was decreased in both the anterior wall and the inferior wall. Uptake of 99mTc-MIBI was not significantly different between the anterior and inferior walls in control (anterior wall, 17.9±4.42
    inferior wall, 18.1±4.52) and GK rats (anterior wall, 16.6±8.03
    inferior wall, 16.7±7.90), indicating that myocardial blood flow did not change regionally in either control or GK rats, and that the blood flow was not responsible for the differential decrease in MIBG accumulation in GK rats. Cardiac and plasma NE levels were measured using an HPLC-electrochemical detection system. The cardiac and plasma NE concentrations were not significantly different between control (anterior wall, 347±56 ng/g
    inferior wall, 354±31 ng/g
    plasma 9.38±2.10 ng/ml) and GK rats (anterior wall, 323±62 ng/g
    inferior wall, 344±35 ng/g
    plasma, 9.41±2.39 ng/ml). The density and affinity of NET were investigated by studying the binding of [3H]desipramine to cardiac membranes. The Bmax (fmol/mg protein) in the inferior wall was significantly higher than that in the anterior wall in the control rats (anterior wall, 364±28
    inferior wall, 459±36: P<
    0.05). On the other hand, there was no significant difference in the Bmax value between the anterior and inferior walls in GK rats (anterior wall, 263±42
    inferior wall, 251±27). In conclusion, myocardial MIBG uptake was differentially reduced in GK rats, and this decrease was associated with a decrease in NET density, but the regional myocardial blood flow and the NE concentration were not responsible for the alterations in MIBG uptake. Thus, NET density was identified as the factor responsible for decreases in MIBG accumulation.
  • Direct single step F-18 fluorination of peptides.
    Ogawa M, Hatano K, Oishi S, Miyake Y, Kawasumi Y, Ito K, Fujii N, Iida H
    Journal of Nuclear Medicine, 43, 5, 137P, 2002年, ［査読有り］
  • Synthesis and in vivo evaluation of [C-11]methyl-Ro 64-6198 as an ORL1 receptor imaging agent
    M Ogawa, K Hatano, Y Kawasumi, E Wichmann, K Ito
    NUCLEAR MEDICINE AND BIOLOGY, 28, 8, 941, 947, ELSEVIER SCIENCE INC, 2001年11月, ［査読有り］
    英語, 研究論文（学術雑誌）, (1S,3aS)-8-(2,3,3a,4,5,6-Hexahydro-1H-phenalen-1-yl)-3-N-[C-11]methyl-1-phenyl-1,3,8-triaza-spiro[4,5]decan-4-one ([C-11]methyl-Ro 64-6198), a N-methylated analog of Ro 64-6198, was synthesized and evaluated as a potential radiopharmaceutical for investigating brain nociceptin/orphanin FQ receptors (ORL1 receptors) by positron emission tomography. A racemate of methyl-Ro 64-6198, Ro 66-7931, showed a high affinity and selectivity for the ORL1 receptor in vitro. An in vivo distribution study in mice demonstrated moderate brain uptake, however, only slight difference was observed among brain regions. Furthermore, pretreating with nociceptin or Ro 66-7931 did not affect the accumulation. Therefore, despite its high affinity, [C-11]methyl-Ro 64-6198 does not appear to be a suitable tracer for in vivo ORL1 receptor imaging studies. (C) 2001 Elsevier Science Inc. All rights reserved.
  • Compartment analysis of cerebral glucose metabolism and in vitro glucose-metabolizing enzyme activities in the rat brain
    Y Ouchi, H Fukuyama, S Matsuzaki, M Ogawa, J Kimura, H Tsukada, T Kakiuchi, T Kosugi, S Nishiyama
    BRAIN RESEARCH, 706, 2, 267, 272, ELSEVIER SCIENCE BV, 1996年01月, ［査読有り］
    英語, 研究論文（学術雑誌）, To clarify the relationship between cerebral glucose metabolic rate constants and glucose-metabolizing enzyme activities in the cerebral cortex, we evaluated the cerebral metabolic rate of glucose (CMRGlu), metabolic rate constants of [F-18]-2-fluoro-2-deoxy-D-glucose (FDG) and related enzyme activities in the frontal cortex under normal and glucose metabolism-suppressed conditions. Applying a three-compartment four-parameter model, metabolic rate constants were obtained by dynamic positron emission tomography with FDG, and CMRGlu was calculated based on these rate constants. The glycolytic enzyme activities were determined by in vitro biochemicai assay. Three days after ibotenic acid injection into the basal forebrain, CMRGlu was decreased in the ibotenic acid-treated frontal cortex as well as k3* (phosphorylation), while K1* (plasma to brain) showed no remarkable change. No significant reductions of the enzyme activities except for hexokinase activity were found in the frontal cortex. Regression analysis showed a significant positive correlation between k3* and the hexokinase activity. These results suggested that k3* in the compartment analysis reflects hexokinase activity.
  • Cholinergic projection from the basal forebrain and cerebral glucose metabolism in rats: A dynamic PET study
    Y Ouchi, H Fukuyama, M Ogawa, H Yamauchi, J Kimura, Y Magata, Y Yonekura, J Konishi
    JOURNAL OF CEREBRAL BLOOD FLOW AND METABOLISM, 16, 1, 34, 41, LIPPINCOTT-RAVEN PUBL, 1996年01月, ［査読有り］
    英語, 研究論文（学術雑誌）, To investigate the influence of cholinergic projections from the basal forebrain on cerebral cortex metabolism, we evaluated the cerebral metabolic rate of glucose (CMR(Glu)) after selective inhibition of cholinergic neurons in the rat basal forebrain using the pyruvate dehydrogenase complex inhibitor 3-bromopyruvic acid (BPA), and compared the results with those obtained after lesioning the basal forebrain with ibotenic acid, as well as with those from a sham-operated control group. CMR(Glu) was measured using positron emission tomography (PET) with [F-18]-2-fluoro-2-deoxy-D-glucose (FDG). Three days after surgery, CMR(Glu) and k3 (phosphorylation of FDG) were reduced similarly in the frontal cortex on the BPA-injected side and in the ibotenic acid-treated group, whereas K1 (transport rate of FDG from the plasma to brain) showed no marked changes. At 3 weeks postoperatively, the CMR(Glu) and k3 of the frontal cortex in both groups recovered to levels similar to those of the sham-operated group. The main difference between the BPA and ibotenic acid groups was that CMR(Glu) showed mild reduction on the side contralateral to the operation in the former, while such reduction was confined to the ipsilateral hemisphere in the latter. The present results indicate that the cholinergic system in the basal forebrain regulates cerebral cortex glucose metabolism through direct excitation of cortical neurons.
  • SCOPOLAMINE ABOLISHES CEREBRAL BLOOD-FLOW RESPONSE TO SOMATOSENSORY STIMULATION IN ANESTHETIZED CATS - PET STUDY
    M OGAWA, Y MAGATA, Y OUCHI, H FUKUYAMA, H YAMAUCHI, J KIMURA, Y YONEKURA, J KONISHI
    BRAIN RESEARCH, 650, 2, 249, 252, ELSEVIER SCIENCE BV, 1994年07月, ［査読有り］
    英語, 研究論文（学術雑誌）, The effect of the cholinergic blocker, scopolamine on the cerebral blood flow (CBF) response to vibrotactile stimulation of a fore paw was studied using high-resolution positron emission tomography and (H2O)-O-15 in 5 pentobarbital-anesthetized cats. Before scopolamine injection, the CBF response to the stimulation was found in the contralateral somatosensory cortex (mean ratio (contralateral/ipsilateral) control: stimulated 1.02 +/- 0.02: 1.17 +/- 0.05; P < 0.01). After intravenous injection of scopolamine (0.35 mg/kg), the CBF response was abolished. However, the cerebral metabolic rate of glucose (CMRGlu) response to the same stimulation was unchanged after scopolamine injection in the same cats. We concluded that scopolamine abolishes the CBF response but not neuronal response to stimulation. We suggest that cholinergic mechanisms may play an important role for mediating CBF coupling to neuronal activity during physiological stimulation.
  • CROSSED CEREBELLAR HYPOPERFUSION IN UNILATERAL MAJOR CEREBRAL-ARTERY OCCLUSIVE DISORDERS
    H YAMAUCHI, H FUKUYAMA, S YAMAGUCHI, T DOI, M OGAWA, Y OUCHI, J KIMURA, N SADATOH, Y YONEKURA, N TAMAKI, J KONISHI
    JOURNAL OF NUCLEAR MEDICINE, 33, 9, 1637, 1641, SOC NUCLEAR MEDICINE INC, 1992年09月, ［査読有り］
    英語, 研究論文（学術雑誌）, We evaluated regional blood flow and oxygen metabolism in the cerebral and cerebellar cortices of 15 patients with unilateral major cerebral artery occlusive disorders with PET. These patients showed a cortical blood flow asymmetry in middle cerebral artery distribution. Only subcortical abnormalities were detected on computed tomography. Nine patients showed crossed cerebellar hypoperfusion, a reduction in contralateral cerebellar blood flow, while six did not. No difference in the degree of cerebral blood flow asymmetry existed between the two patient groups. However, oxygen metabolism asymmetry was more pronounced and was more closely matched to blood flow asymmetry in patients with crossed cerebellar hypoperfusion. These findings suggest that a major cause of cerebral cortical blood flow reduction is reduced metabolic demand in patients with crossed cerebellar hypoperfusion. Crossed cerebellar hypoperfusion may have clinical significance as a reflection of the cerebral metabolic state on blood flow images.

その他活動・業績

共同研究・競争的資金等の研究課題

  • エネルギー代謝に着目した核医学イメージングによるがん微小環境評価
    科学研究費助成事業
    2022年04月01日 - 2026年03月31日
    小川 美香子, 平田 健司, 久下 裕司, 鍛代 悠一
    日本学術振興会, 基盤研究(B), 北海道大学, 22H03009
  • がん特異的糖鎖抗原を用いた小児がんに対する近赤外光線免疫療法の確立：前臨床モデル
    科学研究費助成事業
    2022年04月01日 - 2025年03月31日
    長 祐子, 真部 淳, 小川 美香子, 樋田 泰浩, 植木 将弘, 中島 孝平
    日本学術振興会, 基盤研究(C), 北海道大学, 22K07884
  • フェロトーシス誘導がん治療のPETイメージング
    科学研究費助成事業
    2021年04月01日 - 2025年03月31日
    久下 裕司, 安井 博宣, 小川 美香子, 平田 健司, 水野 雄貴
    近年、フェロトーシスと呼ばれる新しい細胞死様式が報告され、フェロトーシスを誘導する薬剤が新たながん治療薬として注目されている。このフェロトーシスの進行には、トランスフェリン受容体1 (TfR1) が深く関与することが知られている。本研究の目的は、TfR1の特異的イメージングを可能とする新たなPETイメージング剤を合成し、PETによるTfR1イメージングがフェロトーシス誘導剤の治療効果予測/判定やフェロトーシス誘導剤の開発に有効な手段となるか否かを明らかにすることにある。
    本目的達成のため、これまでに主に新たなPETイメージング剤の合成検討、及びIn vitro細胞実験を行った。その結果、TfR1への親和性を有する7残基直鎖ペプチド (DT7) を母体とした68Ga標識プローブ（68Ga-DT7）が、T98G (TfR1高発現細胞株) に対してTfR1特異的に集積することを見出した。一方で、その集積量はやや低かったことから、分子内に2つのDT7ペプチドを有する2価DT7を新たに設計し、合成に成功した。しかし、68Gaで標識した2価DT7のT98Gへの集積量は予想に反して低かった。さらに、直鎖上のDT7ペプチドを環状化した環化ペプチドを合成し、T98Gへの集積量を評価したが、TfR1特異的集積量の向上には繋がらなかった。
    上記検討結果から、TfR1への親和性がより高いリガンドを母体としたプローブを開発する必要性が示唆された。そこで、cystine dense peptideの１種でありTfR1との高い結合親和性を有するTfRB1G3を母体としたプローブの開発を開始した。
    日本学術振興会, 基盤研究(B), 北海道大学, 21H02858
  • 外部からの光照射を必要としない革新的な光免疫療法の開発
    科学研究費助成事業
    2021年07月09日 - 2024年03月31日
    花岡 宏史, 小川 美香子, 石岡 典子
    光免疫療法は新たながん治療法として注目されており、臨床において優れた治療効果を示している。しかし光免疫療法においては、がんに対してどのように光を照射するかというのが一つの課題である。一方、放射性薬剤が放出するチェレンコフ光は、光免疫療法の光源として利用可能であると考えられる。そこで本研究では、光免疫療法に用いるのに適した新規放射性薬剤を開発することで、外部からの光照射を必要としないチェレンコフ光による新たな光免疫療法を確立することを計画した。
    今年度はチェレンコフ光を利用した光免疫療法の基礎検討として、高エネルギーβ線放出核種であるイットリウム-90(90Y)を用いたチェレンコフ光の検出実験を行った。しかし用いた装置の検出感度が不十分であり、90Yから放出されるチェレンコフ光を検出するには至らなかった。現在、どのように検出を行うか検討中である。
    一方、新規放射性薬剤の開発においては、新たな薬剤を設計し、合成に取りかかっている。90Y標識薬剤としては対してクリック反応を起こすテトラジンをリンカーを介してキレート剤に結合した化合物を、76Br標識体としてはBrチロシンを用いることとし、前駆体としてチロシンに対してリンカーを介してテトラジンを結合した化合物を用いる予定である。
    またテトラジンとクリック反応するTrans-Cyclooctene（TCO）を結合した抗体とテトラジンを結合した分子が、生体内でクリック反応を起こすことは、マウスを用いた検討により確認することができた。
    日本学術振興会, 挑戦的研究(萌芽), 関西医科大学, 21K19459
  • PETによるフェロトーシスイメージング：動脈硬化プラークの不安定性評価への挑戦
    科学研究費助成事業
    2021年07月09日 - 2024年03月31日
    久下 裕司, 安井 博宣, 小川 美香子, 横田 千晶, 水野 雄貴
    動脈硬化病変の評価においては、早期治療を必要とする“破綻しやすいプラーク（不安定プラーク）”を的確に診断することが重要である。最近、鉄依存性酸化ストレスに起因するフェロトーシスと呼ばれる細胞死の様式が、動脈硬化の病態にも深く関与していることが報告された。本研究の目的は、フェロトーシス関連分子のPETイメージングにより、不安定プラークの診断が可能となるか検証することにある。
    フェロトーシスの進行には、トランスフェリン受容体1 (TfR1) が深く関与することが知られている。令和3年度は、TfR1への高い結合親和性を有する直鎖ペプチド (DT7) を母体とした68Ga標識プローブ（68Ga-DT7）を合成し、in vitro実験条件下でTfR1イメージング剤としての有用性を評価した。その結果、68Ga-DT7は、TfR1特異的に集積したが、細胞集積量は十分ではなかった。そこで、細胞集積量の向上を目指してペプチドの多量体化や環状化などを実施したが、68Ga-DT7の細胞集積量を上回る誘導体の創成には至らなかった。
    一方、不安定プラークにおけるフェロトーシスの関与をより多角的に評価するため、プラークにおける酸化ストレスを可視化できるプローブの合成と評価を開始した。合成した標識体は活性酸素種 (ROS)との反応によって錯体が崩壊し、酸化ストレスイメージング剤として機能する可能性が示された。
    以上の検討結果から、TfR1への結合親和性がより高いリガンドの68Ga標識体を作製する必要性が示唆された。今後、cystine dense peptideの1種であるTfRB1G3の68Ga標識体を合成し、TfR1イメージング剤としての評価を行う。また、フェロトーシス関連分子のイメージングによる不安定プラークの多角的評価に向けて、酸化ストレスイメージング剤の開発も継続する。
    日本学術振興会, 挑戦的研究(萌芽), 北海道大学, 21K19433
  • 肺がん糖鎖抗原を用いた光免疫とiRGDナノ粒子によるsiRNA送達システムの開発
    科学研究費助成事業
    2021年04月01日 - 2024年03月31日
    加藤 達哉, 櫻井 遊, 畑中 佳奈子, 小川 美香子, 樋田 泰浩, 畑中 豊
    本研究はMUC1がん特異的糖鎖抗原のみを選択的に認識する新規モノクローナル抗体（MUC1-Tn抗体）と光感受性物質であるIR700との結合体を用いて、がん細胞のみを特異的に攻撃する新たな治療法を確立し、新規の肺がん治療法の開発を目指すものである。
    今年度は、まず本研究の肝となるMUC1-Tn抗体の供給源である㈱医化学創薬と共同で研究をすすめ、MTAを締結し、本実験で想定される抗体量の確保に努め、動物実験まで含めた十分量の抗体を得ることに成功した。
    さらに今年度は、研究実施計画に則り、まず今後in vitro実験およびin vivo実験に用いる予定のMUC1-Tn高発現の細胞株の選定を行った。乳癌細胞株であるT47DがMUC1-Tnが高発現していることが判明したが、その後21個の肺癌細胞株のセルブロックを作成し、抗MUC1-Tn抗体を用いて免疫染色を行った。うち2株（RERF-LC-KJ, H2228）に高発現が認められ、今後、in vitroおよびin vivo実験に使用可能と判断した。その他、陰性コントロールとしての細胞株も複数選定した。
    また、実験遂行者はすでにIR700と抗MUC1-Tn抗体を合成する技術を習得しており、予備実験として、MUC1-Tn抗体とIR700の結合体を作成し、T47Dに導入後、FACSにて細胞膜表面に抗体が結合していることを確認した。また、タイムラプス顕微鏡でレーザー照射により導入細胞で細胞膜よりブレブが隆起し、細胞死に至ることを確認することができた。したがって今後肺癌細胞株を用いた本実験を開始できる状況にある。
    日本学術振興会, 基盤研究(C), 北海道大学, 21K08876
  • マウス肺癌モデルを用いたCD73を標的とした赤外光線免疫療法の確立
    科学研究費助成事業
    2021年04月01日 - 2024年03月31日
    畑中 豊, 加藤 達哉, 小川 美香子, 畑中 佳奈子
    がん微小環境において，低酸素状態下ではATPからAMPを介しアデノシンを生成する
    CD39/CD73カスケード分子の発現が誘導され，さらにアデノシンはリンパ球上のA2受容体を介して免疫抑制状態を誘導することから，免疫チェックポイント阻害（ICI）療法に対し抵抗性を示す．
    本研究は，先行研究として実施した非小細胞肺癌（NSCLC）の一部でCD73発現が亢進し，またPD-L1発現と相関する点に着目し，(a) NSCLC組織検体を用いたCD73およびPD-L1発現と腫瘍微小環境との関連性について検討し，次いで(b) ヒトおよびマウス肺癌細胞株を用いたCD73-IR700-Cのがん細胞への集積確認と治療効果のin vitro評価，および(c) ヒトおよびマウス肺癌細胞株の移植腫瘍モデルを用いたCD73抗体-IR700結合体（CD73-IR700-C）の腫瘍集積性の確認および近赤外線免疫療法（NIR-PIT）の抗腫瘍効果のin vivo評価を行う．
    本年度は以下の課題に取り組んだ．肺扁平上皮癌症例を用いた組織マイクロアレイ（TMA）標本123例を用いた低酸素関連タンパクの臨床病理学的検討：CD73，PD-L1およびHIF-1a発現について検討したところ，先行研究同様，CD73とPD-L1発現間に有意な関連性（p=0.019）が認められ，またCD73とHIF-1a発現間にも関連傾向（p=0.0548）が観察された．これら３分子の生存解析においては，低発現群に比べ高発現群で，それぞれ有意な無再発生存期間（RFS）の短縮が認められ，さらにCD73高発現/HIF-1a高発現群ではさらに短縮した（p=0.0187）．
    日本学術振興会, 基盤研究(C), 北海道大学, 21K07189
  • 硬X線による化合物活性化を利用した新しいがん治療法の開拓
    科学研究費助成事業
    2021年04月01日 - 2023年03月31日
    小川 美香子
    日本学術振興会, 新学術領域研究(研究領域提案型), 北海道大学, 21H00158
  • α線治療はなぜ効くのか？ーがん免疫から迫るー
    科学研究費助成事業
    2019年06月28日 - 2022年03月31日
    小川 美香子, 東川 桂
    最近、がん治療では免疫細胞の関与が重要であることが明らかとなってきている。そこで、飛程が長いβ線治療ではがん細胞の周囲にあるT細胞・樹状細胞などの免疫細胞を巻きこみ死滅させる可能性があるが、飛程が短いα線治療では放射標識薬剤が結合したがん細胞のみに影響を与えるのではないかと発想した。すなわち、標的化α治療ではがん免疫が活性化していることにより、大きな治療効果が現れているのではないかと考え、α線治療とがん免疫の関連について検討することを本研究の目的とする。
    昨年度までに、還元型At-211を利用した新規標識法を開発した。本年度はさらに多くの化合物へ展開し、9種類の化合物の標識合成に成功した。また、樹脂を使った固相での標識合成も達成した。
    また、I-131標識体の合成のため、I-125での事前検討を行った。さらに、昨年に引き続き、X線による外照射によるがん免疫の検討を行った。昨年は腫瘍が小さすぎたのと線量が高すぎたので腫瘍がほぼ消失してしまい、フローサイトメータなどによるアッセイがほとんど行えなかったので、今年度は腫瘍が100 mm3超えてから照射することとし、かつ線量を10 Gyから8 Gyに落とし検討を行った。照射開始日（Day0）とDay3にPD-1抗体を投与し、Day4およびDay10に安楽殺し、フローサイトメトリーにより免疫細胞の評価を行った。この結果、X線照射直後に抗腫瘍免疫を担うCD8 T細胞の減少が観察され、外照射により腫瘍組織内の免疫活性が一時的に低下することが示唆された。CD4 T細胞X線照射直後での変化は少ないものの、照射から1週間後では顕著に減少していた。CD4は免疫記憶などにも関与することからその減少は抗腫瘍免疫の減弱につながると考えられる。放射線照射により免疫原性が高まった際にPD-L1の発現が増加するとの報告があったが変化は認められなかった。
    日本学術振興会, 挑戦的研究(萌芽), 北海道大学, 19K22587
  • イメージングを駆使した光免疫治療のメカニズム解明と汎用性向上へ向けた展開
    科学研究費助成事業
    2019年04月01日 - 2022年03月31日
    小川 美香子, 久下 裕司
    光免疫治療法は、光感受性色素IR700を抗体に結合させた薬剤を用いるがんの新しい光治療法である。本研究では、申請者の専門領域であるインビボ分子イメージング法を用い、PITを評価した。さらに長波長化・ペプチド薬剤の開発による汎用性・応用性向上を目指した。
    PETおよびARGの結果から、PITにより照射側腫瘍の中心部への酸素供給が亢進されることで、低酸素状態が解消されたことが示唆された。小分子薬剤GUL-IR700は抗体-IR700よりも1O2の寄与が大きいものの凝集体形成を介しても細胞を傷害する可能性が示された。
    日本学術振興会, 基盤研究(B), 北海道大学, 19H03593
  • PET,CT,MRIによる包括的映像法を用いた不安定プラークの病態評価
    科学研究費助成事業
    2018年04月01日 - 2021年03月31日
    玉木 長良, 小川 美香子, 酒井 晃二, 納谷 昌直, 真鍋 治, 久下 裕司, 板谷 慶一, 真鍋 徳子, 益田 淳朗
    PETは動脈硬化(プラーク)の不安定性の評価に利用される.他方CTによる形態情報や,MRIによる形態・機能情報も役立つ.本研究ではモデル動物を用いて,PET薬剤の集積程度と免疫病理組織学的所見と対比した.また臨床では、PETに加えてCTやMRIとの融合画像法を導入し,多方面から病態評価を行った.以上の基礎的・臨床的検討より、プラークの病態評価のための最適な画像診断法の確立に寄与できた.
    日本学術振興会, 基盤研究(B), 京都府立医科大学, 18H02769
  • 自己会合型環境応答性光音響イメージング剤の開発
    科学研究費助成事業
    2018年04月01日 - 2020年03月31日
    小川 美香子
    日本学術振興会, 新学術領域研究(研究領域提案型), 北海道大学, 18H04723
  • チェレンコフ光を利用した癌治療への挑戦
    科学研究費助成事業
    2016年04月01日 - 2019年03月31日
    小川 美香子
    本研究では、癌に集積したPETプローブのチェレンコフ光を利用し、Cerenkov luminescence resonance energy transfer (CRET)現象による光反応性薬剤の励起を行うことで、深部癌の治療、さらには発見が困難である微小癌の治療を目指した。
    チェレンコフ光にて励起可能なIR700分子のSoret吸収帯の励起により、近赤外領域であるQ帯の励起と同じように細胞死が起こることは確認した。しかし、18F標識抗体や抗体フラグメントを用いても細胞死は見られなかった。そこで、X線での励起・電離を利用することを試みたところ、光反応性化合物の活性化が認められた。
    日本学術振興会, 挑戦的萌芽研究, 北海道大学, 16K15568
  • インビボイメージングを駆使したTheranostics法の開発
    科学研究費助成事業
    2016年04月01日 - 2019年03月31日
    小川 美香子, 間賀田 泰寛, 久下 裕司, 志賀 哲
    Photo-immuno therapy (PIT)は、近赤外光を用いた新しい癌治療法である。本研究では、核医学と光技術を組み合わせ、癌の「診断(diagnosis)」と「治療(therapeutics)」の融合技術である“Theranostics”法の確立を目指した。マウス腫瘍に光を当てると蛍光が消失した。このマウスにおいて治療前後にてPET撮像を行ったところ、光照射直後の組織に傷害が無い状態から[18F]FDG, [18F]FMISOの低下を認めた。すなわち、治療効果をPETで診断可能であることが判った。
    日本学術振興会, 基盤研究(B), 北海道大学, 16H05382
  • PETによる心血管疾患の活動性の映像化と治療戦略への応用
    科学研究費助成事業
    2015年04月01日 - 2018年03月31日
    玉木 長良, 小川 美香子, 納谷 昌直, 吉永 恵一郎, 中山 若樹, 久下 裕司, 真鍋 徳子, 西嶋 剣一
    分子機能情報の映像化と定量的解析に優れたPETの特徴を活かして、心血管疾患の活動性を映像化した。
    実験動物では、動脈硬化の活動性とマクロファージ活性を反映するFDGや低酸素マーカーのFMISOの集積とよく一致した。臨床例では15O標識水PETで計測された心筋血流予備能とFFRとは、概ね相関を示した。また上腕動脈の血管弾力性との相関を明らかにした。さらには心サルコイドーシスの活動性病変検出にFDG-PETが役立った。
    PETは動脈硬化病変の重症度判定や心筋の活動性評価など、治療戦略にかかわる幅広い領域で活用されることが期待できる。
    日本学術振興会, 基盤研究(B), 15H04898
  • 薬剤送達に対するリンパ管の役割：転写因子FOXC2に着目したリンパ管機能解析
    科学研究費助成事業
    2014年04月01日 - 2018年03月31日
    平川 聡史, 青戸 一司, 小川 美香子, 三浦 直行
    本研究では、癌微小環境におけるリンパ管の機能を、薬物送達に関わる重要な因子の一つとして解明することに取り組んだ。癌血管新生について、そのプロセスが多様な細胞によって組織されることが明らかになる一方、癌リンパ管新生のプロセスについては、いまだ不明な点が多い。本研究では、癌組織を始めとする病的リンパ管新生の生物学的意義を解明すべく、血管内投与した物質の送達を可視化すべく観測した。具体的には、表皮特異的VEGF-Aトランスジェニック・マウス及びFOXC2+/-マウスを用いて、病的リンパ管の機能解析を行い、リンパ管の新たな機能評価系を構築すべく取り組んだ。
    日本学術振興会, 基盤研究(B), 浜松医科大学, 26293257
  • オールイン型デンドリマーを用いた癌の「見張り」リンパ節のイメージング・薬物送達
    科学研究費助成事業
    2014年04月01日 - 2017年03月31日
    児島 千恵, 近藤 英作, 小川 美香子
    日本の死因の第一位である癌の克服のため、本研究では、転移性癌細胞の最初の通り道であるリンパ節の正確なイメージングと薬物送達を行うことを目的とした。まず、サイズや構造を制御でき、かつデリバリー機能をもつデンドリマーとよばれる合成高分子の構造最適化を行い、リンパ節へ多く移行するデンドリマーを得た。そして、このデンドリマーにイメージング剤を付与し、リンパ節の検出に成功した。さらに、癌細胞集積性と抗腫瘍活性を併せ持つデンドリマーを作製し、癌細胞に選択的な殺傷効果を示すデンドリマーを作製することにも成功した。
    日本学術振興会, 基盤研究(C), 大阪府立大学, 26410227
  • PETプローブのチェレンコフ光を利用した光イメージングと光治療法への技術展開
    科学研究費助成事業
    2013年04月01日 - 2016年03月31日
    小川 美香子
    PETでは、シグナル部位としてポジトロン放出核種を用いる。PETでは低分子量のプローブの作成が可能であるため、脳の分子イメージングが容易である。一方、光イメージングは簡便であるが、蛍光分子の分子量が大きいため脳機能イメージングは難しい。そこで、PETイメージングプローブが放出するチェレンコフ光を利用することで、これまで不可能と考えられていた脳機能の光イメージングが可能になると考え検討を行った。この結果、チェレンコフ光イメージングによる[18F]FDGを用いた脳糖代謝測定、[11C]raclopride, [11C]b-CFTを用いた脳受容体・トランスポータイメージングに成功した。
    日本学術振興会, 挑戦的萌芽研究, 25670528
  • 治療応答に伴うミトコンドリア機能変化に反応する新規がんイメージング薬剤の開発
    科学研究費助成事業
    2013年04月01日 - 2016年03月31日
    間賀田 泰寛, 阪原 晴海, 鈴木 千恵, 小川 美香子, 高島 好聖
    がん治療後のミトコンドリア機能変化を画像化し得る新規イメージングプローブ開発を行った。これまでに開発した放射性ヨウ素標識脂溶性カチオン誘導体であるI-125-DPPはミトコンドリア膜電位に依存して細胞に集積するものの、P-gpにより細胞外へ排泄されたため、P-gpの阻害剤であるスチルベンをその構造に導入したI-125-DESPを開発した。腫瘍細胞を用いた取込実験では、I-125-DDPに比べて6.7倍高い取込を示すとともに、P-gpに一定の阻害効果を示して細胞内に蓄積し、本薬剤デザインのPOCが得られた。インビボ試験の結果、肝臓に高く集積し、残念ながら腫瘍への取り込みは低値を示した。
    日本学術振興会, 基盤研究(B), 浜松医科大学, 25293262
  • 不安定プラークの診断・薬物治療効果評価を合目的的に施行するためのシステムの構築
    科学研究費助成事業
    2012年04月01日 - 2016年03月31日
    小川 美香子
    本研究では、不安定プラークのイメージングを目指し、FDG, FMISO, NaF, PK11195, Cholineを用い同一個体（WHHLウサギ）にて経時的にPETイメージングを行った。FDGはプラークを不安定化させるマクロファージに多く取り込まれ、不安定化へ向かう病変を捉える可能性が示された。NaFは正常細胞への取り込みが限られているため、最も大きなSN比を得ることができた。また、CTでみられる石灰化とは異なる分布を示した。Cholineは超早期病変を捉える可能性が示されたが、PK11195とともに集積量が十分ではない個体が多く認められた。FMISOはほとんどの個体に集積が見られなかった。
    日本学術振興会, 若手研究(A), 24689049
  • アルツハイマー病におけるアミロイド蛋白生成γセクレターゼ活性の生体画像法の開発
    科学研究費助成事業
    2011年04月01日 - 2014年03月31日
    尾内 康臣, 植木 孝俊, 小川 美香子, 間賀田 泰寛
    アルツハイマー病の脳内のβアミロイド蓄積の程度が必ずしも認知活動と並行しないことが指摘されているため、βアミロイド生成の上流にあるγセクレターゼの活性の生体画像化を試みた。その結果、γセクレターゼ活性依存的に発生するように設計したMRIプローブはin vitro系ではうまくシグナルを発生したが、生体実験ではシグナルが得られず、より効率に細胞内移行を示し高シグナルを出すプローブが必要であると結論した。
    日本学術振興会, 基盤研究(B), 浜松医科大学, 23390287
  • ミトコンドリア機能変化に着目したがん治療応答の新規画像法開発
    科学研究費助成事業
    2010年 - 2012年
    間賀田 泰寛, 阪原 晴海, 松島 芳孝, 小川 美香子, 高島 好聖
    がん治療法選択・効果予測、治療効果の早期判定を目的として、「アポトーシス」、「酸素」といったキーワードと関連の深いミトコンドリア機能変化を非侵襲的にかつ、利用の広汎性の高い手法により評価可能なイメージング法の開発を目的として検討を行った。その結果、利用の広汎性の高い放射性ヨウ素標識IDPPがミトコンドリア膜電位に依存して細胞に集積することが示された。また、光線力学的療法における治療応答性についてFDGおよびMIBIの取り込み率をマーカーとして用いて検討を行ったところ、治療前のFDGの取り込みの高い細胞系ほど高いPDT治療効果が期待され、また、PDT後はMIBIの取り込み低下がPDT治療効果に相関することが認められた。
    日本学術振興会, 基盤研究(B), 浜松医科大学, 22390232
  • 動脈硬化不安定プラークを特異的に検出する分子標的イメージング剤の開発
    科学研究費助成事業
    2009年 - 2011年
    小川 美香子
    動脈硬化病変に生じる不安定プラークは、破綻し血管を閉塞させ脳梗塞・心筋梗塞などを引き起こすため、早期に検出し治療を行うことが重要である。そこで本研究では、不安定プラークへの特異性が高い分子イメージング剤の開発を機能性リポソームを用いて行った。この結果、ホスファチジルセリンにより修飾したリポソームを用いることで、不安定プラークに多く存在するマクロファージを標的としたイメージングに成功し、動脈硬化モデル動物を用いて病変を画像化することができた。
    日本学術振興会, 若手研究(B), 浜松医科大学, 21791181
  • 血管内滞留型新規X線CT用造影剤の開発
    科学研究費助成事業
    2009年 - 2011年
    阪原 晴海, 間賀田 泰寛, 山口 博司, 淵上 剛志, 小川 美香子, 児島 千恵, 堺 俊博, 高島 好聖
    組織の血管構築や虚血性変化、癌の血管新生を画像化するため、血管内滞留性の高い新規X線CT造影剤の開発を目的とした。造影効果を上げる元素としてヨウ素あるいは金を用いることとし、それらの担体として、血清アルブミンあるいはPEG修飾デンドリマーを用いた。ヨウ素造影剤はそれぞれインビトロで一定の造影効果を示したが、インビボでは造影効果が得られなかった。金ナノ粒子内包PEG修飾デンドリマーはインビボで市販のヨウ素造影剤と比較して長時間血管を造影できることが明らかとなった。
    日本学術振興会, 基盤研究(B), 浜松医科大学, 21390343
  • 脂肪酸代謝疾患として捉える自閉症の生物学的基盤の解明
    科学研究費助成事業
    2009年 - 2011年
    松崎 秀夫, 財満 信宏, 岩田 圭子, 小川 美香子, 辻井 正次, 瀬藤 光利, 土屋 賢治, 伊東 宏晃, 間賀田 泰寛
    自閉症者血清中の脂質VLDL分画の低下から(1)自閉症者血清中の脂肪酸解析、(2)脂肪酸所見に基づく自閉症動物モデルの確立とその解析、(3)動物モデルを用いた新規自閉症治療法を検討した。その結果、VLDL分画の低下に関連の深い脂肪酸としてω６脂肪酸を含む6種類の脂肪酸を見出した。ついでCD38KOマウスに自閉症者同様の血清中脂質VLDL分画・ω６脂肪酸の低下を認め、血中ω６脂肪酸の低下を出生直後に補うと社会認識行動の修復につながることを見出した。VLDLR-Tgラットにも多動と組織中のアラキドン酸の欠乏が示された。
    日本学術振興会, 新学術領域研究(研究課題提案型), 21200014
  • 動脈硬化病変に生じる不安定プラークの検出に有用な核医学イメージング剤に関する検討
    科学研究費助成事業
    2007年 - 2008年
    小川 美香子
    最近、内臓脂肪の蓄積、高血圧、高血糖、高脂血症を特徴とする『メタボリックシンドローム』が、心筋梗塞や脳梗塞といった動脈硬化性疾患の発症要因となるマルチプルリスクファクター症候群として提唱され、適切な対策が求められている。この動脈硬化病変に生じる不安定プラークは、プラークの破綻、血栓形成、血管内腔の狭窄・閉塞という一連の病態を引き起こし、動脈硬化性疾患発症の原因となる。本研究では不安定プラークの検出に有用な、核医学イメージング剤に関する検討を行うものである。
    これまでに我々は、[^<18>F]フルオロデオキシグルコース([^<18>F]FDG)が不安定プラークに浸潤するマクロファージの数に応じて集積することを報告してきた。そこで本年度は不安定プラークにおけるマクロファージの成熟段階に応じて[^<18>F]FDGの集積量が変化するかより詳細な検討を行った。すなわち、泡沫化する前のマクロファージとacLDLを添加することにより泡沫化させたマクロファージを培養し、それぞれへの[^<18>F]FDGの取り込み量を検討した。この結果、泡沫化12,24,48時間後すべてにおいて、泡沫化による影響は認められなかった。なお、マクロファージはacLDL添加後48時間で成熟した泡沫細胞となる。本検討結果は、[^<18>F]FDGでは不安定プラークの詳細な進展過程を追跡できないことを示すものであり、不安定プラークの進展過程で変化するマクロファージ表面抗原などを認識するような、新たなイメージング剤開発の必要性が示唆された。
    日本学術振興会, 若手研究(B), 浜松医科大学, 19790865
  • ガン治療効果予測を可能とする指標および放射性薬剤の開発-酸素効果を中心として
    科学研究費助成事業
    2005年 - 2007年
    間賀田 泰寛, 阪原 晴海, 小川 美香子, 平野 達, 大石 真也, 塚田 秀夫
    ガン治療における放射線の外照射や内照射、あるいは光線力学的療法(PDT)の治療効果にはガン自体の大きさ、進展度や血管新生をはじめ多くの因子が関連する。中でも酸素効果の存在は良く知られているところであり、低酸素部位では治療効果が低減する。これに関してはこれまでにも多くの研究が行われ、臨床的にもガンの由来や分化度等により酸素効果の大小はある程度知られているが、個体によるばらつきも大きく臨床的分類のみで一般化するのは困難な面がある。この様な観点から治療施行前に治療効果の予測が立てられれば治療方針の決定や予後予測に役立つものと期待される。本研究ではこの様な背景の元、新しいガン診断用放射性医薬品の開発を含めてPETを中心とした核医学的手法によるガン治療効果予測システムの構築を目的とするものである。
    Oxymap装置を用い、インビボで腫瘍内酸素濃度分布の評価法を確立した。また、酸素濃度の影響を強く受けることが知られているPDT療法に用いる新規PDT薬の開発を目的として約500個のライブラリより一重項酸素が発生する化合物を見出し、細胞実験レベルにてPDT薬となり得るものと考えられた。生理活性を有するペプチド誘導体の体内動態評価を可能とする標識プローブとして、F-18-SFBの自動合成装置合成法を確立し、これを用いて腫瘍転移能に関連すると言われているGPR54結合性ペプチド、TOM80の標識体の開発に成功した。また18年度に設置された動物用PET/SPECT/CT装置を用いてイメージング研究を行うため、Tc-99mとFDGの連続撮像法を開発した。これらの成果を統合することにより腫瘍イメージング研究に有用な指針を与えるものと考えられた。
    日本学術振興会, 基盤研究(B), 浜松医科大学, 17390331
  • ミトコンドリア膜電位依存的腫瘍集積性を示す放射性薬剤の集積意義と新規薬剤への展開
    科学研究費助成事業
    2005年 - 2007年
    阪原 晴海, 間賀田 泰寛, 小川 美香子
    腫瘍核医学においてT1-201やTc-99m-MIBI(以下、MIBIと略す)のような脂溶性カチオンが一部の腫瘍に集積し、腫瘍イメージング上有用であることは良く知られている。T1-201およびMIBIはいずれも心筋血流シンチグラフィに用いられているが、最近の研究では心筋集積機序に大きな違いがあり、異なった輸送系により細胞内に取り込まれるとともに、細胞内での動態も異なることが報告されている。特にMIBIは細胞内でその多くがミトコンドリア画分に存在し、ミトコンドリア膜電位に依存した動態を示すと考えられている。事実、心筋細胞の膜電位は他の組織に比べてより低いことが知られている。同様に、正常細胞に比べて腫瘍細胞のミトコンドリア膜電位はより負に帯電しているものもあることから、この電位差に依存してMIBIが腫瘍に取り込まれているものと考えられる。そこで、この様な脂溶性カチオンの腫瘍集積性に関してモデル実験系を用いて検討し、その集積性を利用した病態機能分析を本研究の目的として検討を行った。
    種々の腫瘍細胞系を準備し、JC-1により相対的ミトコンドリア膜電位を測定したところ細胞により異なる値を示すことが認められた。インビトロ実験系ではミトコンドリア膜電位とMIBIの取り込みに高い相関性があることと共に、FDGとの取り込みに相関性があることが確認された。また、T1-201についても弱いながら相関が観察された。これらのことを基礎として、光線力学療法時における細胞のMIBIおよびFDGの集積変化を観察したところ、MIBIのみ照射1〜3時間後に細胞あたりの取り込み量が低下した。アポトーシスに伴うミトコンドリア機能変化を示していると考えられ、今後の治療効果判定に有用と考えられた。
    日本学術振興会, 基盤研究(B), 浜松医科大学, 17390330
  • 神経細胞選択的なエネルギー代射活動イメージング法の開発
    科学研究費助成事業
    2005年 - 2006年
    小川 美香子
    脳循環障害や神経変性疾患において、生理機能を保った神経細胞を特異的に描出することが、適切な治療や病態解明のために重要である。脳には神経細胞のほか、その約10倍ものグリア細胞が存在する。よって、神経細胞選択的なエネルギー代謝イメージング法を開発するためには、神経細胞特異的なエネルギー基質を標的にする必要がある。
    これまでに我々は、脳スライスのイメージングシステムを用い、脳の活動時には神経細胞はブドウ糖だけでなくグリア細胞で作られた乳酸も利用していることを見いだした。そこで、乳酸代謝を画像化する核医学イメージング剤を用いれば、神経細胞の活動を非侵襲的に描出することができると考え、[^<18>F]L-fluorolactateの合成・利用を検討してきた。
    本年度は、in vivoで検証することとし、脳エネルギー源としての乳酸の役割について[^<18>F]FDG-PETを指標とし検討を行った。20匹のラットを麻酔群、無麻酔群に分け、各群をさらに乳酸投与群、コントロール群に分け(n=5)、[^<18>F]FDG(7.4MBq)を投与後45分間、動物用PET装置にてdynamic PET撮像を行った。得られた画像から速度定数(K1,k2,k3,k4)を求め、CMRglcを計算した。無麻酔群において、乳酸の投与によりCMRglcが有意に上昇した(乳酸投与群:55.1μmol/100g/min、コントロール群:39.7μmol/100g/min)。一方、麻酔群においては乳酸投与による影響は観察されなかった(乳酸投与群:37.1μmol/100g/min、コントロール群:35.3μmol/100g/min)。さらに、無麻酔群においてk3は上昇傾向が認められた。
    神経細胞がグルコースの代わりとしてエネルギー源に乳酸を利用するならば、神経細胞の活動が活発な無麻酔群においては、乳酸負荷によりグルコース利用能が低下することとなる。しかしながら、本検討では無麻酔群においてk3およびCMRglcの上昇が観察された。乳酸が糖代謝を活性化する原因について、乳酸の取り込み阻害剤を用いて現在さらに検討を進めている。
    日本学術振興会, 若手研究(B), 浜松医科大学, 17790854
  • 統合失調症の定量的評価を目的とする分子イメージング法の開発研究
    科学研究費助成事業
    2005年 - 2006年
    間賀田 泰寛, 小川 美香子, 塚田 秀夫
    近年、アルツハイマー病などの神経変成疾患では、臨床症状だけではなく、神経伝達物質やその受容体などの機能分子の変化を核医学の手法を用いて捉えることよる定量的評価が行われている。精神疾患である統合失調症においても死後脳を用いた研究により、ニコチン受容体α7サブタイプ(α7 nAChR)の関与が示唆されているが、現在α7 nAChRを非侵襲的に捉えるイメージング剤は無く、生体内での変化を画像化することはできない。そこで、α7 nAChRの核医学イメージング剤の開発を試みることとした。
    17年度、azabicyclo環構造を有する放射性ヨウ素標識体I-TSAを開発し、ラット脳ホモジネートを用いてα7 nAChRへの親和性を検討したところ、Ki値は0.54nMとなり高い親和性を持つことが示されるとともに、高い放射化学的収率で放射性ヨウ素標識体の合成にも成功した。しかしながら、マウス体内動態を検討したところ、高い脳への取り込み、特に受容体の多い海馬からの消失が遅いなど、特徴的な動態を示したが、非放射性のI-TSAの同時投与により非特異的結合が高いことが示唆され、α7 nAChR in vivoイメージング剤として適さないことが示された。そこで18年度は同じくazabicyclo環構造を有する2-amino-5-bromo-benzoic acid 1-azabicyclo[2.2.2]oct-3-yl ester (BrQAA)およびその誘導体を開発した。BrQAAについてα7 nAChRへの親和性を検討したところ、Ki値は約500nMとそれほど高い値は示さなかった。しかしながらその他の誘導体における親和性の検討の結果より、azabicyclo環の窒素原子がα7 nAChRへの親和性を維持するために重要であることが見出され、今後の誘導体開発に重要な知見を与えることが出来た。今後更に、azabicyclo環構造を基本とする誘導体の開発を行っていく予定である。
    日本学術振興会, 萌芽研究, 浜松医科大学, 17659364
  • 神経細胞選択的なエネルギー代謝イメージング法の開発
    科学研究費助成事業
    2002年 - 2004年
    小川 美香子
    脳循環障害や神経変性疾患において、生理機能を保った神経細胞を特異的に描出することが、適切な治療や病態解明のために重要である。脳には神経細胞のほか、その約10倍ものグリア細胞が存在するといわれており、特にグリア細胞の一種であるアストロサイトの脳エネルギー代謝における役割が注目されている。よって、神経細胞選択的なエネルギー代謝イメージング法を開発するためには、神経細胞特異的なエネルギー基質を見いだし標的にする必要がある。
    前年度までに、生きた脳スライスの経時的イメージングシステムを用い、脳の活動時には神経細胞はグルコースだけでなくグリア細胞で作られた乳酸も利用していることを見いだした。このことは、乳酸代謝を画像化する核医学イメージング剤を用いれば、神経細胞の活動を非侵襲的に描出することができる可能性を示すものである。そこで、ポジトロン断層撮像法(PET)によるイメージングが可能であり、TCAサイクルの途中までしか代謝されないことが予想される[^<18>F]L-fluorolactateの合成を試みた。生体で利用可能なL体を立体選択的に合成する必要があるため、[^<18>F]pyruvateから乳酸脱水素酵素を用いて合成することを計画し、まず、[^<18>F]pyruvateの合成を試みた。サイクロトロンより得られる[^<18>F]KFを前駆体のbromopyruvate methylesterに反応させたが、前駆体が標識条件下で不安定であった。そこで、[^<18>F]KFを[^<18>F]FCH_2Brへ変換したのち、酵素反応により[^<18>F]fluoroalanine,[^<18>F]fluoropyruvate,[^<18>F]lactateへと変換させる経路をみいだし、標識合成を行った。さらなる条件検討を行うことにより、[^<18>F]lactateによるPETでの乳酸代謝イメージングが可能になると思われる。
    日本学術振興会, 若手研究(B), 浜松医科大学, 14770486