Polymer-brush-afforded SPIO Nanoparticles Show a Unique Biodistribution and MR Imaging Contrast in Mouse Organs

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Author(s)

    • Chen Ting
    • Biofunctional Imaging Laboratory, WPI Immunology Frontier Research Center (WPI IFReC), Osaka University|Functional Imaging Technology, Center for Information and Neural Networks (CiNet), National Institute of Information and Communications Technology (NICT) and Osaka University
    • Yoshioka Yoshichika
    • Biofunctional Imaging Laboratory, WPI Immunology Frontier Research Center (WPI IFReC), Osaka University|Functional Imaging Technology, Center for Information and Neural Networks (CiNet), National Institute of Information and Communications Technology (NICT) and Osaka University
    • Mori Yuki
    • Biofunctional Imaging Laboratory, WPI Immunology Frontier Research Center (WPI IFReC), Osaka University|Functional Imaging Technology, Center for Information and Neural Networks (CiNet), National Institute of Information and Communications Technology (NICT) and Osaka University
    • Inui-Yamamoto Chizuko
    • Biofunctional Imaging Laboratory, WPI Immunology Frontier Research Center (WPI IFReC), Osaka University|Functional Imaging Technology, Center for Information and Neural Networks (CiNet), National Institute of Information and Communications Technology (NICT) and Osaka University
    • Komai Yutaka
    • Biofunctional Imaging Laboratory, WPI Immunology Frontier Research Center (WPI IFReC), Osaka University
    • Isaka Yoshitaka
    • Department of Nephrology, Osaka University Graduate School of Medicine
    • Ohno Kohji
    • Institute for Chemical Research, Kyoto University

Abstract

<p>Introduction: To investigate the biodistribution and retention properties of the new super paramagnetic iron oxide (new SPIO: mean hydrodynamic diameter, 100 nm) nanoparticles, which have concentrated polymer brushes in the outer shell and are difficult for phagocytes to absorb, and to compare the new SPIO with clinically approved SPIO (Resovist: mean hydrodynamic diameter, 57 nm).</p><p>Materials and Methods: 16 male C57BL/6N mice were divided in two groups according to the administered SPIO (<i>n</i> = 8 for each group; intravenous injection does, 0.1 ml). <i>In vivo</i> magnetic resonance imaging (MRI) was performed before and one hour, one day, one week and four weeks after SPIO administration by two dimensional-the fast low angle shot (2D-FLASH) sequence at 11.7T. <i>Ex vivo</i> high-resolution images of fixed organs were also obtained by (2D-FLASH). After the <i>ex vivo</i> MRI, organs were sectioned and evaluated histologically to confirm the biodistribution of each particle precisely.</p><p>Results: The new SPIO was taken up in small amounts by liver Kupffer cells and showed a unique <i>in vivo</i> MRI contrast pattern in the kidneys, where the signal intensity decreased substantially in the boundaries between cortex and outer medulla and between outer and inner medulla. We found many round dark spots in the cortex by <i>ex vivo</i> MRI in both groups. Resovist could be detected almost in the cortex. The shapes of the dark spots were similar to those observed in the new SPIO group. Transmission electron microscopy revealed that Resovist and the new SPIO accumulated in different cells of glomeruli, that is, endothelial and mesangial cells, respectively.</p><p>Conclusion: The new SPIO was taken up in small amounts by liver tissue and showed a unique MRI contrast pattern in the kidney. The SPIO were found in the mesangial cells of renal corpuscles. Our results indicate that the new SPIO may be potentially be used as a new contrast agent for evaluation of kidney function as well as immunune function.</p>

Journal

  • Magnetic Resonance in Medical Sciences

    Magnetic Resonance in Medical Sciences 16(4), 275-283, 2017

    Japanese Society for Magnetic Resonance in Medicine

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