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2018 Fiscal Year Research-status Report

変性網膜内層機能の最適化とiPSC由来網膜移植時のシナプス形成の促進に関する研究

Research Project

Project/Area Number 17K16994
Research InstitutionInstitute of Physical and Chemical Research

Principal Investigator

Tu HungYa  国立研究開発法人理化学研究所, 生命機能科学研究センター, 訪問研究員 (10780835)

Project Period (FY) 2017-04-01 – 2020-03-31
Keywordsretinal transplantation / multi-electrode arrary
Outline of Annual Research Achievements

The present study has been proposed to clarify and optimize the host bipolar cell properties in the degenerated retinas for a more efficient synaptogenesis with the transplanted photoreceptors. A part of the present study is to test the possibility and effect of reducing inner retinal hyperactivity on transplantation of stem cell-derived retina into degenerated retinas, aiming to increase the connectivity between host rod bipolar cells and transplanted photoreceptors. In addition, the suppression of light-independent, spontaneous activities exhibited by cone bipolar cells and downstream ganglion cells would lead to a higher signal-to-noise ratio of the restored light signaling.The preliminary results show that a long-term, low dose of flupirtine treatment to transplanted mice may lead to increased graft-originated responsiveness detected by multi-electrode array (MEA) recording, However, a locally controlled release method restricted intraocularly is required, instead of the systematic application of flupirtine maleate dissolved in DMSO, to efficiently raise the working concentration of flupirtine right to the targeted AII amacrine cells of the host retina. On the other hand, the established MEA recording and analysis protocol has also been utilized in other transplantation preparations. showing its power in evaluating transplanted retinal tissues that exhibit degenerating, regenerating, mature and immature properties simultaneously.

Current Status of Research Progress
Current Status of Research Progress

2: Research has progressed on the whole more than it was originally planned.

Reason

The pharmacological suppression of hyperactivity is expected to facilitate the host rod bipolar cells to better form synaptic connection with the transplanted photoreceptors, as well as the cone bipolar cells and downstream ganglion cells to exhibit less light-independent, spontaneous activities as noises.The preliminary results show that a lower dose of flupirtine treated to transplanted mice may lead to increased graft-originated responsiveness detected by MEA recording, while the higher doses failed with a drop of responsiveness, which is very likely due to the thus increased concentration of DMSO as the solvent.
On the other hand, the quantitative evaluation of transplantation by MEA recording has been utilized in parallel on many other preparations, including mouse allo-transplantation and human-rat xeno-transplantation aside from the present study. The protocol of recording and analysis has been much improved during the past year and invited to be published as a methodology book chapter.

Strategy for Future Research Activity

An inevitable elevation of DMSO concentration happens when applying higher flupirtine dosage. Also, a recent study indicates that the metabolic rate of flupirtine in postnatal rats (similar to mice in size) is much higher than in larger mammals (horses and humans) that i.v. injection of flupirtine results the peak of concentration observation after only a few hours in various organs including eyes. A locally controlled release method restricted intraocularly is therefore required instead of the systematic application of flupirtine maleate dissolved in DMSO. On the other hand, the direct/indirect elevation of host rod bipolar cell excitability has to be further tested by targeted patch clamp recording. The dual patch clamp recording of transplanted photoreceptor-host bipolar cell pairs may also be conducted to test the direct synaptic inputs, taking the advantage of genetic labeling of both transplants and host retinas.

Causes of Carryover

The travel expense has been lower than expected because of the generous coverage by other funding sources and also the travel grant provided by the international conference committee. Also, the expected expense for conducting targeted patch clamp recording has been postponed. Besides the planned expenses, the residual amount will partially be used for development of controlled release method of flupirtine or other channel blockers that may suppress the inner retinal hyperactivity of degenerated retinas.

  • Research Products

    (5 results)

All 2019 2018

All Journal Article (3 results) (of which Int'l Joint Research: 3 results,  Peer Reviewed: 2 results,  Open Access: 3 results) Presentation (2 results) (of which Int'l Joint Research: 2 results)

  • [Journal Article] Medium- to long-term survival and functional examination of human iPSC-derived retinas in rat and primate models of retinal degeneration2019

    • Author(s)
      Tu Hung-Ya、Watanabe Takehito、Shirai Hiroshi、Yamasaki Suguru、Kinoshita Masaharu、Matsushita Keizo、Hashiguchi Tomoyo、Onoe Hirotaka、Matsuyama Take、Kuwahara Atsushi、Kishino Akiyoshi、Kimura Toru、Eiraku Mototsugu、Suzuma Kiyoshi、Kitaoka Takashi、Takahashi Masayo、Mandai Michiko
    • Journal Title

      EBioMedicine

      Volume: 39 Pages: 562~574

    • DOI

      10.1016/j.ebiom.2018.11.028

    • Peer Reviewed / Open Access / Int'l Joint Research
  • [Journal Article] Quantitative and Qualitative Evaluation of Photoreceptor Synapses in Developing, Degenerating and Regenerating Retinas2019

    • Author(s)
      Akiba Ryutaro、Matsuyama Take、Tu Hung-Ya、Hashiguchi Tomoyo、Sho Junki、Yamamoto Shuichi、Takahashi Masayo、Mandai Michiko
    • Journal Title

      Frontiers in Cellular Neuroscience

      Volume: 13 Pages: eCollection

    • DOI

      10.3389/fncel.2019.00016

    • Peer Reviewed / Open Access / Int'l Joint Research
  • [Journal Article] Genetically engineered iPSC-retina for improved retinal reconstruction after transplantation2018

    • Author(s)
      Tu Hung-Ya、Matsuyama Takesi、Sun Jianan、Hashiguchi Tomoyo、Sho Junki、Sunagawa Genshiro A.、Fujii Momo、Onishi Akishi、Takahashi Masayo、Mandai Michiko
    • Journal Title

      Investigative Ophthalmology & Visual Science

      Volume: 59 Pages: 1987

    • Open Access / Int'l Joint Research
  • [Presentation] Functional examination of genetically engineered human ESC-retinas transplanted in an immunodeficient rat model with retinal degeneration2019

    • Author(s)
      Tu Hung-Ya, Yamasaki Suguru, Matsuyama Take, Kuwahara Atsushi, Kishino Akiyoshi, Kimura Toru, Takahashi Masayo, Mandai Michiko
    • Organizer
      ARVO Annual Meeting 2019
    • Int'l Joint Research
  • [Presentation] Functional integration of human ESC-derived retinal sheets after transplantation into immune-deficient retinal degeneration mice2018

    • Author(s)
      Tu Hung-Ya, Iraha Satoshi, Yamasaki Suguru, Matsuyama Take, Sunagawa Genshiro A., Watanabe Takehito, Hashiguchi Tomoyo, Sho Junki, Takahashi Masayo, Mandai Michiko
    • Organizer
      TERMIS World Congress 2018
    • Int'l Joint Research

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Published: 2019-12-27  

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