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        Developing a treatment for

        vision loss through transplant

        of photoreceptor precursors

          nherited retinal diseases (IRDs)
          are a group of genetically and
       Iclinically homogeneous illnesses
        characterised by progressive retinal
        damage leading to vision loss.
        The global incidence of IRDs is
        approximately 1 in 2000 persons.
        These disorders are amongst some
        of the leading causes of blindness

        While the introduction of gene
        therapy has been a significant
        development, its effectiveness has
        been blunted by the sheer extent
        of genetic heterogeneity, with
        more than 260 genes implicated in
        IRDs. This limits the widespread
        application of gene therapy for all
        IRDs. Additionally, gene therapy
        has limited efficacy in clinical cases
        of advanced retinal degeneration
        in which significant photoreceptor
        cell death has already occurred.
        Photoreceptor cells are found in
        the retina and respond to light,        Retinal progenitor cells derived from RxCell induced pluripotent stem cells (iPSCs)
        converting it into electrical signals   can mature into retina photoreceptors after transplantation into the preclinical models,
        that activate physiological chain       enabling restored vision. Photo Credits: NUS Yong Loo Lin School of Medicine
        reactions. These signals are sent
        through the optic nerve to the brain   A recently published study in the   Story Source:
        for processing.                      journal Stem Cell Research and      Materials provided by National
                                             Therapy led by Assistant Professor   University of Singapore, Yong
        With the advent of induced           Su Xinyi from the Department        Loo Lin School of Medicine. Note:
        pluripotent stem cell (iPSC)         of Ophthalmology at the NUS         Content may be edited for style
        and embryonic stem cell (ESC)        Yong Loo Lin School of Medicine     and length.
        technology, regenerative stem cell   examines the therapeutic potential
        therapy has the potential to be an   of photoreceptor precursors         Journal Reference:
        alternative treatment for end-stage   derived from clinically compliant   1. Zengping Liu, Tanja Ilmarinen,
        retinal degeneration, independent    iPSCs. The study demonstrated       Gavin S. W. Tan, Heidi Hongisto,
        of the underlying genetic defect.    the safety and therapeutic potential   Edmund Y. M. Wong, Andrew
        Retinal regenerative therapies       of clinically compliant iPSC-       S. H. Tsai, Sami Al-Nawaiseh,
        therefore hold great promise for the   derived photoreceptor precursors   Graham E. Holder, Xinyi Su,
        treatment of IRDs. Studies in animal   as a cell replacement source      Veluchamy Amutha Barathi,
        models of IRDs have suggested        for future clinical trials. These   Heli Skottman, Boris V. Stanzel.
        visual improvement following         include performing a first-in-man   Submacular integration of hESC-
        retinal photoreceptor precursors     clinical trial for photoerecptor    RPE monolayer xenografts in
        transplantation, though there is     precursor transplant in Singapore,   a surgical non-human primate
        limited evidence on the ability of   in collaboration with RxCELL, a     model. Stem Cell Research
        these transplants to rescue retinal   biotechnology company focused on   & Therapy, 2021; 12 (1) DOI:
        damage in higher mammals.            therapeutic applications iPSCs.     10.1186/s13287-021-02395-6

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