Retinal degeneration is largely a hereditary disease that is characterized by the death of photoreceptors--the light-sensitive neurons in the eye--which eventually leads to blindness. While many have attempted to treat the disease through retinal transplants, and some have shown that transplanting graft photoreceptors to the host without substantial integration can rescue retinal function, until now, no one has conclusively succeeded in transplanting photoreceptors that functionally connect to host cells and send visual signals to the host retina and brain. The research team led by Masayo Takahashi, Ph.D., of the RIKEN Center for Developmental Biology in Japan, studied this problem using a mouse model for end-stage retinal degeneration in which the outer nuclear layer of the retina is completely missing. This is an important issue because in clinical practice this type of therapy would most likely target end-stage retinas in which the photoreceptors are dead and the next neurons up the chain do not have any input. The Takahashi group has recently shown that 3D retinal sheets derived from mouse embryonic stem cells develop normal structure connectivity. "Using this method was a key point," explains first author Michiko Mandai, Ph.D. "Transplanting retinal tissue instead of simply using photoreceptor cells allowed the development of more mature, organized morphology, which likely led to better responses to light." The new results were published in the January 10, 2017 issue of Stem Cell Reports. The open-access article is titled “iPSC-Derived Retina Transplants Improve Vision in rd1 End-Stage Retinal-Degeneration Mice.” (iPSC stands for induced pluripotent stem cells).
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