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Stem cells lead the blind

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Science Translational Medicine  20 Jan 2016:
Vol. 8, Issue 322, pp. 322ec9
DOI: 10.1126/scitranslmed.aaf0858

Transplantation of stem cell–derived retinas has been gaining momentum in the treatment of blinding retinal degenerations, as small animal models show positive outcomes with transplanted grafts. This progress is due to developments in techniques of differentiation of stem cells into retinal tissues. However, the clinical relevance of transplantation therapy remains uncertain, as the host acceptability and compatibility in primates is untested. Now, Shirai and co-workers confirm in rats and in macaques that transplanted human embryonic stem cell (hESC)–derived retinas integrate and develop as fully mature retinal grafts. The authors first worked out the parameters for obtaining a functional graft in nude rats, which involved testing grafts of different stages of differentiation for their ability to directly integrate and form mature photoreceptors. Then, they assessed the clinical potential of this approach in two newly developed monkey models of retinal degeneration. To induce retinal degeneration in monkeys, Shirai et al. took two different retinal injury approaches, exposing some to chemicals and others to a laser, both resulting in photoreceptor degeneration. Between 46 and 109 days after injury, the hESC-derived retinal sheets were implanted into the damaged retinas. The grafts integrated into the primate eyes and continued to differentiate into the two types of photoreceptor cells in the retina, rods, and cones. Further functional studies will reveal if vision can be improved, but these new macaque models confirm the clinical potential of stem cell–derived grafts for retinal blindness caused by photoreceptor degeneration, such as retinitis pigmentosa, which affects 1 in 4000 people.

H. Shirai et al., Transplantation of human embryonic stem cell-derived retinal tissue in two primate models of retinal degeneration. Proc. Natl. Acad. Sci. U.S.A. 113, E81–E90 (2015). [Full Text]

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