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Hung-Ya Tu, Takesi Matsuyama, Jianan Sun, Tomoyo Hashiguchi, Junki Sho, Genshiro A. Sunagawa, Momo Fujii, Akishi Onishi, Masayo Takahashi, Michiko Mandai; Genetically engineered iPSC-retina for improved retinal reconstruction after transplantation. Invest. Ophthalmol. Vis. Sci. 2018;59(9):1987. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
iPSC-retina transplantation is a promising treatment to restore visual function to degenerated retinas. The retinal sheet transplantation, which supplies photoreceptors and secondary retinal neurons, has been shown able to reintroduce visual function in mice with end-stage retinal degeneration. Transplanted retina sheets generally survive for a longer period than suspended cells, however, the presence of secondary neurons often becomes a physical hindrance and restrains photoreceptors from making contact with the host secondary neurons. The goal of this study was to introduce a new strategy for iPSC-retina transplantation which overcomes this difficulty while preserving the advantages of retina sheet transplantation.
We prepared Bhlhb4 and Ilet-1 mouse knock out (KO) iPS cell lines, and tested whether bipolar cells decrease as iPSC-retinas mature, as these genes are known to regulate maturation and survival of ON bipolar cells. These KO cell lines were differentiated in vitro to iPSC-retinas and characterized by immunohistochemistry and micro array analyses. Then differentiated iPSC-retina sheets were transplanted to end-stage rd1 mice, and tissue integration was characterized and compared by immunohistochemistry. Finally, light response of the grafted host retinas was evaluated by MEA recording and two-photon calcium imaging of the ganglion cell activities.
We successfully prepared two KO iPSC lines with a similar in vitro retinal differentiation potency to wildtype cell lines, indicating normal early retinal development. After transplantation, both KO iPSC-retinas readily integrated to the host, with an apparently improved contact judging by the overall proximity of graft photoreceptor cells and host bipolar cells. Importantly, the number of graft ON bipolar cells was drastically decreased in the KO lines. Synaptic contact between graft photoreceptors and host bipolar cells was confirmed by immunohistochemistry. Both MEA recording and two-photon calcium imaging showed that grafted cells could elicit light responses in the host ganglion cells.
Genetically engineered iPSC-retina is a viable strategy for preparing retinal sheets for transplantation with fewer secondary neurons. These grafts can readily integrate to the host as the wildtype retinal sheets do, while improving the contact of graft photoreceptors with host bipolar cells.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.
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