Transplantation of Reprogrammed Embryonic Stem Cells Improves Visual Function in a Mouse Model for Retinitis Pigmentosa

Abstract

Purpose: : To study if C57BL/6J-Tyr^c-2j/J (C2J) mouse embryonic stem (ES) cells can differentiate into retinal pigment epithelial (RPE) cells in vitro and then restore retinal function in a model for retinitis pigmentosa: Rpe65^rd12/Rpe65^rd12 C57BL6 mice.

Methods: : Yellow fluorescent protein (YFP)-labeled C2J ES cells were induced to differentiate into RPE-like structures on PA6 feeders. Immunoblots were used to determine expression of RPE-specific markers from in vitro differentiated cells. After differentiation, ES cell-derived RPE-like cells were transplanted into the subretinal space of postnatal day 5 Rpe65^rd12/Rpe65^rd12 mice. Live imaging of YFP-labeled C2J ES cells was carried out to determine the survival of the graft. Electroretinograms (ERGs) were performed on transplanted mice to evaluate the functional outcome of transplantation.

Results: : RPE-like cells derived from ES cells sequentially express multiple RPE-specific markers. After transplantation, YFP-labeled cells can be tracked with live imaging for as long as 7 months. Although more than half of the mice were complicated with retinal detachments or tumor development, one-fourth of the mice showed increased ERG responses in the transplanted eyes. Rpe65^rd12/Rpe65^rd12 mice transplanted with RPE-like cells showed significant visual recovery over a 7-month period, while those injected with saline, PA6 feeders or undifferentiated ES cells showed no rescue.

Conclusions: : ES cells have the potential to differentiate, morphologically and functionally, into RPE-like cells. Based on these findings, differentiated ES cells have the potential for the development of new therapeutic approaches for RPE-specific diseases such as certain forms of retinitis pigmentosa and macular degeneration.

Keywords: retinal pigment epithelium • electroretinography: non-clinical • transplantation