Short–term Course of Retinal Pigment Epithelial Sheets Transplanted into Monkey Retina

Abstract

Abstract: : Purpose: To evaluate a method of transplanting ES–derived retinal pigment epithelial cells (ESRPEs) into the subretinal space of monkeys as an intact sheet and the following host immune response. Methods: Using a modified instrument, we transplanted sheets of sufficiently purified ESRPEs cultured on cross–linked collagen filters into 2 separate subretinal spots of 8 eyes of 8 monkeys. After the transplantation, 4 monkeys received either systemic or intraocular (suspended in silicon oil) cyclosporine A (CsA) (CsA–treated group) and 4 monkeys recieved no CsA (no CsA–treated group). They were monitored by fundus photography and fluorescein angiography, and were sacrificed one month after transplantation, and processed for histologic and immunohistochemical analysis. Results: All the ESRPE sheets had been successfully transplanted in the subretinal space. In the CsA–treated group, transplanted ESRPEs remained well organized as intact sheets on the collagen films, with no evidence of inflammation in any spot. In no CsA–treated group, one spot that had had host RPE damage during surgery showed moderate rejection but ESRPEs appeared to be similarly well organized in the remaining spots although the invasion of T cells and macrophages were observed. Conclusion:The current short–term results suggest that ESRPE cells can be successfully transplanted into the monkey subretinal space as intact sheets and that they survive better with immunosuppression although survival can be achieved well without immunosuppression if the blood–retina barrier is intact.

Keywords: retinal pigment epithelium • transplantation