Nanofibrous scaffolds with ex vivo cultured human iPSC‐derived RPE cells for transplantation into porcine eyes

Purpose: There are several retinal degenerative diseases including age‐related macular degeneration (AMD) where the retinal pigment epithelium (RPE) is affected primarily and photoreceptors secondarily. The RPE replacement based on changing of diseased RPE by ex vivo cultured iPSC‐derived RPE cells on nanofibrous membranes can prolong the survival of adjacent photoreceptors. Methods: The feeder‐free system of culturing and differentiation of human iPSCs was used. The phenotypic maturation was examined using immunolabelling for the differentiation and polarization markers. Scaffolds with confluent human iPSC‐derived RPE were implanted into the right eye of 7 minipigs using 3‐port pars plana vitrectomy. Because the human cells were transplanted into the porcine eye (xenogeneic transplantation), immunosuppression therapy with Tacrolimus was applied. At 1–4 weeks upon transplantation, noninvasive examinations of the implanted retina were performed by OCT and fundus camera. Results: The iPSC‐derived RPE cells showed typical cellular morphology and express the RPE markers such as ZO1, BEST, RPE65, and others, with no traces of pluripotent stem cells. Scaffolds with seeded RPE were successfully implanted into subretinal space of porcine eyes. OCT and fundus camera examinations were able to localize the implant in the retina and demonstrated a normal neuroretina in the place of the implant with healed retinotomy, without inflammatory reaction on the implant. Conclusions: In conclusion, we can state that the functional and morphological properties of human iPSC‐derived RPE cells cultured on nanomembranes confirmed the good quality of this epithelium including proper differentiation, confluency of the polarized monolayer, and ability to long‐term survival. The correct placing of implants in the subretinal space testified to the rightness of employed surgical techniques and functionality of the delivery instrumentarium.