Subretinal Transplant of Induced Pluripotent Stem Cell-Derived Retinal Pigment Epithelium on Nanostructured Fibrin-Agarose

Damage to the retinal pigment epithelium (RPE) in age-related macular degeneration and other diseases results in photoreceptor cell death and blindness. Replacement of RPE is therefore being explored as a therapy for several retinal diseases. To move toward a future personalized autologous transplant approach, we have prepared a biocompatible implant using RPE derived from induced pluripotent stem cells (iPSCs) reprogrammed from a healthy donor's monocytes. The correct positioning of the polarized RPE is essential to fulfill its role and protect photoreceptors from degeneration. Hence, we have used a biocompatible hydrogel matrix of fibrin and agarose that allows the surgical placement of an RPE sheet in the subretinal space, keeping its functional orientation. Our aim was to demonstrate safety and viability of the transplant in preclinical models. Pigs were used to test the feasibility of a regular vitreoretinal surgery. Our results show that this implant is suitable for subretinal transplantation allowing human RPE cells to survive and maintain their phenotype and orientation without any local or systemic adverse events. The ability to transplant the iPSC-derived RPE sheet in its natural orientation will surely increase the chance to obtain a therapeutic effect in future translational studies. Impact Statement In the promising field of cellular therapy for retinal degenerative diseases, a new biomaterial is proposed as a scaffold to grow and surgically introduce a monolayer of retinal pigment epithelial cells into the subretinal space, keeping the orientation of the cells for a proper functional integration of the transplant. The use of induced pluripotent stem cells as the starting material for retinal pigment epithelial cells is intended to advance toward a personalized medicine approach.