Submacular Integration of hESC-RPE Monolayer Xenografts in a Surgical Non-Human Primate Model

Abstract

Background Human pluripotent stem cells (hPSCs) provide a promising cell source for retinal cell replacement therapy, but often lack standardized cell production and live-cell shipment logistics as well as rigorous analyses of surgical procedures for cell transplantation in delicate macula area. We have previously established a xeno- and feeder cell-free production system for hPSC differentiated retinal pigment epithelial (RPE) cells and herein, a novel immunosuppressed non-human primate (NHP) model with a disrupted ocular immune privilege is presented for transplanting human embryonic stem cell (hESC)-derived RPE on a scaffold, and the safety and submacular graft integration are assessed. Furthermore, the feasibility of intercontinental shipment of live hESC-RPE is examined. Methods Cynomolgus monkeys were systemically immunosuppressed and implanted with a hESC-RPE monolayer on a permeable polyester-terephthalate (PET) scaffold. Microscope integrated intraoperative optical coherence tomography (miOCT) guided surgery; postoperative follow-up incorporated scanning laser ophthalmoscopy, spectral domain (SD-) OCT, and full-field electroretinography (ERG) were used as outcome measures. In addition, histology was performed after 28-days follow-up. Results Intercontinental cell shipment, which took > 30 hours from the manufacturing to the transplantation site, did not alter the hESC-RPE quality. The submacular hESC-RPE xenotransplantation was performed in 11 macaques. The miOCT typically revealed foveal disruption. ERG showed amplitude and peak time preservation in cases with favorable surgical outcome. Histology confirmed photoreceptor preservation above the grafts and in vivo phagocytosis by hESC-RPE, albeit evidence of cytoplasmic redistribution of opsin in photoreceptors and glia hypertrophy. The immunosuppression protocol efficiently suppressed retinal T-cell infiltration and microglia activation. Conclusion These results suggest both structural and functional submacular integration of hESC-RPE xenografts. It is anticipated that surgical technique refinement will further improve engraftment of macular cell therapeutics with significant translational relevance to improve future clinical trials.

Cell maturation influences the ability of hESC-RPE to tolerate cellular stress

“…In addition, maturation level has been shown to affect transplant efficacy, but this has been evaluated only using the suspension transplantation approach [ 10 ]. In this study, most of the analyses were conducted with PET carriers which allow RPE maturation in monolayer format with physiologically relevant nutrient flow from the basolateral side and has also been used in transplantation setting [ 33 ]. We aimed to analyze the consequences of sublethal cellular stress induced by H 2 O 2 and proteasome inhibitor MG132 to hESC-RPE with early versus late maturation status.…”