Abstract
BackgroundHuman 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 the 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.MethodsCynomolgus 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 a 28-day follow-up.ResultsIntercontinental cell shipment, which took >30 h 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 outcomes. 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.ConclusionThese results suggest both structural and functional submacular integrations of hESC-RPE xenografts. It is anticipated that surgical technique refinement will further improve the engraftment of macular cell therapeutics with significant translational relevance to improve future clinical trials.
Highlights
Human pluripotent stem cells 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 the delicate macula area
Long-distance shipment of live human embryonic stem cell (hESC)-retinal pigment epithelial (RPE) monolayers The in vitro RPE characteristics and functionality were authenticated by transepithelial electrical resistance (TEER, 130–430 Ω*cm2), polarized expression of RPE markers, phagocytosis of porcine photoreceptor outer segments (POS), and apically polarized pigment epithelium-derived factor (PEDF) secretion (Fig. S1, Additional file 1)
The live hESC-RPE monolayers were manufactured at the cell production facility in Finland and shipped for on average 33 h (5 separate shipments, Fig. S2, Additional file 1) at room temperature (RT) to the surgical site in Singapore using a high glucose CO2-independent medium
Summary
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 the delicate macula area. We have previously established a xeno- and feeder cell-free production system for hPSC differentiated retinal pigment epithelial (RPE) cells, and 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. The eye is a frontline target for regenerative medicine utilizing human pluripotent stem cell (hPSC)-derived cells. This reflects the high demand for novel treatments for common blinding diseases, age-related macular degeneration (AMD), and the ability for noninvasive graft monitoring. Delivery of novel retinal therapeutic agents, RPE cell therapy, has received considerable interest since hPSC-RPE were introduced for clinical applications since the feasibility of RPE transplantation in non-human primates (NHP) in the 1980s [2]. As the macula is the target site for RPE transplantation in AMD, it is essential to study surgical protocols and their implications in a NHP model
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