Abstract
Purpose :
Retinal ganglion cell (RGC) replacement has been proposed as an approach to recover lost vision in glaucoma and other optic neuropathies. While studies addressing axonal regeneration are progressing at fast pace, promising the possibility to rewire the eye-to-brain connection, RGC transplantation has only been published for primary cells - a strategy not suited for the clinic. Following our previous success in generating diverse RGC subtypes from mouse pluripotent stem cells (iPSC and ES), we studied the ability of those RGCs to survive and integrate following transplantation within healthy and diseased hosts.
Methods :
RGCs were differentiated for 21 days within 3-dimensional retinal organoids, derived from Thy1-GFP iPSC (C57Bl/6 background). Thy1+ cells were isolated by magnetic micro-beads for syngeneic transplantation. As hosts, healthy adults, adults with RGC loss (NMDA and microbead-induced IOP elevation) and p2-p4 pups were used. RT-PCR, Flow Cytometry, Immunohistochemistry and Calcium Imaging confirmed molecular, functional identity of donor RGCs within re-plated cultures.
Results :
Transplantation success, measured as host retinas containing more than 10 donor RGCs, was highest in pups (83%, n=12). The survival of donor RGCs in healthy adult recipient retinas was higher (57%, n=14) than previously observed for primary RGCS (10%). Notably, transplantation success was even higher in models of RGC loss: microbead mediated elevation of IOP (67%, n=6) or NMDA toxicity injection (67%, n=6). On average, 2-3 weeks post-transplantation, host retinas contained a few hundred donor cells, extending both dendritic and axonal projections, which if cells integrated adjacent to the optic nerve entered the optic nerve head (Fig.1, see arrows). Subtype diversity observed within transplanted RGCs was comparable to the initial donor population. In-vitro, RGCs displayed spontaneous and light-mediated activity, implying functional maturation pre-transplant.
Conclusions :
Thy1+, miPSC-derived RGCs are capable to survive post-transplantation within both, healthy and diseased host retinas and retain subtype specific identities. Following the observed electrical functionality of the generated RGCs in-vitro, our work opens the possibility for further transplantation studies eventually addressing the functionality of donor RGCs in-vivo.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.