Transplanted human induced pluripotent stem cells- derived retinal ganglion cells embed within mouse retinas and are electrophysiologically functional

Internal limiting membrane disruption facilitates engraftment of transplanted human stem cell derived retinal ganglion cells

“…61 In addition, those donor neurons did not express RBPMS, leaving open the question of whether the donor cells had matured into a functional RGC phenotype. Vrathasha et al 37 transplanted AAV-GFP labeled human induced pluripotent stem cell-derived RGCs into immunocompetent mice and reported a remarkable degree of survival, dendritic complexity, and light responsivity at 2-5 months following transplantation. In comparison to that study, a critical strength of the current work is the rigorous control experiments to rule out the possibility of intercellular material transfer or leaky labeling with the AAV vector leading to erroneous identification of endogenous murine RGCs as donor-derived neurons.…”

“…As noted below (methods), we have found that the manufacturer-reported enzymatic activity of pronase does not correlate well to its observed effects in the eye, necessitating that end users either acquire the same lots reported here or perform a lab-specific bioassay to determine the optimal concentration of pronase that will digest the ILM without causing intraocular bleeding, neurotoxicity, or gliotoxicity. It is also worth noting that since the enzymatic activity (U/mg) varies across lots of enzyme, reporting the dose of administered enzyme as a concentration percentage (g/100mL) is uninformative 37 and instead should be reported in terms of U/mL based on lot-specific conversion of enzymatic activity per mg of enzyme. We have documented destructive effects with high doses of intraocular pronase (Fig 1B), and it is likely that concentration drives the differences between the effects of pronase noted here, and elsewhere.…”

“…We have documented destructive effects with high doses of intraocular pronase (Fig 1B), and it is likely that concentration drives the differences between the effects of pronase noted here, and elsewhere. 37 Finally, though provocative evidence for functional engraftment is derived from structural localization of hRGC dendrites to the IPL and mobilization of synaptic machinery to those dendrites, electrophysiologic functional assessments are the subject of ongoing work.…”

“…The absolute number of surviving hRGCs was generally <1% of the number injected (Fig 2F ), commensurate with prior reports. [34][35][36][37][38] There was a modest increase in hRGC survival in pronase-treated eyes compared to BSS-treated eyes, but no increase in Lama1 nmf223 eyes (Fig 2F).…”

“…Though transplantation of non-neuronal cells has been trialed to confer neuroprotection to injured endogenous RGCs, [30][31][32][33] RGC replacement necessitates transplanting progenitors with neuronal potential or differentiated neurons. Preliminary studies have been successful in documenting rare instances of functional integration by transplanted primary neonatal mouse RGCs, 34 murine stem cell derived RGCs, 35,36 and human stem cell-derived RGCs (hRGCs) 37 in recipient retinas. However, among the relatively few RGCs that survive transplantation (typically <1%), [34][35][36][37][38] even fewer RGCs successfully engraft into the retina by migrating into the host retinal ganglion cell layer (RGCL) and extending dendrites into the inner plexiform layer (IPL), where synaptogenesis with host bipolar and amacrine cells could occur.…”