Abstract
Purpose :
Glaucoma is a group of multifactorial diseases with a unifying pathology retinal ganglion cells (RGCs) degeneration, leading to irreversible blindness. To test the hypothesis that human RGCs are intrinsically vulnerable in glaucoma we have developed an in vitro disease model using the primary open angle glaucoma (POAG) patient-specific induced pluripotent stem cells (iPSCs) for generating functional RGCs. We have previously demonstrated that RGCs derived from a POAG patient-specific iPSCs with the risk allele of a developmentally relevant gene, SIX6 display developmental and functional abnormalities. Here we have examined the developmental susceptibility of RGCs derived from a POAG patient-specific iPSCs containing mutation in a non-developmental gene, MYOC.
Methods :
The model was created using the iPSC technology. Briefly, peripheral blood mononuclear cells (PBMCs) were harvested from patients’ and age matched controls’ blood samples. PBMCs were reprogrammed using the transduction of Sendai virus, expressing Yamanaka factors (Oct4, Klf4, Sox2, and c-Myc). Multiple MYOC and control iPS clones were generated for the characterization of pluripotency. RGCs were generated by a chemical induction protocol, using small molecules, that recapitulates the mechanism of normal RGC genesis.
Results :
A modification of neural induction protocol to generate retinal progenitor cells (RPCs) led to the generation of Rx+ and Pax+ cells from both MYOC patient-specific and control iPSCs, however there was a significant decrease in the number of Rx+ and Pax6+ RPCs in the former versus latter. The neural rosettes (NRs) containing the Rx+ and Pax6+ RPCs appeared less compact in MYOC patient-specific versus control groups. Examination of select gene expression in RGCs derived from patient-specific RPCs suggested developmental abnormalities. For example, the levels of transcripts of RGC regulators (Atoh7, Brn3b, Isl1), markers (SCNG, Thy1), axon growth and guidance regulators (GAP43, DCC, EPHB3) were significantly decreased in MYOC patient-specific RGCs, compared to controls. The complexity of neurites and length of axons (SM132+ and Tau1+) were also observed decreased in MYOC patient-specific RGCs versus controls.
Conclusions :
Our preliminary results suggest that the mutation in MYOC gene may make human RGCs susceptible to developmental abnormalities.
This abstract was presented at the 2022 ARVO Annual Meeting, held in Denver, CO, May 1-4, 2022, and virtually.