Abstract
Purpose :
Purpose: Stargardt retinopathy is an inherited macular degeneration driven by mutations in gene ABCA4 and characterized by the accumulation of the lipid deposits in the retinal pigment epithelium (RPE), leading to its atrophy and photoreceptor death. The presence of ABCA4 in the apical membrane of human RPE cells suggests the involvement of this protein in RPE physiology and Stargardt disease pathogenesis. We developed Stargardt-iPS cells derived in vitro disease model to understand how ABCA4 loss of function promotes disease phenotype in the RPE - a primary injury site in Stargardt and other age-related maculopathies.
Methods :
Fully characterized Stargardt- iPSCs (ABCA4 knock out and patient iRPE) were differentiated into RPE using a developmentally guided protocol. Stargardt-iRPE were cultured on semi-permeable membranes for six weeks to obtain a functionally mature and polarized monolayer tissue. Cells were evaluated for RPE-specific functions, including digesting photoreceptors outer segments. In addition, lipid accumulation phenotype was evaluated using a photoreceptor outer segment regimen to determine the human pathogenetic sequence.
Results :
ABCA4 loss of function in Stargardt -iRPE triggers a cell-autonomous disease phenotype in RPE cells, including sub and intra-cellular lipid deposits while exposed to photoreceptor outer segment regimen. Stargardt -iRPE exhibited a reduced ability to digest photoreceptor outer segments that this defect was restored by lysosome acidifying drugs.
Conclusions :
Our work shows Stargardt-iRPE offers a physiologically relevant in-vitro disease model for Stargardt disease and that ABCA4 loss of function initiates a cell-autonomous disease phenotype in RPE cells contributing to Stargardt disease pathology.
This abstract was presented at the 2022 ARVO Annual Meeting, held in Denver, CO, May 1-4, 2022, and virtually.