Abstract
Purpose :
RPE secreted extracellular vesicles (exosomes) have been implicated to promote pro-maculopathy cellular changes in macular degeneration. However, the precise role of exosomes in age-related macular degeneration (AMD) and related macular dystrophies like Sorsby’s fundus dystrophy (SFD) has not been established. The purpose of this study was to use induced pluripotent stem cell (iPSC)-based disease modeling studies to evaluate the unambiguous role of exosomes released from patient- derived iPSC-RPE (iRPE) in promoting drusen and choroidal neovascularization (CNV) in SFD.
Methods :
Exosomes were isolated from control and SFD iRPE cells using differential gradient ultracentrifugation and nanoparticle tracking analysis and untargeted proteomics was performed. Exosome uptake in iRPE and endothelial cells (ECs) was evaluated using PKH26 dye. Immunocytochemical analyses was used to evaluate the impact of both i) control versus SFD iRPE- derived exosomes and ii) exosome inhibition (using GW4869) for drusen accumulation and vascular network properties in iRPE and iPSC-derived choriocapillaris (iCC) model(s).
Results :
No differences were seen in the size and concentration of exosomes released by control and SFD iRPE cells. Proteomics showed increased levels of several drusen associated proteins (e.g., APOE, CRYAB) and angiogenic proteins (e.g., MMP2, TGFB1, TIMP1, EDIL3) in basal iRPE exosomes. iRPE-secreted basal exosomes were taken up by iECs and treatment of control iCC with SFD iRPE exosomes led to CC atrophy (reduced area and tube length of vascular networks) when compared to parallel cultures of control iCC treated with control iRPE exosomes. Consistently, GW4869-mediated exosome inhibition ameliorated CC atrophy in SFD iCC. In contrast, there was no uptake of basally-secreted iRPE exosomes by iRPE cells and SFD iRPE exosome supplementation did not increase the count/area of drusen in control iRPE cultures. However, GW4869-mediated exosome inhibition increased drusen area/count in control iRPE cells.
Conclusions :
iPSC-based disease modeling studies show that i) basally-secreted RPE exosomes derived from SFD iRPE cells can independently initiate CC atrophy but not drusen and ii) exosome inhibition promotes drusen in control iRPE cells.
This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.