Environmental stress impairs photoreceptor outer segment (POS) phagocytosis and degradation and induces autofluorescent material accumulation in hiPSC-RPE cells

a Representative electron microscopy images depicting the presence of RPE-characteristic microvilli structures and apically migrating melanosomes in all hiPSC-RPE lines, lines 1–3 (scale bar？=？1？μm). b Graphical representation of transepithelial resistance (TER) measurements showing TER？≥？150？Ω？cm2 (dotted line; the reported in vivo TER threshold40) in all hiPSC-RPE lines. Data are represented as mean？±？SEM. c Representative confocal images displaying the expected localization of tight junction marker, ZO-1, and apically expressed RPE protein, EZR, in all hiPSC-RPE lines (scale bar？=？20？μm). d Representative western blot images showing robust expression of several RPE signature proteins (BEST1, CRALBP, EZR, and RPE65) in all hiPSC-RPE lines. Of note, ACTN served as a loading control for western blot analyses. e Light microscopy images showing the presence of fluid domes, a characteristic of polarized epithelium, in hiPSC-RPE lines grown on nonporous tissue culture plastic support. Of note, the RPE morphology in focal plane 1 can be seen in the RPE monolayer outside the fluid dome, whereas the RPE cells within the fluid dome can be clearly seen in focal plane 2 (scale bar？=？250？μm