Characterization of the hESC-derived RPE sheets.

<p>(A) Immunostaining of ZO-1 (red) on hESC-derived RPE cells at Day 30 indicated the presence of tight junctions. Pigmented cells displayed polygonal shape. (B–D) Electron microscopic analyses of hESC-derived RPE cells at Day 50. hESC-derived RPE cells had abundant apical microvilli (mv), melanin granules (mel) in the apical half and the nucleus (nu) in their basal half. A basement membrane (bm) was visible. Tight junctions (tj) and desmosomes (de) could be found. (E) The transepithelial resistance (TER) of hESC-derived RPE progenitor or RPE cells increases during differentiation. (F) Cross-sections through the pigmented cell sheet immunostained for RPE65 and BESTROPHIN. hESC-derived RPE cells at Day 40 expressed the mature RPE cell markers RPE65 and BESTROPHIN. (G) hESC-derived RPE cells exited the cell cycle by Day 30 as demonstrated by RPE cultures pulse labeled with EdU at Day 7, 15 and 30. EdU incorporation by proliferating cells was observed at Day 7 and 15, but rarely observed at Day 30.