Abstract
Purpose:
Age-related macular degeneration is the leading cause of blindness in elderly populations in the developing countries, and currently there are no effective long-term treatments available. In order to better understand AMD disease pathology, there has been significant interest in studying patient-specific iPSC-derived retinal pigmented epithelium (RPE) cells, which are known to play a central role in AMD. To confirm that iPSC-derived RPE cells recapitulate the cell morphology and function of native RPE, we compared them to cultures often used to study AMD, including human fetal RPE, ARPE 19 cells and human embryonic stem cell (hESC) derived RPE.
Methods:
iPSC- and hESC-derived RPE cells, human fetal RPE (gestational age 18-20 weeks), and ARPE-19 cells were cultured on transwell filter membranes in order to establish cell polarity and monolayers that replicate native RPE. After 4 and 8 weeks, cell cultures were assessed by light, confocal, and transmission electron microscopy (TEM). They were also assessed by transepithelial resistance (TER) measurements in order to detect the formation of tight junctional complexes. Secreted proteins in media (both apical and basal) were analyzed by multiplex protein analysis after 4 and 8 weeks in culture.
Results:
All cell types expressed RPE markers (CRALBP, ZO-1, and Otx2) by 4 weeks in culture. iPSC-RPE, hESC-RPE, and human fetal RPE, but not ARPE-19 cells, developed tight junctional complexes and apical microvilli, as determined by TEM. In addition, all cell lines except ARPE-19 cells exhibited TER measurements similar to that of native RPE by 8 weeks, indicating the establishment of tight junctions. In a profile of 44 secreted proteins in apical and basal media, iPSC-RPE cells were most similar to hESC-RPE and least similar to ARPE-19 cells. iPSC-RPE were similar to fetal RPE in a polarized (basal > apical) secretion of VEGF-A and apolipoprotein E, two important factors in AMD disease development.
Conclusions:
Human iPSC-derived RPE cells have similar structure and cytokine profiles compared to native RPE and are the most similar to ES cell derived RPE cells in our study. Our findings provide support for the use of patient-specific iPSC-derived RPE in studying the pathology of retinal degenerative diseases, including AMD.