Differentiation and Maturation Effect of All-Trans Retinoic Acid on Cultured Fetal RPE and Stem Cell-Derived RPE Cells for Cell-Based Therapy

Abstract

Purpose: Clinical trials using fetal retinal pigment epithelium (fRPE), human embryonic stem cell (hESC)-derived RPE, or human induced pluripotent stem cell (hiPSC)-derived RPE for cell-based therapy for degenerative retinal diseases have been carried out. We investigated the culture-induced changes in passaged fRPE, hESC-RPE, and hiPSC-RPE cells and explored the differentiation and maturation effect of all-trans retinoic acid (ATRA) on cells for manufacturing and screening high-quality RPE cells for clinical transplantation.

Methods: RPE cell lines were set up and the culture-induced changes in subsequent passages caused by manipulating plating density, dissociation method, and repeated passaging were studied by a microscope, real-time quantitative PCR, western blot, and immunofluorescent assays. Gene and protein expression and functional characteristics of RPE cells incubated with ATRA were evaluated.

Results: Compared with fRPE, hESC-RPE, and hiPSC-RPE showed decreased gene and protein expression of RPE markers. RPE cells underwent mesenchymal changes showing increased expression of mesenchymal markers including a-SMA, N-cadherin, fibronectin and decreased expression of RPE markers including RPE65, E-cadherin, and ZO-1, as a subsequence of low plating density, inappropriate dissociated method, and repeated passaging. RPE cells treated by ATRA showed increased expression of RPE markers and increased expression of negative complement regulatory proteins (CRPs) and increased transepithelial resistance as well.

Conclusions: Differences in protein and gene expression among three RPE types exist. ATRA can increase RPE markers, CRPs gene expression in fRPE, and stem cell-derived RPE. These can be used to guide the standard of screening RPE cells for clinical translational cell therapy.

Keywords: Retinal pigment epithelium; all-trans retinoic acid; epithelial-mesenchymal transition; human embryonic stem cells; human induced pluripotent stem cells.