Human Ocular Epithelial Cells Endogenously Expressing SOX2 and OCT4 Yield High Efficiency of Pluripotency Reprogramming

Abstract

A variety of pluripotency reprogramming frequencies from different somatic cells has been observed, indicating that cell origin is a critical contributor to the efficiency of pluripotency reprogramming. Identification of the cell source for efficient induced pluripotent stem cell (iPSCs) generation, and defining its advantages or disadvantages on reprogramming, is therefore important. Human ocular tissue-derived conjunctival epithelial cells (OECs) exhibited endogenous expression of reprogramming factors OCT4A (the specific OCT 4 isoform on pluripotency reprogramming) and SOX2. We therefore determined whether OECs could be used for high efficiency iPSC generation. We compared the endogenous expression levels of four pluripotency factors and the pluripotency reprogramming efficiency of human OECs with that of ocular stromal cells (OSCs). Real-time PCR, microarray analysis, Western blotting and immunostaining assays were employed to compare OECiPSCs with OSCiPSCs on the molecular bases of reprogramming efficiency and preferred lineage-differentiation potential. Using the traditional KMOS (KLF4, C-MYC, OCT4 and SOX2 ) reprogramming protocol we confirmed that OECs, endogenously expressing reprogramming factors OCT4A and SOX2, yield very high efficiency iPSC generation (~1.5%). Furthermore, higher efficiency retinal pigmented epithelial differentiation (RPE cells) was observed in OECiPSCs compared with OSCiPSCs or skin fibroblast iMR90iPSCs. The findings in this study suggest that conjunctival-derived epithelial (OECs) cells can be more easily converted to iPSCs than conjunctival-derived stromal cells (OSCs). This cell type may also have advantages in retinal pigmented epithelial differentiation.