Abstract
Purpose:
Retinal pigment epithelia (RPE) derived from induced pluripotent stem cells (iPS) are a source of cells that may be used to replace damaged RPE. Studies have shown that iPS-RPE can only be cultured for a limited number of passages before they become senescent. MicroRNAs (miRNAs) are a class of small RNAs that suppress translation of message RNA. miRNAs have been shown to be involved in RPE differentiation, function and survival. We hypothesize that early passage iPS-RPE have a different miRNA expression profile than later passage iPS-RPE. The purpose of this study is to characterize the differential expression of miRNA in early and late passage iPS-RPE.
Methods:
RPE derived from iPS was cultured up to passage five. Total RNA was extracted and hybridized to the Agilent human v16 miRNA microarray. The miRNA profile of early (passage 3) iPS-RPE was compared to the profile from later (passage 5) iPS-RPE. MiRNAs with greater than 2 fold higher or lower differential expression in early passage iPS-RPE were selected for further analysis with Ingenuity IPA sotware to determine the miRNA target gene pathway.
Results:
At day 3 of culture, one miRNA was found to be expressed greater than 2 fold higher in early passage iPS-RPE compared to later passage cells. However by day 17 of culture, 13 microRNAs were found to be differentially expressed greater than 2 fold in early passage iPS-RPE compared to late passage cells. Five miRNAs from early passage day 17 iPS-RPE were expressed >2 fold higher compared to later passage cells, while eight miRNAs from early passage day 17 iPS-RPE were expressed >2 fold lower compared to later passage cells. The miRNAs with the highest fold change of differential expression have been selected for validation and analysis.
Conclusions:
Early passage iPS-RPE expressed only one miRNA differently from later passage cells after day 3 in culture. This miRNA is involved in the network that regulates cytoskeletal remodeling and cell-cell contact. Early passage iPS-RPE expressed 13 miRNAs differently from later passage cells after 17 days in culture. These miRNAs are involved in the networks that regulate cell cycle progression, DNA replication, recombination, and repair. Further analysis will provide novel insights into the functions of these miRNAs and how they regulate the growth and proliferation of iPS-RPE.
Keywords: 721 stem cells •
535 gene microarray •
701 retinal pigment epithelium