Molecular signature of primary retinal pigment epithelium and stem-cell-derived RPE cells

Abstract

Age-related macular degeneration (AMD) is characterized by the loss or dysfunction of retinal pigment epithelium (RPE) and is the most common cause of vision loss among the elderly. Stem-cell-based strategies, using human embryonic stem cells (hESCs) or human-induced pluripotent stem cells (hiPSCs), may provide an abundant donor source for generating RPE cells in cell replacement therapies. Despite a significant amount of research on deriving functional RPE cells from various stem cell sources, it is still unclear whether stem-cell-derived RPE cells fully mimic primary RPE cells. In this report, we demonstrate that functional RPE cells can be derived from multiple lines of hESCs and hiPSCs with varying efficiencies. Stem-cell-derived RPE cells exhibit cobblestone-like morphology, transcripts, proteins and phagocytic function similar to human fetal RPE (fRPE) cells. In addition, we performed global gene expression profiling of stem-cell-derived RPE cells, native and cultured fRPE cells, undifferentiated hESCs and fibroblasts to determine the differentiation state of stem-cell-derived RPE cells. Our data indicate that hESC-derived RPE cells closely resemble human fRPE cells, whereas hiPSC-derived RPE cells are in a unique differentiation state. Furthermore, we identified a set of 87 signature genes that are unique to human fRPE and a majority of these signature genes are shared by stem-cell-derived RPE cells. These results establish a panel of molecular markers for evaluating the fidelity of human pluripotent stem cell to RPE conversion. This study contributes to our understanding of the utility of hESC/hiPSC-derived RPE in AMD therapy.

Induced Pluripotent Stem Cell-Derived Retinal Pigmented Epithelium: A Comparative Study Between Cell Lines and Differentiation Methods

“…These data also revealed that iPSC-3-RPE maintained expression of cell cycle markers on day 30 at passage 3, which could suggest incomplete maturation/differentiation of these cells. These data are supported by previous findings that show iPSC-RPE maintains hypermethylation of cell adhesionrelated genes (hypomethylated in fRPE) 50 and gene expression profiles indicative of an immature RPE differentiation status 51 when compared to fRPE. The lagging maturity of the directed cells could explain the decreased RPE65 expression trend seen in Fig.…”

Memory in Induced Pluripotent Stem Cells: Reprogrammed Human Retinal-Pigmented Epithelial Cells Show Tendency for Spontaneous Redifferentiation

“…Feng et al [24] reported that iPS-IMR90-1 and iPS-foreskin-2 did not form RPE colonies that could be propagated. Most recently, Liao et al [53] examined six iPS lines generated from endodermal and neuroectodermal lineages and found very low production of RPE colonies. Furthermore, other iPS lines driven to retinal and RPE phenotypes using factors were reported to be similar to hES [31].…”

HTRA1, an age‐related macular degeneration protease, processes extracellular matrix proteins EFEMP1 and TSP1

“…To determine how the HTRA1/ARMS2 risk allele at 10q26 causes AMD, we make use of new technologies in stem cells and protein biology. RPE is generated from patients' own skin cells through induced pluripotent stem (iPS) cells, yielding matched RPE that expresses key molecular markers (Liao et al., 2010). This allows us to study patient‐specific genomes.…”