Generation and Utilization of Human Induced Pluripotent Stem Cells (iPS) from Primary Endothelial Cells for Studying Endothelial Gene Regulation

Abstract

The mechanism(s) that establishes endothelial cells (EC) phenotype is not known. We aimed to study endothelial gene regulation by generating induced pluripotent stem cells (iPS) from human umbilical vein EC (HUVEC) and differentiating the resulting iPS back into EC. This model provides a system with a homogenous genetic background to explore how EC phenotype is revoked (HUVEC to iPS), and reestablished (iPS to EC). iPS colonies were generated using originally reported transcription factors. Quantitative RT-PCR, immunofluorescence and microarray analysis were used to characterize iPS and cell lineages derived from iPS. Pluripotency of the iPS were demonstrated by generation of embryoid bodies (EB) and detection of the three germ layer markers, as well as direct differentiation to functional specific cell types (including neurons, cardiomyocytes, and EC). We examined the mechanism of activation and repression of a highly EC-specific gene, von Willebrand factor (VWF), in HUVEC, iPS, EB and iPS that was differentiated into EC (EC-diff). We explored whether the expression pattern of transcription factors that regulate VWF are associated with establishment of EC phenotype. The expression levels of both VWF activators and repressors are reduced in iPS and EB but detected to similar levels in HUVEC and EC-diff, suggesting a more prominent role for activators in establishing EC gene activation and consequently EC phenotype. This system provides an opportunity for exploring endothelial gene regulation and consequently enables us to develop new therapeutic approaches for vascular diseases.