Abstract 16086: A Genomic Blueprint of Human Endothelial Cell Differentiation From Pluripotent Stem Cells Identifies Unique Epigenetic Signatures and Anti-Osteogenic Responses to Laminar Shear Stress
Endothelial cells (ECs) sense hemodynamic shear stress and transduce these signals to direct vascular development and to prevent calcification in adults. Here, we studied a time-course of EC differentiation from human pluripotent cells to understand the transcriptional and epigenetic mechanisms governing endothelial cell specification. We then exposed the ECs to either static or laminar shear stress conditions to understand how hemodynamic flow protects vessels and valves from calcification. We found that stage-specific gene expression was enriched for processes including WNT signaling at the mesodermal stage, angiogenesis at the EC precursor stage, and matrix metalloproteinases at the EC stage, the latter of which may prevent calcification via extracellular matrix degradation. We used a random forest machine-learning algorithm to identify stage-predictive transcription factors such as SOX2, a known cell fate determinant, which was predictive for the pluripotent stage. STAT6 or SMAD6 expression was predictive of static or shear-stress conditions respectively. In addition, immune response or inhibition of the TGFβ osteogenic pathways was enriched in static or shear-specific gene expression respectively. Taken together, this suggests an anti-inflammatory and anti-osteogenic EC response to shear-stress. We also identified stage-specific epigenetic states. For instance, those genes expressed specifically at the mesodermal stage showed a unique epigenetic signature with expression being most correlated with loss of the repressive histone modification H3K27me3 and residence in regions of DNA hypomethylation. This signature was more pronounced in developmental genes compared to non-developmental genes. Our findings represent the first comprehensive transcriptional and epigenetic analysis of human EC differentiation and provide a blueprint for the gene networks involved in formation and maintenance of ECs. Specifically, we found that human ECs have an anti-osteogenic and anti-inflammatory response to shear-stress providing a basis for understanding endothelial cell dysfunction in disease states.
Author Disclosures: C.V. Theodoris: None. M. Li: None. M.P. White: None. L. Liu: None. D. He: None. K.S. Pollard: None. B.G. Bruneau: None. D. Srivastava: None.
- © 2014 by American Heart Association, Inc.