Comparison of human embroynic stem cell derived vascular cells to mature human vascular and hematopoietic cells

The pathways involved in hierarchical differentiation of human embryonic stem cells (hESC) into abundant and durable endothelial cells (EC) are unknown. We employed an EC-specific VE-cadherin promoter driving GFP (hVPr-GFP) to screen for factors that augmented yields of vascular-committed ECs from hESCs. In phase 1 of our approach, inhibition of TGFb, precisely at day 7 of hESC differentiation, enhanced emergence of hVPr-GFP+ ECs by 10-fold. In the second phase, TGFb-inhibition preserved proliferation and vascular identity of purified ECs, resulting in net 36-fold expansion of homogenous EC-monolayers, and allowing transcriptional profiling that revealed a unique angiogenic signature defined by the VEGFR2highId1highVE-cadherin+EphrinB2+CD133+HoxA9- phenotype. Using an Id1-YFP hESC reporter line, we showed that TGFb-inhibition sustained Id1 expression in hESC-derived ECs, which was required for increased proliferation and preservation of EC commitment. These data provide a multiphasic method for serum-free differentiation and long-term maintenance of authentic hESC-derived ECs, establishing clinical-scale generation of transplantable human ECs.

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James D, Nam HS, Seandel M, Nolan D, Janovitz T, Tomishima M, Studer L, Lee G, Lyden D, Benezra R, Zaninovic N, Rosenwaks Z, Rabbany SY, Rafii S