Role of ROCK signaling on endothelial differentiation of mouse embryonic stem cell

Abstract

Successful differentiation and expansion of endothelial cells (ECs) from embryonic stem cell (ESC)-derived Flk1+ mesodermal precursor cells (MPCs) requires supplementation of vascular endothelial growth factor-A (VEGF-A). While analyzing VEGF-A/VEGFR2 downstream signaling pathway that underlies the VEGF-A-induced differentiation and ex-pansion of ECs, we fortuitously found that Rho-associated protein kinase (ROCK) inhibitor Y27632 profoundly promoted the differentiation and expansion of ECs from Flk1+ MPCs, while reducing the differentiation and expansion of mural cells. The ROCK suppression-induced expansion of ECs appears to have resulted from promotion of proliferation of ECs via activation of PI3-kinase-Akt signaling. The ECs obtained by the combination of ROCK suppression and VEGF-A supplementation faithfully expressed most pan-EC surface mak-ers, and phenotypic analyses revealed that they were differentiated toward arterial EC. Fur-ther incubation of the ICAM2+ ECs with Y27632 and VEGF-A for 2 days promoted expansion of ECs by 6.5-fold compared to those incubated with only VEGF-A. Importantly, the ROCK suppression-induced ECs displayed neovasculogenic abilities in vitro and in vivo. Thus, supplementation of ROCK inhibitor Y27632 along with VEGF-A in 2D Matrigel culture system provides a simple, efficient, and versatile method for obtaining ample amount of ESC-derived ECs at high purity suitable for use in therapeutic neovascularization.