Vascular endothelial growth factor does not accelerate endothelial differentiation of human mesenchymal stem cells

For clinical applications of engineered vascular replacements, endothelial cells may not be available in sufficient quantities due to limited harvesting sites and slow in vitro expansion rates. Soluble vascular endothelial growth factor (VEGF) is often added to differentiate mesenchymal stem cells (MSCs) into endothelial cells; however, recent studies demonstrate that VEGF is not required to upregulate endothelial markers. In contrast to previous assumptions, this study demonstrates that exogenous VEGF does not enhance or accelerate the upregulation of common endothelial markers during endothelial differentiation of human MSCs. MSCs were cultured at confluence for up to 3 weeks in either basal medium or medium containing VEGF. Cells were examined for gene and protein expression as well as the ability to internalize acetylated low density lipoprotein. With either treatment, endothelial differentiation occurred as evidenced by upregulation of gene and protein expression of typical endothelial markers and the ability to internalize acetylated low density lipoproteins. Interestingly, the addition of VEGF at typical or high concentrations (50 or 100 ng/ml) did not result in differences in gene or protein expression levels of many typical endothelial markers. However, high concentrations of VEGF did significantly increase protein expression of the arterial marker Ephrin-B1. Thus, VEGF did not accelerate or enhance differentiation of human MSCs towards endothelial cells but was vital for specification of arterial fate.