Pathway for differentiation of human embryonic stem cells to vascular cell components and their potential for vascular regeneration

Objective-We demonstrated previously that mouse embryonic stem (ES) cell-derived vascular endothelial growth factor receptor-2 (VEGF-R2)-positive cells can differentiate into both vascular endothelial cells and mural cells. This time, we investigated kinetics of differentiation of human ES cells to vascular cells and examined their potential as a source for vascular regeneration. Methods and Results-Unlike mouse ES cells, undifferentiated human ES cells already expressed VEGF-R2, but after differentiation, a VEGF- R2-positive but tumor rejection antigen 1-60 (TRA1-60)-negative population emerged. These VEGF- R2-positive but tumor rejection antigen 1-60-negative cells were also positive for platelet-derived growth factor receptor alpha and beta chains and could be effectively differentiated into both VE-cadherin(+) endothelial cell and alpha-smooth muscle actin(+) mural cell. VE-cadherin(+) cells, which were also CD34(+) and VEGF-R2(+) and thought to be endothelial cells in the early differentiation stage, could be expanded while maintaining their maturity. Their transplantation to the hindlimb ischemia model of immunodeficient mice contributed to the construction of new blood vessels and improved blood flow. Conclusions-We could identify the differentiation process from human ES cells to vascular cell components and demonstrate that expansion and transplantation of vascular cells at the appropriate differentiation stage may constitute a novel strategy for vascular regenerative medicine.