Outgrowing endothelial progenitor-derived cells display high sensitivity to angiogenesis modulators and delayed senescence.

Outgrowing endothelial progenitor-derived cells (EPDCs) originate from a novel hierarchy of endothelial progenitor cells. In this study, EPDCs isolated from human cord blood were examined for phenotype and functional features upon aging. Young or aged EPDCs were similar to human umbilical vein endothelial cells (HUVECs), in exhibiting typical endothelial phenotypes. However, EPDCs were more sensitive to angiogenesis inducers or inhibitors in proliferation and migration. In addition, EPDCs underwent senescence markedly slowly with sustained endothelial NO synthase expression and activation, and their ability to undergo capillary morphogenesis was retained throughout longterm culture. Thus, these results suggest that a homogenous population of EPDCs derived from clonogenic expansion may provide an effective vasculogenesis tool.