Figure 6

Schematic model of endothelial progenitor cell (EPC) development. In an endothelial progenitor cell colony-forming assay (EPC-CFA), three different stages of EPC development were classified: (1) stem cell stage as EPC-sprouting cells, (2) early stage of EPCs as large-EPC-CFU-sprouting cells, which contained mostly immature small cells, and (3) late stage of EPCs as functional EPCs, which contained mostly big spindle cells. EPC-CFU, endothelial progenitor cell colony-forming unit. EC, endothelial cell; KSL, c-Kit+/Sca-1+ lineage-negative.