Figure 5

Characterization scheme for EPCs and MPCs. (a) EPCs are defined by a set of morphological and phenotypic characteristics. These cells show properties of bone fide endothelial cells including expression and localization of CD31 and ve-cadherin on the cell membrane and von willebrand factor in the Wieble Palade bodies. Vascular endothelial growth factor is a mitogen for endothelial cells and EPCs. Also, EPCs induce adhesion molecules when challenged with cytokines, similar to mature endothelial cells. The progenitor properties include cloncal growth potential and in vivo vasculogenesis. (b) MPCs are also defined by morphological and phenotypic characteristics of mature mesenchymal cells (such as perivascular cells) and mesodermal progenitors. Similar to mature smooth muscle cells, MPCs express CD90, -smooth muscle actin, and calponin. Upon treatment with specific growth factors, such as plateled-derived growth factor and epidermal growth factor, MPCs proliferate and also exhibit chemotaxis. The progenitor phenotype involves the ability of the cells to give rise to mesenchymal lineage-specific cells such as adipocytes, osteocytes, and chondrocytes.