Co-expression of EC marker and PDGFRβ after EPC-CM incubation.

<p>Co-expression of vWF and PDGFRβ was measured using dual color FACS analysis. HUVEC were kept in control medium containing only 1% FCS or EPC-CM for 24 h before the measurement. HUVEC incubated in control medium showed only a fractional amount of vWF⁺/PDGFRβ⁺ cells (<b>A</b>). After EPC-CM exposure the proportion of vWF⁺/PDGFRβ⁺ double positive population was significantly increased, suggesting a strong phenotype shift of endothelial cells towards PDGFRβ⁺ (<b>B</b>). The addition of neutralizing antibody AF385 did not block the upreguation of the PDGFRβ by EPC-CM stimulation (<b>C</b>). However, such enhanced PDGFRβ expression could not be evoked by solely adding 100 ng/ml (<b>D</b>) or 100 pg/ml (<b>E</b>) rhPDGF-BB to the control medium. *, P<0.01 compared to controls.