Background: Direct transfection of ischemic myocardium with naked plasmid DNA encoding for vascular endothelial growth factor-165 (VEGF165) has been shown to mobilize endothelial progenitor cells (EPCs). This study examined the kinetics of circulating EPCs isolated from peripheral blood mononuclear cells after gene transfer, and their role in neovascularization of ischemic myocardium.
Methods: The mononuclear cell population was isolated from peripheral venous blood samples of patients with functional class III or IV angina receiving intramyocardial VEGF165 gene transfer. Peripheral blood mononuclear cells were examined by an in vitro EPC culture assay and fluorescent-activated cell sorting. The data were compared with a control group consisting of patients who had undergone off-pump coronary artery bypass grafting without receiving gene transfer.
Results: Coinciding with a rise in VEGF levels, mobilization of EPCs increased significantly over base line for 9 weeks after the treatment (121+/-14 cells/mm2 versus 36.8+/-8 cells/mm2, p < 0.0005), followed by a subsequent decrease. Fluorescent-activated cell sorting analysis confirmed culture assay data, with a statistically significant rise in cells expressing vascular endothelial-cadherin, CD51/61 [alphavbeta3], CD62E [E-selectin], CD34, and KDR. The control group failed to show significant mobilization of EPCs.
Conclusions: Mobilization of EPCs with resultant postnatal vasculogenesis, may play a role in revascularizing ischemic myocardium following human gene transfer with VEGF165.