| Summary: | Endothelial progenitor cells (EPCs) have reduced neovascularization capacity in the context of coronary artery disease (CAD) or cardiac risk factors (RFs). Since, endothelial NO synthase (eNOS) is critical to normal EPC function, we hypothesized that bone marrow cells (BMCs) from rats with RFs and EPCs from humans with CAD and/or RFs show dramatically reduced neovascularization capacity in vitro and in vivo, which can be reversed by eNOS overexpression. BMCs were isolated from rat models of type II diabetes and the metabolic syndrome, and we showed a significant reduction in their ability to stimulate neovascularization in vitro and in vivo. In humans, we isolated circulating ‘early EPCs’ from healthy subjects and patients with CAD and RFs, and transduced them using lentiviral vectors containing either eNOS or GFP (sham). EPCs from patients had reduced in vitro migration in response to SDF-1 or VEGF, which was reversed by eNOS-transduction. In co-culture with human umbilical vein endothelial cells (HUVECs) on Matrigel, eNOS-transduced EPCs contributed to increased and more complex angiogenic tube formation compared to sham-transduced cells. Human EPCs from patients were ineffective in enhancing ischemic hind limb neovascularization and perfusion in a nude mouse, whereas eNOS-transduced EPCs resulted in a significant improvement compared to sham-transduced cells. In a swine model of acute myocardial infarction (MI), eNOS- and non-transfected BMCs both increased left ventricular function compared to sham. However, there was no benefit to eNOS overexpression in this model. Various differences in the models and procedures may explain the incongruous results obtained. Taken together, these results show that eNOS overexpression significantly improves the neovascularization capacity of EPCs of human subjects with CAD and RFs and could represent an effective adjunctive approach for the improvement of autologous cell therapies for cardiovascular disease.
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