Abstract 1039: Endothelial Progenitor Cells from Patients with Multiple Coronary Artery Disease Risk Factors Exhibit Reduced Regenerative Capacity in vitro and in vivo
The use of endothelial progenitor cells (EPCs) to enhance neovascularization is an exciting potential therapy for patients suffering from chronic ischemia. However, risk factors for coronary artery disease (CAD) may reduce the regenerative capacity of EPCs, at least in part due to impaired bioavailability of nitric oxide (NO).
Hypotheses: EPCs from patients with multiple CAD risk factors exhibit molecular and functional abnormalities in vitro contributing to reduced neovascularization in vivo.
Methods: EPCs were isolated from the blood of human subjects with multiple CAD risk factors (>15% Framingham score; FS) (± diagnosed CAD) as well as control subjects (<5% FS) by Ficoll gradient separation and differential culture for 7 days. Cell migration toward VEGF (50 ng/mL) and SDF-1 (100 ng/mL) were quantified using modified Boyden chambers. Relative mRNA expression of eNOS, VEGFA, CXCR4 and PDGFB were assessed using qRT-PCR. The ability of the cells to stimulate neovascularization was studied in a nude mouse model of hind limb ischemia using laser Doppler perfusion imaging.
Results: Compared to controls, EPCs from patients with CAD and/or risk factors had reduced migration (cells/HPF) toward VEGF (127±14, n=9 vs. 80±8, n=21, respectively; p<0.01) and toward SDF-1 (123±14, n=8 vs. 87±9, n=21, respectively; p<0.05). This was associated with reduced expression of VEGFA (0.60±0.11 vs. 0.24±0.07; p<0.05) and trends toward reduced expression of CXCR4 (103±32 vs. 32±5) and eNOS (0.08±0.03 vs. 0.03±0.01), but no difference in PDGFB expression (PCR units relative to β-actin expression, n=8–13/group). Moreover, the restoration of perfusion in the hind limb ischemia model, assessed by the ratio of blood flow in the ischemic/non-ischemic limbs, was significantly less following administration of EPCs from individuals with CAD risk factors (0.42±0.04, n=7) compared to control (0.56±0.01, n=7; p<0.05).
Conclusions: These data show that the EPCs from subjects with multiple CAD risk factors have reduced migration, reduced expression of angiogenic genes as well as an impaired ability to stimulate neovascularization. Strategies to enhance the regenerative capacity of EPCs will be required to optimize the potential of autologous cell therapy in patients with CAD.