Kinetics of circulating endothelial progenitor cells in patients undergoing carotid artery surgery

Endothelial progenitor cells (EPCs) are primitive cells found in the bone marrow and peripheral blood (PB). In particular, the potential of EPCs to differentiate into mature endothelial cells remains of high interest for clinical applications such as bio-functionalized patches for autologous seeding after implantation. The objective of this study was to determine EPCs' kinetics in patients undergoing carotid artery thromboendarterectomy (CTEA) and patch angioplasty.

Twenty CTEA patients were included (15 male, mean age 76 years). PB samples were taken at 1 day preoperatively, and at 1, 3, and 5 days postoperatively. Flow cytometric analysis was performed for CD34, CD133, KDR, and CD45. Expression of KDR, SDF-1α, and G-CSF was analyzed by means of enzyme-linked immunosorbent assay.

Fluorescence-activated cell sorting analysis revealed 0.031%±0.016% (% of PB mononuclear cells) KDR+ cells and 0.052%±0.022% CD45-/CD34+/CD133+ cells, preoperatively. A 33% decrease of CD45-/CD34+/CD133+ cells was observed at day 1 after surgery. However, a relative number (compared to initial preoperative values) of CD45-/CD34+/CD133+ cells was found on day 3 (82%) and on day 5 (94%) postoperatively. More profound upregulated levels of CD45-CD34+/CD133+ cells were observed for diabetic (+47% compared to nondiabetic) and male (+38% compared to female) patients. No significant postoperative time-dependent differences were found in numbers of KDR+ cells and the concentrations of the cytokines KDR and G-CSF. However, the SDF-1α levels decreased significantly on day 1 postoperatively but returned to preoperative levels by day 3.

CTEA results in short-term downregulation of circulating EPCs and SDF-1α levels. Rapid return to baseline levels might indicate participation of EPCs in repair mechanisms following vascular injury.