Endothelial progenitor cells (CD34+KDR+) and monocytes may provide the development of good coronary collaterals despite the vascular risk factors and extensive atherosclerosis.

Objective: Endothelial progenitor cells (EPC) have a regenerative role in the vascular system. In this study, we aimed to evaluate simultaneously the effects of EPC and inflammatory cells on the presence and the extent of coronary artery disease (CAD) and the grade of coronary collateral growth in patients with clinical suspicion of CAD.

Methods: This study has a cross-sectional and observational design. We enrolled 112 eligible patients who underwent coronary angiography consecutively (mean age: 59±9 years). The association of circulating inflammatory cells and EPC (defined by CD34+KDR+ in the lymphocyte and monocyte gate) with the presence, severity and extent of CAD and the degree of collateral growth were investigated. Logistic regression analysis was used to define the predictors of collateral flow.

Results: Of 112 patients 30 had normal coronary arteries (NCA, 27%, 55±9 years) and 82 had CAD (73%, 61±8 years). Among the patients with CAD, the percent degree of luminal stenosis was <50% in 12 patients; 50-90% in 35 patients; and ≥90% in the other 35 patients. Circulating inflammatory cells were higher (leukocytes, 7150±1599 vs 8163±1588 mm(-3), p=0.001; neutrophils, 4239±1280 vs 4827±1273 mm(-3), p=0.021; monocytes, 512±111 vs 636±192 mm(-3), p=0.001) and EPCs were lower (0.27±0.15% vs 0.17±0.14%, p<0.001; 21±15 vs 13±12 mm(-3), p=0.004) in CAD group than NCA group. When we investigated the collateral growth in patients having ≥90% stenosis in at least one major coronary artery, we found that the patients with good collateral growth had significantly higher EPC (0.22±0.17% vs 0.10±0.05%, p=0.009; 18±15 vs 7±3 mm(-3), p=0.003) in comparison to patients with poor collateral growth. Presence of EPC was associated with reduced risk for coronary artery disease (OR: 0.934, 95%CI: 0.883-0.998, p=0.018) and was an independent predictor for good collateral growth (OR: 1.295, 95%CI: 1.039-1.615, p=0.022). A sum of CD34+KDR-, CD34+KDR+ and CD34-KDR+ cells (192±98 mm(-3)), and a CD34-KDR- cell subpopulation within monocyte gate (514±173 mm(-3)) reached to highest counts in good collateral group among all study population.

Conclusion: Endothelial progenitor cells can be mobilized from bone marrow to induce the coronary collateral growth in case of myocardial ischemia even in presence of the vascular risk factors and extensive atherosclerosis. This finding may be supportive to investigate the molecules, which can specifically mobilize EPC without inflammatory cells.