Aging and hypertension are independent risk factors for reduced number of circulating endothelial progenitor cells

Abstract

Background: Recent studies have revealed the existence of bone marrow-derived endothelial progenitor cells (EPCs). The number of circulating EPCs might reflect the pathogenesis of atherosclerosis and progression of cardiovascular diseases (CVDs). The purpose of this study was to evaluate the relationship between the number of EPCs and cardiovascular risk factors.

Methods: Flow cytometry analysis was used to quantify the number of EPCs (CD34(+)AC133(+)CD45(low)) in 135 consecutive hospitalized patients with CVD and 25 healthy subjects.

Results: The number of EPCs was less in the patients than in the healthy subjects (1,047.4 +/- 521.1 vs. 612.8 +/- 461.6/ml, P < 0.0001). The number of EPCs significantly correlated with the number of risk factors (r = 0.424, P < 0.0001). The numbers of EPCs in patients with hypertension and diabetes mellitus were less than those in patients without those diseases (762.6 +/- 579.5 vs. 495.2 +/- 297.7/ml, P < 0.01 and 666.8 +/- 505.5 vs. 477.0 +/- 290.4/ml, P < 0.05, respectively). In healthy subjects a reduced number of EPCs was found in smokers compared with nonsmokers (833.3 +/- 347.5 vs. 1,274.6 +/- 560.9/ml, P < 0.05), whereas smoking did not alter the number of EPCs in the patients group. In multivariate analysis, hypertension and age were independent predictors of reduced number of EPCs. Renin-angiotensin system (RAS) inhibitors increased the number of EPCs (464.7 +/- 252.1/ml vs. 617.5 +/- 343.5/ml, P < 0.05), while calcium antagonists, diuretics, and beta-blockers did not alter the number of EPCs in patients with hypertension.

Conclusions: These findings suggest that both aging and hypertension are risk factors for reduced number of EPCs and that RAS inhibitors increase the number of EPCs.