Circulating endothelial progenitor cell deficiency contributes to impaired arterial elasticity in persons of advancing age

Reduced arterial elasticity is a hallmark of ageing in healthy humans and appears to occur independently of coexisting disease processes. Endothelial-cell injury and dysfunction may be responsible for this fall in arterial elasticity. We hypothesized that circulating endothelial progenitor cells (EPCs) are involved in endothelial repair and that lack of EPCs contributes to impaired arterial elasticity. A total of 56 healthy male volunteers were divided into young (n = 26) and elderly (n = 30) groups. Large and small artery elasticity indices were noninvasively assessed using pulse wave analysis. The number of circulating EPCs was measured by using flow cytometry. Cells demonstrating DiI-acLDL and FITC-ulex lectin double-positive fluorescence were identified as EPCs. C1 large artery elasticity and C2 small artery elasticity indices were significantly reduced in the elderly group compared with the young group 11.73+/-1.45 vs 16.88+/-1.69 ml/mmHg x 10, P<0.001; 8.40+/-1.45 vs 10.58+/-1.18 ml/mmHg x 100, P<0.001, respectively). In parallel, the number of circulating EPCs was significantly reduced in the elderly group compared with the young group (0.13+/-0.02 vs 0.17+/-0.04%, P<0.05). The number of circulating EPCs correlated with C1 large and C2 small artery elasticity indices (r = 0.47, P<0.01; r = 0.4, P<0.01). The present findings suggest that the fall in circulating EPCs with subsequently impaired endothelial-cell repair and function contributes to reduced arterial elasticity in humans with ageing. The decrease in circulating EPCs may serve as a surrogate biologic measure of vascular function and human age.