Endothelial function and circulating endothelial progenitor cells in patients with sleep apnea syndrome

Background: Endothelial dysfunction and cardiovascular diseases are frequent in patients with obstructive sleep apnea (OSA). Circulating endothelial progenitor cells (EPCs) contribute to repair dysfunctional endothelium and have been related to increased cardiovascular risk. Objectives: We tested the hypothesis that the number of circulating EPCs may be altered in OSA patients. Methods: EPCs (CD34+VEGF-R2+) were isolated and quantified from peripheral blood samples of OSA patients (n = 13) and healthy controls (n = 13) matched for age and sex. All subjects were free of any other known cardiovascular risk factors. The plasma levels of vascular endothelial growth factor (VEGF) were also determined, and the endothelium-dependent and endothelium-independent vascular function was assessed in all subjects. Results: Patients with OSA had lower levels of EPCs (p < 0.05) and higher plasma levels of VEGF (p < 0.05) than controls. Endothelial function was not different between OSA and controls. Conclusions: Patients with OSA free of any other known cardiovascular risk factor show a reduced number of circulating EPCs and an increase in plasma VEGF levels. These alterations may contribute to future endothelial dysfunction in these patients. Copyright (C) 2007 S. Karger AG, Basel.