Decreased numbers of endothelial progenitor cells in patients in the early stages of systemic sclerosis

Introduction: Microangiopathy and endothelial dysfunction are present in the early stages of systemic sclerosis (SSc). Defective vasculogenesis mediated by bone marrow-derived endothelial progenitor cells (EPCs) might be involved in the vascular abnormalities found in SSc.Objectives: To evaluate the circulating EPC levels and EPC subtypes via flow cytometry and early outgrowth colony-forming units (CPUs) in patients with SSc compared to healthy subjects.Methods: Thirty-nine female SSc patients (30 in the early stages of SSc) and 44 age-matched healthy women were included. Peripheral blood EPCs were quantified using flow cytometry and by counting the early outgrowth CFUs.Results: the EPCs quantified with flow cytometry and the CPU numbers were significantly lower in SSc patients than in control subjects (155.1 +/- 95.1 vs. 241.3 +/- 1842 EPC/10(6) lymphomononuclear cells, p = 0.011; 15.4 +/- 8.6 vs. 23.5 +/- 10.9 CFU, p