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

• Endothelial progenitor cells were identified by means of flow cytometry and culture.
• The patients with SSc exhibited decreased EPC levels than the controls.
• EPC levels were also lower in patients in the early stages of SSc compared to the controls.
• The late scleroderma pattern on capillaroscopy was related to lower levels of EPCs.

IntroductionMicroangiopathy 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.ObjectivesTo evaluate the circulating EPC levels and EPC subtypes via flow cytometry and early outgrowth colony-forming units (CFUs) in patients with SSc compared to healthy subjects.MethodsThirty-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.ResultsThe EPCs quantified with flow cytometry and the CFU numbers were significantly lower in SSc patients than in control subjects (155.1 ± 95.1 vs. 241.3 ± 184.2 EPC/106 lymphomononuclear cells, p = 0.011; 15.4 ± 8.6 vs. 23.5 ± 10.9 CFU, p < 0.001; respectively), as well as in the group of patients in the early stages of SSc compared to the controls. Patients with digital ulcers had significantly higher CFU counts than those without ulcers (p = 0.013). Among patients with the scleroderma pattern on nailfold capillaroscopy, patients with the late pattern had significantly lower EPC levels than those with the early and active patterns (p = 0.046). There were no significant correlations of EPCs or CFU levels with RP duration.ConclusionsThe present study revealed decreased EPCs in SSc patients, including those with early disease onset. These findings suggest that defective vasculogenesis occurs in the early phases of the disease. Therefore, EPCs might be an important therapeutic target for the prevention of vascular complications in SSc patients.