Background/Purpose: Microangiopathy and endothelial dysfunction are present in early phases of Systemic sclerosis (SSc), resulting in decreased blood flow and tissue ischemia. Several mechanisms including insufficient angiogenesis, and defective vasculogenesis mediated by endothelial progenitor cells (EPCs), might be involved in the vascular abnormalities in SSc patients. However, different data have been reported regarding the number and function of EPCs in different clinical subsets of SSc patients. This study aimed to evaluate the circulating number and the in vitro culture of EPCs in SSc patients with early disease compared to healthy controls.

Methods: Thirty-one consecutive SSc female patients (mean age 42.7 years) with less than four years of Raynaud’s phenomenon (RP) and 20 age-matched healthy women (mean age 39.9 years) were included. All patients fulfilled the ACR classification criteria for SSc (1980) or the LeRoy and Medsger criteria (2001). Peripheral blood samples (30mL) were collected from each subject at rest. Flow cytometry was performed to quantify the absolute number of EPCs. EPCs were identified by the co-expression of CD34, CD133 and vascular endothelial growth factor receptor type 2 (VEGFR2) and were expressed as the number of EPCs per 10⁶ lymphomononuclear (LMN) cells. Besides, in vitro culture of EPCs was performed, and the number of EPC colony-forming units (CFU) per well was quantified in each sample. All procedures were performed according the EULAR recommendations and executed immediately after blood collection. Plasma VEGF levels were assessed by ELISA. p<0.05 were considered statistically significant.

Results: Among SSc patients, the mean duration of RP was 3.75±1.96 years and the mean duration of the first SSc symptom other than RP was 3.24±1.85 years. Digital ulcers were present in ten patients. SSc patients showed decreased number of EPCs (108.6±87.2 vs 246.8±241.4 /10⁶LMN, respectively, p=0.04), and decreased number of EPC CFUs compared to controls (14.6±9.1 vs 20.9±11.5 CFUs, respectively, p=0.034). There was no significant difference in the number of EPCs between SSc patients with digital ulcers and those without digital ulcers at the time of the evaluation (90.5±73.2 vs 121.4±96.5 /10⁶LMN, respectively, p=0.4). There was a positive correlation between the number of circulating EPCs and the number of EPC CFUs. There was no difference in VEGF levels between patients and controls (88.3±57.9 vs 83.8±74.6 ng/mL, p=0.34).

Conclusion: The present study showed originally decreased EPCs in SSc patients with early disease onset, suggesting presence of defective vasculogenesis in early stages of the disease. Therefore, EPCs could be an important therapeutic target for preventing vascular complications in patients with early stages of SSc.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/decreased-number-of-endothelial-progenitor-cells-in-systemic-sclerosis-patients-with-early-disease/