Circulating endothelial progenitor cells in acromegaly

Background:Endothelial progenitor cells (EPCs), involved in the repairing mechanisms of vascular damage, are positively correlated to insulin-like growth factor I (IGF-I) concentrations in healthy adults. However, the levels of EPCs and their role in acromegalic patients have never been investigated. Aim:We conducted a cross-sectional study in order to assess the levels of the different phenotypes of circulating EPC in acromegalic patients. Subjects and methods:The study was performed at the Endocrinology Unit of Federico II University and at the Unit of Metabolic Diseases and Endocrinology of the Second University of Naples. Fifty-five acromegalic patients and 65 healthy controls were studied. EPCs were assessed by flow cytometry and IGF-I by immunoradiometric assay. Results:Compared with subjects of the control group, acromegalic patients showed significantly higher levels of EPCs phenotypes expressing KDR antigen [KDR+, cells per 106events, median and interquartile range, 44 (28–67) vs 23 (13–40), p=0.006; CD34+KDR+ 25 (18–38) vs12 (8–17), p<0.001; CD133+KDR+ 17 (13–30) vs8 (6–12), p<0.001; CD34+KDR+CD133+ 16 (12–25) vs8 (6–10), p<0.001]. There was a positive correlations between CD34+KDR+CD133+ cells count and IGF-I in acromegaly group (r=0.79, p<0.001). Conclusions:Acromegalic patients show higher circulating EPCs levels expressing KDR, positively correlated with IGF-I, suggesting a role for IGF-I in regulating the expression of this surface marker in the early phase of EPCs differentiation.