Increased osteocalcin-positive endothelial progenitor cells in hypogonadal male patients

OBJECTIVE: Endothelial dysfunction is considered a key factor in the development of cardiovascular diseases. Endothelial regeneration is necessary for the maintenance of endothelial function and circulating endothelial progenitor cells (EPC) participate of it in both direct and indirect manner. The molecular phenotype of EPC is not univocally defined and recent studies identified an osteocalcin (OCN)-positive (EPC-OCN+) subpopulation of EPC highly correlated with atherosclerosis progression. AIM: Considering that hypogonadism is a risk factor for cardiovascular diseases and atherosclerosis, we investigated the circulating levels of EPC-OCN+ in hypogonadal patients. SUBJECTS AND METHODS: Ten hypogonadotropic hypogonadal (HH) male patients and 30 healthy eugonadal men were evaluated for clinical status and hormonal levels. Circulating levels of CD34+/CD133+/kinase insert domain-receptor+ EPC and EPC-OCN+ were also determined by flow cytometry. RESULTS: Compared to controls, HH patients displayed lower FSH, LH, estradiol, testosterone, and EPC levels. On the contrary, EPC-OCN+ were significantly increased. CONCLUSIONS: The observed association of low levels of circulating EPC and increased values of EPC-OCN+ sub-population in hypogonadal men strengthens the significance of hypogonadism as cardiovascular risk factor.