Hormonal status modulates circulating endothelial progenitor cells

Objective Endothelial progenitor cells (EPCs) may have an important role in vascular homeostasis and repair. Methods We examined the level of circulating EPCs in pre- (n=22; mean age 28.7 years), and postmenopausal healthy females without (n=30; mean age 61.6 years) or under current hormone replacement therapy (HRT) (n=19; mean age 59.8 years). Results Premenopausal females had the highest level of circulating EPCs (0.147 +/- 0.076 parts per thousand of polymorphnuclear cells). The level of EPCs was lowest in postmenopausal females (0.094 +/- 0.058 parts per thousand), and increased significantly with HRT on average by 25.5%. In addition, the proliferative capacity of circulating EPCs was assessed under cell culture conditions. This capacity was significantly increased in EPCs isolated from postmenopausal subjects under current HRT as compared to corresponding samples obtained from postmenopausal females without HRT. Conclusions This observation is in line with the hypothesis that the hormonal status in females modulates the cardiovascular risk and that circulating EPCs could be involved in this phenomenon.