Circulating endothelial progenitor cells in postmenopausal women with and without coronary artery disease

Background Middle-aged women have a lower prevalence of coronary artery disease (CAD) compared with age-matched men, but mechanisms underlying this phenomenon remain controversial. To verify whether there is a link between circulating endothelial progenitor cells (EPCs) and gender-specific difference of CAD, we compared subpopulations of EPCs among postmenopausal normal women, patients with CAD, and age-matched men. Methods We studied 71 consecutive middle-aged patients with stable CAD (30 postmenopausal women and 41 men) and 40 middle-aged normal controls (20 postmenopausal women and 20 men). Blood samples were drawn at time of coronary angiography and subpopulations of EPCs were measured by flow cytometry. Results Women and men with CAD had similar age, risk factors, clinical presentation, left ventricular function, extension of CAD, and medical therapy at time of coronary angiography. Hematologic analysis showed that men and women with CAD had similar white cell count, mononuclear cells, and subpopulations of EPCs. Postmenopausal normal women, conversely, had significantly higher absolute numbers of CD34+, CD133+, CD105+ and CD14+ cells than other groups. Conclusions Increased numbers of subpopulations of EPCs in normal postmenopausal women might contribute to the gender-specific difference of CAD in middle age. Lack of difference in EPCs between women and men with CAD suggests that stem cells become unable to play a protective role when the disease is clinically evident.