Circulating Endothelial Progenitor Cells in Women with Coronary Microvascular Dysfunction: A Pilot Study

Background: Endothelial progenitor cells (EPCs) are a diverse population of mononuclear cells derived from bone marrow that are mobilized in response to vascular injury, circulate in peripheral blood and contribute to vascular repair. We evaluated circulating EPCs in women with coronary microvascular dysfunction (CMD) compared to matched controls. Methods: Twenty-nine symptomatic women with no obstructive coronary atherosclerosis (<50% epicardial coronary stenosis), and diagnosed with CMD invasively, and eleven reference control women were included. EPCs were defined as cells either expressing cell surface markers CD34+/CD133+ or CD34+/VEGFR2+. Results: Mean and median levels of CD34+/CD133+ and CD34+/VEGFR2+ in the CMD group trended lower than the reference control group, although this was not statistically significant. There was a significant positive correlation between CD34+/CD133+ subsets and LDL levels which was not found with CD34+/VEGFR2+. Conclusions: These pilot data in women with CMD demonstrate no difference in EPCs between CMD women compared to reference control subjects. Our study combined with prior publications in similarly characterized and larger populations suggests that absolute EPC levels (BMDAC), but not EPCs alone, may be adequately sensitive for providing a complete depiction of endothelial injury or function in this population.