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. *Corresponding Author: C. Noel Bairey Merz, MD, Barbra Streis and Women’s Heart Center, Cedars Sinai Heart Institute, 127 S San Vicente Blvd A3206, Los Angeles, California 90048, USA. Tel: (310) 423-9680 Fax: (310) 423-9681 Email: merz@cshs.org Received: October 06, 2016 Accepted: November 07, 2016 Published: November 08, 2016 Citation: Phancao A, Mehta PK, Dhawan S, Cook-Wiens G, Bairey Merz CN, et al., (2016) Circulating Endothelial Progenitor Cells in Women with Coronary Microvascular Dysfunction: A Pilot Study. Int J Stem Cell Res Transplant. 4(9), 256-259. doi: http://dx.doi. org/10.19070/2328-3548-1600039 Copyright: Bairey Merz CN© 2016. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution and reproduction in any medium, provided the original author and source are credited. Introduction Endothelial progenitor cells (EPCs) are a diverse population of mononuclear cells derived from bone marrow that are mobilized in response to vascular injury [1, 2], and circulate in peripheral blood and contribute to vascular repair [3, 4]. Subpopulations of circulating EPCs expressing cell surface makers CD34+, CD133+, or vascular endothelial growth factor receptor (VEGFR) 2+ have been linked with coronary vascular dysfunction [5-11]. In addition, reduced circulating EPC levels are associated with cardiovascular events [11] and acceleration of atherosclerosis [8]. Women with chest pain, evidence of ischemia, and no obstructive coronary artery disease (CAD) often have coronary microvascular dysfunction (CMD) [12, 13]. CMD is related to both endothelial dependent and non-endothelial dependent mechanisms, and associated with adverse cardiovascular outcomes [12]. Invasive coronary reactivity testing (CRT) can be used to diagnose CMD [14]. We evaluated circulating EPCs in women with CMD compared to age and BMI matched controls, and studied relationships between CD34+/VEGFR2+ and CD34+/CD133+ subsets of EPCs and measures of CRT.