Circulating endothelial progenitor cells: Do they live up to their name?

Preclinical and clinical studies have suggested that specific subsets of cells isolated from the bone marrow or peripheral blood, collectively named endothelial progenitor cells (EPCs), play an essential role in neovascularization and are biomarkers of atherosclerosis, inversely related to the presence and progression of the disease. Conclusive evidence for both the pathophysiological and the biomarker role of these cells is, however, missing, with lack of a unique and universally accepted interpretation for their role, and the absence of general agreement to prompt their use by the practicing clinician. In fact, the engraftment of EPCs after injection into ischemic areas is poor, their secretome is still largely unknown, and there are still many confounding factors-such as co-morbidities and medications-that limit their use as a faithful biomarker of disease. Here we briefly review the literature on EPCs and discuss their significance in cardiovascular disease both as mediators and as biomarkers, including current methods for their identification.