Circulating Stem/Progenitor Cells as Prognostic Biomarkers in Macro- and Microvascular Disease: A Narrative Review of Prospective Observational Studies

Circulating progenitor cells (CPCs) and endothelial progenitor cells (EPCs) are immature cells involved in vascular repair and related to many aspects of macro and microvascular disease.We aimed to review studies reporting the prognostic role of CPCs/EPCs measurement on development of cardiovascular disease and microangiopathy.We reviewed the English language literature for prospective observational studies reporting the future development of cardiovascular disease or microangiopathy in patients having a baseline determination of CPCs/EPCs. We retrieved 34 studied reporting on cardiovascular outcomes and 2 studies reporting on microvascular outcomes. Overall, a reduced baseline level of CPCs/EPCs was associated with a significant increased risk of cardiovascular events, all-cause death, and onset/progression of microangiopathy. The most predictive phenotypes were CD34+ and CD34+CD133+. The main limitation was related to the high heterogeneity among studies in terms of patient characteristics and cell phenotypes.The present review shows that a reduced level of circulating progenitor cells is a risk factor for the development of future cardiovascular events and death. In addition, low CPCs/EPCs levels predict the onset or worsening of microalbuminuria and retinopathy in diabetic patients.