title: Levels of Circulating Progenitor Cells, Cardiovascular Outcomes and Death: A Meta-Analysis of Prospective Observational Studies.
abstract: Circulating progenitor cells (CPCs), including endothelial progenitor cells (EPCs) are biologically related to many aspects of cardiovascular disease, as they promote angiogenesis and vascular repair.
  
  
  
  We herein aimed to meta-analyze studies reporting the prognostic role of the CPC/EPC measure on cardiovascular outcomes and death.
  
  
  
  We screened the English-language literature for longitudinal studies reporting the association between baseline CPC/EPC levels, future cardiovascular events, and death. We retrieved 28 studies, 21 of which contained poolable data and entered the meta-analysis, for a total of 4155 patients, mostly with a high baseline cardiovascular risk. Sixty percent of the studies met at least 11 of 16 items of quality assessment. Overall, reduced CPC/EPC levels were associated with a ≈2-fold increased risk of future cardiovascular events and cardiovascular death. The most predictive phenotype was CD34(+)CD133(+): low versus high levels predicted cardiovascular events, restenosis after endovascular intervention, cardiovascular death, and all-cause mortality. Heterogeneity among studies and according to the CPC/EPC phenotype was generally high. Excluding studies for which the risk estimate had to be extrapolated or limiting the analyses to higher quality studies still indicated a significant risk for future cardiovascular events and death in patients with low versus high progenitor cell counts.
  
  
  
  This meta-analysis shows that a reduction in the levels of circulating cells putatively provided with vasculoregenerative properties represents a risk factor for adverse cardiovascular outcomes and death.
authors.affiliation: From the Department of Medicine, University of Padova, Padova, Italy.
authors.forename: Mauro
authors.initials: M
authors.lastname: Rigato
authors.affiliation: From the Department of Medicine, University of Padova, Padova, Italy.
authors.forename: Angelo
authors.initials: A
authors.lastname: Avogaro
authors.affiliation: From the Department of Medicine, University of Padova, Padova, Italy. gianpaolo.fadini@unipd.it.
authors.forename: Gian Paolo
authors.initials: GP
authors.lastname: Fadini
mesh_terms: D000071916:AC133 Antigen / Q000235:genetics / Q000378:metabolism; D018952:Antigens, CD34 / Q000235:genetics / Q000378:metabolism; D015415:Biomarkers / Q000097:blood; D002318:Cardiovascular Diseases / Q000097:blood* / Q000401:mortality / Q000473:pathology; D066026:Endothelial Progenitor Cells / Q000378:metabolism / Q000473:pathology*; D006801:Humans; D064887:Observational Studies as Topic
chemical_list: D000071916:AC133 Antigen; D018952:Antigens, CD34; D015415:Biomarkers
keywords: endothelial progenitor cells; epidemiology; prevention & control; regeneration; stem cells