title: A quantitative assessment of circulating progenitor cells in competitive athletes and in sedentary subjects.
abstract: OBJECTIVE
  Hematopoietic stem cells (HSCs) and endothelial progenitor cells (EPCs) are known to play a role in the vascular responses and adaptations to exercise. We performed a quantitative assessment of HSCs and EPCs in adolescents in order to investigate whether resting levels of circulating HSCs and EPCs are comparable between elite athletes and sedentary healthy subjects.
  
  
  METHODS
  HSCs and EPCs levels were measured in adolescent competitive football players and in age- and sex-matched sedentary controls. A laboratory testing was also performed to determine the white blood cells count and the lipid profile. All athletes were evaluated at the same stage of their training program, after 6 months of training. Controls were not engaged in any kind of routine training program.
  
  
  RESULTS
  Twenty male competitive athletes (18.4 ± 0.5 years) and 9 sedentary controls (18.7 ± 0.4 years) participated in the study. As expected, HDL cholesterol was higher in athletes as compared with controls (P<0.05). No significant differences in the other laboratory parameters were observed among groups. Circulating levels of HSCs were significantly lower in athletes in comparison with sedentary controls (P<0.05). Conversely, EPCs and KDR+ cell subpopulations did not substantially differ between athletes and controls.
  
  
  CONCLUSIONS
  Adolescent athletes exhibit lower levels of circulating HSCs but not of EPCs compared to sedentary controls. The process of tissue repair associated with intensive training can contribute to this difference, acting as a stimulus for mobilization and homing of HSCs in the site of injuries.
authors.affiliation: Department of Cardiovascular Diseases, University of Siena, Siena, Italy - flavio.dascenzi@libero.it.
authors.forename: F
authors.initials: F
authors.lastname: D'ascenzi
authors.forename: V
authors.initials: V
authors.lastname: Zacà
authors.forename: S
authors.initials: S
authors.lastname: Maiorca
authors.forename: A
authors.initials: A
authors.lastname: Neri
authors.forename: C
authors.initials: C
authors.lastname: Aldinucci
authors.forename: V
authors.initials: V
authors.lastname: Sorrentino
authors.forename: A
authors.initials: A
authors.lastname: Causarano
authors.forename: M
authors.initials: M
authors.lastname: Bonifazi
authors.forename: S
authors.initials: S
authors.lastname: Mondillo
mesh_terms: D000293:Adolescent; D056352:Athletes; D016022:Case-Control Studies; D008076:Cholesterol, HDL / Q000097:blood; D066026:Endothelial Progenitor Cells / Q000378:metabolism*; D006412:Hematopoietic Stem Cells / Q000378:metabolism*; D006801:Humans; D008297:Male; D057185:Sedentary Behavior
chemical_list: D008076:Cholesterol, HDL