title: Haematopoietic stem cells and endothelial progenitor cells in healthy men: effect of aging and training.
abstract: The number of hematopoietic stem cells (HSC) and endothelial progenitor cells (EPC) is thought to be a marker for neovascularization and vascular repair. Because physical inactivity and aging are risk factors for cardiovascular diseases, these factors may influence the numbers of HSCs and EPCs. Therefore, we examined baseline and exercise-induced levels of HSCs and EPCs in sedentary and trained young and older men. To study the role of aging in eight sedentary young (19-28 years) and eight sedentary older men (67-76 years), baseline and acute exercise-induced numbers of HSCs (CD34+-cells) and EPCs (CD34+/VEGFR-2+-cells) were quantified by fluorescence-activated cell sorter (FACS) analysis. To examine the effect of chronic training, eight age-matched trained young men (18-28 years) were compared with sedentary young men, whereas older men performed an 8-week endurance training. Older men showed significantly lower baseline and exercise-induced levels of HSCs/EPCs than the young men (P < 0.05). In young and older men, acute exercise significantly increased HSCs (P < 0.01), but not EPCs. The absolute increase in numbers of HSCs was attenuated in older men (P = 0.03). Apart from the lower baseline numbers of EPCs after chronic training in older men, training status did not alter baseline or exercise-induced levels of HSCs/EPCs in young and older men. We concluded that advancing age results in lower circulating numbers of HSCs and EPCs and attenuates the acute exercise-induced increase in HSCs. Interestingly, in young as well as in older men chronic endurance training does not affect baseline and exercise-induced numbers of HSCs and EPCs.
authors.affiliation: Department of Physiology, Institute of Fundamental and Clinical Movement sciences, Radboud University Nijmegen Medical Centre, The Netherlands. d.thijssen@fysiol.umcn.nl
authors.forename: Dick H J
authors.initials: DH
authors.lastname: Thijssen
authors.forename: Joost B
authors.initials: JB
authors.lastname: Vos
authors.forename: Caroline
authors.initials: C
authors.lastname: Verseyden
authors.forename: Anton Jan
authors.initials: AJ
authors.lastname: van Zonneveld
authors.forename: Paul
authors.initials: P
authors.lastname: Smits
authors.forename: Fred C G J
authors.initials: FC
authors.lastname: Sweep
authors.forename: Maria T E
authors.initials: MT
authors.lastname: Hopman
authors.forename: Hetty C
authors.initials: HC
authors.lastname: de Boer
mesh_terms: D000328:Adult; D000368:Aged; D000375:Aging / Q000502:physiology*; D002452:Cell Count; D049109:Cell Proliferation; D042783:Endothelial Cells / Q000502:physiology*; D005081:Exercise Therapy; D017079:Exercise Tolerance / Q000502:physiology; D005434:Flow Cytometry; D006412:Hematopoietic Stem Cells / Q000502:physiology*; D006801:Humans; D008297:Male; D018919:Neovascularization, Physiologic / Q000502:physiology; D010809:Physical Fitness / Q000502:physiology*; D013234:Stem Cells / Q000502:physiology*; D015854:Up-Regulation / Q000502:physiology