Edinburgh Napier University

  Ageing is associated with a dysfunctional endothelial phenotype, as well as reduced angiogenic capabilities. Exercise exerts beneficial effects on the cardiovascular system, possibly by increasing/maintaining the number and/or function of circulating angiogenic cells (CACs) that are known to decline with age. However, the relationship between cardiorespiratory fitness (CRF) and age related changes in frequency of CACs, as well as the exercise-induced responsiveness of CACs in older individuals has not yet been determined. One hundred and seven healthy male volunteers, aged 18-75 years, participated in the study 1. CRF was estimated using submaximal cycling ergometer test. Circulating endothelial progenitor cells (EPCs), angiogenic T-cells (TANG) and their CXCR4 cell surface receptor expression were enumerated by flow cytometry using peripheral blood samples obtained under resting conditions prior to the exercise test. Study 2 recruited 17 healthy males (8 young, 18-25yrs; 9 older, 60-75yrs) and these participants undertook a 30-minute cycling exercise bout at 70% V ̇O2max, with CACs enumerated pre- and immediately post-exercise. Age was inversely associated with both CD34+ progenitor cells (r2=-0.140, p=0.000) and TANG (r2=-0.176, p=0.000) cells, as well as CXCR4-expressing CACs (CD34+, r2=-0.167, p=0.000; EPCs: r2=-0.098, p=0.001; TANG, r2=-0.053, p=0.015). However, after correcting for age, CRF had no relationship with either CAC subset. In addition, older individuals displayed attenuated exercise-induced increases in CD34+ progenitor cells, TANG, CD4+ TANG, and CD8+CXCR4+ TANG cells. Older men display lower CAC levels, which may contribute to increased CVD risk, and older adults display an impaired exercise-induced responsiveness of these cells.