Circulating Endothelial Progenitor Cells in Youth: Fitness, Physical Activity and Adiposity

Circulating endothelial progenitor cells (EPCs) are early markers of cardiovascular impairment. The role of EPCs in youth remains unclear, and is complicated by differences in how cells are identified. This study (1) described EPCs in pre- and late-pubertal males and females, (2) examined their association with fitness, activity and adiposity, and (3) compared EPCs to published cell definitions. 94 participants completed 2 sessions. During the first session, aerobic fitness (Wpeak) and moderate-to-vigorous physical activity (MVPA) were assessed. During the second session, percent body fat (%BF) was determined by DXA, and a fasted blood sample was collected to measure EPCs by flow cytometry. EPCs were identified as CD31(+)CD34(bright)CD45(dim)CD133(+). Samples were reanalyzed and cell counts were compared to 8 previously published EPC definitions. EPCs were similar in pre- and late-pubertal males and females (p>0.05). Neither EPC concentrations nor proportions were correlated with Wpeak (ρ=- 0.04 to-0.06), MVPA (ρ=- 0.09 to - 0.07) or %BF (ρ=0.20 to 0.14). Agreement between cell data analyzed according the different cell definitions ranged from Κ=-0.06 to 0.82. Our findings suggest that EPCs were not associated with fitness, MVPA or adiposity in youth. The overall poor agreement across definitions may be indicative of distinct EPC subpopulations.