The effect of acute exercise on circulating CD34+ stem cell in early and late pubertal boys

Purpose Hematopoietic stem cells are found in the peripheral circulation and may play a role in tissue growth and repair. In adults exercise acutely increases the number of circulating CD34 + stem cells in the peripheral blood. Whether this occurs during childhood (a stage in life characterized by vigorous physical activity as well as growth and development) or is influenced by maturational status is not known. Methods Eight healthy pre/early pubertal (EARLY, age 10.2 ± 0.41) and eight late pubertal (LATE, age 16.7 ± 0.74) males participated in the study. Pubertal status was estimated by a standardized self‐assessment questionnaire. Each participant performed 20 min heavy cycle ergometry exercise. Venous blood was drawn at pre‐exercise and immediately following exercise through an indwelling catheter. Cells were stained for CD34 + using ISHAGE definition for identifying CD34 + , i.e., cells gated on CD45+ dim /low side scatter CD34 + positive cells. Samples were acquired using a FACS Calibur flow cytometer (Becton Dickinson, San Jose, CA). Results The brief bout of vigorous exercise increased the total number of circulating CD34 + stem cells in both groups. In EARLY boys CD34 + stem cells increased from 127 ± 32 cells/μl to 224 ± 98 at end‐exercise (p<0.03). In late pubertal boys stem cells increased from 59 ± 10 to 175 ± 26 (p<0.003). The difference between the resting values in the EARLY and LATE subjects approached, but did not achieve, statistical significance <0.08. Conclusion Frequently occurring, daily life activities like brief exercise can increase circulating stem cells in children. The extent to which this cells are involved in growth or repair function; or are influence by pubertal status, is not yet known.