Changes in Circulating Stem and Progenitor Cell Numbers Following Acute Exercise in Healthy Human Subjects: a Systematic Review and Meta-analysis

Abstract

Despite of the increasing number of investigations on the effects of acute exercise on circulating stem and progenitor cell (SC) numbers, and in particular on respective subgroups, i.e. endothelial (ESC), hematopoietic (HSC), and mesenchymal (MSC) stem and progenitor cells, a consensus regarding mechanisms and extent of these effects is still missing. The aim of this meta-analysis was to systematically evaluate the overall-effects of acute exercise on the different SC-subgroups and investigate possible subject- and intervention-dependent factors affecting the extent of SC-mobilization in healthy humans. Trials assessing SC numbers before and at least one timepoint after acute exercise, were identified in a systematic computerized search. Compared to baseline, numbers were significantly increased for early and non-specified SCs (enSCs) until up to 0.5 h after exercise (0-5 min: +0.64 [Standardized difference in means], p < 0.001; 6-20 min: +0.42, p < 0.001; 0.5 h: +0.29, p = 0.049), for ESCs until 12-48 h after exercise (0-5 min: +0.66, p < 0.001; 6-20 min: +0.43 p < 0.001; 0.5 h: +0.43, p = 0.002; 1 h: +0.58, p = 0.001; 2 h: +0.50, p = 0.002; 3-8 h: +0.70, p < 0.001; 12-48 h: +0.38, p = 0.003) and for HSCs at 0-5 min (+ 0.47, p < 0.001) and at 3 h after exercise (+ 0.68, p < 0.001). Sex, intensity and duration of the intervention had generally no influence. The extent and kinetics of the exercise-induced mobilization of SCs differ between SC-subpopulations. However, also definitions of SC-subpopulations are non-uniform. Therefore, finding a consensus with a clear definition of cell surface markers defining ESCs, HSCs and MSCs is a first prerequisite for understanding this important topic.

Keywords: Acute exercise; Endothelial; Hematopoietic; Kinetics; Mesenchymal; Meta-analysis; Moderator variables; Stem and progenitor cells; Stem cell mobilization; Systematic review.

Fig. 1

Flow diagram of the selection process

Fig. 2

Forest plot of enSCs 0–5 min (a), 6–20 min (b), 0.5 h (c), 1 h (d), 2 h (e) and 3–96 h post-exercise (f). Std diff = standardized difference, CI = confidence interval

Fig. 2

Forest plot of enSCs 0–5 min (a), 6–20 min (b), 0.5 h (c), 1 h (d), 2 h (e) and 3–96 h post-exercise (f). Std diff = standardized difference, CI = confidence interval

Fig. 2

Forest plot of enSCs 0–5 min (a), 6–20 min (b), 0.5 h (c), 1 h (d), 2 h (e) and 3–96 h post-exercise (f). Std diff = standardized difference, CI = confidence interval

Fig. 3

Forest plot of ESCs 0–5 min (a), 6–20 min (b), 0.5 h (c), 1 h (d), 2 h (e), 3–8 h (f) and 12–48 h post-exercise (g). Std diff = standardized difference, CI = confidence interval

Fig. 3

Forest plot of ESCs 0–5 min (a), 6–20 min (b), 0.5 h (c), 1 h (d), 2 h (e), 3–8 h (f) and 12–48 h post-exercise (g). Std diff = standardized difference, CI = confidence interval

Fig. 3

Forest plot of ESCs 0–5 min (a), 6–20 min (b), 0.5 h (c), 1 h (d), 2 h (e), 3–8 h (f) and 12–48 h post-exercise (g). Std diff = standardized difference, CI = confidence interval

Fig. 4

Forest plot of HSCs 0–5 min (a), 6–20 min (b), 0.5 h (c), 1 h (d), 3 h (e) and 12–24 h post-exercise (f). Std diff = standardized difference, CI = confidence interval

Fig. 4

Forest plot of HSCs 0–5 min (a), 6–20 min (b), 0.5 h (c), 1 h (d), 3 h (e) and 12–24 h post-exercise (f). Std diff = standardized difference, CI = confidence interval

Fig. 4

Forest plot of HSCs 0–5 min (a), 6–20 min (b), 0.5 h (c), 1 h (d), 3 h (e) and 12–24 h post-exercise (f). Std diff = standardized difference, CI = confidence interval

Fig. 5

Forest plot of MSCs 0–5 min (a) and 2 h post-exercise (b). Std diff = standardized difference, CI = confidence interval

Fig. 6

Graphical summary of the main outcomes. enSCs = early and non-specified stem and progenitor cells, ESCs = endothelial stem and progenitor cells, HSCs = hematopoietic stem and progenitor cells, MSCs = mesenchymal stem and progenitor cells. Data is given as Std diff in means ± SE, with the size of each datapoint representing the number of included effect sizes in the respective meta-analysis. Significant effects are depicted by filled symbols and level of significance: *p < 0.050, **p < 0.010, ***p < 0.001