Fig. 4

Hypoxia promotes the activation and proliferation of mrSCs. a CFU-F number and relative area of mrSCs isolated from the control muscle cultured in normoxic incubator condition (called “Normoxia”) or in hypoxia (1% O₂). More cells were activated and proliferated, forming 2.7 times more colonies (> 50 cells), when they were cultured in hypoxia. In addition, colonies cultured in hypoxia were significantly bigger (1.7-fold) than cells cultured in normoxic incubator condition (mean ± SEM of four independent experiments; n = 4–6/experiment; ***p < 0.001). b Graph showing the incorporation of ³H-thymidine (cpm) by mrSCs cultured in hypoxia vs. mrSCs cultured in normoxic incubator condition. After 24 and 72 h, the cells cultured in hypoxia were significantly more proliferative than those cultured in normoxic incubator condition (1.6- and 2.4-fold, respectively) (mean ± SEM of two independent experiments; n = 3/experiment; *p < 0.05)