Fig. 2: FoxM1 deficiency impairs SC maintenance by impeding cell cycling of SCs.

a Skeletal muscles were harvested from mice at 8 months of age and then were digested as mononuclear cells. The cells were stained with cell surface markers (CD45, Sca1, CD11b, CD31,CD34, α7-integrin). The population of SCs (defined as CD45⁻Sca1⁻CD11b⁻CD31⁻CD34⁺α7-integrin⁺ cells) was analyzed by flow cytometry. b Quantification of the relative percentage of SCs per total mononuclear cells isolated from the skeletal muscles of mice at 8 months of age (n = 4). c Skeletal muscles were harvested from mice (8 months of age) and digested as myofibers. Representative fluorescent images of fresh myofibers immunostained with Pax7 antibody (green) and DAPI (blue). Scale bars, 50 μm. d Quantification of the numbers of Pax7⁺ SCs per myofiber of mice at 8 months of age (n = 5, 20 myofibers per mouse). e The mononuclear cells were isolated from the skeletal muscles of mice (2 months of age) and stained with cell surface markers, DAPI and Ki67. The quiescent percentage of SCs was analyzed by flow cytometry. f Quantification of the percentage of G0 phase of SCs in mice (2 months of age) (n = 7). g The mononuclear cells were isolated from the skeletal muscles of mice (2 months of age) and were stained with cell surface markers and DAPI. The cell cycle of SCs was analyzed by flow cytometry. h Quantification of the percentage of cell cycle distribution of SCs in mice at 2 months of age (n = 4). i In vitro proliferation assay (CCK8) of cultured SCs isolated from mice (2 months of age; n = 5). j The mononuclear cells were isolated from the skeletal muscles of mice (2 months of age) and were stained with SC markers, as well as Annexin-V and DAPI. The percentage of apoptotic SCs (Annexin-V⁺ SCs) was analyzed by flow cytometry (n = 4). Error bars represent the means ± SD. **p < 0.01, ***p < 0.001; Student’s t test.