Figure 1. Aged MuSCs exhibited a reduced growth rate compared to young MuSCs. (A) Micrographs of young and aged MuSCs at day 1 and 3 of culture. (B–G) Fold-change in cell number of young and aged MuSCs in vitro at three passages (P1-P3). Each graph shows young and aged MuSCs, n = 1 (from 1 young or aged mouse). (H) Fold-change in cell number of young and aged MuSCs at three passages (P1-P3; pooled data), over the initial cell number seeded, as a function of time (days). n = 3 (from 3 young or aged mice). (I) Growth rate r of young and aged MuSCs at three passages (P1-P3) over two days illustrating an increased growth rate of young MuSCs at P2 and P3. n = 3 (from 3 young or aged mice). (J–M) Gene expression of Pax7, MyoD, Myog, Ccnd1, Cdk4, Cdkn2a, Timp1, c-fos, and IL-6. Young MuSCs, n = 11 (from 4 young mice). Aged MuSCs, n = 9 (from 3 aged mice). Abbreviation: MuSCs: muscle stem cells. Values are mean ± SEM. Significant effect of age, *p < 0.1, **p < 0.05. Scale bar, 200 μm.