Figure 6. SAM restoration is associated with improved muscle regeneration of aged mice.

a, Schematic showing the experimental design of MuSC isolation (b-d) and tissue collection (e-g), after BaCl₂ injury. In order to isolate activated MuSCs, MuSCs were isolated from injured the muscles at 2 days post injury (dpi). During the 2 days after injury, mice were continuously treated with vehicle, MCHA, or SAM. TA muscles were collected at 7 dpi. During the 7 days of after injury, mice were continuously treated with vehicle, MCHA, or SAM. b, (Left) Representative images of cells after alkaline comet assay (Scale bar, 50 μm). (Right) The percentage of comet positive cells (n=4). c, (Left) Representative images of TUNEL positive or negative MuSCs (Scale bar, 50 μm). (Right) Quantification of TUNEL positive MuSCs (n=4 for vehicle-treated young mice and vehicle- or MCHA-treated old mice, n=3 for SAM-treated old mice). d, (Left) The percentage of PI positive cells (n=3). (Right) The representative FACS plot. e, (Left) Representative immunofluorescence images of cross-sections of TA muscles (Scale bar, 100 μm). (Right) The cross-sectional areas (CSAs) of centrally nucleated myofibers of each tissue were quantified (n=3). f, Representative tissue immunostaining images of TA muscle sections (n=4 for young mice, n=3 for old mice per group, Scale bar, 100 μm). g, Quantification of the number of Pax7-positive MuSCs per each tissue section (n=4 for young mice, n=3 for old mice per group). h, Grip force measured from each group of mice at 16 dpi (n=8 for young mice, n=7 for old mice per group). i, Graphical depiction of parameters of a mouse’s gait. j-l, Gait measurements of each group of mice at 14 dpi. Mice were placed individually on a motor-driven treadmill at 10 cm/sec, and brake time (j), propel time (k), and swing time (l) of each mouse were measured (n=8 for young mice, n=7 for old mice treated with vehicle or SAM, n=6 for old mice treated with MCHA). Data are shown as mean ± SD (b-e, g, h, j-l). P values were calculated by two-sided unpaired Student’s t-tests (b-e, g, h, j-l). *P < 0.05; **P < 0.01; ***P < 0.001.