Extended Data Figure 4: Geroconversion of geriatric, progeric and Bmi1-null satellite cells in vitro and in vivo.

a, Equal number of FACS-isolated satellite cells from adult, old and geriatric mice were cultured in growth medium containing high serum and FGF2 for 4 days and BrdU incorporation was tested after 1 h pulse. b, Sorted satellite cells from adult, old and geriatric mice, cultured in growth medium as in panel a, and immunostained with antibodies against γH2AX. The levels of γH2AX per nucleus were determined. c, Representative pictures of cryosections from tibialis anterior muscles from adult, old and geriatric mice injured with CTX injection and obtained 1 week after injury immunostained for γH2AX. Scale bar, 50 μm. d, Percentage of satellite cells (Pax7⁺) positive for γH2AX in adult, old and geriatric muscles 1 week after CTX injury. e, An equal number of FACS-isolated satellite cells from adult, old and geriatric mice transplanted into regenerating muscle of young mice, as reported in Fig. 4a, d. Representative images of GFP⁺ satellite cells co-expressing Pax7 and p16^INK4a or γH2AX in 4-day-injured muscles. Scale bar, 25 μm. Data are mean ± s.e.m. Two-sided Mann–Whitney U-test was used to assess statistical significance. P values are indicated. a, d, n = 5 biological replicates; b, n = 6 biological replicates. n.s., not significant.