Fig. 7

mini-MEndR assay captures response of treatment known to stimulate MuSC self-renewal. A Detailed experimental timeline of donor-derived MuSC niche repopulation. B Representative confocal images of Pax7⁺GFP⁺ donor derived MuSCs in mini-MEndR tissues treated with p38\(\alpha\)/\(\beta\) MAPKi at 7 DPI. Tissues are immunostained for Pax7 (grey), GFP (green), and DAPI (cyan). Magenta arrowheads point to the Pax7⁺ GFP⁺ donor MuSCs and yellow arrowheads point to the Pax7⁺ GFP⁻ reserve cells derived from the myotube template. Scale bar, 50 \(\upmu\)m. C-F Quantification of Pax7⁺ GFP⁺ cells derived from donor MuSCs (C-D) or Pax7⁺ GFP⁻ reserve cells derived from the myotube template (E–F) in mini-MEndR tissues generated with 18M (C, E) and 19F (D, F) cell lines, following treatment with DMSO or p38α/β MAPKi in the context of injury and analyzed at 7 DPI. Graphs display mean ± s.e.m.; Unpaired two-tailed T-test with Welch’s correction. * p < 0.5, *** p < 0.001, **** p < 0.0001. n = 6–9 tissues from N = 3 independent experiments per cell line