Fig. 6: Clearance of senescent cells in DM1 improves myogenesis in vitro and in vivo.

a Representative micrographs of DM1 myoblasts immunolabeled with KI67 (red) after 72 h of treatment with vehicle (Veh) or A1155463 (Sen). Scale bars: 300 μm. b Quantification of the proportion of KI67+ cells treated with A1155463 (Sen) relative to vehicle (n = 4 Ctrl and 7 DM1 cell lines; average of 1064 cells [142-2873 cells] counted per sample). *p = 0.017 (one-way ANOVA with multiple comparisons). c Cell proliferation of healthy myoblasts cultured with conditioned media (CM) from DM1-untreated or DM1-senolytic-treated myoblasts for 5 days; (n = 3 biological samples). *p = 0.033 (Two-tailed unpaired T-test). d Representative micrographs of DM1 myoblasts differentiated for 5 days after treatment with vehicle (Veh) or A1155463 (Sen) and immunolabeled with MYOG (green). Scale bars: 300 μm. e Quantification of the number of MYOG+ cells treated with A1155463 (Sen) relative to vehicle (n = 4 Ctrl and 5 DM1 cell lines, average number of 1388 cells [104-4218 cells] counted per sample) *p = 0.0134 (one-way ANOVA with multiple comparisons). f Representative Western blots showing the expression of MYOG in control and DM1 myoblasts differentiated for 5 days after treatment with vehicle (Veh) or A1155463 (Sen). g Quantification of MYOG expression by Western blot (relative to β-actin as loading control). Data are expressed as fold change relative to non-treated (Veh) cells (n = 3 Ctrl and 7 DM1 cell lines). *p = 0.039 (two-way ANOVA with Sidak’s multiple comparisons test). h Schematic representation of DM1 myoblast transplantation experiment. Created with BioRender.com. i Representative micrographs of muscle sections of TA muscles (21 days post-cardiotoxin injection) of NSG mice transplanted with DM1 myoblasts treated with vehicle (upper images) or A1155463 (bottom images). Sections were immunostained with human dystrophin (hDMD; green), total dystrophin (tDMD, magenta), and DAPI (nuclei, blue). White arrows indicate myofibers expressing hDMD and tDMD. Scale bars: 50 μm. j Quantification of the number of myofibers expressing hDMD in transplanted cells treated with A1155463 (Sen) relative to vehicle (n = 3 different DM1 cell lines transplanted in three different mice per cell line; average number of 3388 myofibers [2100–5140 myofibers] counted per biological sample. *p = 0.014 (Two-tailed unpaired t-test with Welch’s correction). Data are expressed as means ± SEM. Source data are provided as a Source Data file.