Fig. 3. Intramuscular treatment with rMETRNL improves aged muscle regeneration through transition of the inflammatory/anti-inflammatory immune profile.

a Graphical representation of rMetrnl treatment groups and timeline for experiments. b Example gating strategy used for macrophage identification and subtype analysis. The final dot plot (F4/80 vs Ly6C) represents the data shown in c–e. Representative flow cytometry results and bar graphs of cells isolated from tibialis anterior muscles c 1 day (n = 6 young, 10 old, 10 old +rMetrnl), d 3 days (n = 8 young, 6 old, 8 old + rMetrnl), and e 5 days (n = 5 animals/group) post injury; one-way ANOVA was used with Fisher’s LSD post hoc analysis. f Hematoxylin and Eosin-stained micrographs of tibialis anterior muscles 14 days follow BaCl₂-induced muscle damage and g quantified cross-sectional area (n = 6/group); one-way ANOVA was used with Fisher’s LSD post hoc analysis. h Representative force generation following tetanic stimulation of tibialis anterior muscles in situ. Summary data (n = 7 young, 6 old, 6 old+rMetrnl animals) for maximum force (i) and specific force (j); one-way ANOVA was used with Fisher’s LSD post hoc analysis. Source Data are provided as a source data file. All p values are indicated with line connecting comparison groups. Graphics created with BioRender.com. Data are presented as mean values ± SEM.