Fig. 2: Replacement of circulating Metrnl improves aged muscle regeneration following BaCl₂ injection.

a Graphical representation of Heterochronic parabiosis groups (n = 6/old WT parabionts tested per group). b Metrnl mRNA content measured by qPCR from uninjured and 24-hours post-injury TA muscles of old wild-type parabiont (n = 5 animals/group); 2 × 3 ANOVA was used with Fisher’s LSD post hoc analysis only to compare differences between injured groups. c Cross-sectional area quantified from micrographs (n = 6 animals/group); 2 × 3 ANOVA was used with Fisher’s LSD post hoc analysis only to compare differences between injured groups. d Representative Hematoxylin and Eosin-stained micrographs from c—14 days following BaCl2-induced muscle damage in the old wild-type parabionts. e Graphical representation of Bone marrow chimera experiment. f Metrnl mRNA content measured by qPCR from uninjured and 24-hours post-injury TA muscles of Old chimera (n = 5 animals/group); 2 × 3 ANOVA was used with Fisher’s LSD post hoc analysis only to compare differences between injured groups. g Cross-sectional area quantified from micrographs (n = 6 animals/group); 2 × 3 ANOVA was used with Fisher’s LSD post hoc analysis only to compare differences between injured groups. h Representative Hematoxylin and Eosin-stained micrographs of g 14 days following BaCl2-induced muscle damage in the Old chimera. Source Data are provided as a source data file. Graphics created with BioRender.com. All p values are indicated with lines connecting comparison groups. Data are presented as mean values ± SEM.