MSCs + PE exert therapeutic effects on CIM muscle via immuno-activation. (a) Protocol for treatment of CIM mice using MSCs with or without PE supplementation. (b) Detection of the macrophage phenotype switch in CIM 1, 2, and 5 days after MSC treatment. (c-d) Percentage of CD11b + F4/80+ (total) macrophages (c), CD11b + F4/80+ Ly6Chi pro-inflammatory macrophages (d), and CD11b + F4/80+ Ly6Clow pro-fibrosis macrophages (d) (n = 4 per group). (e) Representative confocal images of F4/80- and p16INK4A-immunostained triceps surae in CIM 1, 2, and 3 days after injection of PKH-labelled MSCs. (f–j) Flow cytometry analysis of CD11b and Gr-1 (Neutrophil) (f), and CD11b and CD49 (NK cell) (i), and quantification following MSC treatment (g, h, and j). (k) Representative confocal images of CD49b- and p16INK4A-immunostained triceps surae in CIM 5 days after injection of PKH-labelled MSCs. Quantitative data are shown as means ± SEM (dot plot). P-values were determined by one-way ANOVA adjusted by Tukey's method. (*P < .05, **P < .001).