Fig. 5

M2 polarization induced by strain alteration is crucial for regeneration. a, b Representative FACS histograms (a) and quantification (b) of the percentages of CD45⁺F4/80⁺CD206⁺CD86^- M2 macrophages activated in response to stretch (day 1 and day 7) and release of stretch (day 9 and day 14); n = 6 for each group. c–e Real-time PCR for Arginase-1 (Arg1) (c), Ym1 (d), and Il4 (e) in response to stretch (day 1 and day 7) and release of stretch (day 9 and day 14); n = 6 for each group. f Quantification using flow cytometry of M2 macrophages in response to 20 or 33% strain; n = 3 for each group. g Dual immunostaining of F4/80 and Arginase indicated that double positive M2 macrophages were more conspicuous at day 14. h Schematic of subcutaneous injection with mannosylated clodronate liposomes (M-Clodronate) to deplete M2 macrophages. i Stretch-induced hair regeneration was perturbed by mannosylated clodronate liposomes (M-Clo) injection; n = 6 for each group. j Transplantation of unpolarized and polarized M1 or M2 macrophages into the back skin of mice during the telogen phase. Note only M2 macrophages caused hair regeneration, and the intensity of hair growth was proportional to the number of transplanted cells. The red circle at day 0 indicates the injection area; n = 6 for each group. Statistical significance was determined by conducting ANOVA followed by a Bonferroni post hoc test (b–e) or Student’s two-tailed t-test (f). Data are presented as means ± SEM. *p < 0.05. **p < 0.01. ***p < 0.001. Scale bar = 50 μm. Source data are provided as a Source Data file