Fig. 3: Treg-mediated tissue healing depends on Mo/MΦ.

Wildtype C57BL6/J mice were depleted of Mo/MΦ using clodronate liposomes (CL), compared to control liposomes (PBS liposomes, PL), and tissue healing was assessed for critical-size cranial defects, quadriceps volumetric muscle loss defect or full-thickness dorsal skin wounds in response to Treg delivery. a Schematic of the macrophage depletion experiment. b–c Cranial regeneration assessed by microCT. Defect coverage and new bone volume at D28 post-injury in (b) (n = 8 defects). Representative cranial reconstructions in (c). The original defect area is shaded with a dashed red outline. d–e Muscle regeneration evaluated by histomorphometric analysis of tissue sections. Fibrotic area and muscle area at D10 post-injury in (d) (n = 8 defects). Representative histology of a transverse section of the rectus femoris stained with Masson’s trichrome at D10 post-injury in (e). Muscle tissue is stained in red, and the fibrotic area is in blue. Scale bar = 1 mm. f–g Skin wound closure measured by histomorphometric analysis of tissue sections. Wound closure at D10 post-injury in (f) (n = 8 wounds). Representative histology of haematoxylin and eosin staining at D10 post-injury in (g). Black arrows indicate wound edges and red arrows indicate tips of epithelium tongue. Scale bar = 1 mm. Data are plotted in box plots showing the median (central line) and IQR (bounds) with whiskers extending to the minimum and maximum values. One-way ANOVA with Bonferroni post hoc test was used in (b, d, f) for multiple comparisons; n.s.: non-significant. (PL: PBS/control liposomes, CL: clodronate liposomes, Mo/MΦ: monocytes/macrophages). a Created with BioRender.com released under a Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International license (https://creativecommons.org/licenses/by-nc-nd/4.0/deed.en).