Fig. 3: MSCs-IT ameliorate SSc by acting on macrophages.

A, B Mice were i.c. injected with BLM or PBS daily for 4 weeks to induce SSc and then euthanized and examined on day 30. A The infiltration of macrophages in the skin was assessed by immunofluorescence staining of CD64 (green). Scale bars, 100 μm. B The colocalization of CD64 (red) and TGF-β1 (green) in the skin of SSc mice was determined by immunofluorescence staining. Scale bars, 100 μm. C Experimental design of the BLM-induced SSc mouse model, Clodronate liposome (Clo)/Control liposome (Ctrl) treatment, and MSC-IT treatment. Mice were euthanized and examined on day 30. n = 4–5 mice for each group. D 100 μL Clo liposomes (5 mg/mL) or 100 μL of Ctrl liposomes was administered to normal mice, and the depletion efficiency of Clo liposome treatment on macrophages (CD11b⁺CD64⁺) in the skin was analyzed by flow cytometry on day 3. n = 3 mice for each group. E H&E staining of the skin sections. The distance between the two yellow lines was assessed. Scale bars, 200 μm. F Sirius Red staining of the skin sections. The distance between two black dotted lines was assessed. Scale bars, 200 μm. G Immunofluorescence staining of α-SMA (red) in the skin sections. The percentage of α-SMA⁺ area was assessed. Scale bars, 200 μm. Data were shown as means ± SEM. Data are representative of two or three experiments with similar results. *P < 0.05; **P < 0.01; ***P < 0.001; ns not significant.