Fig. 3

Effects of melatonin on transplanted cells in the HFD-induced obese mouse model. Obese mouse model was prepared by feeding high-fat-diet (HFD) for 14 weeks. a, b Weight and the level of total cholesterol in serum of HFD-induced obese mice were compared with normal diet (ND) feeding mice (n = 7, *p < 0.05 vs ND). Mice were divided into the 8 groups and skin wound healing model was conducted. After making wounds on the skin of the back, UCB-MSCs with or without DIDS pretreatment were inoculated near the wound site and melatonin (30 mg/kg/day) was injected to the mice of melatonin treatment group. c, d Wound size and vasculogenesis around the wound site were observed (n = 7, *p < 0.05 vs ND + vehicle, ^#p < 0.05 vs HFD + UCB-MSC, ^$p < 0.05 vs HFD + UCB-MSC + melatonin). e Immunohistochemistry (IHC) was conducted with an antibody for human nuclear antigen (HNA, green) and DAPI (blue) staining and visualized by fluorescence microscopy. Scale bars were set as 100 μm (magnification × 100). The percentage of HNA-positive cells in total cells were analyzed with Fiji software (n = 5, *p < 0.05 vs ND + UCB-MSC, #p < 0.05 vs HFD + UCB-MSC, ^$p < 0.05 vs HFD + UCB-MSC + melatonin, N.D. indicates not detected). f H&E staining was conducted on tissues of wound site and compared. Scale bars are 200 μm (magnification × 50). D dermis, E epidermis, G granulation tissue. g Masson’s trichrome staining was conducted on skin wound tissues. Scale bars are 100 μm (magnification × 100) h IHC was conducted with an antibody for alpha-smooth muscle antigen (α-SMA, green) and DAPI (blue) staining. Scale bars were set as 200 μm (magnification × 50), (n = 5, *p < 0.05 vs ND + UCB-MSC, ^#p < 0.05 vs HFD + UCB-MSC, ^$p < 0.05 vs HFD + UCB-MSC + melatonin). All images are representative and quantitative data are presented as a mean ± standard error of the mean