Protective effect of HUCMSCs-Exo on IFN-γ-mediated melanocyte injury

Objective To explore the protective effect of exosomes derived from human umbilical cord mesenchymal stem cells (HUCMSCs-Exo) against interferon-gamma (IFN-γ)-mediated melanocyte injury.Methods Human epidermal melanocytes were cultured in vitro. Melanocytes were treated with different concentrations of IFN-γ (100, 200, 400, 800 ng/mL) for 48 hours, and cell survival rate was detected by CCK-8 assay to screen an appropriate IFN-γconcentration for establishing an immunosuppressive model. Melanocytes were treated with different concentrations of HUCMSCs-Exo for 48 hours, and cell proliferation activity was detected by CCK-8 assay to determine the safe concentration of exosomes for subsequent experiments. Melanocytes were pretreated with exosomes at a safe concentration and then incubated with or without 100 ng/mL IFN-γ for 48 hours. Cell proliferation activity was assessed using the CCK-8 assay; mitochondrial membrane potential was detected by JC-1 staining; apoptosis was evaluated by flow cytometry; and tyrosinase activity was measured by the dopamine oxidation method.Results With the increase in IFN-γ concentration, cell survival rate gradually decreased. The cell survival rates in the 100, 200, 400, and 800 ng/mL IFN-γ groups were significantly different from those in the control group (P ＜ 0.05). 100 ng/mL IFN-γ was selected to establish an epidermal melanocyte immunosuppressive model. Melanocytes treated with 10 and 20 μg/mL exosomes for 48 hours showed significant differences compared with the control group (P ＜ 0.05), and 10 μg/mL exosomes were selected for subsequent experiments. Compared with the IFN-γ group, exosomes significantly increased cell proliferation activity.Conclusions HUCMSCs-Exo has a protective effect against IFN-γ-mediated immunosuppressive injury in melanocytes.