Human Mesenchymal Stem Cell-Derived Exosomes Promote the Proliferation and Melanogenesis of Primary Melanocytes by Attenuating the H 2 O 2 -Related Cytotoxicity in vitro.

BACKGROUND: Mesenchymal stem cell-derived exosomes (MSC-Exo) have therapeutic potential. However, the impact of MSC-Exo on the survival and melanogenesis of human primary melanocytes following H2 O2 -induced damage has not been clarified. We therefore investigated the effects of MSC-Exo on the H2 O2 -affected survival of human primary melanocytes and their proliferation, apoptosis, senescence, and melanogenesis in vitro.

METHODS: MSC-Exo were prepared from human MSCs by sequential centrifugations and characterized by Transmission Electron Microscopy, Western blot and Nanoparticle Tracking Analysis. Human primary melanocytes were isolated and treated with different concentrations of MSC-Exo, followed by exposing to H2 O2 . Furthermore, the impact of pretreatment with MSC-Exo on the proliferation, apoptosis, senescence and melanogenesis of melanocytes were tested by CCK-8, flow cytometry, Western blot, L-Dopa staining, tyrosinase activity and RT-qPCR.

RESULTS: Pretreatment with lower doses of MSC-Exo protected human primary melanocytes from the H2 O2 -triggered apoptosis, while pretreatment with higher doses of MSC-Exo enhanced the H2 O2 -induced melanocyte apoptosis. Compared with the untreated control, pretreatment with a lower dose (1 µg/mL) of MSC-Exo enhanced the proliferation of melanocytes, abrogated the H2 O2 -increased p53, p21, IL-1β, IL-6 and IL-8 expression and partially rescued the H2 O2 -decreased L-dopa staining reaction, tyrosinase activity, MITF and TRP1 expression in melanocytes.

CONCLUSION: Our findings indicate that treatment with a low dose of MSC-Exo promotes the proliferation and melanogenesis of human primary melanocytes by ameliorating the H2 O2 -induced apoptosis and senescence of melanocytes. MSC-Exo may be a promising therapeutic strategy of vitiligo.