3D‐hUMSCs Exosomes Ameliorate Vitiligo by Simultaneously Potentiating Treg Cells‐Mediated Immunosuppression and Suppressing Oxidative Stress‐Induced Melanocyte Damage

Abstract Vitiligo is an autoimmune disease characterized by epidermal melanocyte destruction, with abnormal autoimmune responses and excessive oxidative stress as two cardinal mechanisms. Human umbilical mesenchymal stem cells‐derived exosomes (hUMSCs‐Exos) are regarded as promising therapeutic choice for autoimmune diseases due to potent immunosuppressive and anti‐oxidative properties, which can be potentiated under 3D cell culture condition. Nevertheless, whether exosomes derived from 3D spheroids of hUMSCs (3D‐Exos) exhibit considerable therapeutic effect on vitiligo and the underlying mechanism remain elusive. In this study, systemic administration of 3D‐Exos showed a remarkable effect in treating mice with vitiligo, as revealed by ameliorated skin depigmentation, less CD8 + T cells infiltration, and expanded Treg cells in skin, and 3D‐Exos exerted a better effect than 2D‐Exos. Mechanistically, 3D‐Exos can prominently facilitate the expansion of Treg cells in vitiligo lesion and suppress H 2 O 2 ‐induced melanocytes apoptosis. Forward miRNA profile analysis and molecular experiments have demonstrated that miR‐132‐3p and miR‐125b‐5p enriched in 3D‐Exos greatly contributed to these biological effects by targeting Sirt1 and Bak1 respectively. In aggregate, 3D‐Exos can efficiently ameliorate vitiligo by simultaneously potentiating Treg cells‐mediated immunosuppression and suppressing oxidative stress‐induced melanocyte damage via the delivery of miR‐132‐3p and miR‐125b‐5p. The employment of 3D‐Exos will be a promising treament for vitiligo.