Induced pluripotent stem cells-derived microvesicles accelerate deep second-degree burn wound healing in mice through miR-16-5p-mediated promotion of keratinocytes migration.

Background: Induced pluripotent stem cells (iPSCs) have emerged as a promising treatment paradigm for skin wounds. Extracellular vesicles are now recognized as key mediators of beneficial stem cells paracrine effects. In this study, we investigated the effect of iPSCs-derived microvesicles (iPSCs-MVs) on deep second-degree burn wound healing and explored the underlying mechanism. Methods: iPSCs-MVs were isolated and purified from conditioned medium of iPSCs and confirmed by electron micrograph and size distribution. In deep second-degree burn model, iPSCs-MVs were injected subcutaneously around wound sites and the efficacy was assessed by measuring wound closure areas, histological examination and immunohistochemistry staining. In vitro, CCK-8, EdU staining and scratch assays were used to assess the effects of iPSCs-MVs on proliferation and migration of keratinocytes. Next, we explored the underlying mechanisms by high-throughput microRNA sequencing. The roles of the miR-16-5p in regulation of keratinocytes function induced by iPSCs-MVs were assessed. Moreover, the target gene which mediated the biological effects of miR-16-5p in keratinocytes was also been detected. Finally, we examined the effect of local miR-16-5p treatment on deep second degree-burns wound healing in mice. Results: The local transplantation of iPSCs-MVs into the burn wound bed resulted in accelerated wound closure including the increased re-epithelialization. In vitro, iPSCs-MVs could promote the migration of keratinocytes. We also found that miR-16-5p is a critical factor in iPSCs-MVs-induced promotion of keratinocytes migration in vitro through activating p38/MARK pathway by targeting Desmoglein 3 (Dsg3). Finally, we confirmed that local miR-16-5p treatment could boost re-epithelialization during burn wound healing. Conclusion: Therefore, our results indicate that iPSCs-MVs-derived miR-16-5p may be a novel therapeutic approach for deep second-degree burn wound healing.