Human umbilical cord mesenchymal stem cell‐derived exosomes combined with gelatin methacryloyl hydrogel to promote fractional laser injury wound healing

To investigate whether human umbilical cord mesenchymal stem cell‐derived exosomes combined with gelatin methacryloyl (GelMA) hydrogel are beneficial in promoting healing of laser‐injured skin wounds in mice. Supernatants of cultured human umbilical cord mesenchymal stem cells (HUC‐MSCs) were collected to obtain human umbilical cord MSC‐derived exosomes (HUC‐MSCs‐Exos), which were combined with GelMA hydrogel complex to treat a mouse fractional laser injury model. The study was divided into PBS group, EX (HUC‐MSCs‐Exos) group, GEL (GelMA hydrogel) group and EX+GEL (HUC‐MSCs‐Exos combined with GelMA hydrogel) group. The healing of laser‐injured skin in each group was observed by gross view and dermatoscopy, and changes in skin structure, angiogenesis and proliferation‐related indexes were observed during the healing process of laser‐injured skin in each group. The results of the animal experiments showed that the EX and GEL groups alone and the EL+EX group exhibited less inflammatory response compared to the PBS group. The EX and GEL groups showed marked tissue proliferation and favourable angiogenesis, which promoted the wound healing well. The GEL+EX group had the most significant promotion of wound healing compared to the PBS group. qPCR results showed that the expression levels of proliferation‐related factors, including KI67 and VEGF and angiogenesis‐related factor CD31, were significantly higher in the GEL+EX group than in the other groups, with a time‐dependent effect. The combination of HUC‐MSCs‐Exos and GelMA hydrogel is beneficial in reducing the early inflammatory response of laser‐injured skin in mice and promoting its proliferation and angiogenesis, which in turn promotes wound healing.