A moisturizing chitosan-silk fibroin dressing with silver nanoparticles-adsorbed exosomes for repairing infected wounds

Refractory wounds caused by microbial infection impede wound healing, vascular regeneration, nerve system repairing and other skin appendages regeneration. In addition, large-area infected wounds cause the appearance of multidrug-resistant (MDR) bacterial strains, which poses a major challenge both in clinical and scientific research. Although many stem cell-derived exosomes were demonstrated to promote skin repair and regeneration, exosomes were seldom applied in the treatment of infective wounds due to the lack of antimicrobial function. In this study, we fabricated an asymmetric wettable dressing with a composite of exosomes and silver nanoparticles (CTS-SF/SA/Ag-Exo dressing) for promoting angiogenesis, nerve repair and infected wound healing. The CTS-SF/SA/Ag-Exo dressing possessed multifunctional properties including broad-spectrum antimicrobial activity, promoting wound healing, retaining moisture and maintaining electrolyte balance. It could effectively inhibit the growth of bacterial and promote the proliferation of human fibroblasts in vitro. Moreover, the in vivo results showed that the CTS-SF/SA/Ag-Exo dressing enhanced the wound healing by accelerating the collagen deposition, angiogenesis and nerve repair in a P. aeruginosa infected mouse skin wound defect model. We hope the dressing may provide a solution for the repair of infected wounds for the treatments in clinic.