Engineering Bioactive Self-Healing Antibacterial Exosomes Hydrogel for Promoting Chronic Diabetic Wound Healing and Complete Skin Regeneration

<b>Rationale:</b> Chronic nonhealing diabetic wound therapy and complete skin regeneration remains a critical clinical challenge. The controlled release of bioactive factors from a multifunctional hydrogel was a promising strategy to repair chronic wounds. <b>Methods:</b> Herein, for the first time, we developed an injectable, self-healing and antibacterial polypeptide-based FHE hydrogel (F127/OHA-EPL) with stimuli-responsive adipose-derived mesenchymal stem cells exosomes (AMSCs-exo) release for synergistically enhancing chronic wound healing and complete skin regeneration. The materials characterization, antibacterial activity, stimulated cellular behavior and <i>in vivo</i> full-thickness diabetic wound healing ability of the hydrogels were performed and analyzed. <b>Results:</b> The FHE hydrogel possessed multifunctional properties including fast self-healing process, shear-thinning injectable ability, efficient antibacterial activity, and long term pH-responsive bioactive exosomes release behavior. <i>In vitro</i>, the FHE@exosomes (FHE@exo) hydrogel significantly promoted the proliferation, migration and tube formation ability of human umbilical vein endothelial cells (HUVECs). <i>In vivo</i>, the FHE@exo hydrogel significantly enhanced the healing efficiency of diabetic full-thickness cutaneous wounds, characterized with enhanced wound closure rates, fast angiogenesis, re-epithelization and collagen deposition within the wound site. Moreover, the FHE@exo hydrogel displayed better healing outcomes than those of exosomes or FHE hydrogel alone, suggesting that the sustained release of exosomes and FHE hydrogel can synergistically facilitate diabetic wound healing. Skin appendages and less scar tissue also appeared in FHE@exo hydrogel treated wounds, indicating its potent ability to achieve complete skin regeneration. <b>Conclusion:</b> This work offers a new approach for repairing chronic wounds completely through a multifunctional hydrogel with controlled exosomes release.