Thermosensitive chitosan hydrogel encapsulating exosomes inhibits NLRP3 activation to promote diabetic foot ulcer healing

• First study using chitosan hydrogel encapsulating adipose-derived mesenchymal stem cell-derived exosomes for diabetic foot ulcer treatment. • Hydrogel-exosomes inhibit NLRP3 inflammasome activation. • Exosomes promote macrophage polarization toward the M2 phenotype to accelerate wound healing. • Hydrogel-exosomes enhance healing efficiency, offering a new strategy for chronic inflammation therapy. The study investigated the therapeutic potential of thermosensitive chitosan hydrogels encapsulating adipose-derived mesenchymal stem cell-derived exosomes (ADMSCs-Exos) for enhancing wound healing in diabetic foot ulcers (DFUs). Hydrogels prepared at varying concentrations were characterized for gelation behavior and structural properties, and Exos were isolated and validated through biomarker analysis. The encapsulated Exos significantly inhibited NLRP3 inflammasome formation and activation in vitro , reducing the expression of NLR family pyrin domain-containing 3 (NLRP3), caspase-1, and interleukin (IL)-1β. Exos also promoted macrophage polarization toward the M2 phenotype, thereby supporting tissue repair. In vivo , the Hydrogel-Exo treatment group demonstrated a 90% wound healing efficiency, demonstrating a statistically significant improvement compared with the control group in DFU models ( P < 0.0001). Mechanistic analysis revealed that Exos hindered the interaction between NLRP3, caspase-1, and apoptosis-associated speck-like protein containing a CARD (ASC), which was further confirmed by gene knockouts. This study innovatively combined a thermosensitive chitosan hydrogel with ADMSC-derived exosomes for the treatment of DFU, significantly accelerating wound healing by inhibiting the NLRP3 inflammasome pathway and promoting M2 macrophage polarization. These findings provide new experimental evidence and a potential therapeutic strategy for the clinical application of exosomes in chronic inflammatory diseases.