Engineering chitosan fibers with MSC-exosome cargo: a clinically translatable multifunctional dressing for regenerative therapy in infected wound management

BACKGROUND: Chronic wound healing is a complex clinical challenge, particularly due to microbial colonization and the deactivation of repair cells. This study presents an innovative strategy involving the combination of micron-scale chitosan fibers with exosomes, aiming to develop a new type of dressing with multiple functionalities, including dynamic exudate management, antimicrobial properties, angiogenesis promotion, and tissue repair. The goal is to offer a cost-effective and clinically translatable treatment solution for infected wounds. METHODS: Chitosan (CS) fibers were prepared using a wet-spinning technique and subsequently modified through N-succinylation (NCS), followed by needle-punching to construct CS/NCS blended nonwoven fabrics. The physicochemical properties, water absorption/retention, and mechanical behavior of the materials were characterized using scanning electron microscopy (SEM), Fourier-transform infrared (FTIR) spectroscopy, and X-ray diffraction (XRD). Antibacterial and hemostatic performance were also evaluated. Mesenchymal stem cell-derived exosomes (MSC-EXO) were loaded onto the modified chitosan fibers via electrostatic assembly, forming the CS/NCS-EXO composite dressing, which was further tested in a rat model for infected wound repair. RESULTS: Compared to pure CS fibers and NCS fibers, the CS/NCS material demonstrated superior mechanical properties and moisture retention capacity in a wet state. Antibacterial assays showed that the CS/NCS material exhibited significantly enhanced antimicrobial activity against Staphylococcus aureus and Escherichia coli. Hemostatic experiments revealed that the CS/NCS group significantly shortened bleeding time and reduced blood loss. In the infected skin defect repair experiment, the CS/NCS-EXO group significantly accelerated wound healing, demonstrating the most prominent tissue repair effect, accompanied by abundant angiogenesis as confirmed by immunohistochemical staining. CONCLUSION: This study successfully developed a chitosan fiber-based exosome composite dressing system, which effectively coordinates infection control and tissue regeneration through a triple mechanism of "structural water-locking, mechanical adaptation, and bioactive synergy." This material provides a scalable solution for chronic wound management and shows promising clinical application prospects.