RGD Peptide-Functionalized CMC Hydrogel Enhances Skin Wound Repair in Mice

Disruption of the wound microenvironment by bacterial infection and excessive inflammation severely delays tissue repair, making multifunctional hydrogels that combine infection control and immune regulation highly desirable. Building on our previously reported carboxymethyl chitosan (CMC) hydrogel incorporating hyaluronic acid (HA) and RGD peptide (RGD), this study extended its evaluation to antibacterial activity, hemostatic behavior, and in vivo wound repair. Four formulations-CMC, CMC-HA, CMC-RGD, and CMC-HA-RGD-contained 1 wt% CMC with 0.9 wt% HA and/or 0.02 mg/mL RGD. Antibacterial activity against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) was assessed by agar diffusion, while hemostatic behavior and wound repair were evaluated using mouse tail-transection and aseptically established full-thickness skin-wound models. Histology, immunohistochemistry, and serum enzyme-linked immunosorbent assays were used to assess tissue repair and inflammatory markers. CMC-HA-RGD produced inhibition-zone areas of 2.0 cm² against E. coli and 6.0 cm² against S. aureus. The RGD-containing formulations showed reductions in visible bleeding. Wound closure with CMC-HA-RGD reached 41.39%, 71.18%, and 95.56% on days 3, 7, and 14, respectively, compared with 16.47%, 58.18%, and 79.85% for CMC. Histology showed more complete epidermal-dermal architecture and denser collagen deposition. On day 14, relative to CMC, CMC-HA-RGD showed 35.37% and 37.74% lower interleukin-1β (IL-1β)- and tumor necrosis factor-α (TNF-α)-positive areas, respectively, while the collagen I-positive area increased from 63.36% to 72.58%. Serum interferon-γ (IFN-γ), IL-1β, and TNF-α concentrations were 9.08%, 18.01%, and 11.85% lower than those in the CMC group. Collectively, incorporating HA and RGD improved the antibacterial and hemostatic performance of the CMC hydrogel, attenuated local and systemic inflammatory responses, and promoted tissue remodeling, supporting its potential as a multifunctional wound dressing.