Purified Native Collagen Extracellular Matrix Plus Polyhexamethylene Biguanide Functions as a Barrier to Protect Complex Wounds in an In Vivo Model

Complex surgical wounds often necessitate repeated irrigation and debridement (I&D), resulting in substantial burdens. Purified native collagen extracellular matrix plus polyhexamethylene biguanide (PCMP) is a protective antimicrobial barrier that supports innate wound healing and was hypothesized to protect an in vivo complex wound. Canines underwent bilateral fibular defects, which were stabilized using screws and plates pre-incubated with methicillin-resistant Staphylococcus aureus. Wounds were clinically infected seven days post-op and underwent I&D prior to application with either PCMP or non-adherent pads. Outcome assessments included radiography, wound scoring, microbial culture, histology, and gene expression. PCMP application resulted in significantly improved clinical wound healing scores at days 3 and 7, while histological analysis trended towards improved wound repair. Radiological assessments showed no loosening, confirming implant stability. Quantitative microbial assessments showed a minor reduction in bacterial load (0.5 log fold-change) on day 10. Gene expression analysis showed significant upregulation of matrix metalloproteinases and immune-modulating cytokines. Protection of the wound with PCMP resulted in improved wound scores, reduced bacterial load, and significant upregulation in key gene expression pathways compared to controls. Overall, this study suggests that PCMP effectively limited bioburden and biofilm reformation and supported wound progression in a challenging environment. These findings suggest PCMP could enhance complex wound patient outcomes.