Crosslinked Native Collagen Matrices Containing Polyhexamethylene Biguanide (PHMB) Modulate Matrix Metalloproteinases, Function as Scaffold for Cell Growth, and Inhibit Bacterial Growth In Vitro and In Vivo

Introduction: Collagen-based wound matrices are widely used for treating acute and chronic wounds due to their role in wound management. The addition of an antimicrobial to these matrices can also prevent bacterial contamination of the material and act as an antimicrobial barrier to wounds. This study examined two novel matrices, PCMP* and PCMP-XT§, consisting of purified native cross-linked collagen with polyhexamethylene biguanide (PHMB), compared with an ovine forestomach matrix (OFM†). These matrices were evaluated for their ability to reduce MMP activity, resist enzymatic degradation, support cell attachment and growth, and provide antimicrobial effectiveness against methicillin-resistant Staphylococcus aureus (MRSA) in vitro and in vivo.Methods:Matrices were assessed for MMP modulation via fluorometric assays, and durability with an in vitro degradation model using simulated wound fluid containing collagenases type I and II. Scaffold functionality was evaluated using a primary human dermal fibroblast cell attachment and growth model. For antimicrobial testing, matrices soaked in phosphate-buffered saline for up to 10 days were placed on soy agar plates inoculated with MRSA (108 CFU/mL), and ZOI were measured after 24 hours using ImageJ. In vivo, deep dermal wounds (22mmX22mmX3mm) were created on pig backs, inoculated with MRSA (104 CFU/mL), and allowed to form biofilms for 72 hours before sharp debridement and matrix application. Protection of the wound bed was assessed by MRSA counts measured from wound biopsies on days 4, 8, and 11 post-treatment.Results:All matrices reduced MMPs, with PCMP and PCMP-XT overall more effective than OFM. PCMP-XT and PCMP resisted rapid degradation, retaining measurable weights after 7 days, while OFM degraded within 3 hours. Fibroblasts attached and proliferated significantly on both intact and degraded PCMP and PCMP-XT matrices by day 7 (p