Enhanced Wound Healing via Collagen-Turnover-Driven Transfer of PDGF-BB Gene in a Murine Wound Model

Wound healing is a complex biological process that requires coordinated cell proliferation, migration, and extracellular matrix production/remodeling, all of which are inhibited/delayed in chronic wounds. In this study, a formulation was developed that marries a fibrin-based, provisional-like matrix with collagen-mimetic peptide (CMP)/platelet-derived growth factor (PDGF) gene-modified collagens, leading to the formation of robust gels that supported temporally controlled PDGF expression and facile application within the wound bed. Analysis employing in vitro co-gel scaffolds confirmed sustained and temporally controlled gene release based on matrix metalloproteinase (MMP) activity, with an ∼30% higher PDGF expression in MMP-producing fibroblasts as compared with that in non-MMP-expressing cells. The integration of fibrin with the gene-modified collagens resulted in co-gels that strongly supported both fibroblast cell recruitment/invasion and multiple aspects of the longer-term healing process. The excisional wound-healing studies in mice established faster wound closure using CMP-modified PDGF polyplex-loaded co-gels, which exhibited up to 24% more wound closure (achieved with ∼2 orders of magnitude lower growth factor dosing) after 9 days as compared to PDGF-loaded co-gels and 19% more wound closure after 9 days as compared to CMP-free polyplex-loaded co-gels. Moreover, minimal scar formation, as well as improved collagen production, myofibroblast activity, and collagen orientation, will be observed following CMP-modified PDGF polyplex-loaded co-gel application on wounds. Taken together, the combined properties of the co-gels, including their stability and capacity to control both cell recruitment and cell phenotype within the murine wound bed, strongly support the potential of the co-gel scaffolds for the improved treatment of chronic nonhealing wounds.