Gene therapy is a compelling strategy with a high potential for clinical success in wound repair applications. Gene manipulations are low cost with a proven capacity for sustained, spatiotemporally controlled release, and address key issues in existing chronic repair approaches by allowing modulation of progenitor cell healing potential as well as in situ production of nascent GF protein bearing authentic post-translational modifications. Substrate-based gene therapies offer additional compelling advantages. Like viral infection, in which various pathogens bind to extracellular matrix (ECM) and use it to facilitate cellular entry and enhance activity, gene delivery from synthetic and natural scaffolds has marked an important advance in gene delivery technologies by its capacity to increase the local concentration and stability of gene products while decreasing overall doses. Gene/gene activated matrix (GAM) strategies to deliver PDGF and other factors exhibit superior healing in experimental chronic wounds as compared with topical GFs. However, key concerns with construct escape/safety and limited gene transfer efficacy continue to inhibit translation of gene/GAM strategies. Improved control over the level, duration, and localization of GF release is necessary to advance chronic wound therapies.
To address these issues, we have designed an innovative strategy to improve control over the location and extent of gene delivery by harnessing collagen mimetic peptides (CMP)s to create DNA polyplex-modified collagens with tailorable release profiles and improved gene transfer. Through varying both CMP display and sequence, we have demonstrated an improved ability to control retention and delivery of DNA polyplexes from both 2-D and 3-D collagen structures. Variation of CMP display enabled tuning of polyplex retention vs. release over 2.5 weeks on collagen films and over a month on gels, whereas non-modified polyplexes were retained for only 2 days and 20 days, respectively. Bound polyplexes also demonstrated enhanced stability in the presence of serum-containing media for over a month, and CMP-mediated attachment altered intracellular trafficking to significantly improve gene delivery efficiency. MMP-stimulated cells exhibited significantly higher levels of transfection, suggesting that collagen remodelling plays a role in gene release and expression. This study is the first to utilize CMPs to deliver genes and to study the ability to “hijack” the natural process of collagen remodeling to achieve enhanced transfection efficiency.