A CMP-based method for tunable, cell-mediated gene delivery from collagen scaffolds

Abstract

The use of collagen-based biomaterials in regenerative medicine has rapidly increased over the past decade. The unique structural and biochemical properties of collagen make it a particularly promising material for delivering both protein and DNA-based therapeutics. Although many collagen modification techniques have been developed, the majority of them require multi-step chemical treatments that can modify the natural favourable properties of collagen. We have developed a promising biomimetic modification technique employing collagen-mimetic peptides (CMP)s to control the retention and delivery of DNA polyplexes from collagen structures, including both monomeric 2-D collagen films and fibrous, 3-D gels. Variations in the concentration of CMPs displayed on polyplexes enabled tuning of polyplex retention vs. release over periods of at least 2 weeks on films and a month on gels. Retention of CMP-modified polyplexes (20 days) was substantially improved compared to non-modified polyplexes, which were retained for only 2 days. The activity of bound polyplex in collagen gels was shown, through a series of transfection studies, to be maintained in the presence of serum for a minimum of 2 weeks. Only matrix metalloproteinase (MMP)-stimulated cells exhibited significant levels of transfection suggesting that cell mobility within the gel was vital and that collagen remodelling played a role in stimulating gene release and expression. To our knowledge, this study is the first to deliver genes with CMP-modified polyplexes and to examine the effects of CMP display on DNA release. The results suggest that this technique may be used more broadly to create tuneable, collagen-based delivery systems.