Complex diseases including osteosarcoma (OS) and rheumatoid arthritis (RA) require careful disease management. There is a need to update therapeutic treatments for these diseases, accommodating a more targeted and structurally supportive therapy. The risk of off-target toxicity could be reduced through the use of a hydrogel to deliver and anchor a selective peptide-conjugated prodrug (PCP), cleavable by an overexpressed protease at the disease site.
This study investigates the development of novel Hydrogel-PCP systems, aiming to selectively release naproxen (NAP) from the PCP component, through selective cleavage by matrix metalloproteinase 14 (MMP14), a proteolytic enzyme overexpressed within osteosarcoma and rheumatoid arthritis. Collagen-based hydrogels were initially functionalised with the photo-active monomer 4-vinylbenzyl chloride, prior to drug conjugation and photo-crosslinking under UV light. In light of no network formation by various photo-crosslinking methods a change in the crosslinking strategy was made. Chemical crosslinking using (4-(4,6-dimethoxy-1,3,5-triazin-2-yl)-4-methyl-morpholinium chloride) (DMTMM), successfully formed a gelatin based hydrogel-NAPPCP system (gel-NAPPCP). The release of NAP from gel-NAPPCP was analysed using LCMS after a 72-hour MMP14 recombinant enzyme assay was carried out. Cleavage by MMP14 at the Hof-Gly peptide bond in NAPPCP, a recognised cleavage site, did not occur, however the release of a NAP metabolite was detected at increased concentrations in more acidic conditions, providing an alternative for future drug release.
The DMTMM-induced crosslinking reaction takes place under physiological temperatures, allowing the exploration of an injectable in situ network forming gel-NAPPCP system, which was explored in synthetic bone cavities. Initial investigations demonstrate successful gel-NAPPCP hydrogel formation in these cavities, a promising step towards a more clinically desirable device compared to surgical implantation.
To conclude, this study provides a proof of concept for future investigations to improve MMP14 selective cleavage of NAPPCP in a hydrogel system to selectively target osteosarcoma and rheumatoid arthritis, using a clinically relevant delivery strategy.
