A hydroxamic acid-methacrylated collagen conjugate for the modulation of inflammation-related MMP upregulation.

Medical devices with matrix metalloproteinase (MMP) modulating functionality are highly desirable to restore tissue homeostasis in critical inflammation states, such as chronic wounds, rotator cuff tears and cancer. The introduction of MMP-modulating functionality in such devices is typically achieved via loading of either rapidly-diffusing chelating factors, e.g. EDTA, or MMP-cleavable substrates, raising issues in terms of non-controllable pharmacokinetics and enzymatic degradability, respectively. Aiming to accomplish inherent, long-term, device-induced MMP regulation, this study investigated the synthesis of a hydroxamic acid (HA)-methacrylated collagen conjugate as the building block of a soluble factor-free MMP-modulating hydrogel network with controlled enzymatic degradability. This was realised via a two-step synthetic route: (i) type I collagen was functionalised with photonetwork-inducing methacrylic anhydride (MA) adducts; (ii) this methacrylated product was activated with a water-soluble carbodiimide prior to reaction with hydroxylamine, resulting in MMP-chelating HA functions. Nearly-quantitative methacrylation of collagen amines was observed via 2,4,6-trinitrobenzenesulfonic acid (TNBS) assay. The molar content of HA adducts was indirectly quantified via conversion of remaining carboxyl functions into ethylenediamine (EDA), so that 12-16 mol.% HA was revealed in the conjugate. Resulting UV cured, HA-bearing collagen hydrogels proved to induce up to ~13 and ~32 RFU% activity reduction of MMP-9 and MMP-3, respectively, following 4-day incubation in vitro. No hydrogel-induced toxic response was observed following 4-day culture of G292 cells. The novel synthetic strategies described in this work provide a new insight into the systematic chemical manipulation of collagen materials aiming at the design of biomimetic, inflammation-responsive medical devices.