Study of loading and delivery of drugs from various hydrogel matrices for orthopaedic applications

Nowadays, there are still several unmet medical needs in the field of orthopaedic and trauma surgery leading to the incentive of finding alternative and innovative clinical therapeutics for the treatment of bone regeneration. For example, the entrapment of osteoinductive growth factors in a polymeric matrix with subsequent gradual release and local delivery to the site of trauma. This new technology inspired the activities relating to my project in which I investigated the potential use of synthetic hydrogels for the sustained in situ release of bioactives. The tasks relating to my project were divided into two main experiments; release assays and bioactivity assays. During the release assays, the in vitro release of three osteoinductive growth factors from five different synthetic hydrogels was investigated. The goal was to characterise the release of the protein drugs from the different polymers, selected on the basis of their swelling and degradation behaviour. The quantification of the released bioactives was assessed by performing an enzyme-linked immunosorbent assay (ELISA), for which different parameters were optimised. As a result, release profiles of the different protein drugs from the different hydrogel formulations were obtained. Then, it was investigated if the growth factors were still biologically active or if incubation in synthetic matrices influenced their properties. This was assessed by performing bioassays during which the alkaline phosphatase (ALP) activity of a mouse myoblast cell line (C2C12 cells) was evaluated. Indeed, ALP is a marker of osteoblastic activity which indicates increased levels of osteogenesis, implying biological activity of the tested osteoinductive bioactives. These results gave a good representation of the effect of the synthetic hydrogels and their incubation in release buffer on the bioactivity of the incorporated protein drugs