Synthesis of two-component injectable polyurethanes for bone tissue engineering

The advent of injectable polymer technologies has increased the prospect of developing novel, minimally invasive arthroscopic techniques to treat a wide variety of ailments. In this study, we have synthesised and evaluated a novel polyurethane-based injectable, in situ curable, polymer platform to determine its potential uses as a tissue engineered implant. Films of the polymers were prepared by reacting two pentaerythritol-based prepolymers, and characterised for mechanical and surface properties, and cytocompatibility. This polymer platform displayed mechanical strength and elasticity superior to many injectable bone cements and grafts. Cytotoxicity tests using primary human osteoblasts, revealed positive cell viability and increased proliferation over a period of 7 days in culture. This favourable cell environment was attributed to the hydrophilic nature of the films, as assessed by dynamic contact angle (DCA) analysis of the sample surfaces. The incorporation of beta-TCP was shown to improve mechanical properties, surface wettability, and cell viability and proliferation, compared to the other sample types. SEM/EDX analysis of these surfaces also revealed physicochemical surface heterogeneity in the presence of beta-TCP. Based on preliminary mechanical analysis and cytotoxicity results, these injectable polymers may have a number or potential orthopaedic applications; ranging from bone glues to scaffolds for bone regeneration.