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AB0093 Natural polymer-based hydrogels for cartilage regeneration

Background Cartilage is a tough, flexible tissue found throughout the body. It can become damaged because of a sudden injury, such as a sports injury, or gradual wear and tear (osteoarthritis). Injured articular cartilage has a poor regenerative capability, for this reason, tissue engineering may provide a fundamental therapeutic solution to repair cartilage injury. Human articular cartilages are composed of dense extracellular matrix and chondrocytes. One of the major components in the extracellular matrix is hyaluronic acid. The combination of hyaluronic acid with other natural polymers to prepare hydrogel scaffolds may be potentially useful in many tissue engineering applications, including cartilage regeneration. Objectives We propose the synthesis of hydrogels based on hyaluronic acid and chitosan by a new strategy of synthesis using di-isocyanates to obtain an interpenetrated network of chitosan and hyaluronic acid. Methods Different kinds of hydrogels were synthesised using hyaluronic acid (Bioibérica, Spain), natural polymers (gelatine, chitosan) and stabilised with diisocianates. The hydrogels were charged with chondroitin sulfate (Bioibérica, Spain). Morphological Characterisation The hydrogels were characterised by scanning electron microscopy and energy dispersive X-ray microscopy in order to study the morphology and the composition of the hydrogels. Hydrogel Swelling Dynamic swelling experiments were performed by placing discs of stabilised hydrogels in PBS at 37.0°C, and measuring their weight gain as a function of time. Biocompatibility Cytotoxicity in vitro assays (MTT) and cell adhesion tests (Alamar Blue) were performed on the hydrogels using different cell lines to corroborate the biocompatibility of the hydrogels. Results All the synthesised hydrogels presented a high interconnected porosity. The studied hydrogels swelled around 200%. After five hours equilibrium was reached and this equilibrium depended on the ratio hyaluronic acid/natural polymer increasing with the amount of hyaluronic acid present on the hydrogel. MTT assay indicated that the extracts collected at different times from the hydrogels were not cytotoxic and could be considered biocompatible. Cell adhesion assay demonstrated that the hydrogels supported cell adhesion and proliferation, and this behaviour was better on SC-loaded hydrogels. Conclusions Hydrogels based on hyaluronic acid and natural polymers are proposed as scaffolds for tissue engineering. The presence of interconnected porous and the good swelling properties, as well as the biocompatibility, represent a great advantage for application in cartilage regeneration. The addition of drugs or glycosaminoglycans is being studied to improve the cartilage regeneration. Disclosure of Interest None declared