(39h) Chitosan / Cellulose Nanocrystals / Calcium Phosphate Hydrogels for Vertebral Compression Fracture Treatment

Vertebral compression fractures are the most common consequence of osteoporosis accounting for approximately 700,000 out of the 1.5 million total osteoporotic fractures that occur annually in the USA. Injection of poly(methyl methacrylate), a non-biodegradable and non-bioactive polymer, into the vertebral bode as a mechanically stiff bone cement is the most common treatment for vertebral compression fractures. Recently there has been a growing interest to use bioactive, degradable, and mechanically suitable substitutes for the treatment of these fractures. In this research, we focused on creating injectable, chitosan-based hydrogels for the treatment of vertebra compression fractures. First, we investigated the effect of different ratios of ionic and covalent crosslinking on hydrogel physical stability and mechanical properties. Then, cellulose nanocrystals with varying surface charge were utilized to modify the mechanical properties and physical stability of the chitosan matrix. Finally, different calcium phosphates with various solubility were incorporated into the matrix in order to achieve sustained release of calcium and phosphate ions for optimal bone inductivity outcomes without inducing unwanted cytotoxicity.