Mechanical properties of the spinal cord and brain: Comparison with clinical-grade biomaterials for tissue engineering and regenerative medicine

Disorders affecting the central nervous system are a leading cause of disability in the world. Regenerative medicine using biomaterial-based therapies is a growing field that has potential application in the areas of spinal cord injury, neurodegenerative disorders and stroke. The mechanical properties of biomaterials implanted into the central nervous system are critical for effective integration with host tissue, but the biomechanical properties of the host tissue remain poorly characterised and assessing the stiffness of both soft biomaterials and central nervous system tissue remains challenging. Here, we describe a bespoke mechanical characterisation method that facilitates robust measurement of fresh spinal cord and brain tissue and allows direct like-for-like mechanical benchmarking for matching clinical-grade hydrogels suitable for regenerative medicine. We report differences in the mechanical properties of spinal cord tissue dependent on anatomical origin, regional variations in brain tissue stiffness, and quantify the extent of mechanical anisotropy within the cervical spinal cord. We then demonstrate that the mechanical properties of clinical-grade collagen, fibrin and alginate hydrogels can be tuned to closely mimic the mechanical properties of different regions within the central nervous system.