Progress toward finding the perfect match: hydrogels for treatment of central nervous system injury

Injury to the central nervous system remains a significant therapeutic challenge from a tissue engineering perspective because of the soft tissue properties, anatomical and spatial complexities, and highly divergent injury mechanisms that must be addressed. Emerging strategies to approach the difficulties of central nervous system regeneration include the use of hydrogel formulations as scaffolds for cellular and biomolecular delivery. Hydrogels have been used extensively in tissue engineering because they are adaptable to match a number of design considerations to recapitulate native tissues, including their mechanical and biochemical properties. Hydrogel scaffolds are specifically suited for achieving the soft tissue properties of the brain and spinal cord and have much demonstrated evidence for functionalization toward improved neural repair in the central nervous system. This review focuses on developments made in the last five years for advanced hydrogel strategies used in central nervous system repair and regeneration. Specific emphasis is placed on the exploitation of hydrogel properties for enhanced structural, biochemical, and cellular cues for both brain and spinal cord regeneration. Although translational challenges still remain, evidence demonstrates the forward progress in material design and use to validate hydrogels as tissue engineering surrogates for brain and spinal cord injuries. (C) 2019 The Authors. Published by Elsevier Ltd.