Review: Biomaterial systems to resolve brain inflammation after traumatic injury.

The inflammatory response within the central nervous system (CNS) is a tightly regulated cascade of events which is a balance of both cytotoxic and cytotrophic effects which determine the outcome of an injury. The two effects are inextricably linked, particularly in traumatic brain injury or stroke, where permanent dysfunction is often observed. Chronic brain inflammation is a key barrier to regeneration. This is considered a toxic, growth inhibitory mechanism; yet, the inflammatory response must also be considered as a mechanism that can be exploited as protective and reparative. Repurposing this complex response is the challenge for tissue engineers: to design treatments to repair and regenerate damaged tissue after brain insult. Astrocytes are important cells within the CNS which play a key role after traumatic brain injury. A comprehensive understanding of their functions-both cytotrophic and cytotoxic-will enable designed materials and drug delivery approaches for improved treatment options post traumatic injury. Understanding, evaluating, and designing biomaterials that match the healthy neural environment to temporally alter the inflammatory cascade represent a promise neural tissue engineering strategy to optimise repair and regeneration after injury.