Biomaterial and Therapeutic Approaches for the Manipulation of Macrophage Phenotype in Peripheral and Central Nerve Repair

Injury to the peripheral or central nervous systems often results in extensive loss of motor and sensory function that can greatly diminish quality of life. In both cases, macrophage infiltration into the injury site plays an integral role in the host tissue inflammatory response. In particular, the temporally related transition of macrophage phenotype between the M1/M2 inflammatory/repair states is critical for successful tissue repair. In recent years, biomaterial implants have emerged as a novel approach to bridge lesion sites and provide a growth-inductive environment for regenerating axons. This has more recently seen these two areas of research increasingly intersecting in the creation of 'immune-modulatory' biomaterials. These synthetic or naturally derived materials are fabricated to drive macrophages towards a pro-repair phenotype. This review considers the macrophage-mediated inflammatory events that occur following nervous tissue injury and outlines the latest developments in biomaterial-based strategies to influence macrophage phenotype and enhance repair.

Automated summary

Injuries to the nervous system often lead to loss of motor and sensory function, with macrophage infiltration playing a crucial role in the inflammatory response and tissue repair. Recent developments have focused on using biomaterial implants to create a growth-inductive environment for axon regeneration and modulate macrophage phenotype towards a pro-repair state. The intersection of these two areas of research has resulted in the creation of 'immune-modulatory' biomaterials aimed at enhancing tissue repair following nervous tissue injury.