Macrophage Polarization-Based Biomaterials for Repairing Spinal Cord Injury

Spinal cord injury (SCI) remains a serious problem, owing to its severe consequences and therapeutic limitations. It leads to irreversible impairment of both motor and sensory functions, posing a challenge to recovery and imposing an immense socioeconomic burden on patients. Existing treatment strategies for SCI primarily focus on secondary injury, particularly the modulation of the immune microenvironment after SCI. Infiltrating macrophages play a crucial role in regulating inflammation around the injury site. Macrophages alter their functional phenotypes in response to various stimuli. Classically activated macrophages (M1) exacerbate SCI owing to their pro-inflammatory function, whereas alternatively activated macrophages (M2) inhibit the inflammatory response. Therefore, regulating macrophage polarization represents a promising therapeutic strategy for SCI. Several biomaterial-based strategies for repairing SCI have been developed and are constantly being updated with technological advancements owing to their ability to alleviate neuroinflammation and promote neuroregeneration. In this Review, we focus on the role of macrophages in SCI and discuss the recent research progress of biomaterials targeting macrophage-mediated inflammation for repair and regeneration following SCI. Altogether, this Review provides novel insights into the treatment of SCI.