Neutrophil-mimetic M₂ macrophage extracellular vesicle for targeted spinal cord injury therapy

Spinal cord injury (SCI) results in severe neurological dysfunction primarily due to secondary inflammation and neuronal apoptosis. Developing effective therapies with both targeting capability and neuroprotective effects remains a significant challenge. In this study, we engineered a novel biomimetic nanoplatform by fusing neutrophil membranes with M₂ macrophage-derived extracellular vesicles (M₂EVs), generating hybrid vesicles termed N-M₂EVs. These vesicles were uniformly sized, exhibited good biocompatibility, and retained membrane markers from both parent sources. In vitro experiments using oxygen-glucose deprivation/reoxygenation (OGD/R)-injured HT22 neurons demonstrated that N-M₂EVs preferentially targeted damaged cells, enhanced cell viability, reduced reactive oxygen species, and inhibited apoptosis more effectively than M₂EVs alone. In a mouse SCI model, intravenously administered N-M₂EVs showed higher accumulation at injury sites, improved motor function recovery as assessed by BMS score, CatWalk gait analysis, and motor evoked potentials, and promoted neuronal survival and axonal regeneration while reducing glial scarring. Mechanistically, RNA sequencing and Western blot analysis revealed that N-M₂EVs exerted their therapeutic effects by suppressing the TNF-α/NF-κB/apoptosis signaling pathway. Histological examination confirmed the absence of toxicity in major organs, indicating a favorable safety profile. Overall, presents the first application of neutrophil membrane-fused M₂EVs for targeted SCI therapy, combining site-specific homing with immunomodulatory and neuroprotective functions. This biomimetic strategy holds strong translational potential for SCI and other neuroinflammatory disorders.