Engineering integrin αvβ8-targeted extracellular vesicles to deliver BDNF mRNA for motor recovery in spinal cord injury.

Spinal cord injury (SCI) remains difficult to treat, and current interventions provide limited functional restoration and often require invasive procedures. Existing cell- or extracellular vesicles (EV)-based approaches are frequently administered alongside surgery, limiting therapeutic reach and overall efficacy. In this study, we developed an engineered extracellular vesicle (EV) platform by displaying a single-chain variable fragment (scFv) against integrin αvβ8 (αITGEV) and loading brain-derived neurotrophic factor mRNA (mBDNF). The construct maintained canonical EV identity and morphology, and showed predominant single particle co-positivity for targeting ligand and cargo. In neuron-microglia co-culture, mBDNF@αITGEV preferentially entered both cell types under injury-relevant stress, shifted microglia toward a repair-associated phenotype, reduced TNF-α and IL-1β, increased IL-4 and IL-10, and preserved neuronal architecture. Our results indicate that mBDNF@αITG-EVs significantly promote functional motor recovery by modulating the inflammatory microenvironment and inhibiting neuronal ferroptosis. Mechanistically, the delivery of BDNF mRNA bolstered GPX4 expression and stabilized mitochondrial dynamics, thereby mitigating secondary oxidative damage. This study provides a non-invasive strategy for precision nanomedicine in neuro-regeneration. Collectively, this study supports a non-invasive systemically administered, targeted EV-mRNA therapeutic strategy for spinal cord injury with translational potential.