Reprogramming microglia via ShK-modified extracellular vesicles promotes immunomodulation and functional recovery after spinal cord injury

Microglia play a dual role in tissue repair and inflammatory responses following spinal cord injury (SCI), rendering the regulation of their immune activity a key therapeutic objective during disease progression. Single‑cell RNA sequencing revealed a significant upregulation of Kv1.3 expression in microglia following SCI, implicating this channel in the initiation of early neuroinflammation. To selectively target Kv1.3, engineered extracellular vesicles displaying ShK (ShK-EVs), a highly selective Kv1.3‑blocking peptide, were developed. These ShK‑EVs efficiently accumulated at the lesion site and were preferentially internalized by activated microglia. Integrated high‑throughput miRNA sequencing and proteomic profiling indicated that ShK‑EVs possess substantial neurorepair potential. Mechanistically, ShK‑EVs suppressed M1‑type microglial polarization and reduced the secretion of pro‑inflammatory cytokines by modulating the JAK/STAT signaling pathway. This modulation resulted in reduced tissue cavitation and neuronal apoptosis, enhanced neuronal survival and axonal regeneration, and ultimately led to a significant improvement in motor function in SCI mice. Taken together, these findings identify Kv1.3 as a key regulator of microglial activation after SCI and provide a novel, targeted therapeutic strategy using ShK‑EVs, offering new perspectives on immunomodulation of the injury microenvironment and functional neural recovery. Kv1.3 is significantly upregulated in activated microglia at the lesion core during the acute phase after spinal cord injury. Engineered ShK-EVs achieve targeted delivery to the injury site and are preferentially internalized by activated microglia. ShK-EVs synergistically reprogram microglial polarization from M1 to M2 via a dual mechanism involving Kv1.3 blockade and immunomodulatory cargo. ShK-EVs modulate the neuro-immune microenvironment, promoting neuroprotection, axonal regeneration, and functional recovery after SCI.