EXPRESS: Olfactory ensheathing cell transplantation targets macrophage extracellular traps and NKCC1 to alleviate pain after spinal cord injury

Spinal cord injury (SCI) triggers neuropathic pain through inflammatory secondary injury. Olfactory ensheathing cells (OECs) hold therapeutic promise, but their pain-relieving mechanisms are unclear. This study investigated whether OEC transplantation alleviates pain by modulating macrophage extracellular trap (MET) formation and Na⁺-K⁺-Cl⁻ cotransporter 1 (NKCC1) expression. Following ethical approval, a rat contusive SCI model was established. OEC-treated rats received a cell transplant post-injury. Motor and sensory functions were assessed over 35 days. Tissue was analyzed for NKCC1, CD68, and the MET marker H3Cit. In vitro, RAW264.7 macrophages were stimulated with TNF-α to induce METs. OEC transplantation significantly improved functional recovery and reduced mechanical/thermal hypersensitivity. Histology showed preserved tissue structure. Critically, OEC treatment suppressed MET formation (reduced H3Cit/CD68) and downregulated NKCC1 in vivo. In vitro, OEC-conditioned medium inhibited TNF‑α‑induced MET formation and NKCC1 expression in macrophages. Thus, OECs alleviate neuropathic pain and promote recovery after SCI by coordinately suppressing macrophage extracellular traps and regulating NKCC1 expression, revealing a novel immunomodulatory‑ion transport axis for pain intervention.