Netrin-1 derived from BMSC-exosomes promotes axonal regeneration and functional recovery after spinal cord injury via inhibition of the RhoA/ROCK pathway.

Abstract

OBJECTIVE: Spinal cord injury (SCI) leads to severe neurological dysfunction. This study investigated the role of exosome-derived netrin-1 (NTN1) in axonal repair after SCI. METHODS: BMSC-Exos were isolated and characterized, and their uptake by neural stem cells (NSCs) was confirmed. An in vitro axonal injury model was established using microfluidic chambers, and NSCs were treated with BMSC-Exos with or without an NTN1-neutralizing antibody or the ROCK inhibitor Y-27632. Axonal outgrowth and RhoA/ROCK-related signaling were assessed by immunofluorescence and Western blot. In vivo, a rat contusion SCI model received intrathecal BMSC-Exos with or without NTN1 neutralization. Locomotor recovery was evaluated using Basso-Beattie-Bresnahan (BBB) scoring, and spinal cord tissues were analyzed histologically. RESULTS: NTN1 was enriched in BMSC-Exos and increased in NSCs after exosome treatment. In vitro, BMSC-Exos promoted axonal outgrowth after injury, and this effect was partially attenuated by NTN1 neutralization, accompanied by changes in RhoA/ROCK-related signaling. In vivo, BMSC-Exos improved locomotor recovery and reduced spinal cord tissue damage, whereas NTN1 neutralization weakened these effects. CONCLUSION: BMSC-Exos promote axonal repair and functional recovery after SCI, at least in part through exosome-derived NTN1 associated with modulation of RhoA/ROCK signaling.