BMSC-derived exosomal piR-161382 alleviates spinal cord ischemia/reperfusion injury by targeting MCU to inhibit ROS/NLRC4-mediated neuronal pyroptosis.

BACKGROUND

Pyroptosis, NLRC4 and mitochondrial calcium uniporter (MCU)'s role in spinal cord ischemia/reperfusion injury (SCIRI) remain unclear. The role of exosomal piRNAs in SCIRI is underexplored. We aimed to investigate the neuroprotective effects of exosomes obtained from bone marrow mesenchymal stem cells (BMSCs) overexpressing piR-161382 in SCIRI.

METHODS

We studied MCU and NLRC4 expression changes after SCIRI and OGD/R in rats. piR-161382 and piR-161382's interaction with MCU was validated. Exosome were analyzed via TEM and NTA, and confirmed by Western blotting, and DiI-labeled exosomes tracked in vivo. Hindlimb recovery was assessed with Tarlov scores. Effects of NLRC4/MCU inhibition, piR-161382 overexpression, and BMSC-derived exosomal piR-161382 on pyroptosis markers were evaluated. Cell viability, ROS, mitochondrial membrane potential, and BSCB permeability were measured.

RESULTS

MCU and NLRC4 levels expressed in spinal neurons. NLRC4 knockout improved cell viability and reduced pyroptosis markers after OGD/R. Inhibiting MCU or using mito-tempo decreased ROS, increased mitochondrial membrane potential (MMP), and alleviated NLRC4-mediated pyroptosis, while MCU overexpression reversed these effects. PiR-161382's interaction with MCU was confirmed. piR-161382 mimic treatment reduced ROS, improved MMP, and suppressed NLRC4 activation and pyroptosis after OGD/R, with reversal upon MCU agonist SPER. BMSC-derived exosomal piR-161382 reduced MCU, ROS, and pyroptosis markers, enhancing cell survival. In SCIRI rats treated with piR-161382-overexpressing exosomes, hindlimb function improved, MCU, NLRC4, and pyroptosis proteins decreased, and blood-spinal cord barrier integrity was restored.

CONCLUSIONS

BMSC-derived exosomes overexpressing piR-161382 mitigate SCIRI by targeting MCU, reducing ROS, and inhibiting NLRC4-mediated neuronal pyroptosis.