Neural Regeneration Research ›› 2024, Vol. 19 ›› Issue (10): 2259-2269.doi: 10.4103/1673-5374.391194

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Small extracellular vesicles from hypoxia-preconditioned bone marrow mesenchymal stem cells attenuate spinal cord injury via miR-146a-5p-mediated regulation of macrophage polarization

Zeyan Liang1, 2, #, Zhelun Yang1, 2, #, Haishu Xie1, 2, #, Jian Rao1, 2, #, Xiongjie Xu1, 2, Yike Lin1, 2, Chunhua Wang1, 2, *, Chunmei Chen1, 2, *   

  1. 1Department of Neurosurgery, Fujian Medical University Union Hospital, Fuzhou, Fujian Province, China; 2Fujian Neurosurgical Institute, Fuzhou, Fujian Province, China
  • Online:2024-10-15 Published:2024-01-29
  • Contact: Chunmei Chen, MD, PhD, cmchen2009@sina.com; Chunhua Wang, PhD, wchmail@126.com.
  • Supported by:
    This work was supported by the Fujian Minimally Invasive Medical Center Foundation, No. 2128100514 (to CC, CW, and HX) and the Natural Science Foundation of Fujian Province, No. 2023J01640 (to CC, CW, ZL, and HX).

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Abstract: Spinal cord injury is a disabling condition with limited treatment options. Multiple studies have provided evidence suggesting that small extracellular vesicles (SEVs) secreted by bone marrow mesenchymal stem cells (MSCs) help mediate the beneficial effects conferred by MSC transplantation following spinal cord injury. Strikingly, hypoxia-preconditioned bone marrow mesenchymal stem cell-derived SEVs (HSEVs) exhibit increased therapeutic potency. We thus explored the role of HSEVs in macrophage immune regulation after spinal cord injury in rats and their significance in spinal cord repair. SEVs or HSEVs were isolated from bone marrow MSC supernatants by density gradient ultracentrifugation. HSEV administration to rats via tail vein injection after spinal cord injury reduced the lesion area and attenuated spinal cord inflammation. HSEVs regulate macrophage polarization towards the M2 phenotype in vivo and in vitro. MicroRNA sequencing and bioinformatics analyses of SEVs and HSEVs revealed that miR-146a-5p is a potent mediator of macrophage polarization that targets interleukin-1 receptor-associated kinase 1. Reducing miR-146a-5p expression in HSEVs partially attenuated macrophage polarization. Our data suggest that HSEVs attenuate spinal cord inflammation and injury in rats by transporting miR-146a-5p, which alters macrophage polarization. This study provides new insights into the application of HSEVs as a therapeutic tool for spinal cord injury.

Key words: bone marrow mesenchymal stem cells, hypoxia preconditioning, interleukin-1 receptor-associated kinase 1, macrophages, mesenchymal stem cells, small extracellular vesicles, spinal cord injury