Exosomes from Bone Marrow Mesenchymal Stem Cells Inhibit Neuronal Apoptosis and Promote Motor Function Recovery via the Wnt/β-catenin Signaling Pathway

Severe spinal cord injury (SCI) is caused by external mechanical injury, resulting in unrecoverable neurological injury. Recent studies have shown that exosomes derived from bone marrow mesenchymal stem cells (BMSCs-Exos) might be valuable paracrine molecules in the treatment of SCI. In this study, we designed SCI models in vivo and in vitro and then investigated the possible mechanism of successful repair by BMSCs-Exos. In vivo, we established one Sham group and two SCI model groups. The Basso, Beattie, Bresnahan (BBB) scores showed that BMSCs-Exos could effectively promote the recovery of spinal cord function. The results of the Nissl staining, immunohistochemistry, and TUNEL/NeuN/DAPI double staining showed that BMSCs-Exos inhibited neuronal apoptosis. Western blot analysis showed that the protein expression level of Bcl-2 was significantly increased in the BMSCs-Exos group compared with the PBS group, while the protein expression levels of Bax, cleaved caspase-3, and cleaved caspase-9 were significantly decreased. The results of western bolt and qRT-PCR demonstrated that BMSCs-Exos could activate the Wnt/β-catenin signaling pathway effectively. In vitro, we found that inhibition of the Wnt/β-catenin signaling pathway could promote neuronal apoptosis following lipopolysaccharide (LPS) induction. These results demonstrated that BMSCs-Exos may be a promising therapeutic for SCI by activating the Wnt/β-catenin signaling pathway.