Human PMSCs derived exosomes alleviate neuropathic pain through miR-26a-5p/Wnt5a in SNI mice model

Abstract:

Background: Mesenchymal stem cell (MSCs)-derived exosomes are considered as a new cell-free therapy for pain caused by nerve injury, but whether human placental mesenchymal stem cell-derived exosomes relieve pain in sciatic nerve injury and its possible mechanism are still unclear. In this study, we investigated the roles of hPMSCs-derived exosomes and related mechanisms in neuropathic pain.

Methods: The spared nerve injury (SNI) mouse model was employed. Intrathecal injection of exosomes or miR-26a-5p agomir was performed on the seventh day of modeling, to study its anti-nociceptive effect. Exosomes’ miRNA sequencing (miRNA-Seq) and bioinformatics analysis were performed to study the downstream mechanisms of miRNAs. RT-qPCR, protein assay and immunofluorescence were used for further validation.

Results: A single intrathecal injection of exosomes durably reversed mechanical hypersensitivity in the left hind paw of mice with partial sciatic nerve ligation. Immunofluorescence studies found that PKH26-labeled exosomes were visible in neurons and microglia in the dorsal horn of the ipsilateral L4/5 spinal cord and more enriched in the ipsilateral. According to miRNA-seq results, we found that intrathecal injection of miR-26a-5p agomir, the second high counts microRNA in hPMSCs derived exosome, significantly suppressed neuropathic pain and neuroinflammation in SNI mice. Bioinformatics analysis and dual-luciferase reporter gene analysis identified Wnt5a as a direct downstream target gene of miR-26a-5p. The results showed that overexpression of miR-26a-5p in vivo could significantly reduce the expression level of Wnt5a. In addition, Foxy5, a mimetic peptide of Wnt5a, can significantly reverse the inhibitory effect of miR-26a-5p on neuroinflammation and neuropathic pain, and at the same time, miR-26a-5p can rescue the effect of Foxy5 by overexpression.

Conclusion: In conclusion, we reported that hPMSCs derived exosomes as a promising therapy for nerve injury induced neuropathic pain. And we showed that the miR-26a-5p in the exosomes regulated Wnt5a/Ryk/CaMKII/NFAT partly take part in the analgesia through anti-neuroinflammation, which suggests an alleviating pain effect through non-canonical Wnt signaling pathway in neuropathic pain model in vivo.