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MiR-21 derived from the exosomes of MSCs regulates the death and differentiation of neurons in patients with spinal cord injury


In this study, we aimed to investigate the therapeutic effect of miR-21 in the treatment of spinal cord injury (SCI) as well as its underlying molecular mechanisms. Real-time PCR and western blot were performed to measure the expression of miR-21, PTEN, and PDCD4 in SCI rats. Locomotion recovery assessment, Nissl staining, IHC assay, and TUNEL assay were utilized to observe the therapeutic effect of miR-21 in the treatment of SCI. Bioinformatics analysis and luciferase assay were conducted to establish the signaling pathway of miR-21, PTEN, and PDCD4. The regulatory relationships between miR-21 and PTEN/PDCD4 were further validated by real-time PCR, western blot, MTT assay, and flow cytometry. Compared with sham-operated rats, SCI rats showed decreased expression of miR-21 along with increased expression of PTEN/PDCD4. Exosomes were equally distributed in MSCs transfected with miR-21, PTEN siRNA, or scramble controls. The exosomes isolated from the supernatant of cultured MSCs could improve the functional recovery of SCI rats by reducing SCI-induced neuron loss. In addition, miR-21 was shown to inhibit the expression of PTEN/PDCD4 and suppress neuron cell death. Moreover, PTEN and PDCD4 were validated as virtual targets of miR-21. In addition, the miR-21/PTEN/PDCD4 signaling pathway was shown to enhance cell viability and suppress cell death in vivo. The exosomes collected from the supernatant of transfected MSCs contained miR-21, which could improve the functional recovery of SCI rats and suppress cell death both in vivo and in vitro via the miR-21/PTEN/PDCD4 signaling pathway.

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This study was funded by the Shanghai Committee of Science and Technology, China (Grant No. 15411970400) and by the Academic Leaders Training Program of Jingan Health Care Bureau of Shanghai (2016). The Program for Outstanding Medical Academic Leader of Shanghai (Grant No.046), and the Key Disciplines Group Construction Project of Pudong Health Bureau of Shanghai (Grant no. PWZxq2017‑11)

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Correspondence to Guanghui Xu.

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Kang, J., Li, Z., Zhi, Z. et al. MiR-21 derived from the exosomes of MSCs regulates the death and differentiation of neurons in patients with spinal cord injury. Gene Ther 26, 491–503 (2019).

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