miR-21 and miR-19b delivered by hMSC-derived EVs regulate the apoptosis and differentiation of neurons in patients with spinal cord injury

BackgroundIn this study, we aimed to evaluate the therapeutic effects of extracellular vesicles (EVs), which were collected from differentiated PC12 cells and mesenchymal cells (MSCs), on the treatment of spinal cord injury (SCI). In addition, we aimed to identify miRNAs related to the inhibitory effect of EVs against cell apoptosis. MethodsElectron microscopy was used to observe the distributions of EVs in the samples. Real-time PCR, western blot, thiazolyl blue tetrazolium bromide (MTT) assay, and flow cytometry were performed to establish the molecular signaling pathway underlying the effect of EVs in SCI. In addition, a Basso-Beattie-Bresnahan (BBB) score system, Nissl staining, immunohistochemistry assay, and TdT-mediated dUTP nick-end labeling (TUNEL) assay were conducted to validate the molecular signaling pathway established above. ResultsThe expression of miR-21 and miR-19b was upregulated in EVs isolated from induced PC12 cells and MSCs, along with decreased expression of phosphatase and tensin homolog (PTEN) messenger RNA (mRNA)/protein and a lower level of cell apoptosis. The transfection of miR-21/miR-19b precursors into the cells also exhibited an inhibitory effect on cell apoptosis. In addition, in-silicon analysis and luciferase assays validated the role of PTEN as a virtual target of miR-21/miR-19b. Finally, the BBB scores and Nissl staining also validated the therapeutic effects of EVs derived from differentiated P12 cells/MSCs in SCI rats. Accordingly, the negative correlations between miR-21/miR-19b and PTEN mRNA/protein were implicated in the post-SCI recovery. ConclusionsThe increased levels of miR-21/miR-19b in the EVs derived from differentiated PC12 cells and MSCs suppresses the apoptosis of neuron cells by downregulating the expression of PTEN.