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Introduction: This study aimed to investigate the effect of muscle-derived stem cell (MDSC) exosomes with overexpressed miR-214 on the regeneration and repair of rat sciatic nerve after crush injury and its molecular mechanism. Methods: First, primary MDSCs, Schwann cells (SCs) and dorsal root ganglion (DRG) neurons were isolated and cultured, and the characteristics of MDSCs-derived exosomes were identified by molecular biology and immunohistochemistry. NC mimics and miR-214 mimics were transfected to obtain exo-NC and exo-miR-214. An in vitro co-culture system was established to determine the effect of exo-miR-214 on nerve regeneration. The restoration of sciatic nerve function of rats by exo-miR-214 was evaluated by walking track analysis. Immunofluorescence for NF and S100 was used to detect the regeneration of axon and myelin sheath in injured nerve. The Starbase database was used to analyze the downstream target genes of miR-214. QRT-PCR and dual luciferase reporter assays were used to validate the miR-214 and PTEN interaction relationship. And the expression of the JAK2/STAT3 pathway-related proteins in sciatic nerve tissues were detected by western blot. Results: The above experiments showed that MDSCs-derived exosomes with overexpressed miR-214 was found to promote the proliferation and migration of SCs, increase the expression of neurotrophic factors, promote axon extension of DRG neurons and positively affect the recovery of nerve structure and function. In addition, PTEN was a target gene of miR-214. Exo-miR-214 can significantly inhibit the expression level of PTEN, increase the protein expression levels of p-JAK2 and p-STAT3 and the ratio of p-JAK2/JAK2 and p-STAT3/STAT3, also MDSCs-derived exosomes with overexpressed miR-214 can reduce the occurrence of denervated muscle atrophy. Conclusion: In summary, the MDSCs-derived exosomes with overexpressed miR-214 is involved in peripheral nerve regeneration and repair in rats after sciatic nerve crush injury to activate the JAK2/ STAT3 pathway by targeting PTEN.
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Objective:In this study, we established a reliable surgical procedure of lung ischaemia-reperfusion(IR) injury in rats. The research progress of different lung IR injury models and application value was also discussed.Methods:Twenty-eight adult SD rats were randomly divided into SHAM group and lung IR injury group(IR group), 14 rats in each group. In IR group, rats underwent tracheotomy under general anesthesia and received mechanical ventilation. Chest was opened in supine position, and pulmonary hilum was blocked for 30 minutes then the occlusion was removed. Samples were harvested after reperfusion for 45minutes. Rats in SHAM group received surgery and exposure of the right pulmonary artery, and experienced the same amount of time before the chest closed. Arterial blood gas was extracted postoperatively. Gross view of the lungs and pathological changes were observed, and the dry/wet ratio(W/D) was determined. Protein level of pro-inflammatory factors, markers in oxidative stress pathway, and endothelial functional markers in lung were tested by western blot analysis.Results:In IR group, there was pink foamy secretion in the airway, and the lungs exhibited signs of edema and congestion. In IR group, the alveolitis score was significantly increased, the W/D ratio was also increased, p38MAPK and NF-κB signaling pathways were activated, and the expression of TNF-α was significantly increased, while the expression of eNOS was significantly decreased.Conclusion:Left hilum clamping and bilateral reperfusion injury in lung is a practical animal model, it is a simple, low-cost and repeatable animal model for further studies. No microsurgical instruments were required during the procedure. Lung IR injury is characterized by oxidative stress response, inflammatory response and endothelial cell dysfunction.
