Mesenchymal stem cells (MSCs) have been proved to exert considerable therapeutic effects on ischemia‐reperfusion (I/R)‐induced injury, but the underlying mechanism remains unknown. In this study, we aimed to explore the potential molecular mechanism underlying the therapeutic effect of MSCs‐derived exosome reinforced with miR‐20a in reversing liver I/R injury. Quantitative real‐time polymerase chain reaction, Western blot, and IHC were carried out to compare the differential expressions of miR‐20a, Beclin‐I, FAS, Caspase‐3, mTOR and P62 in IR rats and normal rats. TUNEL was performed to assess IR‐induced apoptosis in IR rats, and luciferase assay was used to confirm the inhibitory effect of miR‐20a on Beclin‐I and FAS expression. Among the 12 candidate microRNAs (miRNAs), miR‐486, miR‐25, miR‐24, miR‐20a,miR‐466 and miR‐433‐3p were significantly downregulated in I/R. In particular, miR‐20a, a miRNA highly expressed in umbilical cord‐derived mesenchymal stem cells, was proved to bind to the 3ʹ UTR of Beclin‐I and FAS to exert an inhibitory effect on their expressions. Since Beclin‐I and FAS were aberrantly upregulated in IR, exosomes separated from UC‐MSCs showed therapeutic efficacy in reversing I/R induced apoptosis. In addition, exosomes reinforced with miR‐20a and separated from UC‐MSCs almost fully alleviated I/R injury. Furthermore, our results showed that miR‐20a could alleviate the abnormal expression of genes related to apoptosis and autophagy, such as active Caspase‐3, mTOR, P62, and LC3II. This study presented detailed evidence to clarify the mechanism underlying the therapeutic efficacy of UC‐MSCs in the treatment of I/R injury.

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