Background. Lung ischemia-reperfusion injury after transplantation is associated with worse clinical outcomes. MicroRNA (miR) are critical regulators of gene expression that could provide potential targets for novel gene therapy. Herein, we aim to examine the feasibility of using the ex vivo lung perfusion (EVLP) platform to examine the changes in miR expression in human lungs in response to cold ischemia and ex vivo reperfusion (CI/EVR). Methods. Twenty-four human lungs were perfused in cellular EVLP system for 2 h, and tissue samples were obtained before and after EVLP as well as from control donors. MicroRNA expression profiling of the lung tissue was performed using next-generation sequencing and downstream predicted target genes were examined. In situ hybridization assay of the validated miR was used to identify the expressing cell type. Results. After 2 h of EVLP, cytokines production was significantly increased (IL-1β, IL-6, IL-8, IL-10, and TNF-α). MicroRNA sequencing identified a significant change in the expression of a total of 21 miR after CI and 47 miR after EVR. Validation using quantitative polymerase chain reaction showed significant upregulation of miR-17 and miR548b after CI/EVR. Downstream analysis identified abundant inflammatory and immunologic targets for miR-17 and miR-548b that are known mediators of lung injury. In situ hybridization assays detected positive signals of the 2 miR expression in alveolar epithelial cells. Conclusions. This study demonstrates the feasibility of using the EVLP platform to study miR signature in human lungs in response to CI/EVR. We found that miR-17 and miR-548b were upregulated in alveolar epithelial cells after CI/EVR, which merit further exploration.
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