Mobile Ex Vivo Perfusion of Donor Lungs Alters Early Lung Gene Expression Profiles

Abstract

<h3>Purpose</h3> Despite increasing use of mobile <i>ex vivo</i> lung perfusion (mEVLP) prior to lung transplant, very little is known about biological changes induced by lung perfusion and how long they may last. Use of mEVLP has been associated with improved early graft function, but the mechanisms of this protection remain unknown. We hypothesized that use of mEVLP induces early gene changes that alter early inflammatory responses. <h3>Methods</h3> We collected lung biopsies from 6 donor lungs with mEVLP (TransMedics OCS™) prior to lung transplant, and 6 patients whose donor lungs were preserved in Perfadex solution on ice prior to transplant. EVLP and non-EVLP donors were matched by donor gender, age and smoking status, as well as recipient age, gender and lung disease. Standard immunosuppression for each group was employed with Basiliximab induction. We compared biopsies obtained 1) prior to implant during back-table preparation, 2) at the end of the surgery, after reperfusion, but before chest closure, and 3) 1 month after transplant (Follow up). We measured and analyzed 785 genes using nCounter® human organ transplant panel with nSolver (version 4.0, NanoString) at each time point. <h3>Results</h3> Prior to implant, mEVLP lungs had higher levels of expression for genes associated with apoptosis and cell cycle regulation, autophagy, chemokine, and cytokine signaling. After surgical implantation and reperfusion, mEVLP lungs had increased expression of genes associated with adaptive immune system, apoptosis and cell cycle regulation, autophagy, cell- extracellular matrix interaction score, MAPK signaling, oxidative stress, TH1 differentiation, TGF-β signaling, and TH-17 differentiation. Tissue homeostasis was lower in mEVLP. One month after surgery, transbronchial biopsies from lungs that had undergone mEVLP demonstrated lower levels of angiogenesis, autophagy, inflammasomes, MAPK signaling, metabolism, mTOR signaling, and oxidative stress. <h3>Conclusion</h3> In general, our results demonstrate higher levels of inflammation in mEVLP lungs prior to and immediately after transplant. However, one month after transplant, mEVLP lungs have lower levels of inflammation and oxidative stress. It is possible that early robust gene responses in mEVLP lungs are followed by a more rapid recovery of inflammation.