Cytoprotective and antioxidant effects of steen solution on human lung spheroids and human endothelial cells

Respiratory diseases represent a major healthcare burden worldwide. Lung transplantation (LTx) is the gold-standard for end-stage patients, strongly limited by shortage of available/suitable donor lungs. Normothermic ex vivo lung perfusion (EVLP) has significantly increased the number of lungs suitable for transplantation. Steen solution is used for EVLP, but the mechanisms involved in its beneficial properties remain to be clarified. We investigated the effects of Steen solution in an in vitro protocol of cold starvation and normothermic recovery (CS/NR) on human lung spheroids, named pneumospheres (PSs), containing epithelial/basal cells, and on endothelial HUVEC cells. Steen solution significantly preserved PSs viability, reduced ROS release by PSs and HUVECs, decreased NADPH-oxidase activity in PSs, and reduced inflammatory cytokines expression levels in HUVECs. Steen solution was able to specifically reduce NOX2 isoform activation, particularly in PSs, as detected by soluble-NOX2 peptide and p47-phosphorylation. Interestingly, a specific NOX2-inhibitor could partly mimic the pro-survival effect of Steen on PSs. We provide the first evidence that Steen solution can preserve lung epithelial/progenitor cells viability partially through NOX2-downregulation, and exert anti-oxidant effects on parenchymal cells, with consequent ROS reduction. These results suggest that NOX2 inhibition might be an additional strategy to reduce cellular damage during LTx procedures. This article is protected by copyright. All rights reserved.