Edema and Weight Increase during Organ Preservation - Identification of Solution-Specific Endothelial Leakage

Purpose Lung transplantation remains the only treatment option for patients with end-stage lung disease. Although surgical techniques and organ preservation significantly improved over the last decades, ischemia and reperfusion injuries, which inter alia manifest in edema formation, still represent major limitations affecting clinical outcome. Here we investigated the hypothesis that different lung preservation solutions contribute to solution-specific degrees of transient leaks within the endothelial cell (EC) monolayer, therefore allowing liquid influx into the interstitial space leading to edema formation. Methods Intercellular connectivity within confluent EC monolayers was assessed after 1h, respectively 5.5h storage in the respective preservation solutions OCS™, Steen™, Perfadex™, PerfadexPlus™ or Celsior™ ± 10µM or 100µM 17β-Estradiol (17s), which was used to deliberate disintegration of the monolayer. Furthermore, 5.5h and 24h of regeneration in the preservation solution, respectively EC medium without 17s was analyzed. Monolayer permeability was evaluated using FITC-Dextran transwell-assays, cell viability (Calcein AM) and monolayer integrity (VE-Cadherin) were examined by fluorescence microscopy. Realtime qRT-PCR analyses were carried out to investigate responses on gene expression levels. Results FITC-Dextran assay indicated solution-specific monolayer permeability, after 1h incubation highest was identified for Celsior™, followed by Perfadex™ and OCS™, Steen™ and PerfadexPlus™ showed up with the lowest permeability. While addition of 10µM 17s did not affect solution-specific permeability, all groups treated with 100µM 17s become durable leaky. Comparable results were seen after 5.5h and 24h of regeneration, while previous incubation with 100µM 17s induced irreversible effects. These results could be confirmed by immunofluorescence staining. By contrast, independent of the treatment qRT-PCR analyses indicated negligible effects on gene expressions of activation and thrombogenic state markers. Conclusion The application of different preservation solutions results in solution-specific, partly irreversible endothelial leakage, which may partly explain edema and weight increase during organ preservation. Subsequent analysis will correlate these results with clinical parameters.