Acellular Ex Vivo Lung Perfusion Silences Pro-Inflammatory Signaling in Human Lung Endothelial and Epithelial Cells
Ischemia reperfusion (IR) injury is a key complication following lung transplantation, and it remains to be fully resolved. Ex vivo lung perfusion (EVLP) has shown its significance as a platform to assess and repair marginal donor lungs prior to transplants with good clinical outcomes. Recently, it has been shown that Glutamax supplementation to Steen solution can improve basic cellular function as well as porcine EVLP duration with stable lung quality. To better understand the molecular mechanisms of IR injury, acellular EVLP, and Glutamax supplementation during EVLP, transcriptomic changes in cell culture models simulating IR and EVLP have been investigated. Briefly, human pulmonary microvascular endothelial cells (HPMEC) and human lung epithelial cells (BEAS-2B) were cultured in DMEM+10%FBS, then were perfused with Perfadex at 4°C for 18H to simulate cold ischemic time (CIT). Subsequently, the cells were perfused in either DMEM+10%FBS (IR model) or in Steen solution or Steen with 4mM Glutamax (EVLP models) for 4H. RNA samples were collected for CIT, IR, and two EVLP conditions, and sequencing data were analyzed for differentially expressed genes and pathways. HPMEC and BEAS-2B cells showed significant changes in gene expressions for IR and EVLP models. In pathway analyses, IR models of both cell types had up-regulated pro-inflammatory responses and down-regulated cell metabolism, and there was up-regulation of epithelial process and/or vascular activation. Steen alone EVLP models exhibited down-regulation of cell metabolism, with an absence of inflammatory and vascular or epithelial signals, while Steen with Glutamax exhibited similar down-regulation of cell metabolism as well as down-regulated inflammatory and vascular process. The commonly used EVLP perfusate, acellular Steen solution, can silence the activation of pro-inflammatory signaling in HPMEC and BEAS-2B cell culture models. This finding may yield insights into how acellular EVLP has been successful in safe preservation of the donor lungs during organ evaluation and repair prior to lung transplantation. Overall design: Human pulmonary microvascular endothelial cells (HPMEC) and human lung epithelial cells (BEAS-2B) RNA samples are analyzed. There were 4 groups for each cell line: cold ischemic time 18h, reperfusion 4h, Steen 4h, and Steen with Glutamax 4h. With 4 samples per group, the total number of samples analyzed was 32.