Oxygenated hypothermic machine perfusion after static cold storage improves endothelial function of extended criteria donor livers

Abstract

Background: Lack of oxygen and biomechanical stimulation during static cold storage (SCS) of donor livers compromises endothelial cell function. This study investigated the effect of 2 hours of end-ischemic oxygenated hypothermic machine perfusion (HMP) on endothelial cell function of extended criteria donor (ECD) livers. Method: Sixteen human livers that were declined for transplantation were transported to our center using conventional static cold storage (SCS; 4oC) and subjected to normothermic machine perfusion (NMP) to assess viability and function. Six livers underwent 2 hours oxygenated HMP (12°C) after SCS and prior to NMP. Ten control livers underwent NMP immediately after SCS. Endothelial cell function was assessed by quantification of mRNA expression encoding for transcription factor Krüppel-like-factor-2 (KLF-2), endothelial nitric oxide synthase (eNOS), and thrombomodulin (TM) using real-time PCR. Nitric oxide (NO) production (nitrite/nitrate levels) and release of thrombomodulin (TM) into the perfusion fluid were determined during NMP. Results: In livers that underwent end-ischemic HMP, mRNA expression of KLF-2 (p = 0.04), eNOS (p = 0.03) and TM (p = 0.03) increased significantly during NMP. This response was not observed in the control livers. In parallel, NO levels in the perfusate increased during NMP of livers that first underwent HMP, but not in control livers. Moreover, at the end of NMP cumulative TM release into the perfusate was significantly higher in control livers compared to livers first subjected to HMP (p = 0.03). Conclusion: A short period of 2 hours oxygenated HMP restores endothelial cell function and integrity after conventional static cold preservation and subsequent reoxygenation of ECD livers.