“In 10 years” of debate: Pro—machine perfusion for liver preservation will be universal

In the United States in 2014, 6729 patients underwent liver transplantation while 10,648 patients were added to the liver transplant waiting list, leaving 14,632 candidates awaiting a liver transplant at the end of the calendar year. Given this shortage of available and suitable organs, many centers are using donation after cardiac death (DCD) and extended criteria donors (ECD) livers (such as elderly and steatotic allografts) with increasing frequency. However, primary nonfunction and early allograft dysfunction (EAD) remain significant hurdles that may limit aggressive use of these types of marginal livers. In addition, these allografts are not without other risks that include biliary complications, decreased longterm graft survival, and increased complications with concomitant hospital resource utilization after transplantation. Marginal organs are at higher risk of early graft failure as a result of ischemia/reperfusion injury and EAD. These marginal grafts could significantly benefit from reduction in preservation insults by using ex vivo machine perfusion (MP) for organ preservation. The possibility of ex vivo viability assessment of these types of allografts and potential resuscitation of these organs holds promise for lowering discard rates and facilitating safe transplants. The use of ex vivo MP remains investigational in clinical liver transplantation. MP is a platform that provides continuous circulation of nutrients, metabolic substrates, and oxygen during the ex vivo period (Fig. 1). Over the last few years, several groups worldwide have been actively translating MP into the clinical arena for liver transplantation. Groups are investigating ex vivo MP at various temperatures using different perfusates and devices. Prior to a 2010 report by our group, the totality of the reported experience with MP was in animal models. After the first report of hypothermic machine perfusion (HMP), we saw a rapid expansion of MP utilization in clinical settings by other groups in Europe and the United States. Once the theoretical “barriers” to MP were challenged and conquered, an intense interest in MP began to flourish. Abbreviations: CHA, common hepatic artery; DCD, donation after cardiac death; EAD, early allograft dysfunction; ECD, extended criteria donor; HMP, hypothermic machine perfusion; ICU, intensive care unit; IVC, inferior vena cava; MELD, Model for End-Stage Liver Disease; MP, machine perfusion; NMP, normothermic machine perfusion; PV, portal vein.