Hypothermic oxygenated perfusion (HOPE) protects from biliary injury in a rodent model of DCD liver transplantation

Background & Aims

The use of livers from donors after cardiac arrest (DCD) is increasing in many countries to overcome organ shortage. Due to additional warm ischemia before preservation, those grafts are at higher risk of failure and bile duct injury. Several competing rescue strategies by machine perfusion techniques have been developed with, however, unclear effects on biliary injury. We analyze the impact of an end-ischemic Hypothermic Oxygenated PErfusion (HOPE) approach applied only through the portal vein for 1 h before graft implantation.

Methods

Rat livers were subjected to 30-min in situ warm ischemia, followed by subsequent 4-h cold storage, mimicking DCD-organ procurement and conventional organ transport. Livers in the HOPE group underwent also passive cold storage for 4 h, but were subsequently machine perfused for 1 h before implantation. Outcome was tested by liver transplantation (LT) at 12 h after implantation (n = 10 each group) and after 4 weeks (n = 10 each group), focusing on early reperfusion injury, immune response, and later intrahepatic biliary injury.

Results

All animals survived after LT. However, reperfusion injury was significantly decreased by HOPE treatment as tested by hepatocyte injury, Kupffer cell activation, and endothelial cell activation. Recipients receiving non-perfused DCD livers disclosed less body weight gain, increased bilirubin, and severe intrahepatic biliary fibrosis. In contrast, HOPE treated DCD livers were protected from biliary injury, as detected by cholestasis parameter and histology.

Conclusions

We demonstrate in a DCD liver transplant model that end-ischemic hypothermic oxygenated perfusion is a powerful strategy for protection against biliary injury.

Introduction

In an attempt to reduce the worldwide shortage of organ donors, several liver transplant centers in North America and Europe currently accept liver grafts from donation after cardiac death (DCD) donors [1]. However, the use of DCD livers for transplantation bears a considerable risk in terms of decreased survival rates [2], which often relates to the development of intrahepatic cholangiopathy (IC). This life threatening complication has been documented in 20–50% of the patients in recent series of DCD liver transplantation [2], compared to 1–5% for organs obtained from brain dead donors [3].

Machine perfusion techniques have been mainly developed to protect livers exposed to a warm ischemic insult. Current experimental studies in several animal models suggest promising results with significant reduction of reperfusion injury and better graft outcome [4], [5], [6], [7]. Most studies, however, are limited to the description of early graft injury and seven-day survival omitting information on later biliary injury, as this complication typically occurs several weeks after liver transplantation [8].

Here, we present an experimental study in a model of DCD rat liver transplantation targeting on biliary injury after transplantation. We compare conventional cold storage of DCD livers with a combination of cold storage plus end-ischemic hypothermic oxygenated liver perfusion (HOPE), which is limited to the application of one-hour cold perfusion through the portal vein [4], [5]. The targeted protective mechanism behind this approach is a short term conditioning of hepatocyte mitochondria during recipient hepatectomy [9].

In an initial step, we compare reperfusion injury 12 h after liver transplantation in machine perfused and untreated DCD livers. Next, we analyze biliary injury four weeks following liver transplantation, and finally, we provide a potential mechanism explaining liver graft protection by HOPE.