Ex vivo liver machine perfusion: comprehensive review of common animal models

The most common preservation technique for liver grafts is static cold storage. Due to the organ shortage for liver transplantation, extended criteria donation (ECD) allografts are increasingly used – despite the higher risk of inferior outcome after transplantation. Ex vivo liver machine perfusion has been developed to improve the outcome of liver transplantation, especially with ECD grafts, and is currently under evaluation in clinical trials. We performed a literature search on PubMed and ISI Web of Science to assemble an overview of rodent and porcine animal models of ex vivo liver machine perfusion for transplantation, which are essential for the present and future development of clinical liver machine perfusion. Hypothermic, subnormothermic and normothermic MP systems have been successfully used for rat and pig liver transplantation. In comparison to hypothermic systems, normothermic perfusion often incorporates a dialysis unit. Moreover, it enables metabolic assessment of liver grafts. Allografts experiencing warm ischemic time have a superior survival rate after machine perfusion compared to cold storage alone, irrespective of the temperature used for perfusion. Furthermore, ex vivo machine perfusion improves the outcome of regular and ECD liver grafts in animal models. Small and large animal models of ex vivo liver machine perfusion are available to further foster the development of this new technology.