Normothermic machine perfusion system satisfying oxygen demand of liver could maintain liver function more than subnormothermic machine perfusion.

Liver transplantation plays an important role in the medical field. To improve the quality of a donor liver, there is a need to establish a preservation system to prevent damage and maintain liver function. In response to this demand, machine perfusion (MP) has been proposed as a new liver preservation method instead of the conventional static cold storage. There is controversy about the optimal MP temperature of the donor liver. Since the oxygen consumption of the liver differs depending on the temperature, construction of a system that satisfies the oxygen demand of the liver is crucial for optimizing the preservation temperature. In this study, an MP system, which satisfies the oxygen demand of liver at each temperature, was constructed using an index of oxygen supply; the overall volumetric oxygen transfer coefficient, the amount of oxygen retention of perfusate and oxygen saturation. Both subnormothermic MP (SNMP, 20-25 °C) and normothermic MP (NMP, 37 °C) could maintain liver viability at a high level (94%). However, lactate metabolism of the liver during NMP was more active than that during SNMP. Furthermore, the ammonia metabolism of liver after NMP was superior to that after SNMP. Hence, NMP, which maintains the metabolic activity of the liver, is more suitable for preservation of the donor liver than SNMP, which suppresses the metabolic activity. In summary, normothermia is the optimal temperature for liver preservation, and we succeeded in constructing an NMP system that could suppress liver damage and maintain function.