Normothermic Machine Perfusion (NMP) Versus Static Cold Storage (SCS) in Human Kidney Transplantation

Due to organ shortage in kidney transplantation (KT) several strategies have been implemented in an attempt to increase donor pool utilization, including transplantation of extended criteria donor (ECD) allografts. While the transplantation of ECD organs saves patients from waiting-list dropout, these pre-damaged organs exhibit an increased susceptibility to further injury during organ storage and transplantation. Static cold storage (SCS) involves the transportation of procured donor kidneys on ice and has remained the gold standard for organ preservation for decades. SCS relies on hypothermia to reduce cellular metabolism and oxygen demand while achieving a prolonged preservation time of organs. Upon reperfusion, the reintroduction of oxygen to the ischemic kidney leads to a respiratory burst with massive production of mitochondrial reactive oxygen species and subsequent sterile inflammation of the entire organ. This ischemia-reperfusion injury (IRI) is a central predictor of graft and patient survival. Current clinical preservation strategies are unable to meet the challenges of ECD allograft transplantation and there is a great demand to optimize preservation techniques for such high risk ECD allografts. Currently, two main paradigms prevail in the clinical approach to kidney allograft machine perfusion (MP) in regard to optimized preservation techniques: while end-ischemic hypothermic (HMP) and hypothermic oxygenated MP (HOPE) may be seen as dynamic alternatives of the traditional organ preservation based on hypothermia-induced deceleration of metabolism could not proof a beneficial effect on delayed graft function or primary graft failure, the impact of normothermic perfusion (NMP) on ECD kidney allografts is still missing. NMP aims at re-equilibration of cellular metabolism by preserving the organ at physiological temperatures whilst ensuring sufficient oxygen and nutrient supply. The present trial was therefore designed to provide first level-II evidence fo