24-hour normothermic machine perfusion of discarded human liver grafts: Case series single-center study

The persistent shortage of liver allografts contributes to significant waitlist mortality. Normothermic machine perfusion (NMP) has the potential to extend viability and allow liver function evaluation in discarded organs. The main aim of the study was to evaluate the possibility for extended preservation and the potential recovery of non-usable human livers utilizing NMP. 6 high-risk human liver grafts that were discarded after national allocation underwent normothermic liver preservation for an extended period of 24 hours. Transmedics Organ Care System™ liver perfusion device was used to preserve a donor liver in a functioning, near physiologic state. Parameters of biochemical and synthetic liver function were collected periodically and subsequently analyzed. Liver parenchyma and bile duct biopsies were obtained pre- and 24 hours post-NMP. 4/6 (67%) grafts were DCDs with a median age of 54 (IQR: 42-61) years and median CIT of 262 (IQR: 209-1024) minutes. 5/6 (83%) livers produced a median of 75 ml of bile (Range 55-100) after 24 hours of NMP. Lactate dropped to normal levels (<2 mmol/L) for all livers after around 4 hours on NMP. The overall cellular architecture, lobular steatosis and necrosis grades were preserved after extended NMP. Biopsies showed improvement of liver parenchyma architecture with reduced inflammation for 2/6 (33%) at the end of the perfusion. Prolonged NMP for discarded liver grafts can be safely maintained on NMP and may identify certain grafts that are suitable for transplantation. Further studies utilizing NMP with subsequent transplantation would validate this strategy, as well as existing viability markers.