Ex-situ normothermic machine perfusion (NMP) of donor livers is an emerging innovation in liver transplantation that has made its transition to clinical trials. NMP is applied in an effort to overcome ischemia-reperfusion injury associated with static cold storage, to improve the quality of sub-optimally functioning donor organs and to permit viability testing of potentially transplantable livers. The in-vivo physiological conditions maintained during ex-situ NMP necessitate the need for a perfusion fluid that mimics the composition of whole blood. To date, perfusion fluids used in NMP studies are composed of either plasma-based solutions or plasma-free solutions consisting of colloids such as Gelofusine1 . The latter avoids the use of human plasma which is scarce, costly and logistically challenging. This article is protected by copyright. All rights reserved.