Abstract
Normothermic machine perfusion (NMP) after static cold storage is increasingly used for preservation and assessment of human donor livers prior to transplantation. Biliary viability ...assessment during NMP reduces the risk of post-transplant biliary complications. However, understanding of molecular changes in the biliary system during NMP remains incomplete. We performed an in-depth, unbiased proteomics analysis of bile collected during sequential hypothermic machine perfusion, rewarming and NMP of 55 human donor livers. Longitudinal analysis during NMP reveals proteins reflective of cellular damage at early stages, followed by upregulation of secretory and immune response processes. Livers with bile chemistry acceptable for transplantation reveal protein patterns implicated in regenerative processes, including cellular proliferation, compared to livers with inadequate bile chemistry. These findings are reinforced by detection of regenerative gene transcripts in liver tissue before machine perfusion. Our comprehensive bile proteomics and liver transcriptomics data sets provide the potential to further evaluate molecular mechanisms during NMP and refine viability assessment criteria.
Oxygenated ex situ machine perfusion of donor livers is an alternative for static cold preservation that can be performed at temperatures from 0 °C to 37 °C. Organ metabolism depends on oxygen to ...produce adenosine triphosphate and temperatures below 37 °C reduce the metabolic rate and oxygen requirements. The transport and delivery of oxygen in machine perfusion are key determinants in preserving organ viability and cellular function. Oxygen delivery is more challenging than carbon dioxide removal, and oxygenation of the perfusion fluid is temperature dependent. The maximal oxygen content of water-based solutions is inversely related to the temperature, while cellular oxygen demand correlates positively with temperature. Machine perfusion above 20 °C will therefore require an oxygen carrier to enable sufficient oxygen delivery to the liver. Human red blood cells are the most physiological oxygen carriers. Alternative artificial oxygen transporters are hemoglobin-based oxygen carriers, perfluorocarbons, and an extracellular oxygen carrier derived from a marine invertebrate. We describe the principles of oxygen transport, delivery, and consumption in machine perfusion for donor livers using different oxygen carrier-based perfusion solutions and we discuss the properties, advantages, and disadvantages of these carriers and their use.
Normothermic machine perfusion (NMP) is used to preserve and test donor livers before transplantation. During NMP, the liver is metabolically active and produces waste products, which are released ...into the perfusate. In this study, we describe our simplified and inexpensive setup that integrates continuous renal replacement therapy (CRRT) with NMP for up to 7 d. We also investigated if the ultrafiltrate could be used for monitoring perfusate concentrations of small molecules such as glucose and lactate.
Perfusate composition (urea, osmolarity, sodium, potassium, chloride, calcium, magnesium, phosphate, glucose, and lactate) was analyzed from 56 human NMP procedures without CRRT. Next, in 6 discarded human donor livers, CRRT was performed during NMP by integrating a small dialysis filter (0.2 m
) into the circuit to achieve continuous ultrafiltration combined with continuous fluid substitution for up to 7 d.
Within a few hours of NMP without CRRT, a linear increase in osmolarity and concentrations of urea and phosphate to supraphysiological levels was observed. After integration of CRRT into the NMP circuit, the composition of the perfusate was corrected to physiological values within 12 h, and this homeostasis was maintained during NMP for up to 7 d. Glucose and lactate levels, as measured in the CRRT ultrafiltrate, were strongly correlated with perfusate levels (
= 0.997,
< 0.001 and
= 0.999,
< 0.001, respectively).
The integration of CRRT into the NMP system corrected the composition of the perfusate to near-physiological values, which could be maintained for up to 7 d. The ultrafiltrate can serve as an alternative to the perfusate to monitor concentrations of small molecules without potentially compromising sterility.
Background. Ex situ machine perfusion is increasingly used to preserve and assess donor livers before transplantation. Compared with traditional static cold storage (SCS), machine perfusion exposes ...livers to an additional risk of microbial contamination. However, information on the risk of microbial transmission during machine perfusion is lacking. Methods. All livers that underwent either hypothermic oxygenated machine perfusion (HOPE) or normothermic machine perfusion (NMP) in our center between September 2021 and September 2023, and during which samples were taken from SCS fluid and/or machine perfusion solution for microbiological examination, were included in this retrospective, observational clinical study. Microbial transmission was examined from SCS fluid to machine perfusion solution fluid and, subsequently, to recipients of these livers. Results. A total of 90 cases of liver machine perfusion were included: 59 HOPE and 31 NMP. SCS preservation fluid cultures before HOPE or NMP were positive for at least 1 microorganism in 52% of the cases. After HOPE, there were no cases of positive machine perfusion fluid or evidence of microbial transmission to the recipients. After NMP, in 1 (3%) patient Escherichia coli was grown from abdominal drain fluid, the same bacterial strain that was also grown from the SCS preservation fluid before NMP. This E coli was resistant to the antibiotics that are routinely added to the NMP perfusion fluid. Conclusions. The risk of microbial transmission after machine perfusion is very low but not absent. We recommend routine sampling of machine perfusion fluid at the end of the procedure for microbiological analysis.
IntroductionEnd-ischaemic preservation of a donor liver by dual hypothermic oxygenated machine perfusion (DHOPE) for 2 hours prior to transplantation is sufficient to mitigate ischaemia-reperfusion ...damage and fully restore cellular energy levels. Clinical studies have shown beneficial outcomes after transplantation of liver grafts preserved by DHOPE compared with static cold storage. In addition to graft reconditioning, DHOPE may also be used to prolong preservation time, which could facilitate logistics for allocation and transplantation globally.Methods and analysisThis is a prospective, pseudo-randomised, dual-arm, IDEAL-D (Idea, Development, Exploration, Assessment, Long term study-Framework for Devices) stage 2 clinical device trial designed to determine safety and feasibility of prolonged DHOPE (DHOPE-PRO). The end-time of the donor hepatectomy will determine whether the graft will be assigned to the intervention (16:00–3:59 hour) or to the control arm (4:00–15:59 hour). In total, 36 livers will be included in the study. Livers in the intervention group (n=18) will undergo DHOPE-PRO (≥4 hours) until implantation the following morning, whereas livers in the control group (n=18) will undergo regular DHOPE (2 hours) prior to implantation. The primary endpoint of this study is a composite of the occurrence of all (serious) adverse events during DHOPE and up to 30 days after liver transplantation.Ethics and disseminationThe protocol was approved by the Medical Ethical Committee of Groningen, METc2020.126 in June 2020, and the study was registered in the Netherlands National Trial Registry (https://www.trialregister.nl/) prior to initiation.Trial registration numberNL8740.
Abstract Study objective The present study aimed to validate the Nexfin® monitor and to assess the accuracy compared to classical sphygmomanometry (Riva-Rocci/Korotkoff (RRK)) blood pressure (BP) ...measurements in patients with obesity scheduled for bariatric surgery. Design Validation study. Setting Outpatient clinic for bariatric surgery. Patients 33 patients scheduled for bariatric surgery. Measurements The validation process was done according to the protocols developed by the European Society of Hypertension from 2010. The Nexfin® monitor (Edwards Lifesciences/BMEYE B.V., Amsterdam, The Netherlands) calculates beat-to-beat blood pressure from finger pulse wave analysis. Measurements of systolic and diastolic BP were obtained using classical sphygmomanometry and the Nexfin® alternatingly. Main results In total 99 pairs of BP measurements were used. The device failed pass phase 1 as 65 systolic readings fell within 5 mm Hg (73 required). And 61, 76 and 90 diastolic readings fell within 5, 10 and 15 mm Hg respectively. Finally, it failed to pass phase 2 as 23 patients for systolic and 25 for diastolic had at least 2/3 of their comparisons falling within 5 mm Hg (24 required) but 10 subjects for systolic and 8 for diastolic had all three comparisons more than 5 mm Hg different from the RRK readings (zero allowed). Mean differences were 7.8 ± 6.9 mm Hg for SBP and 8.0 ± 7.2 mm Hg for DBP. Conclusion Using the revised protocol, the Nexfin® device was not able to pass validation. However using the original protocol, the Nexfin® device passed phase 1 and 2.1 of the validation process and failed to pass phase 2.2.
Liver transplantation has become an immense success; nevertheless, far more recipients are registered on waiting lists than there are available donor livers for transplantation. High-risk, extended ...criteria donor livers are increasingly used to reduce the discrepancy between organ demand and supply. Especially for high-risk livers, dynamic preservation using machine perfusion can decrease post-transplantation complications and may increase donor liver utilisation by improving graft quality and enabling viability testing before transplantation. To further increase the availability of donor livers suitable for transplantation, new strategies are required that make it possible to use organs that are initially too damaged to be transplanted. With the current progress in experimental liver transplantation research, (long-term) normothermic machine perfusion may be used in the future as a dynamic platform for regenerative medicine approaches, enabling repair and regeneration of injured donor livers. Currently explored therapeutics such as defatting cocktails, RNA interference, senolytics, and stem cell therapy may assist in the repair and/or regeneration of injured livers before transplantation. This review will provide a forecast of the future utility of normothermic machine perfusion in decreasing the imbalance between donor liver demand and supply by enabling the repair and regeneration of damaged donor livers.
Ex situ normothermic machine perfusion (NMP) is increasingly used for viability assessment of high‐risk donor livers, whereas dual hypothermic oxygenated machine perfusion (DHOPE) reduces ...ischemia‐reperfusion injury. We aimed to resuscitate and test the viability of initially‐discarded, high‐risk donor livers using sequential DHOPE and NMP with two different oxygen carriers: an artificial hemoglobin‐based oxygen carrier (HBOC) or red blood cells (RBC). In a prospective observational cohort study of 54 livers that underwent DHOPE‐NMP, the first 18 procedures were performed with a HBOC‐based perfusion solution and the subsequent 36 procedures were performed with an RBC‐based perfusion solution for the NMP phase. All but one livers were derived from extended criteria donation after circulatory death donors, with a median donor risk index of 2.84 (IQR 2.52–3.11). After functional assessment during NMP, 34 livers (63% utilization), met the viability criteria and were transplanted. One‐year graft and patient survival were 94% and 100%, respectively. Post‐transplant cholangiopathy occurred in 1 patient (3%). There were no significant differences in utilization rate and post‐transplant outcomes between the HBOC and RBC group. Ex situ machine perfusion using sequential DHOPE‐NMP for resuscitation and viability assessment of high‐risk donor livers results in excellent transplant outcomes, irrespective of the oxygen carrier used.
Sequential end‐ischemic hypothermic and normothermic machine perfusion results in safe transplantation of previously discarded, high‐risk, human donor livers, irrespective of the oxygen carrier used for normothermic perfusion.
Although short-term machine perfusion (≤24 h) allows for resuscitation and viability assessment of high-risk donor livers, the donor organ shortage might be further remedied by long-term perfusion ...machines. Extended preservation of injured donor livers may allow reconditioning, repairing, and regeneration. This review summarizes the necessary requirements and challenges for long-term liver machine preservation, which requires integrating multiple core physiological functions to mimic the physiological environment inside the body. A pump simulates the heart in the perfusion system, including automatically controlled adjustment of flow and pressure settings. Oxygenation and ventilation are required to account for the absence of the lungs combined with continuous blood gas analysis. To avoid pressure necrosis and achieve heterogenic tissue perfusion during preservation, diaphragm movement should be simulated. An artificial kidney is required to remove waste products and control the perfusion solution's composition. The perfusate requires an oxygen carrier, but will also be challenged by coagulation and activation of the immune system. The role of the pancreas can be mimicked through closed-loop control of glucose concentrations by automatic injection of insulin or glucagon. Nutrients and bile salts, generally transported from the intestine to the liver, have to be supplemented when preserving livers long term. Especially for long-term perfusion, the container should allow maintenance of sterility. In summary, the main challenge to develop a long-term perfusion machine is to maintain the liver's homeostasis in a sterile, carefully controlled environment. Long-term machine preservation of human livers may allow organ regeneration and repair, thereby ultimately solving the shortage of donor livers.
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