Routine utilization of machine perfusion in liver transplantation:Ready for prime time?

The last decade has been notable for increasing high-quality research and dramatic improvement in outcomes with dynamic liver preservation.Robust evidence from numerous randomized controlled trials has been pooled by meta-analyses,providing the highest available evidence on the protective effect of machine perfusion(MP)over static cold storage in liver transplantation(LT).Based on a protective effect with less complications and improved graft survival,the field has seen a paradigm shift in organ preservation.This editorial focuses on the role of MP in LT and how it could become the new“gold standard”.Strong collaborative efforts are needed to explore its effects on long-term outcomes.

Matched pair analysis of the effect of longer hypothermic machine perfusion time on kidney transplant outcomes

BACKGROUND Hypothermic machine perfusion(HMP)has demonstrated benefits in terms of early kidney transplant function compared to static cold storage.While longer preservation times have shown detrimental effects,a previous paired study indicated that longer pump times(the second kidney in a pair)might lead to improved outcomes.AIM To revisit the prior paired study's somewhat unexpected results by reviewing our program's experience.METHODS A total of 61 pairs of transplant recipients who received kidneys from the same donor(2012-2021)were analyzed.Patients were divided into two groups depending on whether they were transplanted first(K1)or second(K2).Therefore,the patients in each pair had identical donor characteristics,except for time on the pump.Statistical analyses included Kaplan-Meyer analysis and paired tests,including McNemar's test,student's paired t-test,or Wilcoxon's test,as appropriate.RESULTS The two groups of recipients had similar demographics(age,body mass index,diabetes,time on dialysis,sensit-ization and retransplants).Cold ischemic times for K1 and K2 were 8.9(95%CI:7.9,9.8)and 14.7 hours(13.7,15.8)(P<0.0001),respectively.Overall,K2 had a higher rate of freedom from biopsy-proven acute rejection at 1 year(P=0.015).Delayed graft function was less common in K2,12/61(20%)than in K1,20/61(33%)(P=0.046).Finally,K2 showed a higher graft survival than K1(P=0.023).CONCLUSION Our results agree with a previous study that suggested possible advantages to longer pump times.Both studies should encourage further research into HMP's potential anti-inflammatory effect.

Machine perfusion and the prevention of ischemic type biliary lesions following liver transplant:What is the evidence?

The widespread uptake of different machine perfusion(MP)strategies for liver transplant has been driven by an effort to minimize graft injury.Damage to the cholangiocytes during the liver donation,preservation,or early posttransplant period may result in stricturing of the biliary tree and inadequate biliary drainage.This problem continues to trouble clinicians,and may have catastrophic consequences for the graft and patient.Ischemic injury,as a result of compromised hepatic artery flow,is a well-known cause of biliary strictures,sepsis,and graft failure.However,very similar lesions can appear with a patent hepatic artery and these are known as ischemic type biliary lesions(ITBL)that are attributed to microcirculatory dysfunction rather than main hepatic arterial compromise.Both the warm and cold ischemic period duration appear to influence the onset of ITBL.All of the commonly used MP techniques deliver oxygen to the graft cells,and therefore may minimize the cholangiocyte injury and subsequently reduce the incidence of ITBL.As clinical experience and published evidence grows for these modalities,the impact they have on ITBL rates is important to consider.In this review,the evidence for the three commonly used MP strategies(abdominal normothermic regional perfusion[A-NRP],hypothermic oxygenated perfusion[HOPE],and normothermic machine perfusion[NMP])for ITBL prevention has been critically reviewed.Inconsistencies with ITBL definitions used in trials,coupled with variations in techniques of MP,make interpretation challenging.Overall,the evidence suggests that both HOPE and A-NRP prevent ITBL in donated after circulatory death grafts compared to cold storage.The evidence for ITBL prevention in donor after brain death grafts with any MP technique is weak.

Comparison between multiple logistic regression and machine learning methods in prediction of abnormal thallium scans in type 2 diabetes

BACKGROUND The prevalence of type 2 diabetes(T2D)has been increasing dramatically in recent decades,and 47.5%of T2D patients will die of cardiovascular disease.Thallium-201 myocardial perfusion scan(MPS)is a precise and noninvasive method to detect coronary artery disease(CAD).Most previous studies used traditional logistic regression(LGR)to evaluate the risks for abnormal CAD.Rapidly developing machine learning(Mach-L)techniques could potentially outperform LGR in capturing non-linear relationships.AIM To aims were:(1)Compare the accuracy of Mach-L methods and LGR;and(2)Found the most important factors for abnormal TMPS.METHODS 556 T2D were enrolled in the study(287 men and 269 women).Demographic and biochemistry data were used as independent variables and the sum of stressed score derived from MPS scan was the dependent variable.Subjects with a MPS score≥9 were defined as abnormal.In addition to traditional LGR,classification and regression tree(CART),random forest,Naïve Bayes,and eXtreme gradient boosting were also applied.Sensitivity,specificity,accuracy and area under the receiver operation curve were used to evaluate the respective accuracy of LGR and Mach-L methods.RESULTS Except for CART,the other Mach-L methods outperformed LGR,with gender,body mass index,age,low-density lipoprotein cholesterol,glycated hemoglobin and smoking emerging as the most important factors to predict abnormal MPS.CONCLUSION Four Mach-L methods are found to outperform LGR in predicting abnormal TMPS in Chinese T2D,with the most important risk factors being gender,body mass index,age,low-density lipoprotein cholesterol,glycated hemoglobin and smoking.

Impact of machine perfusion of the liver on post-transplant biliary complications: A systematic review

AIM To review the clinical impact of machine perfusion(MP) of the liver on biliary complications post-transplantation, particularly ischaemic-type biliary lesions(ITBL). METHODS This systematic review was performed in accordance with the Preferred Reporting Systematic Reviews and MetaAnalysis(PRISMA) protocol. The following databases were searched: PubMed, MEDLINE and Scopus. The keyword "liver transplantation" was used in combination with the free term "machine perfusion". Clinical studies reporting results of transplantation of donor human livers following ex situ or in situ MP were analysed. Details relating to donor characteristics, recipients, technique of MP performed and post-operative biliary complications(ITBL, bile leak and anastomotic strictures) were critically analysed.RESULTS Fifteen articles were considered to fit the criteria for this review. Ex situ normothermic MP was used in 6 studies, ex situ hypothermic MP in 5 studies and the other 4 studies investigated in situ normothermic regional perfusion(NRP) and controlled oxygenated rewarming. MP techniques which have per se the potential to alleviate ischaemia-reperfusion injury: Such as hypothermic MP and NRP, have also reported lower rates of ITBL. Other biliary complications, such as biliary leak and anastomotic biliary strictures, are reported with similar incidences with all MP techniques. There is currently less clinical evidence available to support normothermic MP as a mitigator of biliary complications following liver transplantation. On the other hand, restoration of organ to full metabolism during normothermic MP allows assessment of hepatobiliary function before transplantation, although universally accepted criteria have yet to be validated.CONCLUSION MP of the liver has the potential to have a positive impact on post-transplant biliary complications, specifically ITBL, and expand extended criteria donor livers utilisation.

Implementing an innovated liver ex-situ machine perfusion technology:The 2018 Joint International Congress of ILTS,ELITA and LICAGE

The 2018 Joint International Congress of ILTS,ELITA and LICAGE were held in Lisbon,Portugal on May 23–26,2018.The exciting and innovative program brought together 1144 experts in liver transplantation(LT)such as surgeons,physicians or basic scientists from 61 countries.The presentations included 110 invited speakers,181 oral presentations,and 545 posters.This editorial highlights some of the most innovative and impactful presentations in

Predicting major adverse cardiovascular events after orthotopic liver transplantation using a supervised machine learning model:A cohort study

BACKGROUND Liver transplant(LT)patients have become older and sicker.The rate of post-LT major adverse cardiovascular events(MACE)has increased,and this in turn raises 30-d post-LT mortality.Noninvasive cardiac stress testing loses accuracy when applied to pre-LT cirrhotic patients.AIM To assess the feasibility and accuracy of a machine learning model used to predict post-LT MACE in a regional cohort.METHODS This retrospective cohort study involved 575 LT patients from a Southern Brazilian academic center.We developed a predictive model for post-LT MACE(defined as a composite outcome of stroke,new-onset heart failure,severe arrhythmia,and myocardial infarction)using the extreme gradient boosting(XGBoost)machine learning model.We addressed missing data(below 20%)for relevant variables using the k-nearest neighbor imputation method,calculating the mean from the ten nearest neighbors for each case.The modeling dataset included 83 features,encompassing patient and laboratory data,cirrhosis complications,and pre-LT cardiac assessments.Model performance was assessed using the area under the receiver operating characteristic curve(AUROC).We also employed Shapley additive explanations(SHAP)to interpret feature impacts.The dataset was split into training(75%)and testing(25%)sets.Calibration was evaluated using the Brier score.We followed Transparent Reporting of a Multivariable Prediction Model for Individual Prognosis or Diagnosis guidelines for reporting.Scikit-learn and SHAP in Python 3 were used for all analyses.The supplementary material includes code for model development and a user-friendly online MACE prediction calculator.RESULTS Of the 537 included patients,23(4.46%)developed in-hospital MACE,with a mean age at transplantation of 52.9 years.The majority,66.1%,were male.The XGBoost model achieved an impressive AUROC of 0.89 during the training stage.This model exhibited accuracy,precision,recall,and F1-score values of 0.84,0.85,0.80,and 0.79,respectively.Calibration,as assessed by the Brier score,indicated excellent model calibration with a score of 0.07.Furthermore,SHAP values highlighted the significance of certain variables in predicting postoperative MACE,with negative noninvasive cardiac stress testing,use of nonselective beta-blockers,direct bilirubin levels,blood type O,and dynamic alterations on myocardial perfusion scintigraphy being the most influential factors at the cohort-wide level.These results highlight the predictive capability of our XGBoost model in assessing the risk of post-LT MACE,making it a valuable tool for clinical practice.CONCLUSION Our study successfully assessed the feasibility and accuracy of the XGBoost machine learning model in predicting post-LT MACE,using both cardiovascular and hepatic variables.The model demonstrated impressive performance,aligning with literature findings,and exhibited excellent calibration.Notably,our cautious approach to prevent overfitting and data leakage suggests the stability of results when applied to prospective data,reinforcing the model’s value as a reliable tool for predicting post-LT MACE in clinical practice.

Study on the preservation effects of the amputated forelimb by machine perfusion at physiological temperature

Purpose:Ischemia and hypoxia are the main factors limiting limb replantation and transplantation.Static cold storage(SCS),a common preservation method for tissues and organs,can only prolong limb ischemia time to 4-6 h.The normothermic machine perfusion(NMP)is a promising method for the preservation of tissues and organs,which can extend the preservation time in vitro by providing continuous oxygen and nutrients.This study aimed to evaluate the difference in the efficacy of the 2 limb preservation methods.Methods:The 6 forelimbs from beagle dogs were divided into 2 groups.In the SCS group(n=3),the limbs were preserved in a sterile refrigerator at 4°C for 24 h,and in the NMP group(n=3),the perfusate prepared with autologous blood was used for the oxygenated machine perfusion at physiological temperature for 24 h,and the solution was changed every 6 h.The effects of limb storage were evaluated by weight gain,perfusate biochemical analysis,enzyme-linked immunosorbent assay,and histological analysis.All statistical analyses and graphs were performed using GraphPad Prism 9.0 one-way or two-way analysis of variance.The p value of less than 0.05 was considered to indicate statistical significance.Results:In the NMP group,the weight gained percentage was 11.72%±4.06%;the hypoxia-inducible factor-1αcontents showed no significant changes;the shape of muscle fibers was normal;the gap between muscle fibers slightly increased,showing the intercellular distance of(30.19±2.83)μm;and the vascularα-smooth muscle actin(α-SMA)contents were lower than those in the normal blood vessels.The creatine kinase level in the perfusate of the NMP group increased from the beginning of perfusion,decreased after each perfusate change,and remained stable at the end of perfusion showing a peak level of 4097.6 U/L.The lactate dehydrogenase level of the NMP group increased near the end of perfusion and reached the peak level of 374.4 U/L.In the SCS group,the percentage of weight gain was 0.18%±0.10%,and the contents of hypoxia-inducible factor-1αincreased gradually and reached the maximum level of(164.85±20.75)pg/mL at the end of the experiment.The muscle fibers lost their normal shape and the gap between muscle fibers increased,showing an intercellular distance of(41.66±5.38)μm.The contents of vascularα-SMA were much lower in the SCS group as compared to normal blood vessels.Conclusions:NMP caused lesser muscle damage and contained more vascularα-SMA as compared to SCS.This study demonstrated that NMP of the amputated limb with perfusate solution based on autologous blood could maintain the physiological activities of the limb for at least 24 h.

Influence of perfusate on liver viability during hypothermic machine perfusion

AIM: To optimize the perfusates used for hypothermicmachine perfusion(HMP).METHODS: Sprague-Dawley rats were assigned randomly to three groups(n = 12 per group) that received either saline, University of Wisconsin coldstorage solution(UW) or histidine-tryptophan-ketoglutarate solution(HTK) as the perfusate. Each group was divided into two subgroups: static cold storage(SCS) and HMP(n = 6 per subgroup). The liver graft was retrieved according to the method described by Kamada. For the SCS group, the graft was directly placed into cold perfusate(0-4?℃) for 6 h after liver isolation while the portal vein of the graft was connected to the perfusion machine for the HMP group. Then the perfusates were collected at different time points for analysis of aspartate aminotransferase(AST), alanine transaminase(ALT) and lactate dehydrogenase(LDH) levels. Liver tissues were obtained for evaluation of histology, dry/wet weight(D/W) ratio, and malondialdehyde(MDA) and adenosine-triphosphate(ATP) levels. The portal vein pressure and velocity were monitored in real time in all HMP subgroups.RESULTS: Comparison of HMP and SCS: Regardless of the perfusate, HMP improved the architecture of donor graft in reducing the congestion around sinusoids and central vein and maintaining sinusoid lining in morphology; HMP improved liver function in terms of ALT, AST and LDH, especially during the 3-6 h period(SCS vs HMP using saline: ALT3, 225.00 ± 105.62 vs 49.50 ± 18.50, P = 0.047; LDH3, 1362.17 ± 563.30 vs 325.75 ± 147.43, P = 0.041; UW: LDH6, 2880.14 ± 948.46 vs 2135.00 ± 174.27, P = 0.049; HTK, AST6, 307.50 ± 52.95 vs 185.20 ± 20.46, P = 0.041); HMP decreased MDA level(saline, 2.79 ± 0.30 vs 1.09 ± 0.09, P = 0.008; UW, 3.01 ± 0.77 vs 1.23 ± 0.68, P = 0.005; HTK, 3.30 ± 0.52 vs 1.56 ± 0.22, P = 0.006). Comparison among HMP subgroups: HTK showed less portal vein resistance than UW and saline(vs saline, 3.41 ± 0.49 vs 5.00 ± 0.38, P < 0.001; vs UW, 3.41 ± 0.49 vs 4.52 ± 0.63, P = 0.007); UW reduced edema most efficiently(vs saline, 0.68 ± 0.02 vs 0.79 ± 0.05, P = 0.013), while HTK maintained ATP levels best(vs saline, 622.60 ± 29.11 vs 327.43 ± 44.66, P < 0.001; vs UW, 622.60 ± 29.11 vs 301.80 ± 37.68, P < 0.001).CONCLUSION: HMP is superior to SCS in maintaining both architecture and function of liver grafts. Further, HTK was found to be the optimal perfusate for HMP.

Mechanisms of autophagy activation in endothelial cell and their targeting during normothermic machine liver perfusion

Ischaemia-reperfusion injury(IRI) is the leading cause of injury seen in the liver following transplantation. IRI also causes injury following liver surgery and haemodynamic shock. The first cells within the liver to be injured by IRI are the liver sinusoidal endothelial cells(LSEC). Recent evidence suggests that LSEC coordinate and regulates the livers response to a variety of injuries. It is becoming increasingly apparent that the cyto-protective cellular process of autophagy is a key regulator of IRI. In particular LSEC autophagy may be an essential gatekeeper to the development of IRI. The recent availability of liver perfusion devices has allowed for the therapeutic targeting of autophagy to reduce IRI. In particular normothermic machine liver perfusion(NMP-L) allow the delivery of pharmacological agents to donor livers whilst maintaining physiological temperature and hepatic flow rates. In this review we summarise the current understanding of endothelial autophagy and how this may be manipulated during NMP-L to reduce liver IRI.

Liver graft preservation methods during cold ischemia phase and normothermic machine perfusion

The growing demand for donor organs requires measures to expand donor pool.Those include extended criteria donors, such as elderly people, steatotic livers,donation after cardiac death, etc. Static cold storage to reduce metabolic requirements developed by Collins in late 1960 s is the mainstay and the golden standard for donated organ protection. Hypothermic machine perfusion provides dynamic organ preservation at 4°C with protracted infusion of metabolic substrates to the graft during the ex vivo period. It has been used instead of static cold storage or after it as short perfusion in transplant center. Normothermic machine perfusion(NMP) delivers oxygen, and nutrition at physiological temperature mimicking regular environment in order to support cellular function. This would minimize effects of ischemia/reperfusion injury.Potentially, NMP may help to estimate graft functionality before implantation into a recipient. Clinical studies demonstrated at least its non-inferiority or better outcomes vs static cold storage. Regular grafts donated after brain death could be safely preserved with convenient static cold storage. Except for prolonged ischemia time where hypothermic machine perfusion started in transplant center could be estimated to provide possible positive reconditioning effect. Use of hypothermic machine perfusion in regular donation instead of static cold storage or in extended criteria donors requires further investigation. Multicenter randomized clinical trial supposed to be completed in December 2021. Extended criteria donors need additional measures for graft storage and assessment until its implantation. NMP is actively evaluating promising method for this purpose.Future studies are necessary for precise estimation and confirmation to issue clinical practice recommendations.

Machine perfusion for liver transplantation:A concise review of clinical trials

Background: With the increased use of extended-criteria donors, static cold storage has failed to provide optimal preservation of liver grafts, resulting in early allograft dysfunction and long-term complications Machine perfusion(MP) is a beneficial alternative preservation strategy for donor livers, particularly fo those considered to be of suboptimal quality, and could expand the limited donor pool. Data sources: A comprehensive search in Pub Med, EMBASE, Ovid databases and Clinical Trials.gov website was conducted using the medical subject heading terms "machine perfusion", "machine preservation""liver transplantation", combined with free text terms such as "hypothermic", "normothermic" and "sub normothermic". The deadline for the search was September 30, 2017. Results: MP can be classified as hypothermic, subnormothermic, and normothermic with the tempera ture maintained at 0–12 °C, 25–34 °C and 35–38 °C, respectively. Twelve clinical trials of MP have been reported in recent years. MP effectively decreased AST/ALT level and the incidence of early allograft dys function. However, the graft and patient survival rate after MP were similar to static cold storage. The detailed clinical characteristics such as liver function, graft survival, patient survival and early allograf dysfunction were reviewed.Conclusions: Clinical trial results showed that MP improves delayed graft function, primary non-function and biliary strictures. However, MP still requires validation in large clinical trials and the key parameters during MP still require optimization.

Hypothermic machine perfusion with metformin-University of Wisconsin solution for ex vivo preservation of standard and marginal liver grafts in a rat model

AIM To compare the effect of University of Wisconsin(UW) solution with or without metformin, an AMP-activated protein kinase(AMPK) activator, for preserving standard and marginal liver grafts of young and aged rats ex vivo by hypothermic machine perfusion(HMP).METHODS Eighteen young(4 mo old) and 18 aged(17 mo old)healthy male SD rats were selected and randomly divided into three groups: control group, UW solution perfusion group(UWP), and UW solution with metformin perfusion group(MUWP). Aspartate aminotransferase(AST), alanine aminotransferase(ALT), lactate dehydrogenase(LDH), interleukin-18(IL-18), and tumor necrosis factor-alpha(TNF-α) in the perfused liquid were tested. The expression levels of AMPK and endothelial nitric oxide synthase(e NOS) in liver sinusoidal endothelial cells were also examined.Additionally, microscopic evaluation of the harvested perfused liver tissue samples was done. RESULTS AST, ALT, LDH, IL-18 and TNF-α levels in the young and aged liver-perfused liquid were, respectively,significantly lower in the MUWP group than in the UWP group(P < 0.05), but no significant differences were found between the young and aged MUWP groups.Metformin increased the expression of AMPK and e NOS protein levels, and promoted the extracellular release of nitric oxide through activation of the AMPK-e NOS mediated pathway. Histological examination revealed that in the MUWP group, the extent of liver cells and tissue damage was significantly reduced compared with the UWP group.CONCLUSION The addition of metformin to the UW preservative solution for ex vivo HMP can reduce rat liver injury during cold ischemia, with significant protective effects on livers, especially of aged rats.

Machine perfusion of the liver: Which is the best technique to mitigate ischaemia-reperfusion injury?

Longstanding research describes the mechanisms whereby the restoration of blood flow and reoxygenation(reperfusion) aggravates the ischaemic injury caused by a period of anoxia to a donor liver. This phenomenon, called ischaemia-reperfusion injury(IRI), leads to parenchymal cell death,microcirculatory failure, and inflammatory immune response. Clinically, IRI is the main factor responsible for the occurrence of posttransplant graft dysfunction and ischaemic-type biliary lesions. While extended criteria donor livers are more vulnerable to IRI, their utilisation is required to address the shortfall in donor organs. Thus, the mitigation of IRI should drive the setting of a new benchmark for marginal organ preservation. Herein, strategies incorporating different modalities of machine perfusion of the liver to alleviate IRI are discussed in conjunction with advantages and disadvantages of individual protocols.Techniques leading to reperfusion of the liver during machine perfusion(in situ normothermic regional perfusion and ex situ normothermic machine perfusion)may mitigate IRI by shortening the ischaemic period of the organs. This benefit potentially escalates from the minimum level, obtained following just partial alleviation of the ischaemic period, to the maximum level, which can be potentially achieved with ischaemia-free organ transplantation. Techniques that do not lead to reperfusion of the liver during machine perfusion(hypothermic,subnormothermic, and controlled-oxygenated rewarming) optimise mitochondrial oxidative function and replenish cellular energy stores, thereby lowering reactive oxygen species production as well as the activation ofdownstream inflammatory pathways during reperfusion. Further mechanistic insights into IRI may guide the development of donor-specific protocols of machine perfusion on the basis of the limitations of individual categories of extended criteria donor organs.

Current and future perspectives on acute-on-chronic liver failure: Challenges of transplantation, machine perfusion, and beyond

Acute-on-chronic liver failure(ACLF)is a syndrome that occurs in patients with chronic liver disease and is characterized by acute decompensation,organ failure and high short-term mortality.Partially due to the lack of universal diagnostic criteria,the actual ACLF prevalence remains unclear;nevertheless,it is expected to be a highly prevalent condition worldwide.Earlier transplantation is an effective protective measure for selected ACLF patients.Besides liver transplantation,diagnosing and treating precipitant events and providing supportive treatment for organ failures are currently the cornerstone of ACLF therapy.Although new clinical specific therapies have been researched,more studies are necessary to assess safety and efficacy.Therefore,future ACLF management strategies must consider measures to improve access to liver transplantation because the time window for this life-saving therapy is frequently narrow.Thus,an urgent and global discussion about allocation and prioritization for transplantation in critically ill ACLF patients is needed because there is evidence suggesting that the current model may not portray their waitlist mortality.In addition,while donor organ quality is meant to be a prognostic factor in the ACLF setting,recent evidence suggests that machine perfusion of the liver may be a safe tool to improve the donor organ pool and expedite liver transplantation in this scenario.

Therapeutics administered during ex vivo liver machine perfusion:An overview

Although the use of extended criteria donors has increased the pool of available livers for transplant,it has also introduced the need to develop improved methods of protection against ischemia-reperfusion injury(IRI),as these"marginal"organs are particularly vulnerable to IRI during the process of procurement,preservation,surgery,and post-transplantation.In this review,we explore the current basic science research investigating therapeutics administered during ex vivo liver machine perfusion aimed at mitigating the effects of IRI in the liver transplantation process.These various categories of therapeutics are utilized during the perfusion process and include invoking the RNA interference pathway,utilizing defatting cocktails,and administering classes of agents such as vasodilators,anti-inflammatory drugs,human liver stem cell-derived extracellular vesicles,and δ-opioid agonists in order to reduce the damage of IRI.Ex vivo machine perfusion is an attractive alternative to static cold storage due to its ability to continuously perfuse the organ,effectively deliver substrates and oxygen required for cellular metabolism,therapeutically administer pharmacological or cytoprotective agents,and continuously monitor organ viability during perfusion.The use of administered therapeutics during machine liver perfusion has demonstrated promising results in basic science studies.While novel therapeutic approaches to combat IRI are being developed through basic science research,their use in clinical medicine and treatment in patients for liver transplantation has yet to be explored.

Machine perfusion in abdominal organ transplantation: Current use in the Netherlands

Scarcity of donor organs and the increment in patients awaiting a transplant increased the use of organs from expanded criteria donors or donation after circulatory death.Due to the suboptimal outcomes of these donor organs,there is an increased interest in better preservation methods,such as ex vivo machine perfusion or abdominal regional perfusion to improve outcomes.This state-ofthe-art review aims to discuss the available types of perfusion techniques,its potential benefits and the available evidence in kidney,liver and pancreas transplantation.Additionally,translational steps from animal models towards clinical studies will be described,as well as its application to clinical practice,with the focus on the Netherlands.Despite the lack of evidence from randomized controlled trials,currently available data suggest especially beneficial effects of normothermic regional perfusion on biliary complications and ischemic cholangiopathy after liver transplantation.For ex vivo machine perfusion in kidney transplantation,hypothermic machine perfusion has proven to be beneficial over static cold storage in a randomized controlled trial,while normothermic machine perfusion is currently under investigation.For ex vivo machine perfusion in liver transplantation,normothermic machine perfusion has proven to reduce discard rates and early allograft dysfunction.In response to clinical studies,hypothermic machine perfusion for deceased donor kidneys has already been implemented as standard of care in the Netherlands.

Concise review of machine perfusion in liver transplantation

With the advances and clinical growth in liver transplantation over the last four decades the focus on expanding deceased donor organs has been in need of scientific research.In the past ten years several researchers have looked at the domain of machine perfusion as it applies to deceased donor livers.The following review focuses on the clinical trials and recent advances that will likely have the earliest entrance into the clinical arena.

Machine perfusion of the liver:Putting the puzzle pieces together

The realm of extended criteria liver transplantation created the'adjacent possible'for dynamic organ preservation.Machine perfusion of the liver greatly expanded donor organ preservation possibilities,reaching before unattainable goals,including the mitigation of ischemia-reperfusion injury,viability assessment,and organ reconditioning prior to transplantation.However,current scientific evidence lacks uniformity between studies,perfusion protocols,and acceptance criteria.Construction of collaborative research networks for sharing knowledge should,therefore,enable the development of high-level evidence and guidelines for machine perfusion utilization,including donor acceptance criteria.Finally,this approach shall guarantee conditions for further progress to occur.