Machine Preservation Research Articles

The 24-hour normothermic machine perfusion of discarded human liver grafts.

Donor organ shortage necessitates use of less than optimal donor allografts for transplantation. The current cold storage preservation technique fails to preserve marginal donor grafts sufficiently. Evidence from large animal experiments suggests superiority of normothermic machine preservation (NMP) of liver allografts. In this study, we analyze discarded human liver grafts that underwent NMP for the extended period of 24 hours. Thirteen human liver grafts which had been discarded for transplantation were entered into this study. Perfusion was performed with an automated device using an oxygenated, sanguineous perfusion solution at normothermia. Automated control was incorporated for temperature-, flow-, and pressure-regulation as well as oxygenation. All livers were perfused for 24 hours; parameters of biochemical and synthetic liver function as well as histological parameters of liver damage were analyzed. Livers were stratified for expected viability according to the donor's medical history, procurement data, and their macroscopic appearance. Normothermic perfusion preservation of human livers for 24 hours was shown to be technically feasible. Human liver grafts, all of which had been discarded for transplantation, showed levels suggesting organ viability with respect to metabolic and synthetic liver function (to varying degrees). There was positive correlation between instantly available perfusion parameters and generally accepted predictors of posttransplant graft survival. In conclusion, NMP is feasible reliably for periods of at least 24 hours, even in highly suboptimal donor organs. Potential benefits include not only viability testing (as suggested in recent clinical implementations), but also removal of the time constraints associated with the utilization of high-risk livers, and recovery of ischemic and other preretrieval injuries (possibly by enabling therapeutic strategies during NMP). Liver Transplantation 23 207-220 2017 AASLD.

Normothermic Machine Perfusion of Deceased Donor Liver Grafts Is Associated With Improved Postreperfusion Hemodynamics.

BackgroundGraft reperfusion poses a critical challenge during liver transplantation and can be associated with hemodynamic instability/postreperfusion syndrome. This is sequel to ischemia-reperfusion injury and normothermic machine preservation (NMP) may affect hemodynamic changes. Herein, we characterize postreperfusion hemodynamics in liver grafts after NMP and traditional cold preservation.Materials and methodsIntraoperative records of patients receiving grafts after NMP (n = 6; NMP group) and cold storage (CS) (n = 12; CS group) were compared. The mean arterial pressure (MAP) was defined as the average pressure in the radial artery during 1 cardiac cycle by invasive monitoring. Postreperfusion syndrome was defined as MAP drop greater than 30% of baseline, lasting for 1 minute or longer within the first 5 minutes from graft reperfusion.ResultsDonor, recipient, demographics, and surgical parameters were evenly matched. Normothermic machine preservation grafts were perfused for 525 minutes (395-605 minutes) after initial cold ischemic time of 91 minutes (73-117 minutes), whereas in CS group cold ischemic time was 456 minutes (347-685 minutes) (P = 0.001). None developed postreperfusion syndrome in the NMP group against n = 2 (16.7%) in CS group (P = 0.529). Normothermic machine preservation group had better intraoperative MAP at 90 minutes postreperfusion (P = 0.029), achieved with a significantly less vasopressor requirement (P = <0.05) and less transfusion of blood products (P = 0.030) compared with CS group.ConclusionsNormothermic machine perfusion is associated with a stable intraoperative hemodynamic profile postreperfusion, requiring significantly less vasopressor infusions and blood product transfusion after graft reperfusion and may have benefit to alleviate ischemia-reperfusion injury in liver transplantation.

Applicability of Combined Use of Extracorporeal Support and Temperature-Controlled Machine Perfusion Preservation for Liver Procurement of Donors After Cardiac Death in Pigs

BackgroundThe use of grafts from donors after cardiac death (DCD) would greatly contribute to the expansion of the donor organ pool. The objective of this study is to determine the benefits of extracorporeal membrane oxygenation (ECMO) and subnormothermic machine perfusion (MP) with rewarming in a large animal model of DCD liver. MethodsAfter cardiac arrest, the abdominal aorta and the inferior vena cava were cannulated and connected to an ECMO circuit. Porcine livers were perfused in situ with ECMO at 22°C for 60 minutes after 60 minutes of cardiac death. Then the livers were perfused for 4 hours by MP as a graft viability test. In group 1, non–in situ ECMO and grafts were preserved hypothermic MP. In group 2, non–in situ ECMO and grafts were preserved subnormothermic rewarming MP. In group 3, we used ECMO and subnormothermic rewarming MP. To assess potential methods and effect, effluent enzymes were measured. Portal vein and hepatic artery pressure during MP were evaluated. ResultsEffluent enzyme of AST, alanine aminotransferase and LDH as viability markers were significantly low (aspartate aminotransferase, 2899, 2292, and 972 IU/L; alanine aminotransferase, 134, 140, and 72 IU/L; and lactate dehydrogenase, 4354, 4455, and 1855 IU/L in each group, respectively). Portal vein and hepatic artery pressure during preservation came down smoothly in group 3 compared with group 1. ConclusionsThe combined use of in situ subnormothermic ECMO and machine preservation with rewarming is more essential for the recovery and resuscitating function of DCD liver grafts.

14-3-3ζ-Mediated Stimulation of Oxidative Phosphorylation Exacerbates Oxidative Damage Under Hypothermic Oxygenated Conditions in Human Renal Tubular Cells (HK-2)

Cellular survival and death are at least partially regulated by the phosphorylation of proteins. A chaperon protein, 14-3-3ζ, regulates the activity of many proteins by covering the phosphorylation site within a 14-3-3 binding motif. Therefore, regulation of 14-3-3ζ activity may affect the fate of cells subjected to cold preservation and/or hypothermic oxygenated conditions. The present study assessed whether 14-3-3ζ protects cells from hypothermic oxygenation-induced injury and clarified its role in mitochondrial functions. Human renal tubular cell line HK-2 or 14-3-3ζ-overexpressed HK-2 (ζHK-2) cells were subjected to 72 hours of normoxic cold preservation in UW solution with or without antioxidants and hydroperoxides. Cellular death, adenosine triphosphate (ATP) content, and MTT catabolism were evaluated. Deferoxamine treatment reduced cellular death and augmented ATP content in both cell types. These indices were higher in ζHK-2, regardless of deferoxamine treatment. Exposure to hydroperoxides did not affect cellular death in either cell type, whereas hydroperoxide supplementation significantly reduced ATP content, except for low-dose hydrogen peroxide in HK-2 cells. MTT assay at normal state showed higher values in ζHK-2 cells, whereas it was impaired by hydroperoxides in both cell types. These results suggest that accumulation of hydroperoxides as a byproduct of the augmented oxidative phosphorylation by 14-3-3ζ overexpression causes mitochondrial dysfunction. In conclusion, despite possessing many potentially protective functions, 14-3-3ζ exacerbates cellular injury under hypothermic oxygenated conditions. 14-3-3ζ accelerates mitochondrial functions together with iron-dependent oxidative damage. Although further investigations are necessary, upregulation of 14-3-3ζ could be a method to maintain mitochondrial function under hypothermic oxygenated conditions, as shown in hypothermic machine preservation of renal grafts, when appropriate antioxidant treatment is administered.

Successful Kidney and Lung Transplantation From a Deceased Donor With Blunt Abdominal Trauma and Intestinal Perforation.

The number of organ donors is limited by many contraindications for donation and poor quality of potential organ donors. Abdominal infection is a generally accepted contraindication for donation of abdominal organs. We present a 43-year-old man with lethal brain injury, blunt abdominal trauma, and intestinal perforation. After withdrawal of life-sustaining treatment and circulatory arrest, a minilaparotomy confirmed abdominal contamination with intestinal content. After closure of the abdomen, organs were preserved with in situ preservation with an aortic cannula inserted via the femoral artery. Thereafter, the kidneys were procured via bilateral lumbotomy to reduce the risk of direct bacterial contamination; lungs were retrieved following a standard practice. There was no bacterial or fungal growth in the machine preservation fluid of both kidneys. All organs were successfully transplanted, without postoperative infection, and functioned well after 6 months. We hereby show that direct contamination of organs can be avoided with the use of in situ preservation and retroperitoneal procurement. Intestinal perforation is not an absolute contraindication for donation, although the risk of bacterial or fungal transmission has to be evaluated per case.

Kidney and liver transplantation in the elderly.

Transplant surgery is facing a shortage of deceased donor organs. In response, the criteria for organ donation have been extended, and an increasing number of organs from older donors are being used. For recipients, the benefits of transplantation are great, and the growing ageing population has led to increasing numbers of elderly patients being accepted for transplantation. The literature was reviewed to investigate the impact of age of donors and recipients in abdominal organ transplantation, and to highlight aspects of the fine balance in donor and recipient selection and screening, as well as allocation policies fair to young and old alike. Overall, kidney and liver transplantation from older deceased donors have good outcomes, but are not as good as those from younger donors. Careful donor selection based on risk indices, and potentially biomarkers, special allocation schemes to match elderly donors with elderly recipients, and vigorous recipient selection, allows good outcomes with increasing age of both donors and recipients. The results of live kidney donation have been excellent for donor and recipient, and there is a trend towards inclusion of older donors. Future strategies, including personalized immunosuppression for older recipients as well as machine preservation and reconditioning of donor organs, are promising ways to improve the outcome of transplantation between older donors and older recipients. Kidney and liver transplantation in the elderly is a clinical reality. Outcomes are good, but can be optimized by using strategies that modify donor risk factors and recipient co-morbidities, and personalized approaches to organ allocation and immunosuppression.

Meeting report of the 2014 joint international congress of the International Liver Transplantation Society, Liver Intensive Care Group of Europe, and European Liver and Intestinal Association.

The 2014 Annual Meeting of the International Liver Transplantation Society was held in London, England. This was the 20th meeting of the Society and was marked by a joint meeting including the European Liver and Intestinal Association as well as the Liver Intensive Care Group of Europe. The meeting included symposia, invited lectures, debates, oral presentations, and posters. The principal themes were living donation, expanding the deceased donor pool, machine preservation, and new oral therapies for hepatitis C virus. This report highlights the scientific discussions of this meeting.

Controlled Rewarming after Hypothermia: Adding a New Principle to Renal Preservation.

Early graft dysfunction due to preservation/reperfusion injury still represents a notable issue after kidney transplantation, affecting long term prognosis of graft viability. One trigger of postischemic cell dysfunction could be recognized in the abrupt temperature shift from hypo‐ to normothermia, leading to mitochondrial dysfunction and proapoptotic signal transduction.Here we propose a technique to cope with this “rewarming injury” by interposing a period of gentle warming up by hypo‐ to subnormothermic machine perfusion of the isolated graft prior to warm reperfusion. Porcine kidneys were subjected either to 18 hours of hypothermic machine preservation (HMP) or 18 hours static cold storage + 3 hours of gentle, machine controlled oxygenated rewarming (COR). Functional integrity was evaluated in both groups by subsequent normothermic reperfusion in vitro.The functional benefit of COR was documented by an approximately twofold increase in renal clearances of creatinine as well as urea upon warm reperfusion, compared to controls. This was accompanied with a notable mitigation of postischemic mitochondrial dys‐homeostasis. COR significantly improved renal oxygen consumption and maintained total NAD tissue content upon reperfusion. Mitochondrial initiation of cellular apoptosis, as evidenced by activation of caspase 9 was also largely prevented after COR but not in controls.The concept of gentle regenerative graft rewarming could become a valuable adjunct in renal transplantation.

Hypothermic Machine Preservation Facilitates Successful Transplantation of “Orphan” Extended Criteria Donor Livers

Hypothermic machine preservation (HMP) remains investigational in clinical liver transplantation. It is widely used to preserve kidneys for transplantation with improved results over static cold storage (SCS). At our center, we have used HMP in 31 adults receiving extended criteria donor (ECD) livers declined by the originating United Network for Organ Sharing region ("orphan livers"). These cases were compared to ECD SCS cases in a matched cohort study design. Livers were matched for donor age, recipient age, cold ischemic time, donor risk index and Model for End-Stage Liver Disease (MELD) score. HMP was performed for 3-7 h at 4-8 °C using our previously published protocol. Early allograft dysfunction rates were 19% in the HMP group versus 30% in the control group (p = 0.384). One-year patient survival was 84% in the HMP group versus 80% in the SCS group (p = NS). Post hoc analysis revealed significantly less biliary complications in the HMP group versus the SCS group (4 vs. 13, p = 0.016). Mean hospital stay was significantly shorter in the HMP group (13.64 ± 10.9 vs. 20.14 ± 11.12 days in the SCS group, p = 0.001). HMP provided safe and reliable preservation in orphan livers transplanted at our center.

Breaking the Ice: Early Clinical Results Using Hypothermic Machine Liver Preservation

Hypothermic machine preservation (HMP) remains investigational in clinical liver transplantation. It is widely used, however, to preserve kidneys for transplantation because it has demonstrated improved results over static cold storage (CS). As with other machine preservations methods, HMP provides continuous circulation of nutrients and metabolic substrates during the ex-vivo period. Over the last few years, several groups worldwide have been actively translating HMP into the clinical arena for liver transplantation. In particular, HMP has been used for livers of varying quality, including those recovered from extended criteria donors (ECD) and donation after cardiac death (DCD) donors. Reports to date have focused on recipient hospital based HMP during the latter portion of the cold ischemic period. While some variability exists in technique, all clinical series to date have reported improved outcomes with reductions in early allograft dysfunction, biliary complications and reduced hospital length of stay. These benefits, together with the development of innovative portable HMP devices and further adoption by more centers worldwide, have “broken the ice” for more widespread use of HMP and subsequent expanded elucidation of its benefits.

Hypothermic Machine Perfusion in Kidney Transplantation: Back to the Future?

Static cold storage is currently the most used method of organ preservation worldwide. However, cutting edge technology and dramatic changes in the donor pattern have lately renewed the interest toward hypothermic machine perfusion. Marginal and cardiac death donors show higher rates of primary non function and delayed graft function compared to standard criteria donors. In this setting, machine perfusion may offer several theoretical advantages such as improved organ preservation, continuous graft evaluation, and ex-vivo conditioning of the graft before implantation. These topics have been recently reassessed by several studies. In particular, perfusion characteristics (renal resistance) and perfusate biomarker concentrations (lactate dehydrogenase, aspartate aminotransferase, heart-type fatty acid binding protein, and IL-18) during machine preservation, proved to be reliable tools to rule out graft viability and predict outcomes after transplantation. Treatment strategies acting on tissue repair, cell metabolism, and allorecognition pathway are also under investigation with promising results. Machine perfusion has finally shown its real potential however, stronger evidences and updated cost-effectiveness analysis are needed to fully support its role for the next future.

Resistance Index Determination in the Pre and Post Kidney Transplantation Time Points in Graft Dysfunction Diagnosis

BackgroundDonor shortage necessitates the development of tools capable of objectively assessing kidney graft quality from expanded criteria donors and kidneys donated after cardiac death. The deteriorating donor profile is leading to a shift from cold storage toward machine perfusion preservation. Several authors found that renal resistance (RR) at the end of machine perfusion was an independent risk factor for the development of delayed graft function (DGF). In contrast, Doppler ultrasonography in the posttransplant period reveals renal hemodynamics and is useful in diagnosing renal allograft dysfunction. We sought to determine concordance between RR and the resistance index (RI) and their diagnostic value in the assessment of graft viability. MethodsRR was determined at the end of perfusion during hypothermic machine preservation and RI was measured by Doppler ultrasonography in the early posttransplant period. Agreement between these 2 measures was established by means of the intraclass correlation coefficient (ICC). Diagnostic validity for RR and RI was determined by sensitivity, specificity and positive and negative predictive values. ResultsThe ICC was 0.135, which indicates a slight agreement. RR and RI had limited value in the prediction of DGF for a specific kidney as reflected by a c-statistic of 0.58 and 0.66, respectively. ConclusionsThere is no agreement between the RR and RI, which may be owing to the different conditions under which measurements are made. The poor predictive power of RR for DGF indicates that kidneys should not be discarded based on RR criteria alone.

Expanded Criteria Donors: The End of an Era.

Expanded criteria donor (ECD) kidneys increase the donor organ pool but their value has been questioned because of expected lower survival outcomes. With the development of the Kidney Donor Risk Index and a new allocation system, the end of the ECD kidney era is imminent. The study purpose was to retrospectively review our 12 year single center experience with ECD kidney transplants (KT). Methods: All patients (pts) received antibody induction with tacrolimus/mycophenolate ± steroids. Standardized management algorithms were implemented to preserve nephron function (including machine preservation) and pt selection was based on low immunological risk and predicted limited nephron need. Results: Over a 12 year period, we performed 1366 deceased donor KTs in adult pts including 468 (34%) from ECDs; 245 pts (53%) had at least 5 years follow-up. 36 KTs were from DCD/ECDs and 46 dual KTs were performed. With a mean follow-up of 4 years, actual pt survival was 75% and graft survival was 59%. 75 pts (16%) experienced death with a functioning graft (DWFG), so death-censored graft survival was 70%. One year pt and graft survival were 94% and 86%. Outcomes were analyzed according to recipient age categories (<50, n=70; 50-59, n=116; 60-69, n=185; >70, n=95). The incidence of primary nonfunction was slightly higher in the oldest and youngest (6%) compared to the 2 mid-age recipient categories (4%, p=NS). DWFGs were significantly higher in the oldest (22%) compared to the youngest recipient category (8.6%, p=0.03), whereas the incidence was intermediate (16%) in the 2 mid-age categories. One-year mortality was also higher in the oldest (9.5%) compared to the three younger recipient age categories (4.9%, p=0.09). Overall mortality rates increased with older age category from 19% in youngest to 28% in oldest recipients (p=NS). One year rates of graft loss were 12.3% in the 2 younger compared to 15% in the 2 older categories (p=NS). However, the overall rate of graft loss was 47% in the youngest compared to 40% in the 3 older categories (p=NS). Conclusions: By appropriate donor and recipient profiling and the use of management algorithms aimed at preserving renal function, acceptable intermediate-term outcomes can be achieved with ECD KTs irrespective of recipient age.

Hypothermic Machine Preservation and Transplantation of “Orphan” Extended Criteria Donor Livers.

Introduction: Hypothermic machine perfusion (HMP) remains investigational in clinical liver transplantation despite widespread utilization in renal transplantation with improved results. Our group has reported the only clinical liver HMP series worldwide with promising results. The aim of this study was to investigate liver HMP in Extended Criteria Donor (ECD) Livers turned down by all other centers in the originating UNOS region (“orphan livers”). Methods: All included HMP livers were “orphan livers” and met at least one of the following ECD Criteria 1) Donor age>65; 2) >25% Macrosteatosis; 3) HCV+ and at least 15% macrosteatosis; 4) donor ischemic injury with AST or ALT>1,000 at time of offer. Thirty one livers were included in the study and underwent HMP for 3-7hrs using centrifugal perfusion with Vasosol® solution and were allografts for solitary, primary transplants in patients with a MELD score<35. These cases were matched to historical Cold Storage (CS) controls based on donor and recipient age, cold ischemic time, donor risk index and MELD score. Results: There were no technical or mechanical failures of HMP. Perfusate electrolytes and parameters were stable in almost all cases. Perfusate levels of AST correlated with the recipient’s peak serum AST on linear regression. There were 2 cases of Primary nonfunction in the CS group and one in the HMP group. Early allograft dysfunction (EAD) rates were 30% in CS controls vs 19% in the HMP group. Time to normalization of serum markers of liver and renal function were lower in the HMP group with serum creatinine on POD 5 being significantly lower in the HMP group. At 12 months, there were five deaths in the HMP group and 6 in the CS group (p=NS). Biliary complications were significantly lower in the HMP group compared to the CS group (4 vs 13, p=0.016) with almost twice as many ERCPs required in the CS group. Mean hospital stay was significantly shorter in the HMP group (13.65±10.9 days vs. 20.14±11.12 days in the CS group, p=0.012). HMP of orphan extended criteria donor livers provided safe and reliable preservation with significantly less biliary complications and overall length of stay in HMP patients. Further multicenter experience with HMP is necessary to further elucidate clinical benefits of HMP in Liver Transplantation.

Biomarkers to assess graft quality during conventional and machine preservation in liver transplantation

A global rising organ shortage necessitates the use of extended criteria donors (ECD) for liver transplantation (LT). However, poor preservation and extensive ischemic injury of ECD grafts have been recognized as important factors associated with primary non-function, early allograft dysfunction, and biliary complications after LT. In order to prevent for these ischemia-related complications, machine perfusion (MP) has gained interest as a technique to optimize preservation of grafts and to provide the opportunity to assess graft quality by screening for extensive ischemic injury. For this purpose, however, objective surrogate biomarkers are required which can be easily determined at time of graft preservation and the various techniques of MP. This review provides an overview and evaluation of biomarkers that have been investigated for the assessment of graft quality and viability testing during different types of MP. Moreover, studies regarding conventional graft preservation by static cold storage (SCS) were screened to identify biomarkers that correlated with either allograft dysfunction or biliary complications after LT and which could potentially be applied as predictive markers during MP. The pros and cons of the different biomaterials that are available for biomarker research during graft preservation are discussed, accompanied with suggestions for future research. Though many studies are currently still in the experimental setting or of low evidence level due to small cohort sizes, the biomarkers presented in this review provide a useful handle to monitor recovery of ECD grafts during clinical MP in the near future.

Analysis of Perfusates During Hypothermic Machine Perfusion by NMR Spectroscopy

Machine perfusion use has been reported to promote graft outcome in case of donation after cardiac death. Our objective was to evaluate the potential for nuclear magnetic resonance (NMR) to predict graft outcome by analyzing perfusates during machine perfusion time. We used a renal autotransplantation model mimicking deceased after cardiac death donors with pigs. Organs were subjected to 60 min of warm ischemia before the hypothermic machine preservation during 22 hr. We studied the correlation between creatinemia after transplantation and the NMR data from perfusates. A metabonomic analysis allowed us to highlight the evolution of several metabolites during perfusion: the concentration of lactate, choline, or amino acids such as valine, glycine, or glutamate increased with time, whereas there was a diminution of total glutathione during this period. The changes in these biomarkers were less severe in the group with the better outcome. Statistical analysis revealed a strong association between the level of those metabolites during machine perfusion and function recovery (Spearman rank ≥0.89; P<0.05). Multivariate analysis of lesion biomarkers during kidney perfusion using NMR data could be an interesting tool to assess graft quality, particularly because analyses times (2 hr total) are compatible with clinical application.

Pulsatile perfusion—time for a prospective trial

Pulsatile perfusion is increasingly being used to preserve kidneys harvested from non-standard-criteria donors. Indeed, retrospective analyses have shown that machine preservation is associated with reduced rates of delayed graft function. However, well-designed prospective clinical trials are needed to evaluate its impact on organ discard, rejection, long-term graft function, and cost.

Normothermic Machine Preservation as an Approach to Decrease Biliary Complications of DCD Liver Grafts

Normothermic Machine Preservation as an Approach to Decrease Biliary Complications of DCD Liver Grafts

Impact of static cold storage VS hypothermic machine preservation on ischemic kidney graft: inflammatory cytokines and adhesion molecules as markers of ischemia/reperfusion tissue damage. Our preliminary results

AbstractAt the present time, deceased heart-beating donor kidney allografts are usually stored cold. Extended-criteria donor (ECD) grafts show higher sensitivity to ischemia–reperfusion damage than standard kidneys. The increasing use of marginal organs in clinical transplantation urgently requires a more effective preservation system. Pulsatile hypothermic machine perfusion has shown major advantages over static cold storage in terms of reduced organ injury during preservation and improved early graft function. This preliminary study aims to compare pulsatile hypothermic machine perfusion and static cold storage of kidney allografts, outlining differences in the levels of early inflammatory cytokines (TNF-α, IL-2 and IL-1β) and soluble intracellular adhesion molecule (sICAM-1) in perfusion and preservation liquid.

Rewarming Machine Perfusion System for Liver Transplantation

The liver is one of the most essential organs, and transplantation is an established treatment for patients with end-stage disease who have lost their liver function. However, organ shortage is a critical problem in transplantation; thus, the development of an innovative preservation system to adopt critical grafts obtained from extended criteria donors or donation after cardiac death donors as viable organs for transplantation is necessary. We recently developed a novel rewarming machine perfusion preservation system for liver transplantation, and herein discuss this system, which allows the perfusion temperature to be controlled during the transition from hypothermic to subnormothermic conditions. This system has two functions: (1) the preservation and recovery of organ function and (2) screening the organ for viability. To achieve these functions, this system has three features: (1) temperature control of the preservation perfusate and liver graft, (2) dual-controlled perfusion of the portal vein and hepatic artery, and (3) real-time monitoring of the perfusion conditions, including the flow rate, perfusion pressure and temperature. This system was useful for liver preservation and for evaluating the graft viability and recovery of functions during machine perfusion before transplantation. This novel rewarming machine preservation system was tested in an experimental model using porcine liver grafts. We report that this system has certain advantages in liver preservation, and believe that this system will positively contribute to the expansion of the organ donor pool.