Current status of donation after cardiac death liver transplantation:

Age and liver graft: a systematic review with meta-regression

Increasing organ shortage results in extended criteria donors (ECD) being used to face the growing demand for liver grafts. The demographic change leads to greater use of elderly donors for liver transplantation, historically considered marginal donors. Age is still considered amongst ECD in liver transplantation as it could affect transplant outcomes. However, what is the cutoff for donor age is still unclear and debated. A search of PubMed, Scopus and Cochrane Library was performed. The primary outcome was 1-year graft survival (GS). The secondary outcome was overall biliary complications and 3-5 years of graft and overall survival. A meta-regression model was used to analyse the temporal trend relation in the survival outcome. The meta-analysis included 11 studies. Hazard ratios for 1-year (age cutoff of 70 and 80,) and 5-year GS (I2:0%) were similar irrespectively of the age group. The meta-regression analysis showed a significant correlation between the 1-year graft survival and the year of publication. (coef. 0.00027, 95% CI - 0.0001 to - 0.0003 p = 0.0009). Advanced-age donors showed an increased risk of overall biliary complications with an odd ratio (OR) of 1.89 (95% CI 1-3.65). Liver grafts potentially discharged because of high-risk failure show encouraging results, and GS in ECD has progressively improved with a temporal trend. Currently, the criteria of marginality vary amongst centres. Age alone cannot be considered amongst the extended criteria. First of all, because of the positive results in terms of septuagenarian graft survival. Moreover, the potential elderly donor-related adjunctive risk can be balanced by reducing other risk factors. A prospective multicentre study should investigate a multi-factorial model based on donor criteria, recipient features and new functional biomarkers to predict graft outcome, as proper donor-recipient matching seems to be the critical point for good outcomes.

The Role of Gut Microbiome-Derived Short-Chain Fatty Acid Butyrate in Hepatobiliary Diseases

The short-chain fatty acid butyrate, produced from fermentable carbohydrates by gut microbiota in the colon, has multiple beneficial effects on human health. At the intestinal level, butyrate regulates metabolism, helps in the transepithelial transport of fluids, inhibits inflammation, and induces the epithelial defense barrier. The liver receives a large amount of short-chain fatty acids via the blood flowing from the gut via the portal vein. Butyrate helps prevent nonalcoholic fatty liver disease, nonalcoholic steatohepatitis, inflammation, cancer, and liver injuries. It ameliorates metabolic diseases, including insulin resistance and obesity, and plays a direct role in preventing fatty liver diseases. Butyrate has different mechanisms of action, including strong regulatory effects on the expression of many genes by inhibiting the histone deacetylases and modulating cellular metabolism. The present review highlights the wide range of beneficial therapeutic and unfavorable adverse effects of butyrate, with a high potential for clinically important uses in several liver diseases.

Temporal Trends in Utilization and Outcomes of DCD Livers in the United States

BACKGROUND

Historically, donation after circulatory death (DCD) livers were frequently discarded because of higher mortality and graft loss after liver transplantation (LT). However, the demand for LT continues to outstrip the supply of "acceptable" organs. Additionally, changes in the donor pool, organ allocation, and clinical management of donors and recipients, and improved clinical protocols might have altered post-DCD-LT outcomes.

METHODS

We studied 5975 recovered DCD livers using US Scientific Registry of Transplant Recipients data from 2005 to 2017, with a comparison group of 78 235 adult donation after brain death (DBD) livers recovered during the same time period. We quantified temporal trends in discard using adjusted multilevel logistic regression and temporal trends in post-LT mortality and graft loss for DCD LT recipients using adjusted Cox regression.

RESULTS

DCD livers were more likely to be discarded than DBD livers across the entire study period, and the relative likelihood of discard increased over time (adjusted odds ratio [aOR] of discard DCD versus DBD 3.854.455.14 2005-2007, 5.225.876.59 2015-2017) despite improving outcomes after DCD LT. Mortality risk for DCD LTs decreased in each time period (compared with 2005-2007, aHR 2008-2011 0.720.840.97, aHR 2012-2014 0.480.580.70, aHR 2015-2017 0.340.430.55), as did risk of graft loss (compared with 2005-2007, aHR 2008-2011 0.690.810.94, aHR 2012-2014 0.450.550.67, aHR 2015-2017 0.360.450.56).

CONCLUSIONS

Despite dramatic improvements in outcomes of DCD LT recipients, DCD livers remain substantially more likely to be discarded than DBD livers, and this discrepancy has actually increased over time. DCD livers are underutilized and have the potential to expand the donor pool.

Changes in the Deceased-Donor Trend in Korea: Establishment of Regional Trauma Centers and KODA

South Korea utilizes living-donor liver transplantation to overcome a shortage of deceased donors. After the Korea Organ Donation Agency (KODA) was established, many hospitals were selected to be donor-managing hospital. A nationwide regional trauma center project was carried out separately in 2015. This study aims to analyze how the trend of deceased-donor recruitment and donation has changed based on policy factors such as independent organ-procurement organization (IOPO) activities and establishing regional trauma centers. KONOS data from 2010-2019 were used to analyze the impacts of these policy changes. The results showed that 62 centers had 4395 deceased donors, and 3863 recipients underwent deceased-donor liver transplantation. The two most common causes of donor death are cerebrovascular events and head trauma. When the rate of deceased donors was analyzed by the early period (2010-2014) and the late period (2015-2019), 53 non-trauma centers went from an average of 29.3 cases to 31.0 cases (6.2% increase) annually. Nine regional trauma centers showed a statistically significant increase from an average of 39.8 cases to 70.3 cases (75.9% increase) annually. Based on these policies, he locations where deceased donors are identified are changing. It is necessary to communicate with regional trauma center staff to recruit more deceased donors.

Design and realization of a normothermic perfusion system for laboratory tests on pig liver

Ex vivo testing is a fundamental step in the development of new medical devices; indeed without it, it is impossible to proceed with in vivo tests. At the University of Florence, a robotic tool for microwave thermal ablation is under development. Up to now, the thermoablation tests for the validation of the tool were carried out on non-perfused ex vivo livers, providing results that inevitably differ from those obtainable with an in vivo liver. The aim is to design, and consequently create, a compact and transportable system which allows to perfuse a swine liver with physiological solution and heparin. This device should also allow the organ to be transported from the explantation place to the laboratory, keeping it under normothermal condition. The perfusor was designed to simulate the physiological flow within the liver in the most realistic way possible. The design, construction, and optimization of the perfusor have been addressed using the physiological values of hepatic flow and pressure identified in the literature, neglecting in the first instance any load losses. Therefore, open circuit tests were conducted, validated through perfusion tests on freshly explanted pig liver; during these tests, the surface temperature of the organ was recorded using an infrared camera, and the fluid temperature was verified using an immersion probe. The perfusion test showed a good alignment with the open circuit tests, demonstrating the validity of the simplifications adopted to treat the complex vascular structure of the liver.

Controlled donation after circulatory death up to 80 years for liver transplantation: Pushing the limit again

Our main objective was to compare liver transplant (LT) results between donation after circulatory death (DCD) and donation after brainstem death (DBD) in our hospital and to analyze, within the DCD group, the influence of age on the results obtained with DCD donors aged >70 years and up to 80 years. All DCD-LTs performed were analyzed prospectively. The results of the DCD group were compared with those of a control group who received a DBD-LT immediately after each DCD-LT. Later, the results obtained within the DCD group were analyzed according to the age of the donors, considering 2 subgroups with a cut-off point at 70 years. Survival results for LT with DCD and super rapid recovery were not inferior to those obtained in a similar group of patients transplanted with DBD livers. However, the cost of DCD was a higher rate of biliary complications, including ischemic cholangiopathy. Donor age was not a negative factor.

Intraoperative Events in Liver Transplantation Using Donation After Circulatory Death Donors

Liver grafts from donation after circulatory death (DCD) are a source of organs to decrease wait-list mortality. While there have been lower rates of graft loss, there are concerns of an increased incidence of intraoperative events in recipients of DCD grafts. We aim to look at the incidence of intraoperative events between recipients of livers from DCD and donation after brain death (DBD) donors. We collected data for 235 DCD liver recipients between 2006 and 2017. We performed a 1:1 propensity match between these patients and patients with DBD donors. Variables included recipient age, liver disease etiology, biological Model for End-Stage Liver Disease (MELD) score, allocation MELD score, diagnosis of hepatocellular carcinoma, and year of transplantation. DCD and DBD groups had no significant differences in incidence of postreperfusion syndrome (P = 0.75), arrhythmia requiring cardiopulmonary resuscitation (P = 0.66), and treatments for hyperkalemia (P = 0.84). In the DCD group, there was a significant increase in amount of total intraoperative and postreperfusion blood products (with exception of postreperfusion packed red blood cells) utilized (P < 0.05 for all products), significant differences in postreperfusion thromboelastography parameters, as well as inotropes and vasopressors used (P < 0.05 for all infusions). There was no difference in patient (P = 0.49) and graft survival (P = 0.10) at 1, 3, and 5 years. In conclusion, DCD grafts compared with a cohort of DBD grafts have a similar low incidence of major intraoperative events, but increased incidence of transient vasopressor/inotropic usage and increased blood transfusion requirements. This does not result in differences in longterm outcomes. While centers should continue to look at DCD liver donors, they should be cognizant regarding intraoperative care to prevent adverse outcomes.

Frozen Sections of the Liver

Intraoperative consultation requires skills in gross examination and histologic diagnosis, as well as an ability to perform rapid interpretations under time constraints. The aim of this review is to provide surgical pathologists with a framework for dealing with hepatic specimens in the frozen section area by covering common clinical scenarios and histologic findings. Differential diagnoses are considered in relation to primary hepatic neoplasia and metastatic diseases. Benign mimics of malignancy and other pitfalls in frozen section diagnosis of lesional tissue are covered. Finally, assessment of donor liver biopsy for organ transplant evaluation is discussed.

Waitlist Outcomes for Patients Relisted Following Failed Donation After Cardiac Death Liver Transplant: Implications for Awarding Model for End-Stage Liver Disease Exception Scores

Understanding of outcomes for patients relisted for ischemic cholangiopathy following a donation after cardiac death (DCD) liver transplant (LT) will help standardization of a Model for End-Stage Liver Disease exception scheme for retransplantation. Early relisting (E-RL) for DCD graft failure caused by primary nonfunction (PNF) or hepatic artery thrombosis (HAT) was defined as relisting ≤14 days after DCD LT, and late relisting (L-RL) due to biliary complications was defined as relisting 14 days to 3 years after DCD LT. Of 3908 DCD LTs performed nationally between 2002 and 2016, 540 (13.8%) patients were relisted within 3 years of transplant (168 [4.3%] in the E-RL group, 372 [9.5%] in the L-RL group). The E-RL and L-RL groups had waitlist mortality rates of 15.4% and 10.5%, respectively, at 3 mo and 16.1% and 14.3%, respectively, at 1 year. Waitlist mortality in the L-RL group was higher than mortality and delisted rates for patients with exception points for both hepatocellular carcinoma (HCC) and hepatopulmonary syndrome (HPS) at 3- to 12-mo time points (p < 0.001). Waitlist outcomes differed in patients with early DCD graft failure caused by PNF or HAT compared with those with late DCD graft failure attributed to biliary complications. In L-RL, higher rates of waitlist mortality were noted compared with patients listed with exception points for HCC or HPS.

A novel compartmentalised stent graft to isolate the perfusion of the abdominal organs

Donation after cardiac death has been adopted to address the critical shortage of donor organs for transplant. Recovery of these organs is hindered by low blood flow that leads to permanent organ injury. We propose a novel approach to isolate the perfusion of the abdominal organs from the systemic malperfusion of the dying donor. We reasoned that this design could improve blood flow to organs without open surgery, while respecting the ethical principle that cardiac stress not be increased during organ recovery. Conditions within the stent were analysed using a computational fluid dynamics (CFD) method and validated on two prototypes in vitro. The hydrodynamic pressure drop across the stent was measured as 0.14-0.22 mmHg, which is a negligible influence. Device placement studies were also conducted on swine model fluoroscopically. All these results demonstrated the feasibility of rapidly isolating the perfusion to abdominal organs using a compartmentalised stent graft design.

Dual chamber stent prevents organ malperfusion in a model of donation after cardiac death

BACKGROUND

The paradigm for donation after cardiac death subjects donor organs to ischemic injury. A dual-chamber organ perfusion stent would maintain organ perfusion without affecting natural cardiac death. A center lumen allows uninterrupted cardiac blood flow, while an external chamber delivers oxygenated blood to the visceral vessels.

METHODS

A prototype organ perfusion stent was constructed from commercial stents. In a porcine model, the organ perfusion stent was deployed, followed by a simulated agonal period. Oxygenated blood perfused the external stent chamber. Organ perfusion was compared between controls (n = 3) and organ perfusion stent (n = 6). Finally, a custom, nitinol, dual chamber organ perfusion stent was fabricated using a retrievable "petal and stem" design.

RESULTS

Endovascular organ perfusion stent deployment achieved visceral isolation without adverse impact on cardiac parameters. Visceral oxygen delivery was 4.8-fold greater compared with controls. During the agonal period, organs in organ perfusion stent-treated animals appeared well perfused in contrast with the malperfused controls. A custom nitinol and polyurethane organ perfusion stent was recaptured easily with simple sheath advancement.

CONCLUSION

An organ perfusion stent maintained organ perfusion during the agonal phase in a porcine model of donation after cardiac death organ donation without adversely affecting cardiac function. Ultimately, the custom retrievable design of this study may help resolve the critical shortage of donor organs for transplant.

Liver and Kidney Transplantation: A Half-Century Historical Perspective

This article describes the evolution of solid organ kidney and liver transplantation and expounds on the challenges and successes that the early transplant researchers and clinicians encountered. The article highlights the surgical pioneers, delves into the milestones of enhanced immunosuppression protocols, discusses key federal legislative and policy changes, and expounds on the ongoing disparities of organ supply and demand and the need for extended criteria and live donor organs to combat these shortages. Finally, recent changes in organ allocation and distribution policies are discussed. The authors also spotlight novel interventions that will further revolutionize abdominal transplantation in the next 50 years.

First Comparison of Hypothermic Oxygenated PErfusion Versus Static Cold Storage of Human Donation After Cardiac Death Liver Transplants: An International-matched Case Analysis

BACKGROUND

Exposure of donor liver grafts to prolonged periods of warm ischemia before procurement causes injuries including intrahepatic cholangiopathy, which may lead to graft loss. Due to unavoidable prolonged ischemic time before procurement in donation after cardiac death (DCD) donation in 1 participating center, each liver graft of this center was pretreated with the new machine perfusion "Hypothermic Oxygenated PErfusion" (HOPE) in an attempt to improve graft quality before implantation.

METHODS

HOPE-treated DCD livers (n = 25) were matched and compared with normally preserved (static cold preservation) DCD liver grafts (n = 50) from 2 well-established European programs. Criteria for matching included duration of warm ischemia and key confounders summarized in the balance of risk score. In a second step, perfused and unperfused DCD livers were compared with liver grafts from standard brain dead donors (n = 50), also matched to the balance of risk score, serving as baseline controls.

RESULTS

HOPE treatment of DCD livers significantly decreased graft injury compared with matched cold-stored DCD livers regarding peak alanine-aminotransferase (1239 vs 2065 U/L, P = 0.02), intrahepatic cholangiopathy (0% vs 22%, P = 0.015), biliary complications (20% vs 46%, P = 0.042), and 1-year graft survival (90% vs 69%, P = 0.035). No graft failure due to intrahepatic cholangiopathy or nonfunction occurred in HOPE-treated livers, whereas 18% of unperfused DCD livers needed retransplantation. In addition, HOPE-perfused DCD livers achieved similar results as control donation after brain death livers in all investigated endpoints.

CONCLUSIONS

HOPE seems to offer important benefits in preserving higher-risk DCD liver grafts.

Increasing the Number of Organ Transplants in the United States by Optimizing Donor Authorization Rates

While recent policies have focused on allocating organs to patients most in need and lessening geographic disparities, the only mechanism to increase the actual number of transplants is to maximize the potential organ supply. We conducted a retrospective cohort study using OPTN data on all "eligible deaths" from 1/1/08 to 11/1/13 to evaluate variability in donor service area (DSA)-level donor authorization rates, and to quantify the potential gains associated with increasing authorization rates. Despite adjustments for donor demographics (age, race/ethnicity, cause of death) and geographic factors (rural/urban status of donor hospital, statewide participation in deceased-donor registries) among 52 571 eligible deaths, there was significant variability (p < 0.001) in donor authorization rates across the 58 DSAs. Overall DSA-level adjusted authorization rates ranged from 63.5% to 89.5% (median: 72.7%). An additional 773-1623 eligible deaths could have been authorized, yielding 2679-5710 total organs, if the DSAs with authorization rates below the median and 75th percentile, respectively, implemented interventions to perform at the level of the corresponding reference DSA. Opportunities exist within the current organ acquisition framework to markedly improve DSA-level donor authorization rates. Such initiatives would mitigate waitlist mortality while increasing the number of transplants.

Machine perfusion in liver transplantation as a tool to prevent non-anastomotic biliary strictures: Rationale, current evidence and future directions

The high incidence of non-anastomotic biliary strictures (NAS) after transplantation of livers from extended criteria donors is currently a major barrier to widespread use of these organs. This review provides an update on the most recent advances in the understanding of the etiology of NAS. These new insights give reason to believe that machine perfusion can reduce the incidence of NAS after transplantation by providing more protective effects on the biliary tree during preservation of the donor liver. An overview is presented regarding the different endpoints that have been used for assessment of biliary injury and function before and after transplantation, emphasizing on methods used during machine perfusion. The wide spectrum of different approaches to machine perfusion is discussed, including the many different combinations of techniques, temperatures and perfusates at varying time points. In addition, the current understanding of the effect of machine perfusion in relation to biliary injury is reviewed. Finally, we explore directions for future research such as the application of (pharmacological) strategies during machine perfusion to further improve preservation. We stress the great potential of machine perfusion to possibly expand the donor pool by reducing the incidence of NAS in extended criteria organs.

Use of model for end-stage liver disease exceptions for donation after cardiac death graft recipients relisted for liver transplantation

Donation after cardiac death (DCD) liver transplantation is associated with increased biliary complications and graft failure. Yet for unclear reasons, DCD recipients relisted for transplantation have lower wait-list mortality than other retransplant candidates. We used Organ Procurement and Transplantation Network and United Network for Organ Sharing data from 2002 to 2011 to evaluate all DCD recipients relisted for transplantation to evaluate the impact of the utilization of Model for End-Stage Liver Disease (MELD) exception points on wait-list outcomes. Of 262 DCD recipients relisted for liver transplantation >2 weeks after initial transplantation, 82 (31.3%) applied for a nonstandardized MELD exception, and 68 (82.9%) had ≥1 exception approved. Of the relisted DCD recipients, 187 (71.4%) underwent retransplantation; among those with an approved MELD exception, 85.2% underwent retransplantation versus 57.1% of those with an exception denied and 69.4% of those not applying for an exception (P=0.02). In contrast, those receiving MELD exception points were significantly less likely to be removed from the wait list for death or clinical deterioration in comparison with those not applying for an exception (7.1% versus 19.4%, P=0.02). In multivariate models, patients with an approved exception were 3.3 times more likely to undergo retransplantation than those not applying for an exception. Standardized criteria for exception points among DCD recipients should be established to ensure uniform access to retransplantation.

Inhibition of histone deacetylase by butyrate protects rat liver from ischemic reperfusion injury

We showed previously that pretreatment of butyrate, which is an endogenous histone deacetylase (HDAC) inhibitor normally fermented from undigested fiber by intestinal microflora, seriously alleviated ischemia reperfusion (I/R)-induced liver injury by inhibiting the nuclear factor κB (NF-κB) pathway. The goal of this study was to investigate the effect of butyrate administrated at the onset of ischemia for HDAC inhibition in hepatic I/R injury. Sprague Dawley rats were subjected to warm ischemia for 60 min followed by 6 and 24 h of reperfusion. Butyrate was administrated at the onset of ischemia. Liver injury was evaluated by serum levels of aminotransferase, inflammatory factors, and histopathology. The levels of acetylated histone H3 and expression of heat shock protein (Hsp) 70 were measured by Western blot. After reperfusion, the levels of acetylated histone H3 significantly decreased. Butyrate treatment markedly prevented the reduction of acetylated histone H3 and upregulated the expression of Hsp70, thereby reducing liver injury. Our study demonstrated that I/R resulted in marked reduction of histone acetylation; butyrate exerted a great hepatoprotective effect through HDAC inhibition and Hsp70 induction.

Subnormothermic ex vivo liver perfusion reduces endothelial cell and bile duct injury after donation after cardiac death pig liver transplantation

An ischemic-type biliary stricture (ITBS) is a common feature after liver transplantation using donation after cardiac death (DCD) grafts. We compared sequential subnormothermic ex vivo liver perfusion (SNEVLP; 33°C) with cold storage (CS) for the prevention of ITBS in DCD liver grafts in pig liver transplantation (n = 5 for each group). Liver grafts were stored for 10 hours at 4°C (CS) or preserved with combined 7-hour CS and 3-hour SNEVLP. Parameters of hepatocyte [aspartate aminotransferase (AST), international normalized ratio (INR), factor V, and caspase 3 immunohistochemistry], endothelial cell (EC; CD31 immunohistochemistry and hyaluronic acid), and biliary injury and function [alkaline phosphatase (ALP), total bilirubin, and bile lactate dehydrogenase (LDH)] were determined. Long-term survival (7 days) after transplantation was similar between the SNEVLP and CS groups (60% versus 40%, P = 0.13). No difference was observed between SNEVLP- and CS-treated animals with respect to the peak of serum INR, factor V, or AST levels within 24 hours. CD31 staining 8 hours after transplantation demonstrated intact EC lining in SNEVLP-treated livers (7.3 × 10(-4) ± 2.6 × 10(-4) cells/μm(2)) but not in CS-treated livers (3.7 × 10(-4) ± 1.3 × 10(-4) cells/μm(2) , P = 0.03). Posttransplant SNEVLP animals had decreased serum ALP and serum bilirubin levels in comparison with CS animals. In addition, LDH in bile fluid was lower in SNEVLP pigs versus CS pigs (14 ± 10 versus 60 ± 18 μmol/L, P = 0.02). Bile duct histology revealed severe bile duct necrosis in 3 of 5 animals in the CS group but none in the SNEVLP group (P = 0.03). Sequential SNEVLP preservation of DCD grafts reduces bile duct and EC injury after liver transplantation.

Donation after cardiac death liver transplantation is associated with increased risk of end-stage renal disease

Limited organ supply has led to greater use of liver allografts with higher donor risk indices (DRI) and/or donated after cardiac death (DCD). DCD status is associated with acute kidney injury after liver transplantation; however, less is known about the association between donor quality and end-stage renal disease (ESRD). Using SRTR data, we assembled a cohort of liver transplant recipients from 2/2002 to 12/2010. We fit multivariable Cox regression models for ESRD. Model 1 included total DRI; model 2 included components of DRI, including DCD, as separate variables. Forty thousand four hundred and sixty-three liver transplant recipients were included. Median DRI was 1.40 (IQR 1.14, 1.72); 1822 (5%) received DCD livers. During median follow-up of 3.93 years, ESRD occurred in 2008 (5%) and death in 11 075 (27%) subjects. There was a stepwise increase in ESRD risk with higher DRI (DRI ≥1.14 and <1.40: HR 1.17, P = 0.06; DRI ≥1.40 and <1.72: HR 1.29, P = 0.003; DRI ≥1.72: HR 1.39, P < 0.001, compared with DRI <1.14). Adjusting for DRI components separately, DCD status was most strongly associated with ESRD (HR 1.40, P = 0.008). Higher DRI is associated with ESRD after liver transplantation, driven in part by DCD status. Donor quality is an important predictor of long-term renal outcomes in liver transplant recipients.

Butyrate protects rat liver against total hepatic ischemia reperfusion injury with bowel congestion

Hepatic ischemia/reperfusion (I/R) injury is an unavoidable consequence of major liver surgery, especially in liver transplantation with bowel congestion, during which endotoxemia is often evident. The inflammatory response aggravated by endotoxin after I/R contributes to liver dysfunction and failure. The purpose of the present study was to investigate the protective effect of butyrate, a naturally occurring four-carbon fatty acid in the body and a dietary component of foods such as cheese and butter, on hepatic injury complicated by enterogenous endotoxin, as well as to examine the underlying mechanisms involved. SD rats were subjected to a total hepatic ischemia for 30 min after pretreatment with either vehicle or butyrate, followed by 6 h and 24 h of reperfusion. Butyrate preconditioning markedly improved hepatic function and histology, as indicated by reduced transaminase levels and ameliorated tissue pathological changes. The inflammatory factors levels, macrophages activation, TLR4 expression, and neutrophil infiltration in live were attenuated by butyrate. Butyrate also maintained the intestinal barrier structures, reversed the aberrant expression of ZO-1, and decreased the endotoxin translocation. We conclude that butyrate inhibition of endotoxin translocation, macrophages activation, inflammatory factors production, and neutrophil infiltration is involved in the alleviation of total hepatic I/R liver injury in rats. This suggests that butyrate should potentially be utilized in liver transplantation.

Technique of subnormothermic ex vivo liver perfusion for the storage, assessment, and repair of marginal liver grafts

The success of liver transplantation has resulted in a dramatic organ shortage. In most transplant regions 20-30% of patients on the waiting list for liver transplantation die without receiving an organ transplant or are delisted for disease progression. One strategy to increase the donor pool is the utilization of marginal grafts, such as fatty livers, grafts from older donors, or donation after cardiac death (DCD). The current preservation technique of cold static storage is only poorly tolerated by marginal livers resulting in significant organ damage. In addition, cold static organ storage does not allow graft assessment or repair prior to transplantation.

These shortcomings of cold static preservation have triggered an interest in warm perfused organ preservation to reduce cold ischemic injury, assess liver grafts during preservation, and explore the opportunity to repair marginal livers prior to transplantation. The optimal pressure and flow conditions, perfusion temperature, composition of the perfusion solution and the need for an oxygen carrier has been controversial in the past.

In spite of promising results in several animal studies, the complexity and the costs have prevented a broader clinical application so far. Recently, with enhanced technology and a better understanding of liver physiology during ex vivo perfusion the outcome of warm liver perfusion has improved and consistently good results can be achieved.

This paper will provide information about liver retrieval, storage techniques, and isolated liver perfusion in pigs. We will illustrate a) the requirements to ensure sufficient oxygen supply to the organ, b) technical considerations about the perfusion machine and the perfusion solution, and c) biochemical aspects of isolated organs.

Donation after circulatory death: current practices, ongoing challenges, and potential improvements

Organ donation after circulatory death (DCD) has been endorsed by the World Health Organization and is practiced worldwide. This overview examines current DCD practices, identifies problems and challenges, and suggests clinical strategies for possible improvement. Although there is uniform agreement on DCD donor candidacy (ventilator-dependent individuals with nonrecoverable or irreversible neurologic injury not meeting brain death criteria), there are variations in all aspects of DCD practice. Utilization of DCD organs is limited by hypoxia, hypotension, reduced--then absent--organ perfusion, and ischemia/reperfusion syndrome. Nevertheless, DCD kidneys exhibit comparable function and survival to donors with brain death kidneys, although they have higher rates of primary graft nonfunction, delayed graft function, discard, and retrieval associated injury. Concern over ischemic organ injury underscores the reluctance to recover extrarenal DCD organs since lack of medical therapy to support inadequate allograft function limits their acceptability. Nevertheless, limited results with DCD pancreas, liver, and lung allografts (but not heart) are now approaching that of donors with brain death organs. Pretransplant machine perfusion of DCD kidneys (vs. static storage) may reduce delayed graft function but has no effect on long-term organ function and survival. Normothermic regional perfusion used during DCD abdominal organ retrieval may reduce ischemic organ injury and increase the number of usable organs, although critical confirmative studies have yet to be done. Minor increases in usable DCD kidneys could accrue from increased use of pediatric DCD kidneys and from selective use of DCD/ECD kidneys, whereas a modest increase could result through utilization of donors declared dead beyond 1 hr from withdrawal of life support therapy. A significant increase in transplantable kidneys could be achieved by extension of the concept of living kidney donation in relation to imminent death of potential DCD donors. Progress in research to identify, prevent, and repair DCD-associated organ retrieval injury should improve utilization of DCD organs. Recent results using ex situ pretransplant organ perfusion of DCD organs has been encouraging in this regard.

Timing of hepatic artery reperfusion and biliary strictures in liver transplantation

During orthotopic liver transplantation (OLT), biliary tract perfusion occurs with hepatic artery reperfusion (HARP), commonly performed after the portal vein reperfusion (PVRP). We examined whether the average time interval between PVRP and HARP impacted on postoperative biliary strictures occurrence. Patients undergoing OLT from 2007 to 2009 were included if they were ≥18 years old, had survived 3 months postoperatively, and had data for PVRP and HARP. Patients receiving allografts from DCD donors were excluded. Patients were followed for 6 months post-OLT. Seventy-five patients met the study inclusion criteria. Of these, 10 patients had a biliary stricture. There was no statistical difference between those with and without biliary stricture in age, gender, etiology, MELD score, graft survival, and time interval between PVRP and HARP. Ninety percent of patients with biliary stricture had a PVRP-HARP time interval >30 minutes, as opposed to 77% of patients without biliary stricture. However, this was not statistically significant. The cold ischemia time was significantly different between the two groups. Time interval for HARP after PVRP did not appear to affect the development of biliary strictures. However, 30 minutes may be suggested as a critical time after which there is an increase in biliary stricture occurrence.

Changing pattern of donor selection criteria in deceased donor liver transplant: a review of literature

During the last couple of decades, with standardization and progress in surgical techniques, immunosuppression and post liver transplantation patient care, the outcome of liver transplantation has been optimized. However, the principal limitation of transplantation remains access to an allograft. The number of patients who could derive benefit from liver transplantation markedly exceeds the number of available deceased donors. The large gap between the growing list of patients waiting for liver transplantation and the scarcity of donor organs has fueled efforts to maximize existing donor pool and identify new avenues. This article reviews the changing pattern of donor for liver transplantation using grafts from extended criteria donors (elderly donors, steatotic donors, donors with malignancies, donors with viral hepatitis), donation after cardiac death, use of partial grafts (split liver grafts) and other suboptimal donors (hypernatremia, infections, hypotension and inotropic support).

Normothermic acellular ex vivo liver perfusion reduces liver and bile duct injury of pig livers retrieved after cardiac death

We compared cold static with acellular normothermic ex vivo liver perfusion (NEVLP) as a novel preservation technique in a pig model of DCD liver injury. DCD livers (60 min warm ischemia) were cold stored for 4 h, or treated with 4 h cold storage plus 8 h NEVLP. First, the livers were reperfused with diluted blood as a model of transplantation. Liver injury was determined by ALT, oxygen extraction, histology, bile content analysis and hepatic artery (HA) angiography. Second, AST levels and bile production were assessed after DCD liver transplantation. Cold stored versus NEVLP grafts had higher ALT levels (350 ± 125 vs. 55 ± 35 U/L; p < 0.0001), decreased oxygen extraction (250 ± 65 mmHg vs. 410 ± 58 mmHg, p < 0.01) and increased hepatocyte necrosis (45% vs. 10%, p = 0.01). Levels of bilirubin, phospholipids and bile salts were fivefold decreased, while LDH was sixfold higher in cold stored versus NEVLP grafts. HA perfusion was decreased (twofold), and bile duct necrosis was increased (100% vs. 5%, p < 0.0001) in cold stored versus NEVLP livers. Following transplantation, mean serum AST level was higher in the cold stored versus NEVLP group (1809 ± 205 U/L vs. 524 ± 187 U/L, p < 0.05), with similar bile production (2.5 ± 1.2 cc/h vs. 2.8 ± 1.4 cc/h; p = 0.2). NEVLP improved HA perfusion and decreased markers of liver duct injury in DCD grafts.

The aggressive phenotype revisited: utilization of higher-risk liver allografts

Organ shortage has led to increased utilization of higher risk liver allografts. In kidneys, aggressive center-level use of one type of higher risk graft clustered with aggressive use of other types. In this study, we explored center-level behavior in liver utilization. We aggregated national liver transplant recipient data between 2005 and 2009 to the center-level, assigning each center an aggressiveness score based on relative utilization of higher risk livers. Aggressive centers had significantly more patients reaching high MELDs (RR 2.19, 2.33 and 2.28 for number of patients reaching MELD>20, MELD>25 and MELD>30, p<0.001), a higher organ shortage ratio (RR 1.51, 1.60 and 1.51 for number of patients reaching MELD>20, MELD>25 and MELD>30 divided by number of organs recovered at the OPO, p<0.04), and were clustered within various geographic regions, particularly regions 2, 3 and 9. Median MELD at transplant was similar between aggressive and nonaggressive centers, but average annual transplant volume was significantly higher at aggressive centers (RR 2.27, 95% CI 1.47-3.51, p<0.001). In cluster analysis, there were no obvious phenotypic patterns among centers with intermediate levels of aggressiveness. In conclusion, highwaitlist disease severity, geographic differences in organ availability, and transplant volume are the main factors associated with the aggressive utilization of higher risk livers.

Liver damage during organ donor procurement in donation after circulatory death compared with donation after brain death

BACKGROUND

During the past decade the number of livers recovered and transplanted from donation after circulatory death (DCD) donors has increased significantly. As reported previously, injuries are more frequent during kidney procurement from DCD than from donation after brain death (DBD) donors. This aim of this study was to compare outcomes between DCD and DBD with respect to liver injuries.

METHODS

Data on liver injuries in organs procured between 2000 and 2010 were obtained from the UK Transplant Registry.

RESULTS

A total of 7146 livers were recovered from deceased donors during the study, 628 (8·8 per cent) from DCD donors. Injuries occurred in 1001 procedures (14·0 per cent). There were more arterial (1·6 versus 1·0 per cent), portal (0·5 versus 0·3 per cent) and caval (0·3 versus 0·2 per cent) injuries in the DBD group than in the DCD group, although none of these findings was statistically significant. Capsular injuries occurred more frequently in DCD than DBD (15·6 versus 11·4 per cent; P = 0·002). There was no significant difference between DCD and DBD groups in liver discard rates related to damage.

CONCLUSION

There were no differences in terms of vascular injuries between DCD and DBD livers, although capsular injuries occurred more frequently in DCD organs. Continuing the trend for increased frequency of DCD liver recovery, and ensuring that there is an adequately skilled surgical team available for procurement, is vital to improving the utilization of DCD livers.

What is the prognosis after retransplantation of the liver?

In patients with failing liver grafts, hepatic retransplantation cannot be abandoned for the ethical and practical reasons that have been detailed previously. The current recommendations involve a strategy for risk stratification of retransplant candidates. The long-term patient and graft survival outcomes after ReLT are excellent and acceptable for the low and intermediate groups, respectively. However, pursuing ReLT in transplant candidates in the high-risk category cannot be recommended. Furthermore, ReLT should be reserved for centers equipped to manage the difficulties of the endeavor because it is a technically demanding operation that requires surgical expertise and excellent anesthesiology and critical care support both before and after transplantation.

Liver transplantation in an African setting

Liver disease in children in the developing world is a frequent occurrence, which is generally inadequately managed because of lack of resources. However, increasingly, there has been a demand for liver transplantation, where primary medical or surgical therapies have failed. The expertise and infrastructure required for a successful outcome are no different from those in more developed countries; if anything, the challenges are greater. Lack of deceased donors because of cultural and religious factors has driven the use of living donors. Short-term survival has generally been good, but long-term outcomes have rarely been reported. In this article, we review the experience of 2 centers at opposite ends of the continent and share our experience of slightly different settings and show that success can be achieved even in resource-reduced environments.

Development of organ-specific donor risk indices

Because of the shortage of deceased donor organs, transplant centers accept organs from marginal deceased donors, including older donors. Organ-specific donor risk indices have been developed to predict graft survival with various combinations of donor and recipient characteristics. Here we review the kidney donor risk index (KDRI) and the liver donor risk index (LDRI) and compare and contrast their strengths, limitations, and potential uses. The KDRI has a potential role in developing new kidney allocation algorithms. The LDRI allows a greater appreciation of the importance of donor factors, particularly for hepatitis C virus-positive recipients; as the donor risk index increases, the rates of allograft and patient survival among these recipients decrease disproportionately. The use of livers with high donor risk indices is associated with increased hospital costs that are independent of recipient risk factors, and the transplantation of livers with high donor risk indices into patients with Model for End-Stage Liver Disease scores < 15 is associated with lower allograft survival; the use of the LDRI has limited this practice. Significant regional variations in donor quality, as measured by the LDRI, remain in the United States. We also review other potential indices for liver transplantation, including donor-recipient matching and the retransplant donor risk index. Although substantial progress has been made in developing donor risk indices to objectively assess donor variables that affect transplant outcomes, continued efforts are warranted to improve these indices to enhance organ allocation policies and optimize allograft survival.

Biliary complications after liver transplantation using grafts from donors after cardiac death: results from a matched control study in a single large volume center

OBJECTIVE

To assess the incidence and impact of biliary complications in recipients transplanted from donors after cardiac death (DCD) at one single large institution.

BACKGROUND

Shortage of available cadaveric organs is a significant limiting factor in liver transplantation (LT). The use of DCD offers the potential to increase the organ pool. However, early results with DCD liver grafts were associated with a greater incidence of ischemic cholangiopathy (IC), leading to several programs to abandoning this source of organs.

METHODS

A retrospective analysis of a prospective database from April 2001 to 2010 focused on 167 consecutive DCD-LT. Each DCD transplant was matched with 2 brain death donors (DBD) grafts (n = 333) according to the period of transplantation. Primary outcome measures were biliary complications including the severity of complications, graft survival and patient survival. Minimum follow-up was 3 months.

RESULTS

Anastomotic stricture was the most common biliary complication (DCD = 30, 19% vs. DBD = 41, 13%). Most were treated endocoscopically (grade IIIa = 72%), whereas hepatico-jejunostomy (grade IIIb) was performed in 22%. Primary IC occurred in 4 (2.5%) recipients from the DCD group and was absent in the DBD group (P = 0.005). However, none of these patients required retransplantation. Patient and graft survival at 1, 3, and 5 years were similar between DCD and DBD groups (P = 0.106, P = 0.138, P = 0.113, respectively).

CONCLUSIONS

The encouraging results with DCD-LT are probably due to the selection of DCD grafts and clear definition of warm ischemia.

Excorporeal normothermic machine perfusion resuscitates pig DCD livers with extended warm ischemia

BACKGROUND

The shortage in donor livers has led to increased use of allografts derived from donation after cardiac death (DCD). The compromised viability in these livers leads to inferior post-transplantation allograft function and survival compared with donation after brain death (DBD) donor grafts. In this study, we reconditioned DCD livers using an optimized normothermic machine perfusion system.

METHODS

Livers from 12 Yorkshire pigs (20-30 kg) were subjected to either 0 min (WI-0 group, n = 6) or 60 min (WI-60 group, n = 6) of warm ischemia and 2 h of cold storage in UW solution, followed by 4 h of oxygenated sanguineous normothermic machine perfusion. Liver viability and metabolic function were analyzed hourly.

RESULTS

Warm ischemic livers showed elevated transaminase levels and reduced ATP concentration. After the start of machine perfusion, transaminase levels stabilized and there was recovery of tissue ATP, coinciding with an increase in bile production. These parameters reached comparable levels to the control group after 1 h of machine perfusion. Histology and gross morphology confirmed recovery of the ischemic allografts.

CONCLUSION

Our data demonstrate that metabolic and functional parameters of livers with extended warm ischemic time (60 min) can be significantly improved using normothermic machine perfusion. We hereby compound the existing body of evidence that machine perfusion is a viable solution for reconditioning marginal organs.

Liver transplantation in the 21st century: expanding the donor options

Over the past decade, use of ECD organs for OLT has allowed many transplant programs to afford patients access to an otherwise scarce resource and to maintain center volume. Although overall posttransplant outcomes are inferior to results with optimal, whole-liver grafts, aggressive utilization of ECD and DCD organs significantly lowers median wait-times for OLT, MELD score at OLT, and death while awaiting transplantation. It is incumbent on the transplant community to provide continued scrutiny of the many factors involved in ECD organ utilization, evaluate the degree of risk and benefit such allografts may impart on particular recipients, and thereby provide suitable “matching” to maximize favorable outcomes. Transplant caregivers need to provide patients with evidence-based care decisions, be good stewards of a scarce resource, and maintain threshold survival results for their programs. This requires balancing the urgency with which a transplant is needed and the utility of such a transplant. There is a clear necessity to pursue additional donor research to improve use of these marginal grafts and assess interventions that enhance the safety of ECD livers.

Current situation of donation after circulatory death in European countries

The aim of the present study was to describe the current situation of donation after circulatory death (DCD) in the Council of Europe, through a dedicated survey. Of 27 participating countries, only 10 confirmed any DCD activity, the highest one being described in Belgium, the Netherlands and the United Kingdom (mainly controlled) and France and Spain (mainly uncontrolled). During 2000-2009, as DCD increased, donation after brain death (DBD) decreased about 20% in the three countries with a predominant controlled DCD activity, while DBD had increased in the majority of European countries. The number of organs recovered and transplanted per DCD increased along time, although it remained substantially lower compared with DBD. During 2000-2008, 5004 organs were transplanted from DCD (4261 kidneys, 505 livers, 157 lungs and 81 pancreas). Short-term outcomes of 2343 kidney recipients from controlled versus 649 from uncontrolled DCD were analyzed: primary non function occurred in 5% vs. 6.4% (P = NS) and delayed graft function in 50.2% vs. 75.7% (P < 0.001). In spite of this, 1 year graft survival was 85.9% vs. 88.9% (P = 0.04), respectively. DCD is increasingly accepted in Europe but still limited to a few countries. Controlled DCD might negatively impact DBD activity. The degree of utilization of DCD is lower compared with DBD. Short-term results of DCD are promising with differences between kidney recipients transplanted from controlled versus uncontrolled DCD, an observation to be further analyzed.

A hierarchical communication model of the antecedents of health care professionals' support for donations after cardiac death

Using structural equation modeling, the direct and indirect impact of five variables on the support of donation after cardiac death from the perspective of health care professionals were investigated: knowledge, trust in the transplant team, whether patients are in a state of irreversibility, whether health care professionals participate in a patient's death, and perceptions about the brain death versus cardiac death donation process. In total, 10/15 relationships posited in the model had significant pathways. The results provide insight into sequential communication strategies for generating support for donations after cardiac death.

Trend and outcome of Korean patients receiving overseas solid organ transplantation between 1999 and 2005

The disparity between patients awaiting transplantation and available organs forced many patients to go overseas to receive a transplant. Few data concerning overseas transplantation in Korea are available and the Korea Society for Transplantation conducted a survey to evaluate the trend and outcome of overseas transplantation. The survey, conducted on June 2006, included 25 hospitals nationwide that followed up patients after receiving kidney transplant (KT) or liver transplant (LT) overseas. The number of KT increased from 6 in 2001 to 206 in 2005 and for LT from 1 to 261. The information about overseas transplant came mostly from other patients (57%). The mean cost for KT was $21,000 and for LT $47,000. Patients were admitted for 18.5 days for KT and 43.4 days for LT. Graft and patient survival was 96.8% and 96.5% for KT (median follow up 23.1 months). Complication occurred in 42.5% including surgical complication (5.3%), acute rejection (9.7%) and infection (21.5%). Patient survival for LT was 91.8% (median follow up 21.2 months). Complication occurred in 44.7% including 19.4% biliary complication. Overseas KT and LT increased rapidly from 2001 to 2005. Survival of patients and grafts was comparable to domestic organ transplantation, but had a high complication rate.

Is the increase in DCD organ donors in the United Kingdom contributing to a decline in DBD donors?

INTRODUCTION

Organ donation after brain death (DBD) has declined in the United Kingdom, whereas donation after cardiac death (DCD) has increased markedly. We sought to understand the reasons for the decline in DBD and determine whether the increase in DCD was a major factor.

METHODS

The UK Transplant Registry was analyzed to determine trends in organ donation. Data from the "Potential Donor Audit," an audit of all patients younger than 76 years who died in noncardiothoracic UK intensive care units, was analyzed to identify trends in clinical demographics and management and to determine whether potential donors (DBD and DCD) were identified and appropriate steps were taken to enable organ donation.

RESULTS

There were 7589 (12.8 per million of population [pmp]) deceased organ donors in the United Kingdom from 1999 to 2009. The total number of deceased donors increased by 16% (to 14.9 pmp), but DBD donors decreased from 744 to 612, and the overall increase in donors was due to an 8-fold increase in DCD donors (33 in 1999 to 2000, 288 in 2008 to 2009). Analysis of the Potential Donor Audit over the 5-year period 2004 to 2005 to 2008 to 2009 showed that the number of patients dying in intensive care units who were possibly brain stem dead (comatose, apparently apnoeic with unresponsive pupils) decreased from 1929 in 2004 to 2005 to 1495 in 2008 to 2009 (22.5% reduction). The proportion of potential DBD donors who became donors increased from 45% to 51%.

CONCLUSION

There is no evidence that the increase in DCD donors has contributed directly to the decline in DBD, which reflects a decrease in the number of patients with brain death.