Early allograft dysfunction after liver transplantation: a definition and predictors of outcome. National Institute of Diabetes and Digestive and Kidney Diseases Liver Transplantation Database

Validation of a current definition of early allograft dysfunction in liver transplant recipients and analysis of risk factors

Translational studies in liver transplantation often require an endpoint of graft function or dysfunction beyond graft loss. Prior definitions of early allograft dysfunction (EAD) vary, and none have been validated in a large multicenter population in the Model for End-Stage Liver Disease (MELD) era. We examined an updated definition of EAD to validate previously used criteria, and correlated this definition with graft and patient outcome. We performed a cohort study of 300 deceased donor liver transplants at 3 U.S. programs. EAD was defined as the presence of one or more of the following previously defined postoperative laboratory analyses reflective of liver injury and function: bilirubin >or=10mg/dL on day 7, international normalized ratio >or=1.6 on day 7, and alanine or aspartate aminotransferases >2000 IU/L within the first 7 days. To assess predictive validity, the EAD definition was tested for association with graft and patient survival. Risk factors for EAD were assessed using multivariable logistic regression. Overall incidence of EAD was 23.2%. Most grafts met the definition with increased bilirubin at day 7 or high levels of aminotransferases. Of recipients meeting the EAD definition, 18.8% died, as opposed to 1.8% of recipients without EAD (relative risk = 10.7 [95% confidence interval: 3.6, 31.9] P < 0.0001). More recipients with EAD lost their grafts (26.1%) than recipients with no EAD (3.5%) (relative risk = 7.4 [95% confidence interval: 3.4, 16.3] P < 0.0001). Donor age and MELD score were significant EAD risk factors in a multivariate model. In summary a simple definition of EAD using objective posttransplant criteria identified a 23% incidence, and was highly associated with graft loss and patient mortality, validating previously published criteria. This definition can be used as an endpoint in translational studies aiming to identify mechanistic pathways leading to a subgroup of liver grafts with clinical expression of suboptimal function.

Sirolimus attenuates reduced-size liver ischemia-reperfusion injury but impairs liver regeneration in rats

BACKGROUND

Evidence has suggested that immunosuppressive drugs impact ischemia-reperfusion injury.

AIMS

The purpose of the present study was to evaluate the effect of sirolimus on hepatic injury and regeneration in a rat reduced-size liver ischemia-reperfusion model.

METHODS

Using a newly developed rat reduced-size liver ischemia-reperfusion injury model, the effects of sirolimus were evaluated by assessing liver cell apoptosis and aspartate aminotransferase, myeloperoxidase, and malondialdehyde levels. In addition, liver regeneration after sirolimus treatment was evaluated by measuring liver weight resumption and by the histological examination of bromodeoxyuridine and proliferating cell nuclear antigen expression.

RESULTS

Sirolimus significantly decreased liver cell apoptosis as well as tissue myeloperoxidase and malondialdehyde levels, but impaired postischemic liver regeneration. Ischemia-reperfusion-induced elevation of aspartate aminotransferase serum levels was significantly decreased by sirolimus.

CONCLUSIONS

Despite an impairment of postischemic liver proliferation, sirolimus demonstrated beneficial amelioration of ischemia-reperfusion-induced liver injury in a reduced-size liver model in rats.

Early diagnosis of primary nonfunction and indication for reoperation after liver transplantation

Initial graft function is a major factor influencing the clinical outcome after liver transplantation (LTX), but a reliable method for assessing and predicting graft dysfunction directly after LTX is not available. Ninety-nine patients undergoing deceased-donor LTX were studied in a prospective pilot study to evaluate the LiMAx test, the indocyanine green test, and conventional biochemical parameters with respect to their sensitivity and prognostic power for the diagnosis of initial graft dysfunction. Patients suffering from initial graft dysfunction (defined as technical complications or primary nonfunction (n = 8)) had significantly decreased LiMAx readouts (43 +/- 18 versus 184 +/- 98 mug/kg/hour, P < 0.001) immediately after LTX. Univariate analysis also showed significant differences for serum bilirubin, ammonia, glutamate dehydrogenase, and the international normalized ratio (P < 0.05), but multivariate analysis revealed LiMAx as the single independent predictor of initial dysfunction (P = 0.008) with an area under the receiver operating characteristic curve (AUROC) of 0.960 (95% confidence interval = 0.921-0.998, P < 0.001). In addition, the diagnosis of primary nonfunction (n = 3) was evaluated with LiMAx and aspartate aminotransferase (AST) activity on the first postoperative day. The calculated AUROC values were 0.992 (0.975-1.0, P = 0.004) for LiMAx and 0.967 (0.929-1.0, P = 0.006) for AST. By a combination of test results obtained directly after LTX and on the first day, LiMAx indicated primary nonfunction with a sensitivity of 1.0 (0.31-1.0) and a positive predictive value of 1.0 (0.31-1.0), whereas AST classification showed a sensitivity of 0.67 (0.13-0.98) and a positive predictive value of 0.29 (0.05-0.70). In conclusion, the assessment of initial graft function using the LiMAx test might be effective for identifying critical complications that could threaten graft survival within 24 hours after LTX.

Hypothermic machine preservation in human liver transplantation: the first clinical series

Hypothermic machine perfusion (HMP) is widely used to preserve kidneys for transplantation with improved results over cold storage (CS). To date, successful transplantation of livers preserved with HMP has been reported only in animal models. In this, the first prospective liver HMP study, 20 adults received HMP-preserved livers and were compared to a matched group transplanted with CS livers. HMP was performed for 3-7 h using centrifugal perfusion with Vasosol solution at 4-6 degrees C. There were no cases of primary nonfunction in either group. Early allograft dysfunction rates were 5% in the HMP group versus 25% in controls (p = 0.08). At 12 months, there were two deaths in each group, all unrelated to preservation or graft function. There were no vascular complications in HMP livers. Two biliary complications were observed in HMP livers compared with four in the CS group. Serum injury markers were significantly lower in the HMP group. Mean hospital stay was shorter in the HMP group (10.9 +/- 4.7 days vs. 15.3 +/- 4.9 days in the CS group, p = 0.006). HMP of donor livers provided safe and reliable preservation in this pilot case-controlled series. Further multicenter HMP trials are now warranted.

A20 protects mice from lethal liver ischemia/reperfusion injury by increasing peroxisome proliferator-activated receptor-alpha expression

The nuclear factor-kappaB inhibitory protein A20 demonstrates hepatoprotective abilities through combined antiapoptotic, anti-inflammatory, and pro-proliferative functions. Accordingly, overexpression of A20 in the liver protects mice from toxic hepatitis and lethal radical hepatectomy, whereas A20 knockout mice die prematurely from unfettered liver inflammation. The effect of A20 on oxidative liver damage, as seen in ischemia/reperfusion injury (IRI), is unknown. In this work, we evaluated the effects of A20 upon IRI using a mouse model of total hepatic ischemia. Hepatic overexpression of A20 was achieved by recombinant adenovirus (rAd.)-mediated gene transfer. Although only 10%-25% of control mice injected with saline or the control rAd.beta galactosidase survived IRI, the survival rate reached 67% in mice treated with rAd.A20. This significant survival advantage in rAd.A20-treated mice was associated with improved liver function, pathology, and repair potential. A20-treated mice had significantly lower bilirubin and aminotransferase levels, decreased hemorrhagic necrosis and steatosis, and increased hepatocyte proliferation. A20 protected against liver IRI by increasing hepatic expression of peroxisome proliferator-activated receptor alpha (PPARalpha), a regulator of lipid homeostasis and of oxidative damage. A20-mediated protection of hepatocytes from hypoxia/reoxygenation and H(2)O(2)-mediated necrosis was reverted by pretreatment with the PPARalpha inhibitor MK886. In conclusion, we demonstrate that PPARalpha is a novel target for A20 in hepatocytes, underscoring its novel protective effect against oxidative necrosis. By combining hepatocyte protection from necrosis and promotion of proliferation, A20-based therapies are well-poised to protect livers from IRI, especially in the context of small-for-size and steatotic liver grafts. Liver Transpl 15:1613-1621, 2009. (c) 2009 AASLD.

Hepatoprotective effects of marine and kuhuang in liver transplant recipients

We aimed to assess the effects of traditional Chinese medicine; marine (MT) and kuhuang (KH), either alone or in combination, on the early graft function of the recipients and overall patient survival rate after liver transplantation (LT) by using diammonium glycyrrhizinate (DG) as a positive control. A total of 151 subjects undergoing LT were included in this prospective study. According to the different regimens given in the first two post-transplant weeks, they were divided into DG group (n = 49), DG + KH group (n = 36), MT group (n = 42) and MT + KH group (n = 24). The graft function in the early post-transplant period and patient survival rate were examined. During the first two post-transplant weeks, there was no significant difference in total bilirubin, alanine transaminase, aspartate transaminase, serum creatinine, and prothrombin time between MT group and DG group. Patient survivals in these two groups were also similar. Compared to DG group, DG + KH group showed a significantly lower total bilirubin value on post-transplant day 5 (3.2 +/- 2.1 mg/dL vs. 5.7 +/- 5.6 mg/dL, p < 0.01) and day 7 (2.8 +/- 1.8 mg/dL vs. 5.8 +/- 6.1 mg/dL, p < 0.01), and higher patient survival. There was no significant difference between DG + KH group and MT + KH group. In conclusion, MT provides an alternative to DG after LT. The combination of MT and KH is highly effective in decreasing the total blirubin in the early post-transplant period and improving patient survival.

Successful use of extended criteria donor grafts with low to moderate steatosis in patients with model for end-stage liver disease scores below 27

Liver transplantation may be performed using extended criteria donor grafts (ECDg). The characteristics of ECDg include age >60 years, long intensive care unit (ICU) stay, history of malignancy or steatosis. Grafts are often discarded due to steatosis, which can be macrovesicular (MaS) or microvesicular (MiS). MaS is the variety most frequently involved with unfavorable outcomes due to primary nonfunction (PNF) or primary dysfunction (PDF). As of January 2000, all livers referred to our institution were considered potentially transplantable. Steatosis was defined as the presence of fat droplets in more than 5% of hepatocytes. We observed 35 steatotic grafts. Grafts were stratified according to MaS and MiS as follows: low steatosis (5%-15%), mild steatosis (16%-30%), moderate steatosis (31%-60%), or severe steatosis (>60%). Fifteen grafts with moderate (n = 2) or severe (n = 13) MaS were discarded. Twenty grafts were harvested: 18 of them were transplanted at our institution, the remaining 2, discarded by our donor team, were transplanted by other Italian centers. Low MaS was detected in 10 grafts (50%), mild MaS in 4 (20%), and moderate MaS in 2 (10%). Low MiS was detected in 8 grafts (40%), mild MiS in 5 (25%), and moderate MiS in 1 (5%). Steatotic grafts were transplanted only into recipients with model for end-stage liver disease (MELD) scores <27. The 6-month graft survival was 80%; the PNF rate was 10%; and the PDF rate was 15%. The careful use of ECDg with low to moderate steatosis is possible if particular care is taken to avoid additional risk factors related to the recipient.

Molecular adsorbent recirculating system (Mars) in patients with primary nonfunction and other causes of graft dysfunction after liver transplantation in the era of extended criteria donor organs

Liver dysfunction is an important cause of morbidity and mortality after orthotopic liver transplantation (OLT). The Molecular Adsorbent Recirculating System (MARS) is an albumin-based dialysis system designed to enhance the excretory function of a failing liver. MARS has been successfully used in patients affected by advanced liver disease and presenting with severe cholestasis. The aim of this study was to evaluate the safety and clinical efficacy of MARS in patients with liver dysfunction after OLT. Seven patients (primary nonfunction, 2 patients; graft dysfunction, 5 patients) fulfilled the inclusion criteria of serum bilirubin level >15 mg/dL and least 1 of the following clinical signs: hepatic encephalopathy (HE) > or = grade II, hepatorenal syndrome (HRS), and intractable pruritus. Graft and patient survival rates at 6 months were 42.8% and 57.1%, respectively. All patients tolerated MARS treatment, with no adverse event. In all patients, a decrease in serum bilirubin (P < .05), bile acids (P < .05), serum creatinine, and ammonia levels was observed after treatment with MARS. A considerable improvement of HE, as well as renal and synthetic liver functions, was observed in 4 of 5 patients with graft dysfunction, but not among those with primary nonfunction. The patients with intractable pruritus showed significant improvement of this symptom after MARS therapy. Thus, MARS is a safe, therapeutic option for the treatment of liver dysfunction after OLT. Further studies are necessary to confirm whether this treatment is able to improve both graft and patient survival.

Hepatic IL-8 release during graft procurement is associated with impaired graft function after human liver transplantation

In experimental models, brain death induces inflammatory cascades, leading to reduced graft survival. Thus far, factors prior to graft preservation have gained less attention in clinical setting. We studied pre-preservation inflammatory response and its effects on graft function in 30 brain dead liver donors and the respective recipients. Before donor graft perfusion, portal and hepatic venous blood samples were drawn for phagocyte adhesion molecule expression and plasma cytokine determinations. Donor intensive care unit stay correlated with donor C-reactive protein (R = 0.472, p = 0.013) and IL-6 (R = 0.419, p = 0.026) levels, and donor (R = 0.478, p = 0.016) and recipient gamma-glutamyl transferase (R = 0.432, p = 0.019) levels. During graft procurement, hepatic IL-8 release was observed in 17/30 donors. Grafts with hepatic IL-8 release exhibited subsequently higher alkaline phosphatase [319 (213-405) IU/L vs. 175 (149-208) IU/L, p = 0.006] and bilirubin [101 (44-139) micromol/L vs. 30 (23-72) micromol/L, p = 0.029] levels after transplantation. Our findings support the concept that inflammatory response in the brain dead organ donor contributes to the development of graft injury in human liver transplantation.

Preservation solutions alter Mrp2-dependent bile flow in cold ischemic rat livers

BACKGROUND

Previously, decreased organic anion transport through multidrug resistance protein 2 (Mrp2) was observed without any notable cell lysis, even when the livers were stored for 8 hours in University of Wisconsin solution (UW). The aim of this study was to examine the bile flow and its constituents, markers of graft dysfunction without necrosis in cold ischemic livers, using the following preservation media: UW, ET-Kyoto solution (ET-K) and histidine-tryptophan-ketoglutarate solution (HTK).

MATERIALS AND METHODS

Rat livers were stored at 4 degrees C for 8 hours in the preservation media, and reperfused to collect the bile and determine their constituents. Glycyrrhizin (GL) and/or glutathione (GSH) were added to the media as necessary. The transport efficiency of Mrp2 was assessed by the biliary excretion of 5-carboxyfluorescein (CF), a fluoroprobe excreted from Mrp2. The Intracellular distribution of Mrp2 was determined by immunostaining.

RESULTS

Livers stored for 8 hours exhibited significantly decreased bile production and biliary glutathione (GSH) levels without notable cell lysis. CF excretion was significantly delayed in all solutions. However, these markers were remarkably improved by the redistribution of Mrp2 from the cytoplasm to the canalicular membrane, when the livers were exposed to UW in the presence of GL. Moreover, livers exposed to the Kyoto and HTK solutions increased their bile production and organic anion transport in the presence of GL and GSH.

CONCLUSION

These results suggest that the addition of GL and GSH to preservation solutions improves bile production and biliary organic anion transport by increasing Mrp2 localization to the bile canaliculi in post-cold ischemic livers. (248 words).

Donor risk index and organ patient index as predictors of graft survival after liver transplantation

In liver transplantation the identification of risk factors and the risk quantification for each single case represent a field of great interest. There are donor-related and recipient-related risk factors. Donor risk index (DRI) was retrospectively calculated in 223 liver transplant cases. We did not include patients with preoperative diagnosis of hepatocarcinoma and retransplants. The cases were stratified into two classes according to the DRI (low risk, DRI<1.7, and high risk, DRI >or= 1.7). A new index, namely the organ patient index (OPI) was calculated adding the Model for End-stage Liver Disease (MELD) score to the DRI. Patients were stratified into two classes according to the OPI (low risk, OPI <or= 2.85, and high risk, OPI>2.85). The cases with low DRI (n=144) showed better survival than the cases with high DRI (n=82; P< .02). The cases with low OPI (n=173) showed better survival than cases with high OPI (n=50; P< .01). The OPI predicted outcomes better than DRI, increasing the gap in the long-term graft survival between the low- and the high-risk class. The inclusion of the MELD in the new index allowed better prediction of graft survival.

Cytoplasmic signaling in the control of mitochondrial uproar?

The concept of a pre-emptive strike as a good means to prevent greater harm may be frequently over-stressed in daily life. However, biological systems in a homeostatic balance are prepared to withstand a certain degree of hostile fire by rather passive means. This also applies to the maintenance of cell survival, where a plethora of protective proteins provide safeguard against erroneous activation of death pathways. Apart from these mechanisms active processes are also essential for the maintenance of cellular homeostasis, commonly referred to as survival signaling. Frequently their targets may be mitochondrial, assuring organelle integrity, which is essential for continued energy production and survival. Transient or permanent failures in these cellular defense strategies result in pathophysiological conditions, which manifest themselves e.g. as cancer or ischemia/reperfusion-associated organ damage.

Should we still offer split-liver transplantation for two adult recipients? A retrospective study of our experience

The role of split-liver transplantation (SLT) for two adult recipients is still a matter of debate, and no agreement exists on indications, surgical techniques, and results. The aim of this study was to retrospectively analyze the outcome of our series of SLT. From May 1999 to December 2006, 16 patients underwent SLT at our unit. We used 9 full right grafts (segments 5-8) and 7 full left grafts (segments 1-4). The splitting procedure was always carried out in situ with a fully perfused liver. Postoperative complications were recorded in 8 (50%) patients: 5 (55%) in full right grafts and 3 (43%) in full left grafts. No one was retransplanted. After a median follow-up of 55.82 months (range, 0.4-91.2), 5 (31%) patients died, and the 1-, 3-, and 5-year overall survival rate for patients and grafts was 69%. We considered as a control group for the global outcome 232 whole liver transplantations performed at our unit in the same period of time. Postoperative complications were recorded in 53 (23%) patients, and after a median follow-up of 57.37 months (mean, 55.11; range, 1-102.83), the 1-, 3-, and 5-year overall patient survival was 87%, 82%, and 80%, respectively. In conclusion, SLT for two adult recipients is a technically demanding procedure that requires complex logistics and surgical teams experienced in both liver resection and transplantation. Although the reported rate of survival might be adequate for such a procedure, more efforts have to be made to improve the short-term outcome, which is inadequate in our opinion. The true feasibility of SLT for two adults has to be considered as still under investigation.

Consequences of cold-ischemia time on primary nonfunction and patient and graft survival in liver transplantation: a meta-analysis

Introduction

The ability to preserve organs prior to transplant is essential to the organ allocation process.

Objective

The purpose of this study is to describe the functional relationship between cold-ischemia time (CIT) and primary nonfunction (PNF), patient and graft survival in liver transplant.

Methods

To identify relevant articles Medline, EMBASE and the Cochrane database, including the non-English literature identified in these databases, was searched from 1966 to April 2008. Two independent reviewers screened and extracted the data. CIT was analyzed both as a continuous variable and stratified by clinically relevant intervals. Nondichotomous variables were weighted by sample size. Percent variables were weighted by the inverse of the binomial variance.

Results

Twenty-six studies met criteria. Functionally, PNF% = −6.678281+0.9134701*CIT Mean+0.1250879*(CIT Mean−9.89535)2−0.0067663*(CIT Mean−9.89535)3, r2 = .625, , p<.0001. Mean patient survival: 93 % (1 month), 88 % (3 months), 83 % (6 months) and 83 % (12 months). Mean graft survival: 85.9 % (1 month), 80.5 % (3 months), 78.1 % (6 months) and 76.8 % (12 months). Maximum patient and graft survival occurred with CITs between 7.5–12.5 hrs at each survival interval. PNF was also significantly correlated with ICU time, % first time grafts and % immunologic mismatches.

Conclusion

The results of this work imply that CIT may be the most important pre-transplant information needed in the decision to accept an organ.

Gene expression profiling of human liver transplants identifies an early transcriptional signature associated with initial poor graft function

Liver ischemia-reperfusion injury occurring in orthotopic liver transplantation (OLT) may be responsible for early graft failure. Molecular mechanisms underlying initial poor graft function (IPGF) have been poorly documented in human. The purpose of this study was to identify the major transcriptional alterations occurring in human livers during OLT. Twenty-one RNA extracts derived from liver transplant biopsies taken after graft reperfusion were compared with 7 RNA derived from normal control livers. Three hundred seventy-one genes were significantly modulated and classified in molecular pathways relevant to liver metabolism, inflammatory response, cell proliferation and liver protection. Grafts were then subdivided into two groups based on their peak levels of serum aspartate amino transferase within 72 h after OLT (group 1, non-IPGF: 14 patients; group 2, IPGF: 7 patients). The two corresponding data sets were compared using a supervised prediction method. A new set of genes able to correctly classify 71% of the patients was defined. These genes were functionally associated with oxidative stress, inflammation and inhibition of cell proliferation. This study provides a comprehensive picture of the transcriptional events associated with human OLT and IPGF. We anticipate that such alterations provide a framework for the elucidation of the molecular mechanisms leading to IPGF.

Effect modification in liver allografts with prolonged cold ischemic time

Although prolonged cold ischemia time (PCIT) is generally associated with worse outcomes following liver transplantation, evidence suggests that some recipients and some donors might be more sensitive to PCIT than others. The purpose of this study was to identify factors that predict a higher risk of graft loss after a transplant with PCIT when compared with a similar transplant with average CIT (ACIT). 14 637 recipients reported to United Network for Organ Sharing (UNOS) in the model for end-stage liver disease (MELD) era were studied by interaction term analysis in proportional hazards models. Recipient diabetes, obesity and donor African American (AA) ethnicity were found to significantly amplify the adverse effects of PCIT. Graft loss was 1.85-fold higher in diabetic or obese PCIT recipients compared with diabetic or obese ACIT recipients, (vs. 1.17 for the same comparison in non-diabetic non-obese recipients). Similarly, graft loss was 1.80-fold higher in AA PCIT donors compared with AA ACIT donors, (vs. 1.31 for the same comparison in non-AA donors). Other factors may also exist, but current clinical practices might already mitigate the risks from those factors. As such, we recommend expanding clinical practice to include our findings, but not abandoning current judgment based on factors already perceived to amplify the adverse effects of PCIT.

Acute thrombocytopenia after liver transplant: role of platelet activation, thrombopoietin deficiency and response to high dose intravenous IgG treatment

BACKGROUND/AIMS

Thrombocytopenia is common after liver transplantation due to platelet sequestration secondary to hypersplenism. The aim of this study was to further investigate the causes of this condition, as well as the response of thrombocytopenia to high dose intravenous immunoglobulins.

METHODS

We retrospectively studied 73 patients who underwent liver transplantation. Out of these 73 patients, 27 had severe thrombocytopenia and were treated with high dose intravenous immunoglobulin. Additionally, we retrospectively studied 8 patients undergoing liver transplantation.

RESULTS

Our data suggest that splenomegaly is not the only factor responsible for thrombocytopenia after liver transplantion and two additional phenomena, namely, reduced platelet production due to reduced thrombopoietin levels and sustained platelets activation take part in the pathogenesis of this condition. The infusion of high dose immunoglobulins induced a safe, prompt, complete and persistent resolution of severe thrombocytopenia in more than 70% of patients.

CONCLUSIONS

Based on these findings, treatment with high dose intravenous immunoglobulins should be considered in the management of severe thrombocytopenia after liver transplant, although additional randomized trials are warranted.

Long-term analysis of primary nonfunction in liver transplant recipients

Long-term allograft and patient survival following liver transplantation continues to improve with the development of new surgical techniques and immunosuppressive agents. Complications such as primary nonfunction (PNF) have not been well characterized in terms of long-term allograft and patient survival. The aim of this study was to determine the incidence of PNF in liver transplant recipients and patient and graft survival, in addition to identifying temporal trends in these parameters.

METHOD

Data were obtained from the United Network for Organ Sharing/Organ Procurement and Transplant Network for all adults (>18 years old) who received a deceased donor liver transplant between January 1990 and December 2004.

RESULTS

Of the 58,576 liver transplant recipients, 2061 had PNF, an overall incidence of 3.5%. There was a 30% annual increase in the incidence of PNF between 1990 and 2000; the incidence of PNF peaked at 7%, and then decreased by 20% annually thereafter. No differences in donor and perioperative variables were identified to account for this variation. One-, 3-, and 5-year patient and graft survival for patients with PNF who underwent retransplant were significantly lower than those with primary liver transplant. In conclusion, there has been decreased incidence of PNF among liver transplant recipients in the last decade.

Initial Poor Function in the Age of Old Donors: Prognostic Factors

INTRODUCTION

The current donor selection criteria have changed from the past years. Primary nonfunction is a serious complication after liver transplantation, but initial poor function (IPF), which occurs from 2% to 23%, also has an increased morbidity and mortality. We analyzed prognostic factors associated with IPF.

MATERIALS AND METHOD

This retrospective study of 551 liver transplants performed from January 2000 to December 2005 excluded retransplantations and transplants by classic surgery. The study cohort was attentified according to the presence or the absence of IPF. The variables included were (1) donor age, gender, cause of death, length of stay in Critical Care Medicine, noradrenaline use, sodium levels, and cardiorespiratory arrest, (2) from the standpoint of surgery: we included ischemia time (IT), intervention time, units of packet red cells (PRC), volume of blood autotransfusion (VBA), postreperfusion syndrome (PRS), and vasoactive drugs within the surgery procedure (VAD); (3) from the recipient's: view we examined age, gender, etiology, functional state, and covermittant pathology; (4) During the postoperative period we noted the presence of postoperative hemorrhage. Statistical analysis used chi-square test, Student t test, multiple logistic regression with significance set at P < .05.

RESULTS

Differences were found in IT (P = .001), VBA (P = .001), PRS (P = .012), VAD (P = .03), fulminant hepatic failure as the cause the transplantation (P = .002), and chronic obstructive pulmonary disease (P = .007). A regression model retained the following variables: IT, VBA, PRS, fulminant hepatic failure, and chronic obstructive pulmonary disease.

CONCLUSIONS

The prognostic factors for IPF need to be modified together with donor selection criteria in liver transplantation.

A cause-specific hazard rate analysis of prognostic factors among 877 adults who received primary orthotopic liver transplantation

BACKGROUND

In orthotopic liver transplantation (OLT) distinct causes of graft failure (GF) and death with a functioning graft (DFG) exist. Prognostic factors for one failure type may be distinctly different from those predictive of other types, and an accurate portrayal of these relationships may more clearly explain each factor's importance.

METHODS

A multivariable cause-specific hazard (CSH) rate analysis using Cox stepwise regression was performed among 877 adults who received primary OLT during 1996-2004 with tacrolimus+steroids as immunosuppression.

RESULTS

Older donor age (P=0.004) implied greater primary dysfunction GF, while primary sclerosing cholangitis (PSC; P=0.0002) implied greater vascular thrombosis GF. Recurrent nonmalignant liver disease GF was higher among hepatitis C virus patients (P<0.00001), and younger recipient age (P=0.005) implied greater death from recurrent (metastatic) hepatocellular carcinoma. African-American race (P<0.00001), PSC (P=0.003), and younger recipient age (P=0.005) were independently associated with greater GF due to chronic rejection. Older donor age (P=0.003) implied greater infection DFG, while older recipient age (P=0.003) and pretransplant diabetes (P=0.03) were independently associated with greater cardiovascular/cerebrovascular DFG. Finally, most of these cause-specific predictors were not significant in an overall Cox model for graft survival.

CONCLUSIONS

The CSH approach should be more widely used in investigations of prognostic factors. The result of older donor age implying greater primary dysfunction GF and infection DFG but having no association with other failure types demonstrates that its impact is specific to the graft's early posttransplant functional status. In addition, while recipient age was an important prognosticator, its direction of association reverses depending upon the outcome being analyzed.

A novel prognostic model based on serum levels of total bilirubin and creatinine early after liver transplantation

BACKGROUND/AIM

We aim to evaluate the impact of early renal dysfunction (ERD), early allograft dysfunction (EAD) on post-transplant mortality, and further explore a simple and accurate model to predict prognosis.

PATIENTS

A total of 161 adult patients who underwent liver transplantation for benign end-stage liver diseases were enrolled in the retrospective study. Another 38 patients were used for model validation.

RESULTS

Poor patient survival was associated with ERD or EAD. A post-transplant model for predicting mortality (PMPM) based on serum levels of total bilirubin and creatinine at 24-h post-transplantation was then established according to multivariate logistic regression. At 3 months, 6 months and 1 year, the area under receiver operating characteristic curves (AUC) of PMPM score at 24-h post-transplantation (0.876, 0.878 and 0.849, respectively) were significantly higher than those of pre-transplant model for end-stage liver diseases (MELD) score (0.673, 0.674 and 0.618, respectively) or the post-transplant MELD score at 24-h post-transplantation (0.787, 0.787 and 0.781, respectively) (P<0.05). Patients with PMPM score <or=-1.4 (low-risk group, n=114) achieved better survival than those with PMPM score >-1.4 (high-risk group, n=47) (P<0.001). The patients in the high-risk group showed a relatively good outcome if their PMPM scores decreased to <or=-1.4 at post-transplant day 7. The subsequent validation study showed that PMPM functioned with a predictive accuracy of 100%.

CONCLUSION

The PMPM score could effectively predict short- and medium-term mortality in liver transplant recipients.

Bradykinin B1 and B2 receptors both have protective roles in renal ischemia/reperfusion injury

To explore the role of the kallikrein-kinin system in relation to ischemia/reperfusion injury in the kidney, we generated mice lacking both the bradykinin B1 and B2 receptor genes (B1RB2R-null, Bdkrb1-/-/Bdkrb2-/-) by deleting the genomic region encoding the two receptors. In 4-month-old mice, blood pressures were not significantly different among B1RB2R-null, B2R-null (Bdkrb2-/-), and WT mice. After 30 min of bilateral renal artery occlusion and 24 h of reperfusion, mortality rates, renal histological and functional changes, 8-hydroxy-2'-deoxyguanosine levels in total DNA, mtDNA deletions, and the number of TUNEL-positive cells in the kidneys increased progressively in the following order (from lowest to highest): WT, B2R-null, and B1RB2R-null mice. Increases in mRNA levels of TGF-beta1, connective tissue growth factor, and endothelin-1 after ischemia/reperfusion injury were also exaggerated in the same order (from lowest to highest): WT, B2R-null, and B1RB2R-null. Thus, both the B1 and B2 bradykinin receptors play an important role in reducing DNA damage, apoptosis, morphological and functional kidney changes, and mortality during renal ischemia/reperfusion injury.

Temporary silastic mesh closure for adult liver transplantation: a safe alternative for the difficult abdomen

Primary fascial closure is often difficult after adult orthotopic liver transplantation (OLT), complicated by donor-to-recipient graft size mismatch, post-reperfusion hepatic edema, coagulopathy, or intestinal edema. Attempts at closing the abdomen under these circumstances can cause increase in intra-abdominal pressures, resulting in significant complications, including graft loss. Temporary closure with silastic mesh has been used as a viable option in children receiving transplants, but there is no experience recorded with its use in adults. A retrospective review was conducted on 200 consecutive liver transplantations performed over 42 months (October 2002 to February 2006). Records were evaluated for patient and donor demographics, perioperative factors including Model for End-Stage Liver Disease and Child-Turcotte-Pugh scores, indications for OLT, ischemic times, blood product administration, and use of temporary silastic mesh closure. Patients requiring silastic mesh were further evaluated for indication, time to primary fascial closure, duration of intubation, length of stay, graft function, and complications (infectious, vascular, biliary, and hernia development). Comparisons were made with a cohort of patients undergoing OLT over the same time period but who were closed primarily, without the use of temporary silastic mesh. Fifty-one liver transplantations (25.5%) of the 200 total transplant cohort used silastic mesh closure. Comparison of the cohorts (primary closure vs. temporary mesh) revealed that no differences existed, except the requirement of all blood products was significantly greater in the silastic mesh group (P < 0.001). Bowel edema (47.1%) and coagulopathy (37.3%) were the most common indications for mesh closure, with less frequent reasons including donor to recipient size mismatch (11.8%), hemodynamic instability, and a large preexisting fascial defect (2.0% each). The average time from transplant to final fascial closure was 3.4 days (range 2-9 days). In the silastic cohort, 41 transplants where closed primarily, 3 required the addition of synthetic mesh, and 6 had component separation and flap closure. After fascial closure, the mean time to extubation was 1 day. The median length of follow-up was 1.3 years for the silastic closure group. Long-term wound complications in the silastic closure group included 1 instance of colonic fistula, 2 incisional hernias, and 2 wound infections. The 30-day and 1-year patient survival for this group were 93.6 and 82.4%, respectively, and the graft survival for those same periods were 90.2 and 77.7%, respectively. Wound complications, rates of hepatic artery thrombosis or stricture, portal vein thrombosis or stricture, biliary complications, and allograft and patient survival were no different than those in patients undergoing initial primary closure. In adult liver transplantation with a difficult (or potentially difficult) abdomen, temporary closure with silastic mesh was found to allow for uncomplicated fascial closure in a short period of time, with rapid extubation times, excellent graft function, and minimal instances of infectious or wound complications. In circumstances where large amounts of blood products are required, where a size mismatch exists, or where bowel edema is present during adult liver transplantation, temporary closure with silastic mesh is an ideal strategy.

Fatores de risco para a falência do transplante ortotópico de fígado no Rio Grande do Sul, Brasil

Fatores de risco para falência do transplante ortotópico de fígado com doador cadáver foram investigados em estudo longitudinal retrospectivo com informações da Central Estadual de Transplantes e prontuário clínico de residentes no Rio Grande do Sul, Brasil, submetidos, após os 15 anos de idade, pela primeira vez, a esse transplante de janeiro de 1999 a julho de 2003 (n = 313). Houve 13% de falências (n = 41) no primeiro mês, 11% (n = 34) de 2 a 12 meses e 5% (n = 17) após esse período; 88% das falências resultaram em óbito, 12%, em retransplante. Nos modelos multivariados, a taxa de falência foi maior para renda familiar menor que dez salários-mínimos, idade maior que 45 anos, cor não branca, mau estado geral à época do transplante e doador com 56 anos ou mais. Gênero feminino evidenciou efeito apenas no modelo bruto, perdendo o efeito no modelo multivariado. Apoio social, com complementação de renda e pronto diagnóstico com ingresso na lista em boas condições clínicas, pode favorecer o sucesso do transplante hepático.

MARS in the treatment of liver failure: controversies and evidence

Molecular Adsorbent Recirculation System (MARS) is a form of extracorporeal detoxification system used as an artificial liver support system. Numerous studies have been published on the topic, with the majority of them describing the capability of MARS in removing albumin-bound toxins and improving systemic hemodynamics. Whether such improvement could be translated into survival benefit is still uncertain, given the paucity of randomized controlled trials available. The outcome of patients receiving MARS treatment is difficult to analyze because liver failure patients constitute a heterogeneous population and different subgroups carry different prognoses. An evidence-based recommendation on the timing of MARS initiation is not available and currently MARS is usually commenced for hyperbilirubinemia or presence of complications of liver failure. MARS is in general a safe procedure, but there are still potential complications that need to be cautioned, along with various operative issues that are worth attention. The future prospects of MARS would rely on the completion of adequately powered randomized controlled trials.

Living donor liver transplantation for biliary atresia: a single-center experience with first 100 cases

The aim of this study is to present our institutional experience in living donor liver transplantation (LDLT) as a treatment for end-stage liver disease in children with biliary atresia (BA). A retrospective review of transplant records was performed. One hundred BA patients (52 males and 48 females) underwent LDLT. The mean follow-up period was 85.5 months. The mean age was 2.4 years. The mean preoperative weight, height, and computed GFR were 12.2 kg, 82.5 cm, and 116.4 ml/min/1.73 m2, respectively. Twenty-seven patients were below 1 year of age, and 49 patients were below 10 kg at the time of transplantation. Ninety-six had had previous Kasai operation prior to transplant. The mean recipient operative time was 628 min. The mean recipient intraoperative blood loss was 176 ml. Thirty-five did not require blood or blood component transfusion. The left lateral segment (64) was the most common type of graft used. There were 27 operative complications which included 3 reoperations for postoperative bleeding, 9 portal vein, 4 hepatic vein, 4 hepatic artery, and 7 biliary complications. There was one in-hospital mortality and one retransplantation. The overall rejection rate was 20%. The overall mortality rate was 3%. The 6-month, 1-year and 5-year actual recipient survival rates were 99%, 98% and 98%, respectively.

Retrograde reperfusion via vena cava lowers the risk of initial nonfunction but increases the risk of ischemic-type biliary lesions in liver transplantation--a randomized clinical trial

Initial nonfunction (INF) and biliary complications such as ischemic-type biliary lesion (ITBL) remain two major complications in clinical orthotopic liver transplantation (OLT). The influence of ischemia and reperfusion injury (I/R) as a significant risk factor for both complications is widely unquestioned. A new reperfusion technique that reduces I/R injury should lead to a reduction in both INF and ITBL. One hundred and thirty two OLT patients were included in this study and randomized into two groups. Group A underwent standard reperfusion with anterograde simultaneous arterial and portal reperfusion and group B received retrograde reperfusion via the vena cava before sequential anterograde reperfusion of portal vein and hepatic artery. Serum transaminase level as a surrogate parameter for I/R injury and serum bilirubin level as a parameter for graft function were significantly reduced during the first week after OLT in group B. INF rate was 7.7% in group A and 0% in group B (P = 0.058). ITBL incidence was 4.55% in group A versus 12.3% in group B (P = 0.053). Retrograde reperfusion seemed to be beneficial for hepatocytes, but was detrimental for the biliary epithelium. The unexplained increased incidence of ITBL after retrograde reperfusion will be focus of further investigation.

Molecular adsorbent recirculating system in patients with early allograft dysfunction after liver transplantation: a pilot study

Early allograft dysfunction (EAD) after orthotopic liver transplantation (OLT) causes marked morbidity and mortality. We conducted a prospective pilot study to assess the safety and efficacy of molecular adsorbent recirculating system (MARS) in treatment of EAD after OLT. Twelve consecutive adult liver allograft recipients with a median age of 48 years, 9 of whom were male, were prospectively included and supported with MARS. EAD was defined as the presence of at least 2 of the following: serum bilirubin >10 mg/dL, prothrombin time <40%, aspartate aminotransferase or alanine transferase >1,000 U/L, and plasma disappearance rate of indocyanine green (PDR(ICG)) <10% per minute within 72 hours after reperfusion. One-year patient and graft survival was 66%. There was a significant decrease in serum bilirubin (P = 0.002), serum creatinine (P = 0.006), and aspartate aminotransferase (P = 0.005) and a significant increase in PDR(ICG) (P = 0.007) after MARS treatment. Prothrombin time, albumin level, and platelet count remained stable. Sustained improvement of renal and neurological function and of mean arterial pressure were observed. No MARS-related adverse effects occurred. MARS treatment provides a safe approach to the treatment of EAD after OLT. On the basis of this pilot study, a multicenter randomized clinical trial that uses MARS treatment in EAD after OLT has been initiated.

Treating hepatitis C infection in liver transplant recipients

Chronic infection with hepatitis C virus (HCV) is a growing problem worldwide, with up to 300 million individuals infected, and those with chronic infection are at risk for cirrhosis and hepatocellular carcinoma. HCV infection is the most common indication for liver transplantation in the United States and Europe. Unfortunately, although transplantation is effective for treating decompensated cirrhosis and limited hepatocellular carcinoma associated with hepatitis C, HCV reinfection is virtually the rule among transplant recipients. Reinfection of the graft is associated with more rapidly progressive disease, with a median time to cirrhosis of 8 to 10 yr. Unfortunately, treatment of chronic HCV in liver transplant recipients is suboptimal. Combination therapy with interferon (pegylated and nonpegylated forms) plus ribavirin appears to provide maximum benefits. Drug therapy is usually administered for recurrent disease. No prophylactic therapy is available. Preemptive regimens offer no distinctive advantages over treatments begun for recurrent disease. Overall, treatment is poorly tolerated, with frequent need for dose reductions, especially from cytopenias, and drug discontinuations in up to 50% of patients. Optimizing drug doses is important in maximizing sustained virological response rates. Future therapies may include ribavirin alternatives with lower rates of anemia, alternative interferons with lower rates of cytopenias, and new antiviral drugs that can be used alone or in combination with either interferon or ribavirin to enhance sustained virological response rates and improve tolerability. Liver Transpl 12:1192-1204, 2006. (c) 2006 AASLD.

Protection of mitochondria during cold storage of liver and following transplantation: comparison of the two solutions, University of Wisconsin and Eurocollins

Injury to allografts during ischaemia/reperfusion contribute to the development of graft failure following transplantation with significant morbidity and mortality to patients. The development of University of Wisconsin solution has significantly improved the quality of graft preservation and transplant outcome relative to formerly used solutions such as Eurocollins. The aim of this study was to further characterize mitochondrial structural and functional alterations occurring in rat livers following cold storage and transplantation. Mitochondrial impairment after prolonged storage in Eurocollins included decreased cyt. c+c1, cyt. b and cyt. a+a3 concentration and dramatic falls in the activities of the respiratory chain enzymes ubiquinol-cyt. c oxidoreductase and cytochrome oxidase. Under the same conditions the highest hydroperoxide but lowest vitamin E concentrations were also found. Although both the Eurocollins and University of Wisconsin preservation solutions have limitations in preventing oxidative injuries following cold storage and reperfusion, our data indicate that mitochondrial impairment was higher in Eurocollins- than in University of Wisconsin-stored livers. Further improvements are necessary in maintaining the stability of mitochondria in order to optimize preservations solutions used in transplantations.

The Nonstandard Liver, a Hidden Resource That Cannot Be Overlooked: Implications for the Identification of the Best Recipient

We described the characteristics of livers already labeled as marginal, nonstandard, or selected with extended criteria: donors of elderly age, steatosis, hemodynamic instability, long cold ischemia time, high serum Na, HbcAb-positive status, HCVAb-positive status. Recipients characteristics (gender, UNOS status, MELD score, indication for transplantation) and their best possible match to nonstandard donors were evaluated with a report of the recent guidelines and the specific algorithms to optimize recipient identification.

K(ICG) value, a reliable real-time estimator of graft function, accurately predicts outcomes in adult living-donor liver transplantation

Reliable monitoring enabling evaluation of graft function is crucial after living-donor liver transplantation (LDLT). A method to identify poor graft function at an early postoperative period would allow opportune intensive clinical management to bring about further improvements in LDLT outcomes. This study assessed the reliability of the indocyanine green (ICG) elimination rate constant (K(ICG)) value as an estimator of graft function and determined the actual temporal changes of K(ICG) after LDLT. K(ICG) values were measured using a noninvasive method in 30 adult recipients up to 28 days after LDLT. The receptor index (LHL15) based on liver scintigraphy, and graft parenchymal damage score based on histopathological findings were evaluated after LDLT and correlated well with simultaneous K(ICG). Thus, K(ICG) measured by noninvasive method was confirmed as accurately evaluating graft function. Changes of K(ICG) after LDLT in recipients with good graft function were maintained, after some falls in the early periods, and had a significant difference compared with those for recipients without good graft function; moreover, there were already significant differences in K(ICG) 24 hours after LDLT. Mean transit time reflecting systemic hemodynamics revealed that recipients without good outcomes fell into an unstable systemic hemodynamic state, and effective hepatic blood flow has a large influence on liver regeneration after LDLT. In conclusion, we suggested that K(ICG) values can predict clinical outcomes at the early postoperative period after LDLT by sharply reflecting the influence of systemic dynamics on splanchnic circulation.

Ischemic preconditioning of cadaver donor livers protects allografts following transplantation

BACKGROUND

Ischemic preconditioning (IP) has been shown in animal models to protect livers against ischemia/reperfusion injury. The aim of this clinical study is to investigate whether IP of cadaver livers prior to retrieval confers protection on the allografts.

METHODS

Cadaveric donor livers were subjected to IP prior to retrieval by clamping of the hepatic pedicle for 10 min followed by reperfusion. Biopsies were obtained from the preconditioned (n=9) and control nonpreconditioned (n=14) liver transplants prior to and 2 hr following reperfusion. Cryosections were stained with antibodies against neutrophils and platelets.

RESULTS

IP livers were associated with significantly lower serum levels of aspartate aminotransferase (240+/-98 IU/L vs. 382+/-163 IU/L; P>0.016) and lactate (0.81+/-0.07 mmol/L vs. 1.58+/-0.9 mmol/L; P>0.018) 24 hr following transplantation. Furthermore, recipients of IP livers spent a significantly shorter time in the intensive care unit following transplantation compared to those given nonpreconditioned allografts (1 vs. 2.8+/-1.6 days; P=0.0008). Increases in neutrophil infiltration were detected in 6/14 (43%; P=0.022) and in CD41 deposition in 5/14 (36%; P=0.042) of nonpreconditioned livers. However, none of the IP allografts showed any change in the levels of platelets or neutrophil infiltration following transplantation.

CONCLUSION

IP is an effective method of protecting cadaver donor allografts from cold ischemia and subsequent reperfusion injury. IP is also associated with a reduction in the nonspecific inflammatory response.

Resveratrol protects against cold ischemia-warm reoxygenation-induced damages to mitochondria and cells in rat liver

Ischemia-reperfusion is a critical event in the development of primary graft dysfunctions after liver transplantations. Ischemia-reperfusion causes cell injuries which are related to the successive cold preservation-warm reperfusion (CPWR) periods required by the graft. Recent evidences suggest that oxidative stress plays an important role in the development of these injuries and that mitochondrial dysfunctions are involved. The purpose of this study was to investigate the effect of the natural phytoalexin resveratrol on the prevention of liver injuries induced by 40-h cold preservation followed by a warm reperfusion. CPWR induced liver mitochondrial and cellular damages as attested by the increase in lipid peroxidation of liver membranes, the alteration of oxidative phosphorylation parameters, mitochondrial swelling and the activation of the cellular markers of necrosis and apoptosis, i.e., lactate dehydrogenase (LDH) leakage, mitochondrial cytochrome c release and caspase activation. Resveratrol inhibits lipid peroxidation and protects mitochondrial functions. It improves respiratory chain activity and prevents opening of the permeability transition pore, allowing better recovery of ATP energetic charge. Resveratrol also limits the activation of the cellular markers of necrosis and apoptosis. These protective effects could be related to the antioxidant properties of the drug but also to its membrane-stabilizing activity. Indeed, further experiments demonstrate that resveratrol is able to prevent the release of cytochrome c caused by oxygen deprivation in isolated liver mitochondria. These data demonstrate that resveratrol ameliorates the liver injury induced by CPWR and appears as a promising drug to improve the primary function of the grafted liver after transplantation.

Causes of early acute graft failure after liver transplantation: analysis of a 17-year single-centre experience

Despite satisfactory overall results reported, early post-operative period after liver transplantation (LT) still represents a critical time with persistently high rate of graft loss. We retrospectively reviewed our experience of 17 yr in LT, analysing the impact on grafts and patient survivals of the acute complications affecting the graft in the early period following LT. To evaluate the changes that occurred over the years in case of early acute graft failure (EAGF), the study population was divided into three equal groups of 223 patients corresponding to three different periods. Ninety (13.5%) experienced an EAGF. Causes of EAGF were hepatic artery thrombosis (HAT) in 32 cases (4.8%), primary graft non-function in 29 cases (4.3%), caval stenosis in 19 (2.8%), early irreversible acute rejection in 6 (0.9%) and portal vein thrombosis in 4 (0.6%). The use of elderly donors and the introduction of the piggyback technique proved to be associated with a higher incidence of HAT and caval stenosis, respectively. Female recipients of male donors were independently associated with Primary graft non-function. Of 90 patients with EAGF, 20 (22.2%) died within the first month after LT, 34 (37.8%) underwent retransplantation (ReLT) and 36 (40%) received conservative treatment. Conservative treatments increased from 3.6% in the first group to 47.0 and 66.8% in the second and third one (p = 0.000). One-year graft and patient survival of patients with EAGF significantly improved over the three eras analysed. The incidence of EAGF remains consistent. Nevertheless, a better understanding of the clinical situations and changes in treatment strategies have led to significant improvements in terms of graft and patient survival rates, now close to the survival rate of EAGF-free patients.

Small-for-size syndrome after partial liver transplantation: definition, mechanisms of disease and clinical implications

Widespread application of cadaveric split or living donor liver transplantation bears considerable potential to increase the pool of available organs and thus alleviate the problem of organ shortage. Although splitting of a cadaveric liver into two grafts for adult recipients can be performed successfully, sufficient function of undersized grafts is a major concern. To minimize the risk for living donors, transplant surgeons aim at procuring the least necessary liver volume, also leading to potentially small grafts. When small partial grafts are unable to meet the functional demands, the recipients can develop a so-called small-for-size syndrome (SFSS). There is currently limited data on the pathogenesis of SFSS, with clinical studies mainly focusing on portal hyperperfusion. Additional aspects include graft-related factors such as functional and regenerative capacity, as well as recipient-related factors, such as overall health status and severity of cirrhosis. However, there is currently no consensus on the definition of SFSS. We propose a novel definition, based on simple clinical criteria, which divides the syndrome into either nonfunction or dysfunction of a small graft after the exclusion of other causes. This definition should ease comparability of future clinical trials, and thus improve understanding of the pathogenesis of SFSS.

The contemporary role of antioxidant therapy in attenuating liver ischemia-reperfusion injury: a review

Oxidative stress is an important factor in many pathological conditions such as inflammation, cancer, ageing and organ response to ischemia-reperfusion. Humans have developed a complex antioxidant system to eliminate or attenuate oxidative stress. Liver ischemia-reperfusion injury occurs in a number of clinical settings, including liver surgery, transplantation, and hemorrhagic shock with subsequent fluid resuscitation, leading to significant morbidity and mortality. It is characterized by significant oxidative stress but accompanied with depletion of endogenous antioxidants. This review has 2 aims: firstly, to highlight the clinical significance of liver ischemia-reperfusion injury, the underlying mechanisms and the main pathways by which the antioxidants function, and secondly, to describe the new developments that are ongoing in antioxidant therapy and to present the experimental and clinical evidence about the role of antioxidants in modulating hepatic ischemia-reperfusion injury.

The impact of total plasma exchange on early allograft dysfunction

INTRODUCTION

Early allograft dysfunction (EAD) is a rare but serious complication encountered among patients undergoing liver transplant surgery. Total plasma exchange (TPE) in EAD has been suggested, but its role is still considered investigational. We retrospectively assessed the efficacy of TPE in EAD and its impact on other parameters of liver function.

MATERIALS AND METHODS

Between 1995 and 2001, 25 orthotopic liver transplant recipients developed EAD, which was defined as early postoperative prothrombin time (PT) >17 seconds, aspartate aminotransferase (AST) and/or alanine aminotransferase (ALT) >2500 IU/L, and/or the presence of hepatic encephalopathy, and development of renal failure. Daily TPE was performed using the Cobe Spectra TPE (Gambro) for 4 hours until an adequate clinical response, the patient underwent retransplantation, or the patient died. International normalizing ratio (INR), partial thromboplastin time (PTT), fibrinogen, ALT, AST, gamma-glutanyl transpeptidase (GGT), blood urea nitrogen (BUN), ammonia, and total bilirubin were analyzed before and after TPE. Student t and chi-square tests were used for statistical analysis.

RESULTS

Twenty-five patients with EAD included 13 females, 12 males of mean age 42.3 years (range, 1-63 years). Coagulopathy and hyperbilirubinemia significantly improved with TPE. Nineteen patients (76%) survived and 2 required retransplantation. Mean number of TPE sessions was 4.3.

CONCLUSION

TPE was effective to correct coagulopathy and improve liver function. These results suggest the benefit of potential temporary liver support until recovery or retransplantation, in the absence of sepsis or multi-system organ failure.

The mismatch choice in liver transplantation: a suggestion for the selection of the recipient in relation to the characteristics of the donor

Two hundred seventy-six liver transplants were retrospectively reviewed to analyze 6-month graft survival in relation to the combination of donor quality (standard donor vs nonstandard donor) and risk related to the severity of recipient liver disease low-risk, ie, United Network for Organ Sharing [UNOS] status 3/2b; high-risk, ie, UNOS status 1/2a). The overall 6-month survival rate of 82% was stratified into 4 classes: (1) standard donor to low-risk recipient = 88%; (2) standard donor to high-risk recipient = 86%; (3) nonstandard donor to low-risk recipient = 84%; and (4) nonstandard donor to high-risk recipient = 67%. According to the observed graft survival in the 4 different classes, 2 simulations were performed: the "match simulation" (transplantation of all low-risk recipients using standard donors, and transplantation of all high-risk recipients using nonstandard donors), and the "mismatch simulation" (transplantation of all the high-risk patients using low-risk donors and transplantation of low-risk patients using high-risk donors). The 6-month survival rates, calculated using the match simulation, were 74% and using the mismatch simulation, 84%. The authors suggest that, in the era of marginal donors, the recipient should be selected in relation to the characteristics of the donor according to the mismatch model.

Ischemic preconditioning and liver tolerance to warm or cold ischemia: experimental studies in large animals

BACKGROUND

In the rodent, ischemic preconditioning (IPC) has been shown to improve the tolerance of the liver to ischemia-reperfusion under normothermic or hypothermic conditions. The aim of the present study was to test this hypothesis in a dog model, which may be more relevant to the human.

METHODS

Beagle dogs were used in two distinct animal models of hepatic warm ischemia and orthotopic liver transplantation (hypothermic ischemia). IPC consisted of 10 minutes of ischemia followed by 10 minutes of reperfusion. In the first model, livers were exposed to 55 minutes prolonged warm ischemia and reperfused for 3 days (n = 6). In the second model, livers were retrieved and preserved for 48 hours at 4 degrees C in University of Wisconsin solution, transplanted, and reperfused without immunosuppression for 7 days (n = 5). In each model, nonpreconditioned animals served as controls (n = 5 in each group). Also, isolated dog hepatocytes were subjected to warm and cold storage ischemia-reperfusion to model the animal transplant studies using IPC.

RESULTS

In the first model (warm ischemia), IPC significantly decreased serum aminotransferase activity at 6 and 24 hours post-reperfusion. After 1 hour of reperfusion, preconditioned livers contained more adenosine triphosphate and produced more bile and less myeloperoxidase activity (neutrophils) relative to controls. In the second model (hypothermic preservation), IPC was not protective. Finally, IPC significantly attenuated hepatocyte cell death after cold storage and warm reperfusion in vitro.

CONCLUSIONS

IPC is effective in large animals for protecting the liver against warm ischemia-reperfusion injury but not injury associated with cold ischemia and reperfusion (preservation injury). However, the IPC effect observed in isolated hepatocytes suggests that preconditioning for preservation is theoretically possible.

Donor Characteristics Associated with Liver Graft Survival

BACKGROUND

Organ availability is affecting the development of liver transplantation in its entirety, leading to transplant teams expanding the criteria for accepting organ donors. In these circumstances, analysis of the impact of the donor's characteristics on graft survival becomes mandatory.

METHODS

Fifty-two donor variables from 5,150 liver transplants performed in Spain between 1994 and 2001 were analyzed through a univariate analysis. Those with statistically significant impact on graft survival were entered in a Cox regression model with the recipients' characteristics and other factors linked to the graft technique.

RESULTS

Several donor factors negatively affect graft survival: donor age, cause of death, body mass index, vasoactive drug administration, prolonged intensive care unit (ICU) stay, increased alkaline phosphatase and liver enzyme levels, low bicarbonate level, and antecedents of hypertension. However, only four can be mentioned as representing a risk for losing the graft when donor variables are controlled with recipient or technique variables in a Cox regression model: donor age, antecedents of hypertension, prolonged ICU stay, and low bicarbonate level. In the same analysis, norepinephrine administration has a relative risk less than 1.

CONCLUSIONS

The multivariate analysis of the impact of 52 donor characteristics on liver graft survival showed the negative effect of an elderly donor, with hypertension combined with the presence of metabolic acidosis, or a prolonged ICU donor stay. The administration of norepinephrine alone during donor management showed a protective effect.

A methodological framework for optimally reorganizing liver transplant regions

BACKGROUND

The United States is divided currently into 11 transplant regions, which vary in area and number of organ procurement organizations (OPOs). Region size affects organ travel time and organ viability at transplant.

PURPOSE

To develop a methodologic framework for determining optimal configurations of regions maximizing transplant allocation efficiency and geographic parity.

METHODS

An integer program was designed to maximize a weighted combination of 2 objectives: 1) intraregional transplants, 2) geographic parity-maximizing the lowest intraregional transplant rate across all OPOs. Two classes of functions relating liver travel time to liver viability were also examined as part of the sensitivity analyses.

RESULTS

Preliminary results indicate that reorganizing regions, while constraining their number to 11, resulted in up to 17 additional transplants/year depending on the travel-viability function; when not constrained, it resulted in up to 18/year of increase.

CONCLUSION

Our analysis indicates that liver transplantation may benefit through region reorganization. The analytic method developed here should be applicable to other organs and sets of organs.

Long-term outcome of pediatric liver transplantation for biliary atresia: a 10-year follow-up in a single center

The aim of this study was to review our experience in orthotopic liver transplantation (OLT) for biliary atresia (BA) in children and analyze the survival and prognostic factors, and long-term outcome. We reviewed 332 OLTs performed in 280 children between the years 1986 and 2000. Univariate and multivariate analysis were performed on patient and graft survivals according to recipients' and donors' characteristics as well as intraoperative data. The long-term outcome among the 80 children living at 10 years after OLT was studied according to growth, immunosuppressive therapy, and liver and renal functions. Liver graft status was eventually documented by liver biopsy. Status of rehabilitation was assessed by reviewing school performance and employment. Overall patient survival rates at 1, 5, and 10 years were 85, 82, and 82%, respectively, and the corresponding overall graft survival rates were 77, 73, and 71%. In the multivariate analysis, we identified 4 independent prognostic factors: polysplenia syndrome (P = .03), United Network for Organ Sharing (UNOS) status (P = .05), donor's age (P = .01), and perioperative surgical complications (P = .03). At 10 years after transplant, 80 children were alive and had normal growth rates. Liver histology was abnormal in 73% of these long-term survivors, mainly due to chronic rejection and centrilobular fibrosis. A total of 63 of the 80 children attended normal school and in 55 children (69%) school performance was not delayed. In conclusion, we discovered that a good long-term survival could be achieved after liver transplantation for BA, with a 82% survival rate at 10 years with normal scholastic studies in the majority of recipients.

The role of mitochondria in ischemia/reperfusion injury in organ transplantation

In organ transplantation, ischemia/reperfusion (I/R) results in damage that may affect cell viability and lead to organ failure. I/R injury involves a complex cascade of events, including loss of energy, derangement of the ionic hemostasis, production of reactive oxygen species, and cell death. In this context, mitochondria may be critical organelles, since they undergo major changes that may contribute to the injury occurring during I/R.