Nazia Selzner

Protective strategies against ischemic injury of the liver.

This article summarizes strategies to protect the liver from injuries caused by ischemia and reperfusion. Three different sections (i.e., surgical and pharmacologic strategies and gene therapy) present approaches to enhance the survival and viability of the liver in various surgical procedures including liver transplantation. The first section reviews approaches using surgical interventions such as ischemic preconditioning and intermittent clamping. Their protective effects are discussed with respect to the mechanism of injury. In the second section, pharmacologic agents targeting microcirculation, oxidative stress, proteases, and inflammation are described. Mechanisms of injury and their suppression by a wide variety of drugs are discussed. The third section focuses on gene therapy. Potential target genes have been identified (e.g., superoxide dismutase or heme oxygenase). Animal experiments in which the liver injury is reduced successfully may pave the way to novel strategies applied to different liver diseases in humans.

Antiviral treatment of recurrent hepatitis C after liver transplantation: predictors of response and long-term outcome.

Background. Efficacy and long-term outcome of antiviral therapy for recurrent hepatitis C after liver transplantation is poorly defined. Aim. This study aimed at assessing the efficacy of antiviral therapy regarding sustained hepatitis C virus (HCV) clearance, liver histology, and patient survival. Methods. We retrospectively reviewed all 446 patients who received a liver allograft at our institution for HCV-related cirrhosis between January 1992 and December 2006. Two hundred thirty-two patients (52%) were eligible for antiviral therapy based on predefined criteria (Metavir stage ≥1 and/or grade ≥2; protocol biopsies). One hundred seventy-two patients (39%) had no contraindication for treatment, received more than or equal to 1 dose of interferon-&agr;–based combination therapy, and form the basis of this analysis. Therapy was aimed for 48 weeks; median posttreatment follow-up was 68 months. Results. The overall sustained virological response (SVR) rate was 50% (genotype 1/4: 40%; genotype 2/3: 76%). SVR was higher on cyclosporine A (CsA) (56%) than on tacrolimus (44%, P=0.05), largely because of a lower relapse rate (6% vs. 19%, P=0.01). In multivariate analysis, genotype 2/3, CsA use, donor age, and pretreatment necroinflammatory activity were independently associated with SVR. SVR significantly improved histology and long-term survival (actuarial 5-year survival 96% vs. 69% in nonresponders, P<0.0001). Conclusion. Antiviral therapy of recurrent hepatitis C after liver transplantation is able to clear HCV in half the patients, more likely on CsA than on tacrolimus, and markedly improves outcome.

Ischemic preconditioning protects the steatotic mouse liver against reperfusion injury: an ATP dependent mechanism.

BACKGROUND/AIMS Hepatic steatosis is a major risk factor for liver surgery and transplantation. The increased susceptibility of fatty livers to ischemic injury is associated with a necrotic form of cell death as opposed to apoptosis in lean animals, and is possibly related to low contents of ATP. Ischemic preconditioning, a brief period of ischemia prior to a prolonged period, protects the lean liver against ischemia through anti-apoptotic properties. We evaluated whether ischemic preconditioning also confers protection in the fatty liver and whether it protects against the ATP loss. METHODS The effect of ischemic preconditioning was tested in steatotic and lean livers subjected to 75 min of ischemia and 4 or 24 h of reperfusion. Tissue ATP contents were assessed at various times, and a model of low hepatic ATP contents (starvation) was studied to assess the type of injury following ischemia and the effects of preconditioning. RESULTS Ischemic preconditioning protected steatotic livers against massive necrosis. ATP levels were significantly higher before and after reperfusion in liver subjected to preconditioning when compared to controls. Liver with low baseline ATP levels (starvation) were also associated with necrosis, and were protected by ischemic preconditioning. CONCLUSIONS Ischemic preconditioning mainly protects the fatty liver against necrosis possibly through preservation and restoration of tissue ATP contents.

Live donor liver transplantation in high MELD score recipients.

Background:In 2002, the New York State Committee on Quality Improvement in Living Liver Donation prohibited live liver donation for potential recipients with Model for End-stage Liver Disease (MELD) scores greater than 25. Despite the paucity of evidence to support this recommendation, many centers in North America remain reluctant to offer living donor (LD) to patients with moderate to high MELD scores. Methods:We analyzed 271 consecutive adult-to-adult right lobe LD liver transplants performed at our institution between 2002 and 2008 to study the relationship, between recipient MELD scores and the outcome of LD liver transplantation. The recipients were categorized according to their MELD score into a low (Low: <25)and high (Hi: ≥25) MELD group. We compared short-term donor morbidity, graft loss within 30 days, length of hospital stay, biochemical markers of hepatocyte injury and graft function, and 90 day posttransplant complications including infection, rejection, bleeding, and renal failure. Long-term posttransplant outcome was measured by graft and patient survival after 1-, 3-, and 5-years. Results:Donor and recipient characteristics were similar between groups. Donor outcomes were similar in both groups. Peak recipient aspartat aminotransferase, alanine aminotransferase, and length of hospital stay were similar between both groups. The proportional decrease in postoperative INR and creatinine within the first week was greater in the high versus low MELD score group. High MELD score recipients had more frequent postoperative pneumonia (Low: 2.2% vs. Hi: 14%, P = 0.003), while no differences were observed in rates of biliary complications, rejection, renal failure, or overall infections. Recipients with a MELD <25 versus ≥25 had a similar 1-year (Low: 92% vs. Hi: 83%), 3-year (Low: 86% vs. Hi: 80%), and 5-year (Low: 78% vs. Hi: 80%) graft survival after LD liver transplantation (P = 0.51). Conclusion:LD liver transplantation can provide excellent graft function and survival rates in high MELD score recipients. Thus, when deceased donor organs are scare, a high MELD score alone should not be an absolute contraindication to living liver donation.

Adult living liver donors have excellent long-term medical outcomes: the University of Toronto liver transplant experience.

Right lobe living donor liver transplantation is an effective treatment for selected individuals with end‐stage liver disease. Although 1 year donor morbidity and mortality have been reported, little is known about outcomes beyond 1 year. Our objective was to analyze the outcomes of the first 202 consecutive donors performed at our center with a minimum follow‐up of 12 months (range 12–96 months). All physical complications were prospectively recorded and categorized according to the modified Clavien classification system. Donors were seen by a dedicated family physician at 2 weeks, 1, 3 and 12 months postoperatively and yearly thereafter. The cohort included 108 males and 94 females (mean age 37.3 ± 11.5 years). Donor survival was 100%. A total of 39.6% of donors experienced a medical complication during the first year after surgery (21 Grade 1, 27 Grade 2, 32 Grade 3). After 1 year, three donors experienced a medical complication (1 Grade 1, 1 Grade 2, 1 Grade 3). All donors returned to predonation employment or studies although four donors (2%) experienced a psychiatric complication. This prospective study suggests that living liver donation can be performed safely without any serious late medical complications and suggests that long‐term follow‐up may contribute to favorable donor outcomes.

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.

Immune-mediated complications of the graft in interferon-treated hepatitis C positive liver transplant recipients

Hepatitis C virus (HCV) re-infection of the graft is universal and interferon based antiviral therapy remains at present the treatment of choice in HCV liver transplant recipients. Apart from the antiviral effects, interferon and ribavirin have both potent immunomodulatory properties resulting in a broad range of immune-related disorders including acute cellular rejection and chronic ductopenic rejection as well as de novo autoimmune hepatitis. Further complicating the picture, HCV infection per se is associated with a variety of autoimmune phenomena. We discuss here the immune-mediated complications and their relationship to chronic HCV and interferon based antiviral therapy.

Increased ischemic injury in old mouse liver: An ATP-dependent mechanism

Although livers exhibit only minimal morphologic changes with age, how older livers tolerate pathologic conditions such as normothermic ischemia is unknown. Young 6‐week‐old mice and old 60‐week‐old mice underwent 60 minutes of hepatic ischemia and various periods of reperfusion. Markers of hepatocyte injury, hepatic energy content, and mitochondrial function were determined. Ischemic preconditioning and glucose injection were evaluated as protective strategies against reperfusion injury in old mice. Reperfusion injury was far worse in old mice compared with mice in the young control group. Ischemic preconditioning was highly protective against reperfusion injury in young but not in old mice. Older livers had dramatically reduced adenosine triphosphate (ATP) levels and glycogen contents. The low intrahepatic energy level in old mice was associated with a reduced mitochondrial ATP production. Preoperative injection of glucose restored the intrahepatic ATP content and protected against reperfusion injury. Furthermore, glucose injection restored the protective effect of ischemic preconditioning, resulting in additive protection when both strategies were combined. Aging of the liver is associated with mitochondrial dysfunction and decreased intrahepatic energy content, resulting in poorer tolerance against ischemic injury. Improving intrahepatic ATP levels in old livers by glucose injection protects the old liver against ischemic injury and restores the protective effects of ischemic preconditioning. Liver Transpl 13:382–390, 2007.

Transgenic mice overexpressing human Bcl-2 are resistant to hepatic ischemia and reperfusion

BACKGROUND/AIMS Apoptosis is a key mechanism of reperfusion injury in the ischemic liver. The apoptotic pathway is highly regulated by anti-apoptotic factors, such as Bcl-2. We evaluated the effect of Bcl-2 overexpression on apoptosis and the activation of the apoptotic cascade after hepatic ischemia and reperfusion. METHODS Ninety minutes of ischemia and reperfusion was performed in Bcl-2 transgenic and non-transgenic mice. Bcl-2 overexpression was determined by immunohistochemistry and Western blot. Liver injury was determined by aspartate aminotransferase (AST), Tunel test and the activation of the apoptotic cascade and animal survival. RESULTS Bcl-2 overexpression was present in all hepatocytes and non-parenchymal liver cells in transgenic mice. Bcl-2 overexpression resulted in significant decreased AST levels after ischemic injury, and complete inhibition of apoptosis. After 90 min of total hepatic ischemia all control mice died, while four transgenic mice survived permanently. Bcl-2 overexpression was associated with inhibition of caspase 3 activation after reperfusion and increased baseline levels of cytoplasmic cytochrome c, caspase 3, and a reduction of Bcl-x(L) production. CONCLUSIONS Bcl-2 overexpression protects against ischemic injury by inhibiting apoptosis. Extensive overproduction of Bcl-2 is associated with a compensatory increase of baseline levels of cytoplasmic cytochrome c and caspase 3, and a deletion of Bcl-x(L).

A graft to body weight ratio less than 0.8 does not exclude adult‐to‐adult right‐lobe living donor liver transplantation

Many centers require a minimal graft to body weight ratio (GBWR) ≥ 0.8 as an arbitrary threshold to proceed with right‐lobe living donor liver transplantation (RL‐LDLT), and there is often hesitancy about transplanting lower volume living donor (LD) liver grafts into sicker patients. The data supporting this dogma, based on the early experience with RL‐LDLT at Asian centers, are weak. To determine the effect of LD liver volume in the modern era, we investigated the impact of GBWR on the outcome of RL‐LDLT with a GBWR as low as 0.6 at the University of Toronto. Between April 2000 and September 2008, 271 adult‐to‐adult RL‐LDLT procedures and 614 deceased donor liver transplants were performed. Twenty‐two living donor liver transplantation (LDLT) cases with a GBWR of 0.59 to 0.79 (group A) were compared with 249 LDLT cases with a GBWR ≥ 0.8 (group B) and with 66 full‐graft deceased donor liver transplants (group C), who were matched 3:1 according to donor and recipient age, Model for End‐Stage Liver Disease score, and presence of hepatitis C and hepatocellular carcinoma with the low‐GBWR group. Portal vein shunts were not used. Markers of reperfusion injury [aspartate aminotransferase (AST) and alanine aminotransferase (ALT)], graft function (international normalized ratio and bilirubin), complications graded by the Clavien score, and graft and patient survival were compared. As expected, LD recipients had a significantly shorter cold ischemia time (94 ± 43 minutes for A, 96 ± 57 minutes for B, and 453 ± 152 minutes for C, P = 0.0001). However, the peak AST, peak ALT, absolute decrease in the international normalized ratio, day 7 bilirubin level, postoperative creatinine clearance, complication rate graded by the Clavien score, and median hospital stay were similar in all groups. The rate of biliary complications was higher with LD grafts than deceased donor grafts (19% for A versus 10% for B and 0% for C, P = 0.2). Patient survival was similar in all groups at 1, 3, and 5 years (91% for A versus 89% for B and 93% for C at 1 year, 87% for A versus 81% for B and 89% for C at 3 years, and 83% for A versus 81% for B and 87% for C at 5 years, P = 0.63). A Cox proportional regression analysis revealed only hepatitis C virus as a risk factor for poorer graft survival and not GBWR as a continuous or categorical variable. In conclusion, we found no evidence of inferior outcomes with smaller size grafts versus larger size LD grafts or full‐size deceased donor grafts. Further studies are warranted to examine the factors affecting the function of smaller grafts for living liver donation and thereby define the safe lower limits for transplantation. Liver Transpl 15:1776–1782, 2009.