Effect of ischemic preconditioning in whole liver transplantation from deceased donors. A pilot study

Hepatoprotection of a Standardized Extract of Cultured Lentinula edodes Mycelia against Liver Injury Induced by Ischemia-Reperfusion and Partial Hepatectomy

A standardized extract of cultured Lentinula edodes mycelia (ECLM, AHCC®) has been shown to have beneficial effects on organ metabolism. ECLM has been indicated to have liver protective properties by suppressing inflammatory responses. The pathogenesis of hepatic ischemia-reperfusion injury is thought to involve the induction of inflammatory mediators. However, whether ECLM affects inflammatory mediators caused by warm hepatic ischemia-reperfusion injury and partial hepatectomy (HIRI+PH) has not been clarified. In this study, we evaluated the protective effects of ECLM against liver damage caused by HIRI+PH. Rats were fed a normal diet (HIRI+PH) or a normal diet with 2% ECLM (HIRI+PH and ECLM) for ten days, then the liver and duodenal ligament were clamped and subjected to 15 min of hepatic ischemia. After 70% hepatectomy, the inflow occlusion was released, and liver and blood samples were collected at 3, 6, and 24 h. The effect of ECLM on mortality induced by 30 min of ischemia and hepatectomy was evaluated. The results showed that ECLM attenuated pathological liver damage, including apoptosis, in the rats treated with HIRI+PH, and decreased serum aminotransferase activity; ECLM decreased mRNA levels of the inflammation-related genes inducible nitric oxide synthase and C-X-C motif chemokine ligand 1, and increased mRNA levels of interleukin 10, an anti-inflammatory cytokine; ECLM increased hepatocyte growth factor mRNA levels and Ki-67 labeled nuclei in the liver at 24 h; ECLM significantly reduced HIRI+PH-induced mortality. In conclusion, ECLM may prevent HIRI+PH-induced liver injury in part by suppressing various inflammatory responses and promoting liver regeneration.

Effects of iNOS in Hepatic Warm Ischaemia and Reperfusion Models in Mice and Rats: A Systematic Review and Meta-Analysis

Warm ischaemia is usually induced by the Pringle manoeuver (PM) during hepatectomy. Currently, there is no widely accepted standard protocol to minimise ischaemia-related injury, so reducing ischaemia-reperfusion damage is an active area of research. This systematic review and meta-analysis focused on inducible nitric oxide synthase (iNOS) as an early inflammatory response to hepatic ischaemia reperfusion injury (HIRI) in mouse- and rat-liver models. A systematic search of studies was performed within three databases. Studies meeting the inclusion criteria were subjected to qualitative and quantitative synthesis of results. We performed a meta-analysis of studies grouped by different HIRI models and ischaemia times. Additionally, we investigated a possible correlation of endothelial nitric oxide synthase (eNOS) and nitric oxide (NO) regulation with iNOS expression. Of 124 included studies, 49 were eligible for the meta-analysis, revealing that iNOS was upregulated in almost all HIRIs. We were able to show an increase of iNOS regardless of ischemia or reperfusion time. Additionally, we found no direct associations of eNOS or NO with iNOS. A sex gap of primarily male experimental animals used was observed, leading to a higher risk of outcomes not being translatable to humans of all sexes.

Mitochondria and Cancer Recurrence after Liver Transplantation—What Is the Benefit of Machine Perfusion?

Tumor recurrence after liver transplantation has been linked to multiple factors, including the recipient’s tumor burden, donor factors, and ischemia-reperfusion injury (IRI). The increasing number of livers accepted from extended criteria donors has forced the transplant community to push the development of dynamic perfusion strategies. The reason behind this progress is the urgent need to reduce the clinical consequences of IRI. Two concepts appear most beneficial and include either the avoidance of ischemia, e.g., the replacement of cold storage by machine perfusion, or secondly, an endischemic organ improvement through perfusion in the recipient center prior to implantation. While several concepts, including normothermic perfusion, were found to reduce recipient transaminase levels and early allograft dysfunction, hypothermic oxygenated perfusion also reduced IRI-associated post-transplant complications and costs. With the impact on mitochondrial injury and subsequent less IRI-inflammation, this endischemic perfusion was also found to reduce the recurrence of hepatocellular carcinoma after liver transplantation. Firstly, this article highlights the contributing factors to tumor recurrence, including the surgical and medical tissue trauma and underlying mechanisms of IRI-associated inflammation. Secondly, it focuses on the role of mitochondria and associated interventions to reduce cancer recurrence. Finally, the role of machine perfusion technology as a delivery tool and as an individual treatment is discussed together with the currently available clinical studies.

Ischemic Preconditioning for Liver Transplantation: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

Background

In recent decades, liver transplantation (LTx) has increased the survival and quality of life of patients with end-stage organ failure. Unfortunately, LTx is limited due to the shortage of donors. A lot of effort is put into finding new ways to reduce ischemia-reperfusion injury (IRI) in liver grafts to increase the number of suitable organs procured from expanded-criteria donors (ECD). The aim of this study was to systematically review the literature reporting LTx outcomes when using ischemic preconditioning (IPC) or remote ischemic preconditioning (RIPC) to reduce IRI in liver grafts.

Methods

A literature search was performed in the MEDLINE, Web of Science, and EMBASE databases. The following combination was used: "Liver" OR "Liver Transplantation" AND "Ischemic preconditioning" OR "occlusion" OR "clamping" OR "Pringle." The following outcome data were retrieved: the rates of graft primary nonfunction (PNF), retransplantation, graft loss, and mortality; stay in hospital and the intensive care unit; and postoperative serum liver damage parameters.

Results

The initial search retrieved 4,522 potentially relevant studies. After evaluating 17 full-text articles, a total of 9 randomized controlled trials (RCTs) were included (7 IPC and 2 RIPC studies) in the qualitative synthesis; the meta-analysis was only performed on the data from the IPC studies. RIPC studies had considerable methodological differences. The meta-analysis revealed the beneficial effect of IPC when comparing postoperative aspartate aminotransferase (AST) corresponding to a statistically lower mortality rate in the IPC group (odds ratio [OR] 0.51; 95% confidence interval [CI] 0.27-0.98; p = 0.04).

Conclusion

IPC lowers postoperative AST levels and reduces the mortality rate; however, data on the benefits of RIPC are lacking.

Methods of Attenuating Ischemia-Reperfusion Injury in Liver Transplantation for Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is one of the most frequent indications for liver transplantation. However, the transplantation is ultimately associated with the occurrence of ischemia-reperfusion injury (IRI). It affects not only the function of the graft but also significantly worsens the oncological results. Various methods have been used so far to manage IRI. These include the non-invasive approach (pharmacotherapy) and more advanced options encompassing various types of liver conditioning and machine perfusion. Strategies aimed at shortening ischemic times and better organ allocation pathways are still under development as well. This article presents the mechanisms responsible for IRI, its impact on treatment outcomes, and strategies to mitigate it. An extensive review of the relevant literature using MEDLINE (PubMed) and Scopus databases until September 2020 was conducted. Only full-text articles written in English were included. The following search terms were used: “ischemia reperfusion injury”, “liver transplantation”, “hepatocellular carcinoma”, “preconditioning”, “machine perfusion”.

Direct, remote and combined ischemic conditioning in liver surgery

Liver ischemia-reperfusion injury is a major cause of postoperative liver dysfunction, morbidity and mortality following liver resection and transplantation. Ischemic conditioning has been shown to ameliorate ischemia-reperfusion injury in small animal models. It can be applied directly or remotely when cycles of ischemia and reperfusion are applied to a distant site or organ. Considering timing of the procedure, different protocols are available. Ischemic preconditioning refers to that performed before the duration of ischemia of the target organ. Ischemic perconditioning is performed over the duration of ischemia of the target organ. Ischemic postconditioning applies brief episodes of ischemia at the onset of reperfusion following a prolonged ischemia. Animal studies pointed towards suppressing cytokine release, enhancing the production of hepatoprotective adenosine and reducing liver apoptotic response as the potential mechanisms responsible for the protective effect of direct tissue conditioning. Interactions between neural, humoral and systemic pathways all lead to the protective effect of remote ischemic preconditioning. Despite promising animal studies, none of the aforementioned protocols proved to be clinically effective in liver surgery with the exception of morbidity reduction in cirrhotic patients undergoing liver resection. Further human clinical trials with application of novel conditioning protocols and combination of methods are warranted before implementation of ischemic conditioning in day-to-day clinical practice.

Control of Ischemia-Reperfusion Injury in Liver Transplantation: Potentials for Increasing the Donor Pool

Background

Organ shortage is a growing problem, with a rising number of organs being harvested from extended criteria donors, and this trend will further continue to increase as organ donors are getting older and have more comorbidities. Since this fact is immutable, efforts have been made to reduce the extent of ischemia-reperfusion injury (IRI) as well as of direct and indirect harvest-related graft injury which affects all organs in a more or less distinct way.

Methods

In liver transplantation (LT), the activation of Kupffer cells during organ reperfusion, thus provoking microcirculatory disturbances, hypoxia, and endothelial cell injury, is one of the key mechanisms causing graft dysfunction. Multiple approaches have been taken in order to find efficient preconditioning methods by pharmacological pretreatment, controlled induction of ischemia, controlled denervation of donor organs, and reconditioning with machine perfusion to prevent IRI, whereas marginal organs (i.e. steatotic grafts) are especially vulnerable.

Results

The above-mentioned approaches have been pursued in experimental and clinical settings. At this time point, however, there is not yet enough clinical evidence available to recommend any particular drug pretreatment or any other intervention for organ preconditioning prior to transplantation.

Conclusion

The multifactorial pathophysiology in the setting of IRI in LT requires a multimodal therapeutic approach with the integration of pharmacological and technical means being applied to the donor, the organ per se, and the recipient. Currently, there is no consensus on standardized pretreatment of donor organs in order to improve the transplant outcome.

Systematic review on the treatment of deceased organ donors

BACKGROUND

Currently, there is no consensus on which treatments should be a part of standard deceased-donor management to improve graft quality and transplantation outcomes. The objective of this systematic review was to evaluate the effects of treatments of the deceased, solid-organ donor on graft function and survival after transplantation.

METHODS

Pubmed, Embase, Cochrane, and Clinicaltrials.gov were systematically searched for randomized controlled trials that compared deceased-donor treatment versus placebo or no treatment.

RESULTS

A total of 33 studies were selected for this systematic review. Eleven studies were included for meta-analyses on three different treatment strategies. The meta-analysis on methylprednisolone treatment in liver donors (two studies, 183 participants) showed no effect of the treatment on rates of acute rejection. The meta-analysis on antidiuretic hormone treatment in kidney donors (two studies, 222 participants) indicates no benefit in the prevention of delayed graft function. The remaining meta-analyses (seven studies, 334 participants) compared the effects of 10 min of ischaemic preconditioning on outcomes after liver transplantation and showed that ischaemic preconditioning improved short-term liver function, but not long-term transplant outcomes.

CONCLUSIONS

There is currently insufficient evidence to conclude that any particular drug treatment or any intervention in the deceased donor improves long-term graft or patient survival after transplantation.

Emerging graft protective strategies in clinical liver transplantation

There have been remarkable efforts to characterize the key responsible pathophysiologic mechanisms, as well as to ameliorate the organ preservation and ischemia reperfusion injury with the ultimate goal of expanding the donor pool and further improvement of the outcomes of liver transplantation. Attempts to translate the experimental results from bench to bedside have yielded no valid protective concepts in the field of clinical liver transplantation yet. Nonetheless, there has been a considerable amount of ongoing clinical research to develop clinically relevant graft protective strategies. Areas covered: This review focuses on the most recent evidence based findings and ongoing clinical trials that might lead to emerging graft protective strategies in the field of clinical liver transplantation. New evidence-based findings in the donor preconditioning, organ preservation, and perioperative pharmacologic graft protection strategies in the recipient are reviewed. Expert commentary: Few strategies have been shown to exert some graft protective effects against ischemia reperfusion injury in recent clinical trials in liver transplantation. Among others, 'dynamic graft preservation' techniques have been emerging as more promising graft optimization strategies.

Ischemic preconditioning modulates ROS to confer protection in liver ischemia and reperfusion

Ischemia reperfusion (IR) injury is a significant cause of morbidity and mortality in liver transplantation. When oxygen is reintroduced to the liver graft it initiates a cascade of molecular reactions leading to the release of reactive oxygen species (ROS) and pro-inflammatory cytokines. These soluble mediators propagate a sterile immune response to cause significant tissue damage. Ischemic preconditioning (IPC) is one method that reduces hepatocellular injury by altering the immune response and inhibiting the production of ROS. Studies quantifying the effects of IPC in humans have demonstrated an improved liver enzyme panel in patients receiving grafts pretreated with IPC as compared to patients receiving the standard of care. In our review, we explore current literature in the field in order to describe the mechanism through which IPC regulates the production of ROS and improves IR injury.

A systematic review and meta-analysis of donor ischaemic preconditioning in liver transplantation

Ischaemic preconditioning (IPC) is a strategy to reduce ischaemia-reperfusion (IR) injury. Its benefit in human liver transplantation is unclear. The aim of this study was to analyse the current evidence for donor IPC in liver transplantation. Systematic review and meta-analysis of studies involving IPC of liver transplant donors. Ovid Medline, Embase and Cochrane CENTRAL were searched up until January 2015. Data retrieved included the primary outcomes of 1-year mortality, incidence of primary graft non-function (PGNF) and retransplantation. Secondary outcomes included aspartate aminotransferase (AST) levels on day 3 post-op. Pooled odds ratios (ORs) were calculated for dichotomous data and mean weighted ratios for continuous data. Ten studies included 593 patients (286 IPC; 307 control). IPC was associated with a reduction in mortality at 1 year (6% vs. 11%) although this was not statistically significant (OR 0.54, 95% C.I. 0.28-1.04, P = 0.06). The IPC group had a significantly lower day 3 AST level (WMD -66.41iU, P = 0.04). This meta-analysis demonstrates that IPC reduces liver injury following transplantation and produces a large reduction in 1-year mortality which was not statistically significant. Confirmation of clinical benefit from IPC requires an adequately powered prospective RCT.

The Effect of High-Mobility Group Box 1 in Rat Steatotic and Nonsteatotic Liver Transplantation From Donors After Brain Death

High-mobility group box 1 (HMGB1) has been described in different inflammatory disorders, and the deleterious effects of brain death (BD) may counteract the protection conferred by ischemic preconditioning (IP), the only surgical strategy that is being applied in clinical liver transplantation. Our study examined how HMGB1 may affect preconditioned and unpreconditioned steatotic and nonsteatotic liver grafts from donors after BD (DBDs) for transplantation. HMGB1 was pharmacologically modulated in liver grafts from DBDs, and HMGB1-underlying mechanisms were characterized. We found that BD decreased HMGB1 in preconditioned and unpreconditioned livers and was associated with inflammation and damage. Exogenous HMGB1 in DBDs activates phosphoinositide-3-kinase and Akt and reduces hepatic inflammation and damage, increasing the survival of recipients. Combination of IP and exogenous HMGB1 shows additional benefits compared with HMGB1 alone. This study provides new mechanistic insights into the pathophysiology of BD-derived liver graft damage and contributes to the development of novel and efficient strategies to ultimately improve liver graft quality.

Post reperfusion syndrome during liver transplantation: From pathophysiology to therapy and preventive strategies

This review aims at evaluating the existing evidence regarding post reperfusion syndrome, providing a description of the pathophysiologic mechanisms involved and possible management and preventive strategies. A PubMed search was conducted using the MeSH database, “Reperfusion” AND “liver transplantation” were the combined MeSH headings; EMBASE and the Cochrane library were also searched using the same terms. 52 relevant studies and one ongoing trial were found. The concept of post reperfusion syndrome has evolved through years to a multisystemic disorder. The implications of the main organ, recipient and procedure related factors in the genesis of this complex syndrome are discussed in the text as the novel pharmacologic and technical approaches to reduce its incidence. However the available evidence about risk factors, physiopathology and preventive measures is still confusing, the presence of two main definitions and the numerosity of possible confounding factors greatly complicates the interpretation of the studies.

Impact of ischemic preconditioning on outcome in clinical liver surgery: a systematic review

Background. Ischemia-reperfusion injury is a major cause of post-liver-surgery complications. Ischemic preconditioning (IPC) has been demonstrated to protect against ischemia-reperfusion injury. Clinical studies have examined IPC in liver surgery but with conflicting results. This systematic review aimed to evaluate the effects of IPC on outcome in clinical liver surgery. Methods. An electronic search of OVID Medline and Embase databases was performed to identify studies that reported outcomes in patients undergoing liver surgery subjected to IPC. Basic descriptive statistics were used to summarise data from individual clinical studies. Results. 1093 articles were identified, of which 24 met the inclusion criteria. Seven topics were selected and analysed by subgroup. There were 10 studies in cadaveric liver transplantation, 2 in living-related liver transplantation, and 12 in liver resection. IPC decreases hepatocellular damage in liver surgery as determined by transaminases but does not translate to any significant clinical benefit in orthotopic liver transplant or liver resection. Conclusions. Available clinical evidence does not support routine use of IPC in liver surgery as it does not offer any apparent benefit in perioperative outcome. Further clinical studies will need to be carried out to determine the subset of patients that will benefit from IPC.

Impact of ischaemic preconditioning on experimental steatotic livers following hepatic ischaemia-reperfusion injury: a systematic review

BACKGROUND

Steatotic livers are vulnerable to the deleterious effects of ischaemia-reperfusion injury (IRI) that occur after hepatic surgery. Ischaemic preconditioning (IPC) has been shown to abrogate the effects of IRI in patients undergoing hepatic surgery. Experimental studies have suggested that IPC may be beneficial in steatotic livers subjected to IRI.

OBJECTIVE

The aim of this systematic review was to evaluate the effects of IPC on steatotic livers following hepatic IRI in experimental models.

METHODS

An electronic search of the OVID Medline and EMBASE databases was performed to identify studies that reported clinically relevant outcomes in animal models of hepatic steatosis subjected to IPC and IRI.

RESULTS

A total of 1093 articles were identified, of which 18 met the inclusion criteria. There was considerable heterogeneity in the type of animal model, and duration and type of IRI. Increased macrovesicular steatosis (> 30%) was associated with a poor outcome following IRI. Ischaemic preconditioning was found to be beneficial in > 30% steatotic livers and provided for decreased histological damage, improved liver function findings and increased survival.

CONCLUSIONS

Experimental evidence supports the use of IPC in steatotic livers undergoing IRI. These findings may be applicable to patients undergoing liver surgery. However, clinical studies are required to validate the efficacy of IPC in this setting.

The effect of brain death in rat steatotic and non-steatotic liver transplantation with previous ischemic preconditioning

BACKGROUND & AIMS

Most liver grafts undergoing transplantation derive from brain dead donors, which may also show hepatic steatosis, being both characteristic risk factors in liver transplantation. Ischemic preconditioning shows benefits when applied in non-brain dead clinical situations like hepatectomies, whereas it has been less promising in the transplantation from brain dead patients. This study examined how brain death affects preconditioned steatotic and non-steatotic liver grafts undergoing transplantation.

METHODS

Steatotic and non-steatotic grafts from non-brain dead and brain dead-donors were cold stored for 6h and then transplanted. After 2, 4, and 16 h of reperfusion, hepatic damage was analysed. In addition, two therapeutic strategies, ischemic preconditioning and/or acetylcholine pre-treatment, and their underlying mechanisms were characterized.

RESULTS

Preconditioning benefits in non-brain dead donors were associated with nitric oxide and acetylcholine generation. In brain dead donors, preconditioning generated nitric oxide but did not promote acetylcholine upregulation, and this resulted in inflammation and damage. Acetylcholine treatment in brain dead donors, through PKC, increased antioxidants and reduced lipid peroxidation, nitrotyrosines and neutrophil accumulation, altogether protecting against damage. The combination of acetylcholine and preconditioning conferred stronger protection against damage, oxidative stress and neutrophil accumulation than acetylcholine treatment alone. These superior beneficial effects were due to a selective preconditioning-mediated generation of nitric oxide and regulation of PPAR and TLR4 pathways, which were not observed when acetylcholine was administered alone.

CONCLUSIONS

Our findings propose the combination of acetylcholine+preconditioning as a feasible and highly protective strategy to reduce the adverse effects of brain death and to ultimately improve liver graft quality.

Advances in the management of the explanted donor liver

Liver transplantation is the best therapy in end-stage liver disease. Donor organ shortage and efforts to expand the donor organ pool are permanent issues given that advances in perioperative management and immunosuppressive therapy have brought the procedure into widespread clinical use. The management of organ procurement, including donor preconditioning and adequate organ storage, has a key role in transplantation. However, the organ procurement process can differ substantially between transplant centres, depending on local and national preferences. Advances in the field have come from experimental and clinical research on dynamic storage systems, such as machine perfusion devices, as an alternative to static cold storage. Determination of the clinical significance of these new systems is a topic worthy of future investigations.

Methods of preventing bacterial sepsis and wound complications after liver transplantation

BACKGROUND

Bacterial sepsis and wound complications after liver transplantation increase mortality, morbidity, or hospital stay and are likely to increase overall transplant costs. All liver transplantation patients receive antibiotic prophylaxis. This is an update of our 2008 Cochrane systematic review on the same topic in which we identified seven randomised clinical trials.

OBJECTIVES

To assess the benefits and harms of different methods aimed at preventing bacterial sepsis and wound complications in people undergoing liver transplantation.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, EMBASE, and Science Citation Index Expanded to February 2013.

SELECTION CRITERIA

We included only randomised clinical trials irrespective of language or publication status. We excluded quasi-randomised and other observational studies for assessment of benefits, but not for harms.

DATA COLLECTION AND ANALYSIS

Two review authors collected the data independently. We calculated the risk ratio (RR) or mean difference (MD) with 95% confidence intervals (CI) using fixed-effect and the random-effects models based on available-case analysis.

MAIN RESULTS

We identified only seven trials for inclusion, including 614 participants. Only one trial was of low risk of bias risk. Overall, the quality of evidence was very low. There were five comparisons in the seven trials: selective bowel decontamination versus inactive control; selective bowel decontamination versus prebiotics with probiotics; selective bowel decontamination versus prebiotics; prebiotics with probiotics versus prebiotics; and granulocyte-colony stimulating factor (G-CSF) versus control. Four trials compared selective bowel decontamination versus placebo or no treatment. In one trial, participants were randomised to selective bowel decontamination, active lactobacillus with fibres (probiotic with prebiotic), or to inactivated lactobacillus with fibres (prebiotic). In one trial, active lactobacillus with fibres (probiotic with prebiotic) was compared with inactive lactobacillus with fibres (prebiotic). In the remaining trial, different doses of G-CSF and placebo were compared. There was no trial comparing different antibiotic prophylactic regimens in people undergoing liver transplantation. Most trials included adults undergoing elective liver transplantation. There was no significant difference in proportion of people who died or required retransplantation between the intervention and control groups in any of the five comparison groups. MORTALITY There were no differences between 190 participants (three trials); 5/87 (adjusted proportion: 6.2%) in selective bowel decontamination group versus 7/103 (6.8%) in inactive control group; RR 0.91 (95% CI 0.31 to 2.72); 63 participants (one trial); 0/32 (0%) in selective bowel decontamination group versus 0/31 (0%) in prebiotics with probiotics group; RR - not estimable; 64 participants (one trial); 0/32 (0%) in selective bowel decontamination group versus 0/32 (0%) in prebiotics group; RR - not estimable; 129 participants (two trials); 0/64 (0%) in prebiotics with probiotics group versus 0/65 (0%) in prebiotics group; RR - not estimable; and 194 participants (one trial); 22/124 (17.7%) in G-CSF group versus 10/70 (14.3%) in placebo group; RR 1.24 (95% 0.62 to 2.47). RETRANSPLANTATION There were no differences between 132 participants (two trials); 4/58 (adjusted proportion: 6.9%) in selective bowel decontamination group versus 6/74 (8.1%) in inactive control group; RR 0.85 (95% CI 0.26 to 2.85); 63 participants (one trial); 1/32 (3.1%) in selective bowel decontamination group versus 0/31 (0%) in prebiotics with probiotics group; RR 2.91 (0.12 to 68.81); 64 participants (one trial); 1/32 (3.1%) in selective bowel decontamination group versus 0/32 (0%) in prebiotics group; RR 3.00 (95% CI 0.13 to 71.00); 129 participants (two trials); 0/64 (0%) in prebiotics with probiotics group versus 1/65 (1.5%) in prebiotics group; RR 0.33 (95% CI 0.01 to 7.9); and 194 participants (one trial); 10/124 (7.1%) in G-CSF group versus 5/70 (7.1%) in placebo group; RR 1.13 (95% CI 0.4 to 3.17).There was no significant difference in the graft rejections, intensive therapy unit stay, or hospital stay between the intervention and control groups in any of the comparisons. Overall, 193/611 participants (31.6%) developed infective complications. The proportion of people who developed infective complications and the number of infective complication episodes were significantly higher in the selective bowel decontamination group than in the prebiotics with probiotics group (1 study; 63 participants; 15/32 (46.9%) in selective bowel decontamination group versus 4/31 (12.9%) in prebiotics with probiotics group; RR 3.63; 95% CI 1.36 to 9.74 and 23/32 participants (0.72 infective complications per participant) in selective bowel decontamination group versus 4/31 participants (0.13 infective complications per participant) in prebiotics with probiotics group; rate ratio 5.58; 95% CI 1.94 to 16.09). There was no significant difference between the proportion of participants who developed infection and the number of infection episodes between the intervention group and control group in any of the other comparisons.No trials reported quality of life and overall serious adverse events.

AUTHORS' CONCLUSIONS

Currently, there is no clear evidence for any intervention offering significant benefits in the reduction of bacterial infections and wound complications in liver transplantation. Selective bowel decontamination may even increase the rate of infections compared with prebiotics with probiotics. The confidence intervals were wide and further randomised clinical trials of low risk of bias are necessary.

Antiviral interventions for liver transplant patients with recurrent graft infection due to hepatitis C virus

BACKGROUND

Antiviral therapy for recurrent hepatitis C infection after liver transplantation is controversial due to unresolved balance between benefits and harms.

OBJECTIVES

To compare the therapeutic benefits and harms of different antiviral regimens in patients with hepatitis C re-infected grafts after liver transplantation.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL; Issue 1, 2013), MEDLINE, EMBASE, and Science Citation Index Expanded to February 2013.

SELECTION CRITERIA

We considered only randomised clinical trials (irrespective of language, blinding, or publication status) comparing various antiviral therapies (alone or in combination) in the treatment of hepatitis C virus recurrence in liver transplantation for the review.

DATA COLLECTION AND ANALYSIS

Two authors collected the data independently. We calculated the risk ratio (RR) or mean difference (MD) with 95% confidence intervals (CI) using the fixed-effect and the random-effects models based on available case-analysis. In the presence of only trials for a dichotomous outcome, we performed the Fisher's exact test.

MAIN RESULTS

Overall, 17 trials with 736 patients met the inclusion criteria for this review. All trials had high risk of bias. Five hundred and one patients randomised in 11 trials provided information for various comparisons in this systematic review after excluding post-randomisation drop-outs and patients from trials that did not report any of the outcomes of interest for this review. The comparisons for which outcomes were available included pegylated (peg) interferon versus control; peg interferon plus ribavirin versus control; ribavirin plus peg interferon versus peg interferon; peg interferon (1.5 μg/kg/week) plus ribavirin versus peg interferon (0.5 μg/kg/week) plus ribavirin; amantadine plus peg interferon plus ribavirin versus peg interferon plus ribavirin; interferon versus control; interferon plus ribavirin versus control; ribavirin versus interferon; and ribavirin versus placebo. Long-term follow-up was not available in these trials. There were no significant differences in mortality, retransplantation, graft rejections requiring retransplantation or medical treatment, or fibrosis worsening between the groups in any of the comparisons in which these outcomes were reported. Quality of life and liver decompensation were not reported in any of the trials. There was a significantly higher proportion of participants who developed serious adverse events in the ribavirin plus peg interferon combination therapy group than in the peg interferon monotherapy group (1 trial; 56 participants; 17/28 (60.7%) in the intervention group versus 5/28 (17.9%) in the control group; RR 3.40; 95% CI 1.46 to 7.94). There was no significant difference in proportion of participants who developed serious adverse events or in the number of serious adverse events between the intervention and control groups in the other comparisons that reported serious adverse events.

AUTHORS' CONCLUSIONS

Considering the lack of clinical benefit, there is currently no evidence to recommend or refute antiviral treatment for recurrent liver graft infection with hepatitis C virus. Further randomised clinical trials with low risk of bias and low risk of random errors with adequate duration of follow-up are necessary.

Antiviral prophylaxis for the prevention of chronic hepatitis C virus in patients undergoing liver transplantation

BACKGROUND

It is not clear whether prophylactic antiviral therapy is indicated to improve patient and graft survival in patients undergoing liver transplantation for chronic decompensated hepatitis C virus (HCV) infection.

OBJECTIVES

To compare the benefits and harms of different prophylactic antiviral therapies for patients undergoing liver transplantation for chronic HCV infection.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL; Issue 1, 2013), MEDLINE, EMBASE, and Science Citation Index Expanded to February 2013.

SELECTION CRITERIA

Only randomised clinical trials irrespective of language, blinding, or publication status and comparing various prophylactic antiviral therapies (alone or in combination) in the prophylactic treatment of patients undergoing liver transplantation for chronic HCV infection.

DATA COLLECTION AND ANALYSIS

Two authors collected the data independently. We calculated the risk ratio (RR) or mean difference (MD) or hazard ratio (HR) with 95% confidence intervals (CI) using the fixed-effect and the random-effects models based on available case analysis.

MAIN RESULTS

A total of 501 liver transplant recipients undergoing liver transplantation for chronic HCV infection were randomised in 12 trials to various experimental interventions and control interventions. The proportion of genotype I varied between 49% and 100% in the seven trials that reported the genotype. Only one or two trials were included under each comparison. All the trials were of high risk of bias. Ten trials including 441 liver transplant recipients provided data for this review.There were no significant differences in the 90-day mortality (1 trial; 81 participants; 5/35 (adjusted proportion: 14.2%) in interferon group versus 5/46 (10.9%) in control group; RR 1.31; 95% CI 0.41 to 4.19); mortality at maximal follow-up (2 trials; 105 participants; 7/47 (adjusted proportion: 14.8%) in interferon group versus 10/58 (17.2%) in control group; RR 0.86; 95% CI 0.36 to 2.08); long-term mortality (1 trial; 81 participants; HR 0.45; 95% CI 0.13 to 1.56); mortality at maximal follow-up (1 trial; 54 participants; 1/26 (3.9%) in pegylated interferon group versus 2/28 (7.1%) in control group; RR 0.54; 95% CI 0.05 to 5.59); 90-day mortality (1 trial; 115 participants; 5/55 (9.1%) in pegylated interferon plus ribavirin group versus 3/60 (5.0%) in control group; RR 1.82; 95% 0.46 to 7.25); 90-day mortality (3 trials; 53 participants; 3/37 (adjusted proportion: 4.3%) in HCV antibody group versus 1/16 (6.3%) in placebo group; RR 0.69; 95% CI 0.15 to 3.11); or 90-day mortality (2 trials; 31 participants; 2/14 (adjusted proportion: 16.2%) in HCV antibody high-dose group versus 1/17 (5.9%) in HCV antibody low-dose group; RR 2.75; 95% CI; 0.30 to 25.35). There were no significant differences in the retransplantation at maximal follow-up (2 trials; 105 participants; 2/47 (adjusted proportion: 4.0%) in interferon group versus 2/58 (3.4%) in control group; RR 1.17; 95% CI 0.22 to 6.2); 90-day retransplantation (1 trial; 18 participants; 1/12 (8.3%) in HCV antibody group versus 0/6 (0%) in control group; RR 1.71; 95% CI 0.09 to 32.93); or 90-day retransplantation (1 trial; 12 participants; 1/6 (17.7%) in HCV antibody high-dose group versus 0/6 (0%) in HCV antibody low-dose group; RR 3.00; 95% CI 0.15 to 61.74). There were no significant differences in serious adverse events, graft rejection, worsening of fibrosis, or HCV recurrence between intervention and control groups in any of the comparisons that reported these outcomes. None of the trials reported quality of life, liver decompensation, intensive therapy unit stay, or hospital stay. Life-threatening adverse events were not reported in either group in any of the comparisons.

AUTHORS' CONCLUSIONS

There is currently no evidence to recommend prophylactic antiviral treatment to prevent recurrence of HCV infection either in primary liver transplantation or retransplantation. Further randomised clinical trials with adequate trial methodology and adequate duration of follow-up are necessary.

What can we learn about stroke from retinal ischemia models?

Retinal ischemia is a very useful model to study the impact of various cell death pathways, such as apoptosis and necrosis, in the ischemic retina. However, it is important to note that the retina is formed as an outpouching of the diencephalon and is part of the central nervous system. As such, the cell death pathways initiated in response to ischemic damage in the retina reflect those found in other areas of the central nervous system undergoing similar trauma. The retina is also more accessible than other areas of the central nervous system, thus making it a simpler model to work with and study. By utilizing the retinal model, we can greatly increase our knowledge of the cell death processes initiated by ischemia which lead to degeneration in the central nervous system. This paper examines work that has been done so far to characterize various aspects of cell death in the retinal ischemia model, such as various pathways which are activated, and the role neurotrophic factors, and discusses how these are relevant to the treatment of ischemic damage in both the retina and the greater central nervous system.

The Current Knowledge of the Role of PPAR in Hepatic Ischemia-Reperfusion Injury

Strategies to improve the viability of steatotic livers could reduce the risk of dysfunction after surgery and increase the number of organs suitable for transplantation. Peroxisome proliferator-activated receptors (PPARs) are major regulators of lipid metabolism and inflammation. In this paper, we review the PPAR signaling pathways and present some of their lesser-known functions in liver regeneration. Potential therapies based on PPAR regulation will be discussed. The data suggest that further investigations are required to elucidate whether PPAR could be a potential therapeutic target in liver surgery and to determine the most effective therapies that selectively regulate PPAR with minor side effects.

The nitric oxide pathway--evidence and mechanisms for protection against liver ischaemia reperfusion injury

Ischaemia reperfusion (IR) injury is a clinical entity with a major contribution to the morbidity and mortality of liver surgery and transplantation. A central pathway of protection against IR injury utilizes nitric oxide (NO). Nitric oxide synthase (NOS) enzymes manufacture NO from L-arginine. NO generated by the endothelial NOS (eNOS) isoform protects against liver IR injury, whereas inducible NOS (iNOS)-derived NO may have either a protective or a deleterious effect during the early phase of IR injury, depending on the length of ischaemia, length of reperfusion and experimental model. In late phase hepatic IR injury, iNOS-derived NO plays a protective role. In addition to NOS consumption of L-arginine during NO synthesis, this amino acid may also be metabolized by arginase, an enzyme whose release is increased during prolonged ischaemia, and therefore diverts L-arginine away from NOS metabolism leading to a drop in the rate of NO synthesis. NO most commonly acts through the soluble guanylyl cyclase-cyclic GMP- protein kinase G pathway to ameliorate hepatic IR injury. Both endogenously generated and exogenously administered NO donors protect against liver IR injury. The beneficial effects of NO on liver IR are not, however, universal, and certain conditions, such as steatosis, may influence the protective effects of NO. In this review, the evidence for, and mechanisms of these protective actions of NO are discussed, and areas in need of further research are highlighted.

Techniques of flushing and reperfusion for liver transplantation

BACKGROUND

Various techniques of flushing and reperfusion have been advocated to improve outcomes after liver transplantation. There is considerable uncertainty as to which method is superior.

OBJECTIVES

To compare the benefits and harms of different methods of flushing and reperfusion during liver implantation in the transplant recipients.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL) in The Cochrane Library, MEDLINE, EMBASE, and Science Citation Index Expanded until March 2011.

SELECTION CRITERIA

We included all randomised clinical trials that were performed to compare different techniques of flushing and reperfusion during liver transplantation.

DATA COLLECTION AND ANALYSIS

Two authors independently identified the trials and extracted the data. We analysed the data with both the fixed-effect model and the random-effects model using RevMan analysis. For each outcome we calculated the hazard ratio (HR), risk ratio (RR), rate ratio, mean difference (MD), or standardised mean difference (SMD) with 95% confidence intervals (CI) based on available case analysis.

MAIN RESULTS

We included six trials involving 418 patients for this review. The sample size in the trials varied from 30 to 131 patients. Only one trial involving 131 patients was of low risk of bias for mortality. This trial was at high risk of bias for other outcomes. Four trials excluded patients who underwent liver transplantation for acute liver failure. All the trials included livers obtained from cadaveric donors. The remaining five trials were of high risk of bias for all outcomes. Liver transplantation was performed by the conventional method (caval replacement) in two trials and piggy-back method (caval preservation) in one trial. The method of liver transplantation was not available in the remaining three trials. The comparisons performed included an initial hepatic artery flush versus initial portal vein flush; blood venting via inferior vena cava in addition to venting of storage fluid versus no blood venting; initial hepatic artery reperfusion versus initial portal vein reperfusion; simultaneous hepatic artery and portal vein reperfusion versus initial portal vein reperfusion; and retrograde inferior vena cava reperfusion versus simultaneous hepatic artery and portal vein reperfusion. Only one or two trials could be included under each comparison. There was no significant difference in mortality, graft survival, or severe morbidity rates in any of the comparisons. Quality of life was not reported in any of the trials.

AUTHORS' CONCLUSIONS

There is currently no evidence to support or refute the use of any specific technique of flushing or reperfusion during liver transplantation. Due to the paucity of data, absence of evidence should not be confused with evidence of absence of any differences. Further well designed trials with low risk of systematic error and low risk of random errors are necessary.

Effect of intermittent hepatic inflow occlusion with the Pringle maneuver during donor hepatectomy in adult living donor liver transplantation with right hemiliver grafts: a prospective, randomized controlled study

To evaluate the effects of intermittent hepatic inflow occlusion (IHIO) during donor hepatectomy for living donor liver transplantation (LDLT) in recipients and donors, we performed a single-center, open-label, prospective, parallel, randomized controlled study. Adult donor-recipient pairs undergoing LDLT with right hemiliver grafts were randomized into IHIO and control groups (1:1). In the IHIO group, IHIO was performed during donor hepatectomy. The primary endpoint was the peak serum alanine aminotransferase (ALT) concentration in the recipients within 5 days after the operation. Blood samples for measurements of interleukin-6 (IL-6), IL-8, tumor necrosis factor α (TNF-α), and hepatocyte growth factor (HGF) were taken from the donors and the recipients during the operation and postoperatively. Biopsy samples for measurements of caspase-3 and malondialdehyde (MDA) were taken from the donors and the recipients. In all, 50 donor-recipient pairs (ie, 25 pairs in each group) completed this study. The mean peak serum ALT levels within 5 days after the operation did not differ in the recipients between the 2 groups (P = 0.32) but were higher in the donors of the IHIO group (P = 0.002). There were no differences in the prothrombin times or total bilirubin levels in the recipients or donors between the 2 groups. The amount of blood loss during donor hepatectomy was significantly lower in the IHIO group versus the control group (P = 0.02). The mean hospital stay for donors was 19.3 ± 7.2 days in the control group and 15.8 ± 4.6 days in the IHIO group (P = 0.046). There were no in-hospital deaths within 1 month and no cases of primary nonfunction or initially poor function in the 2 groups. The concentrations of IL-6, IL-8, TNF-α, and HGF did not differ between the 2 groups, nor did the concentrations of caspase-3 and MDA. In conclusion, although we found differences in postoperative peak serum ALT levels in donors, donor hepatectomy with IHIO for LDLT using a right hemiliver graft with a graft-to-recipient body weight ratio > 0.9% and <30% steatosis can be a tolerable procedure for donors and recipients.

Methods to decrease blood loss and transfusion requirements for liver transplantation

BACKGROUND

Excessive blood loss and increased blood transfusion requirements may have significant impact on the short-term and long-term outcomes after liver transplantation.

OBJECTIVES

To compare the potential benefits and harms of different methods of decreasing blood loss and blood transfusion requirements during liver transplantation.

SEARCH METHODS

We searched The Cochrane Central Register of Controlled Trials in The Cochrane Library, MEDLINE, EMBASE, Science Citation Index Expanded, and metaRegister of Controlled Trials until September 2011.

SELECTION CRITERIA

We included all randomised clinical trials that were performed to compare various methods of decreasing blood loss and blood transfusion requirements during liver transplantation.

DATA COLLECTION AND ANALYSIS

Two authors independently identified the trials and extracted the data. We analysed the data with both the fixed-effect and the random-effects model using RevMan Analysis. For each outcome we calculated the risk ratio (RR), mean difference (MD), or standardised mean difference (SMD) with 95% confidence intervals (CI) based on available data analysis. We also conducted network meta-analysis.

MAIN RESULTS

We included 33 trials involving 1913 patients. The sample size in the trials varied from 8 to 209 participants. The interventions included pharmacological interventions (aprotinin, tranexamic acid, epsilon amino caproic acid, antithrombin 3, recombinant factor (rFvIIa), oestrogen, prostaglandin, epinephrine), blood substitutes (blood components rather than whole blood, hydroxy-ethyl starch, thromboelastography), and cardiovascular interventions (low central venous pressure). All the trials were of high risk of bias. Primary outcomes were reported in at least two trials for the following comparisons: aprotinin versus control, tranexamic acid versus control, recombinant factor VIIa (rFVIIa) versus control, and tranexamic acid versus aprotinin. There were no significant differences in the 60-day mortality (3 trials; 6/161 (3.7%) in the aprotinin group versus 8/119 (6.7%) in the control group; RR 0.52; 95% CI 0.18 to 1.45), primary graft non-function (2 trials; 0/128 (0.0%) in the aprotinin group versus 4/89 (4.5%) in the control group; RR 0.15; 95% CI 0.02 to 1.25), retransplantation (3 trials; 2/256 (0.8%) in the aprotinin group versus 12/178 (6.7%) in the control group; RR 0.21; 95% CI 0.02 to 1.79), or thromboembolic episodes (3 trials; 4/161 (2.5%) in the aprotinin group versus 5/119 (4.2%) in the control group; RR 0.59; 95% CI 0.19 to 1.84) between the aprotinin and control groups. There were no significant differences in the 60-day mortality (3 trials; 4/83 (4.8%) in the tranexamic acid group versus 5/56 (8.9%) in the control group; RR 0.55; 95% CI 0.17 to 1.76), retransplantation (2 trials; 3/41 (7.3%) in the tranexamic acid group versus 3/36 (8.3%) in the control group; RR 0.79; 95% CI 0.18 to 3.48), or thromboembolic episodes (5 trials; 5/103 (4.9%) in the tranexamic acid group versus 1/76 (1.3%) in the control group; RR 2.20; 95% CI 0.38 to 12.64) between the tranexamic acid and control groups. There were no significant differences in the 60-day mortality (3 trials; 8/195 (4.1%) in the recombinant factor VIIa (rFVIIa) group versus 2/91 (2.2%) in the control group; RR 1.51; 95% CI 0.33 to 6.95), thromboembolic episodes (2 trials; 24/185 (13.0%) in the rFVIIa group versus 8/81 (9.9%) in the control group; RR 1.38; 95% CI 0.65 to 2.91), or serious adverse events (2 trials; 90/185 (48.6%) in the rFVIIa group versus 30/81 (37.0%) in the control group; RR 1.30; 95% CI 0.94 to 1.78) between the rFVIIa and control groups. There were no significant differences in the 60-day mortality (2 trials; 6/91 (6.6%) in the tranexamic acid group versus 1/87 (1.1%) in the aprotinin group; RR 4.12; 95% CI 0.71 to 23.76) or thromboembolic episodes (2 trials; 4/91 (4.4%) in the tranexamic acid group versus 2/87 (2.3%) in the aprotinin group; RR 1.97; 95% CI 0.37 to 10.37) between the tranexamic acid and aprotinin groups. The remaining outcomes in the above comparisons and the remaining comparisons included only only trial under the primary outcome or the outcome was not reported at all in the trials. There were no significant differences in the mortality, primary graft non-function, graft failure, retransplantation, thromboembolic episodes, or serious adverse events in any of these comparisons. However, the confidence intervals were wide, and it is not possible to reach any conclusion on the safety of the interventions. None of the trials reported the quality of life in patients.Secondary outcomes were reported in at least two trials for the following comparisons - aprotinin versus control, tranexamic acid versus control, rFVIIa versus control, thromboelastography versus control, and tranexamic acid versus aprotinin. There was significantly lower allogeneic blood transfusion requirements in the aprotinin group than the control group (8 trials; 185 patients in aprotinin group and 190 patients in control group; SMD -0.61; 95% CI -0.82 to -0.40). There were no significant differences in the allogeneic blood transfusion requirements between the tranexamic acid and control groups (4 trials; 93 patients in tranexamic acid group and 66 patients in control group; SMD -0.27; 95% CI -0.59 to 0.06); rFVIIa and control groups (2 trials; 141 patients in rFVIIa group and 80 patients in control group; SMD -0.05; 95% CI -0.32 to 0.23); thromboelastography and control groups (2 trials; 31 patients in thromboelastography group and 31 patients in control group; SMD -0.73; 95% CI -1.69 to 0.24); or between the tranexamic acid and aprotinin groups (3 trials; 101 patients in tranexamic acid group and 97 patients in aprotinin group; SMD -0.09; 95% CI -0.36 to 0.19). The remaining outcomes in the above comparisons and the remaining comparisons included only only trial under the primary outcome or the outcome was not reported at all in the trials. There were no significant differences in the blood loss, transfusion requirements, hospital stay, or intensive care unit stay in most of the comparisons.

AUTHORS' CONCLUSIONS

Aprotinin, recombinant factor VIIa, and thromboelastography groups may potentially reduce blood loss and transfusion requirements. However, risks of systematic errors (bias) and risks of random errors (play of chance) hamper the confidence in this conclusion. We need further well-designed randomised trials with low risk of systematic error and low risk of random errors before these interventions can be supported or refuted.

Preconditioning, postconditioning, and remote conditioning in solid organ transplantation: basic mechanisms and translational applications

Ischemia and reperfusion (I/Rp) injury is inherent to solid organ transplantation and can result in primary nonfunction or delayed function of grafts, which is associated with a significant morbidity and mortality posttransplantation. It is also a major obstacle for the use of marginal grafts to increase the donor pool, as these grafts are prone to a higher degree of I/Rp injury. Pre-, post-, and remote conditioning are protective strategies against I/Rp injury, which can be applied in the transplant setting. These strategies hold the potential to reduce graft injury and to safely expand the donor pool. However, despite convincing experimental data, the protective effects of the "conditioning" protocols remain unclear, and only few have translated to clinical practice. This review summarizes pre-, post-, and remote conditioning strategies in clinical use in solid organ transplantation and discusses an overview of the mechanistic pathways involved in each strategy.

How to protect liver graft with nitric oxide

Organ preservation and ischemia reperfusion injury associated with liver transplantation play an important role in the induction of graft injury. One of the earliest events associated with the reperfusion injury is endothelial cell dysfunction. It is generally accepted that endothelial nitric oxide synthase (e-NOS) is cell-protective by mediating vasodilatation, whereas inducible nitric oxide synthase mediates liver graft injury after transplantation. We conducted a critical review of the literature evaluating the potential applications of regulating and promoting e-NOS activity in liver preservation and transplantation, showing the most current evidence to support the concept that enhanced bioavailability of NO derived from e-NOS is detrimental to ameliorate graft liver preservation, as well as preventing subsequent graft reperfusion injury. This review deals mainly with the beneficial effects of promoting “endogenous” pathways for NO generation, via e-NOS inducer drugs in cold preservation solution, surgical strategies such as ischemic preconditioning, and alternative “exogenous” pathways that focus on the enrichment of cold storage liquid with NO donors. Finally, we also provide a basic bench-to-bed side summary of the liver physiology and cell signalling mechanisms that account for explaining the e-NOS protective effects in liver preservation and transplantation.

Routine drainage for orthotopic liver transplantation

BACKGROUND

Routine use of abdominal drainage in patients undergoing liver transplantation is controversial.

OBJECTIVES

To assess the benefits and harms of routine abdominal drainage after orthotopic liver transplantation versus no drainage and to address different drain types.

SEARCH STRATEGY

We searched the Cochrane Central Register of Controlled Trials (CENTRAL) in The Cochrane Library, MEDLINE, EMBASE, Science Citation Index Expanded, and the MetaRegister of Controlled Trials until March 2011 to identify the randomised trials.

SELECTION CRITERIA

We planned to include only randomised clinical trials (irrespective of language, blinding, or publication status) addressing this issue.

DATA COLLECTION AND ANALYSIS

Two authors identified the trials for inclusion independently. Two authors planned to collect the data independently. We planned to analyse the data with both the fixed-effect and the random-effects model using RevMan Analysis. For each outcome we planned to calculate the risk ratio (RR) or mean difference (MD) with 95% confidence intervals (CI) based on intention-to-treat analysis whenever possible.

MAIN RESULTS

We did not identify any randomised clinical trials addressing this issue.

AUTHORS' CONCLUSIONS

There is currently no evidence to conclude whether routine abdominal drainage is useful or harmful in patients undergoing orthotopic liver transplantation. Evidence from non-randomised studies of high risk of bias showed conflicting results on the impact of routine drainage in orthotopic liver transplantation on serious adverse events, showing that this question is an important clinical research question. Well-designed randomised clinical trials with adequate sample size to decrease systematic errors and to decrease random errors are necessary.

Role of endothelial nitric oxide synthase in remote ischemic preconditioning of the mouse liver

Hindlimb remote ischemic preconditioning (RIPC) reduces liver ischemia/reperfusion (IR) injury in wild-type mice. The underlying mechanisms of RIPC are currently unknown. In this study, we investigated the role of endothelial nitric oxide synthase (eNOS) in mediating the protective effects of RIPC. Endothelial nitric oxide synthase knockout (eNOS(-/-) ) mice were divided into 4 groups: (1) a sham surgery group, (2) an RIPC group (6 cycles of 4 minutes of hindlimb ischemia and 4 minutes of hindlimb reperfusion), (3) an IR group [40 minutes of lobar (70%) hepatic ischemia and 2 hours of reperfusion], and (4) an RIPC+IR group (RIPC followed by the IR group procedures). Plasma liver aminotransferases, hepatic histopathological injury scores, transmission electron microscopy studies, and hepatic microcirculatory blood flow (MBF) were assessed. eNOS protein expression was analyzed in the livers and hindlimb muscles of wild-type mice. Hindlimb RIPC did not protect against subsequent liver IR injury in eNOS(-/-) mice; this was demonstrated by the lack of reduction in the plasma aminotransferase levels, histopathological scores, or ultrastructural features of IR injury in the RIPC+IR group versus the IR group. Hepatic MBF did not recover during liver reperfusion in the RIPC+IR group versus the IR group. eNOS protein expression was similar among all wild-type groups. In conclusion, eNOS is essential for the protective effects of hindlimb RIPC on liver IR injury. eNOS exerts its protective effects through the preservation of hepatic MBF. At 2 hours of reperfusion, eNOS protection is likely due to the increased activation of eNOS rather than increased expression.

Veno-venous bypass versus none for liver transplantation

BACKGROUND

Veno-venous bypass is used to overcome the effects of clamping of the inferior vena cava and portal vein during liver transplanation. The routine use of veno-venous bypass is, however, controversial.

OBJECTIVES

To compare the benefits and harms of veno-venous bypass (irrespective of open or percutaneous technique; heparin-coated or no heparin-coating) versus no veno-venous bypass during liver transplantation. To compare the benefits and harms of the different techniques of veno-venous bypass during liver transplantation.

SEARCH STRATEGY

We searched The Cochrane Hepato-Biliary Group Controlled Trials Register, the Cochrane Central Register of Controlled Trials (CENTRAL) in The Cochrane Library, MEDLINE, EMBASE, and Science Citation Index Expanded until December 2010.

SELECTION CRITERIA

We included randomised clinical trials comparing veno-venous bypass during liver transplantation (irrespective of language or publication status).

DATA COLLECTION AND ANALYSIS

Two authors independently assessed trials for inclusion and independently extracted data. We analysed the data with both the fixed-effect and the random-effects models using RevMan Analysis. For continuous outcomes, we calculated the mean difference (MD) with 95% confidence intervals (CI) based on intention-to-treat or available case analysis. For binary outcomes, we used the Fisher's exact test since none of the comparisons of binary outcomes included more than one trial.

MAIN RESULTS

We identified three trials with high risk of bias which compared veno-venous bypass (n = 65) versus no veno-venous bypass (n = 66). None of the trials reported patient or graft survival. There were no significant differences regarding renal failure or blood transfusion requirements between the two groups. None of the trials reported on the morbidity related to veno-venous bypass or the requirement of veno-venous bypass in the control group.We identified one trial with high risk of bias which compared percutaneous (n = 20) versus open technique (n =19) of veno-venous bypass. The patient or graft survival was not reported. There was no difference in veno-venous bypass related morbidity between the two groups. The operating time was significantly shorter in the percutaneous technique group (MD -59 minutes; 95% CI -102 to -16).

AUTHORS' CONCLUSIONS

There is no evidence to support or refute the use of veno-venous bypass in liver transplantation. There is no evidence to prefer any particular technique of veno-venous bypass in liver transplantation.

Piggy-back graft for liver transplantation

BACKGROUND

Piggy-back method of transplantation, which involves preservation of the recipient retrohepatic inferior vena cava, has been suggested as an alternative to the conventional method of liver transplantation, where the recipient retrohepatic inferior vena cava is resected.

OBJECTIVES

To compare the benefits and harms of piggy-back technique versus conventional liver transplantation as well as of the different modifications of piggy-back technique during liver transplantation.

SEARCH STRATEGY

We searched The Cochrane Hepato-Biliary Group Controlled Trials Register, the Cochrane Central Register of Controlled Trials (CENTRAL) in The Cochrane Library, MEDLINE, EMBASE, and Science Citation Index Expanded until June 2010 for identifying randomised trials using search strategies.

SELECTION CRITERIA

Only randomised clinical trials, irrespective of language, blinding, or publication status were considered for the review.

DATA COLLECTION AND ANALYSIS

Two authors (KSG and VP) independently identified trials and independently extracted data. We calculated the mean difference (MD) or standardised mean difference (SMD) with 95% confidence intervals (CI) using both the fixed-effect and the random-effects models with RevMan 5 based on intention-to-treat analysis for continuous outcomes. For binary outcomes, we used the Fisher's exact test since none of the comparisons of binary outcomes included more than one trial.

MAIN RESULTS

Two trials randomised in total 106 patients to piggy-back method (n = 53) versus conventional method with veno-venous bypass (n = 53). Both trials were at high risk of bias. There was no significant difference in post-operative mortality, primary graft non-function, vascular complications, renal failure, transfusion requirements, intensive therapy unit (ITU) stay, or hospital stay between the two groups. The warm ischaemic time was significantly shorter in the piggy-back method than the conventional method (MD -11.50 minutes; 95% CI -19.35 to -3.65; P < 0.01). The proportion of patients who developed chest complications were significantly higher in the the piggy-back method than the conventional method (75.8% versus 44.1%; P = 0.01).One trial randomised 80 patients to piggy-back with porto-caval bypass (n = 40) versus piggy-back without porto-caval bypass (n = 40). This trial was at high risk of bias. There was no significant difference in post-operative mortality, re-transplantation due to primary graft non-function, vascular complications, renal failure, or hospital stay between the two groups. Fewer patients required blood transfusion in the piggy-back with porto-caval bypass group (55%) than the piggy-back without porto-caval bypass group (75%) (P = 0.02). There was no significant difference in the mean amount of blood transfused between the groups (MD -1.00 unit; 95% CI -2.19 to 0.19; P = 0.10). The ITU stay was significantly shorter in the piggy-back with porto-caval bypass group (2.9 days) than the piggy-back without porto-caval bypass group (4.9 days; MD -2.00 days; 95% CI -3.82 to -0.18; P = 0.03).There were no trials comparing piggy-back method with conventional method without veno-venous bypass or different techniques of piggy-back method.

AUTHORS' CONCLUSIONS

There is currently no evidence to recommend or refute the use of piggy-back method of liver transplantation.

Molecular mechanisms of liver preconditioning

Ischemia/reperfusion (I/R) injury still represents an important cause of morbidity following hepatic surgery and limits the use of marginal livers in hepatic transplantation. Transient blood flow interruption followed by reperfusion protects tissues against damage induced by subsequent I/R. This process known as ischemic preconditioning (IP) depends upon intrinsic cytoprotective systems whose activation can inhibit the progression of irreversible tissue damage. Compared to other organs, liver IP has additional features as it reduces inflammation and promotes hepatic regeneration. Our present understanding of the molecular mechanisms involved in liver IP is still largely incomplete. Experimental studies have shown that the protective effects of liver IP are triggered by the release of adenosine and nitric oxide and the subsequent activation of signal networks involving protein kinases such as phosphatidylinositol 3-kinase, protein kinase C δ/ε and p38 MAP kinase, and transcription factors such as signal transducer and activator of transcription 3, nuclear factor-κB and hypoxia-inducible factor 1. This article offers an overview of the molecular events underlying the preconditioning effects in the liver and points to the possibility of developing pharmacological approaches aimed at activating the intrinsic protective systems in patients undergoing liver surgery.

Antiviral prophylactic intervention for chronic hepatitis C virus in patients undergoing liver transplantation

BACKGROUND

It is not clear whether prophylactic antiviral therapy is indicated in patients undergoing liver transplantation for chronic decompensated hepatitis C virus (HCV) infection.

OBJECTIVES

To compare the benefits and harms of different prophylactic anti-viral therapies for patients undergoing liver transplantation for chronic HCV infection.

SEARCH STRATEGY

We searched The Cochrane Hepato-Biliary Group Controlled Trials Register, the Cochrane Central Register of Controlled Trials (CENTRAL) in The Cochrane Library, MEDLINE, EMBASE, and Science Citation Index Expanded until August 2010.

SELECTION CRITERIA

Only randomised clinical trials irrespective of language, blinding, or publication status and comparing various prophylactic antiviral therapies (alone or in combination) in the prophylactic treatment of patients undergoing liver transplantation for chronic HCV infection.

DATA COLLECTION AND ANALYSIS

Two authors collected the data independently. We calculated the risk ratio (RR) or mean difference (MD) or hazard ratio (HR) with 95% confidence intervals (CI) using the fixed-effect and the random-effects models based on available case analysis.

MAIN RESULTS

A total of 477 liver transplant recipients undergoing liver transplantation for chronic HCV infection were randomised in eleven trials to various interventions and controls. The proportion of genotype I varied between 49% to 88% in the five trials that reported the genotype. Only one or two trials were included under each comparison. All the trials were of high risk of bias. There was no significant differences in the patient survival, graft rejection, re-transplantation, or HCV recurrence between intervention and control groups in any of the comparisons that reported these outcomes. None of the trials reported liver decompensation, primary graft non-function, intensive therapy unit stay, hospital stay, or quality of life. Life-threatening adverse events were not reported in either group in any of the comparisons. Up to 91% of patients required reduction in dose and up to 36% of patients required cessation of treatment in the various comparisons because of adverse events or because of patient's choice to stop treatment.

AUTHORS' CONCLUSIONS

There is currently no evidence to recommend prophylactic antiviral treatment to prevent recurrence of HCV infection either in primary liver transplantation or re-transplantation. Further randomised clinical trials with adequate trial methodology and adequate duration of follow-up are necessary.

Calcium preconditioning triggers neuroprotection in retinal ganglion cells

In the mammalian retina, excitotoxicity has been shown to be involved in apoptotic retinal ganglion cell (RGC) death and is associated with certain retinal disease states including glaucoma, diabetic retinopathy and retinal ischemia. Previous studies from this lab [Wehrwein E, Thompson SA, Coulibaly SF, Linn DM, Linn CL (2004) Invest Ophthalmol Vis Sci 45:1531-1543] have demonstrated that acetylcholine (ACh) and nicotine protects against glutamate-induced excitotoxicity in isolated adult pig RGCs through nicotinic acetylcholine receptors (nAChRs). Activation of nAChRs in these RGCs triggers cell survival signaling pathways and inhibits apoptotic enzymes [Asomugha CO, Linn DM, Linn CL (2010) J Neurochem 112:214-226]. However, the link between binding of nAChRs and activation of neuroprotective pathways is unknown. In this study, we examine the hypothesis that calcium permeation through nAChR channels is required for ACh-induced neuroprotection against glutamate-induced excitotoxicity in isolated pig RGCs. RGCs were isolated from other retinal tissue using a two step panning technique and cultured for 3 days under different conditions. In some studies, calcium imaging experiments were performed using the fluorescent calcium indicator, fluo-4, and demonstrated that calcium permeates the nAChR channels located on pig RGCs. In other studies, the extracellular calcium concentration was altered to determine the effect on nicotine-induced neuroprotection. Results support the hypothesis that calcium is required for nicotine-induced neuroprotection in isolated pig RGCs. Lastly, studies were performed to analyze the effects of preconditioning on glutamate-induced excitotoxicity and neuroprotection. In these studies, a preconditioning dose of calcium was introduced to cells using a variety of mechanisms before a large glutamate insult was applied to cells. Results from these studies support the hypothesis that preconditioning cells with a relatively low level of calcium before an excitotoxic insult leads to neuroprotection. In the future, these results could provide important information concerning therapeutic agents developed to combat various diseases involved with glutamate-induced excitotoxicity.

Antiviral therapy for recurrent liver graft infection with hepatitis C virus

BACKGROUND

Antiviral therapy to treat recurrent hepatitis C infection after liver transplantation is controversial due to unresolved balance between benefits and harms.

OBJECTIVES

To compare the therapeutic benefits and harms of different antiviral regimens in patients with hepatitis C re-infected grafts after liver transplantation.

SEARCH STRATEGY

We searched The Cochrane Hepato-Biliary Group Controlled Trials Register, the Cochrane Central Register of Controlled Trials (CENTRAL) in The Cochrane Library, MEDLINE, EMBASE, and Science Citation Index Expanded until March 2009.

SELECTION CRITERIA

Only randomised clinical trials (irrespective of language, blinding, or publication status) comparing various antiviral therapies (alone or in combination) in the treatment of hepatitis C virus recurrence in liver transplantation were considered for the review.

DATA COLLECTION AND ANALYSIS

Two authors collected the data independently. We calculated the risk ratio (RR) or mean difference (MD) with 95% confidence intervals (CI) using the fixed-effect and the random-effects models based on available case-analysis. In the presence of only trial for a dichotomous outcome, we performed the Fisher's exact test.

MAIN RESULTS

A total of 425 liver transplant recipients with proven hepatitis C recurrence were randomised in twelve trials to various interventions and controls. The mean proportion of genotype I was 79.9% in the nine trials that reported the genotype. All the trials were of high risk of bias. One to two trials were included under each comparison including single drug or multidrug regimens of interferon, ribavirin, and amantadine. There was no significant difference in the mortality, graft rejection, or in re-transplantation between intervention and control in any of the comparisons that reported these outcomes. None of the trials reported liver decompensation or quality of life. Life-threatening adverse effects were not reported in either group in any of the comparisons. Up to 87.5% of patients required reduction in dose and up to 42.9% of patients required cessation of treatment in the various comparisons because of adverse effects or because of patient's choice to stop treatment.

AUTHORS' CONCLUSIONS

Considering the lack of clinical benefit and the frequent adverse effects, there is currently no evidence to recommend antiviral treatment for recurrent liver graft infection with HCV. Further randomised clinical trials with adequate trial methodology and adequate duration of follow-up are necessary.

Effect of ischemic preconditioning on the genomic response to reperfusion injury in deceased donor liver transplantation

Ischemic preconditioning (IP) is an effective method for protecting organs from ischemia/reperfusion (IR) injury; however, the molecular basis of this protective effect is poorly understood. This study assessed the gene expression profile in liver allografts during transplantation and evaluated the impact of IP. Prereperfusion and postreperfusion biopsy specimens from livers subjected to IP (n = 19) or no preconditioning (the IR group; n = 16) were obtained. Total RNA was extracted and hybridized to GeneChip microarrays, and the findings were validated with real-time quantitative reverse-transcription polymerase chain reaction (qRT-PCR). IP livers showed less of an increase in aspartate aminotransferase after transplantation. A microarray analysis of the IR group showed increased expression of 57 genes mainly involved in cell death, inflammation and immune response, stress, and modulation of the cell cycle. The IP group showed attenuation of the expression of these genes after reperfusion. Additionally, IP led to increased expression of 43 genes involved in growth and maintenance, cell-cycle regulation, proliferation, and development. The expression of the 12 most significant genes was validated in all patients with real-time qRT-PCR, and the fold changes of a number of genes correlated with clinical parameters and graft outcomes. IP protection of liver allografts was associated with a reduction in the expression of immune response genes and promotion of those involved in protection and repair.

The hepatic microcirculation: mechanistic contributions and therapeutic targets in liver injury and repair

The complex functions of the liver in biosynthesis, metabolism, clearance, and host defense are tightly dependent on an adequate microcirculation. To guarantee hepatic homeostasis, this requires not only a sufficient nutritive perfusion and oxygen supply, but also a balanced vasomotor control and an appropriate cell-cell communication. Deteriorations of the hepatic homeostasis, as observed in ischemia/reperfusion, cold preservation and transplantation, septic organ failure, and hepatic resection-induced hyperperfusion, are associated with a high morbidity and mortality. During the last two decades, experimental studies have demonstrated that microcirculatory disorders are determinants for organ failure in these disease states. Disorders include 1) a dysregulation of the vasomotor control with a deterioration of the endothelin-nitric oxide balance, an arterial and sinusoidal constriction, and a shutdown of the microcirculation as well as 2) an overwhelming inflammatory response with microvascular leukocyte accumulation, platelet adherence, and Kupffer cell activation. Within the sequelae of events, proinflammatory mediators, such as reactive oxygen species and tumor necrosis factor-alpha, are the key players, causing the microvascular dysfunction and perfusion failure. This review covers the morphological and functional characterization of the hepatic microcirculation, the mechanistic contributions in surgical disease states, and the therapeutic targets to attenuate tissue injury and organ dysfunction. It also indicates future directions to translate the knowledge achieved from experimental studies into clinical practice. By this, the use of the recently introduced techniques to monitor the hepatic microcirculation in humans, such as near-infrared spectroscopy or orthogonal polarized spectral imaging, may allow an early initiation of treatment, which should benefit the final outcome of these critically ill patients.

Role of ischemic preconditioning in liver surgery and hepatic transplantation

INTRODUCTION

The purpose of this review is to summarize intraoperative surgical strategies available to decrease ischemia-reperfusion injury associated with liver resection and liver transplantation.

MATERIAL AND METHOD

We conducted a critical review of the literature evaluating the potential applications of hepatic ischemic preconditioning (IPC) for hepatic resection surgery and liver transplantation. In addition, we provide a basic bench-to-bedside summary of the liver physiology and cell signaling mechanisms that account for the protective effects seen with hepatic IPC.