Comparison of ischemic preconditioning and intermittent and continuous inflow occlusion in the murine liver

Single-cell analysis reveals the immune heterogeneity and interactions in lungs undergoing hepatic ischemia-reperfusion

Hepatic ischemia-reperfusion IR (HIR) is an unavoidable pathophysiological process during liver transplantation, resulting in systematic sterile inflammation and remote organ injury. Acute lung injury (ALI) is a serious complication after liver transplantation with high postoperative morbidity and mortality. However, the underlying mechanism is still unclear. To assess the phenotype and plasticity of various cell types in the lung tissue microenvironment after HIR at the single-cell level, single-cell RNA sequencing (scRNA-seq) was performed using the lungs from HIR-induced mice. In our results, we identified 23 cell types in the lungs after HIR and found that this highly complex ecosystem was formed by subpopulations of bone marrow-derived cells that signaled each other and mediated inflammatory responses in different states and different intervals. We described the unique transcriptional profiles of lung cell clusters and discovered two novel cell subtypes (Tspo+Endothelial cells and Vcan+ monocytes), as well as the endothelial cell-immune cell and immune cell-T cell clusters interactome. In addition, we found that S100 calcium binding protein (S100a8/a9), specifically and highly expressed in immune cell clusters of lung tissues and exhibited detrimental effects. Finally, the cellular landscape of the lung tissues after HIR was established, highlighting the heterogeneity and cellular interactions between major immune cells in HIR-induced lungs. Our findings provided new insights into the mechanisms of HIR-induced ALI and offered potential therapeutic target to prevent ALI after liver transplantation.

Delivering siRNA Compounds During HOPE to Modulate Organ Function: A Proof-of-Concept Study in a Rat Liver Transplant Model

BACKGROUND

Apoptosis contributes to the severity of ischemia-reperfusion injury (IRI), limiting the use of extended criteria donors in liver transplantation (LT). Machine perfusion has been proposed as a platform to administer specific therapies to improve graft function. Alternatively, the inhibition of genes associated with apoptosis during machine perfusion could alleviate IRI post-LT. The aim of the study was to investigate whether inhibition of an apoptosis-associated gene (FAS) using a small interfering RNA (siRNA) approach could alleviate IRI in a rat LT model.

METHODS

In 2 different experimental protocols, FASsiRNA (500 µg) was administered to rat donors 2 h before organ procurement, followed by 22 h of static cold storage, (SCS) or was added to the perfusate during 1 h of ex situ hypothermic oxygenated perfusion (HOPE) to livers previously preserved for 4 h in SCS.

RESULTS

Transaminase levels were significantly lower in the SCS-FASsiRNA group at 24 h post-LT. Proinflammatory cytokines (interleukin-2, C-X-C motif chemokine 10, tumor necrosis factor alpha, and interferon gamma) were significantly decreased in the SCS-FASsiRNA group, whereas the interleukin-10 anti-inflammatory cytokine was significantly increased in the HOPE-FASsiRNA group. Liver absorption of FASsiRNA after HOPE session was demonstrated by confocal microscopy; however, no statistically significant differences on the apoptotic index, necrosis levels, and FAS protein transcription between treated and untreated groups were observed.

CONCLUSIONS

FAS inhibition through siRNA therapy decreases the severity of IRI after LT in a SCS protocol; however the association of siRNA therapy with a HOPE perfusion model is very challenging. Future studies using better designed siRNA compounds and appropriate doses are required to prove the siRNA therapy effectiveness during liver HOPE liver perfusion.

Shaping of Hepatic Ischemia/Reperfusion Events: The Crucial Role of Mitochondria

Hepatic ischemia reperfusion injury (HIRI) is a major hurdle in many clinical scenarios, including liver resection and transplantation. Various studies and countless surgical events have led to the observation of a strong correlation between HIRI induced by liver transplantation and early allograft-dysfunction development. The detrimental impact of HIRI has driven the pursuit of new ways to alleviate its adverse effects. At the core of HIRI lies mitochondrial dysfunction. Various studies, from both animal models and in clinical settings, have clearly shown that mitochondrial function is severely hampered by HIRI and that its preservation or restoration is a key indicator of successful organ recovery. Several strategies have been thus implemented throughout the years, targeting mitochondrial function. This work briefly discusses some the most utilized approaches, ranging from surgical practices to pharmacological interventions and highlights how novel strategies can be investigated and implemented by intricately discussing the way mitochondrial function is affected by HIRI.

Beneficial effects of natural compounds on experimental liver ischemia-reperfusion injury

Liver ischemia-reperfusion injury (IRI) is a phenomenon inherent to hepatic surgery that severely compromises the organ functionality, whose underlying mechanisms involve cellular and molecular interrelated processes leading to the development of an excessive inflammatory response. Liver resident cells and those recruited in response to injury generate pro-inflammatory signals such as reactive oxygen species, cytokines, chemokines, proteases and lipid mediators that contribute to hepatocellular necrosis and apoptosis. Besides, dying hepatocytes release damage-associated molecular patterns that actívate inflammasomes to further stimulate inflammatory responses leading to massive cell death. Since liver IRI is a complication of hepatic surgery in man, extensive preclinical studies have assessed potential protective strategies, including the supplementation with natural compounds, with the objective to downregulate nuclear factor-κB functioning, the main effector of inflammatory responses. This can be accomplished by either the activation of peroxisome proliferator-activated receptor-α, G protein-coupled receptor 120 or antioxidant signaling pathways, the synthesis of specific pro-resolving mediators, downregulation of Toll-like receptor 4 activity or additional contributory mechanisms that are beginning to be understood. The latter aspect is a crucial issue to be accomplished in preclinical studies, in order to establish adequate conditions for the supplementation with natural products before major liver surgeries in man involving warm IR, such as hepatic trauma or resection of large intrahepatic tumors.

Effects of bradykinin preconditioning in an experimental intestinal ischemia reperfusion model on rats

PURPOSE

To investigate the effects of bradykinin on reperfusion injury in an experimental intestinal ischemia reperfusion model.

METHODS

We used 32 Wistar-Albino rats. We composed 4 groups each containing 8 rats. Rats in sham group were sacrified at 100 minutes observation after laparotomy. Thirty minutes reperfusion was performed following 50 minutes ischaemia in control group after observing 20 minutes. Ischaemic preconditioning was performed in one group of the study. We performed the other study group pharmacologic preconditioning by infusional administration of 10 μg/kg/minute bradykinin intravenously. We sacrified all of the rats by taking blood samples to evaluate the lactate and lactate dehydrogenase (LDH) after resection of jejunum for detecting tissue myeloperoxidase (MPO) activity.

RESULTS

Lactate and LDH levels were significantly higher in control and study groups than the sham group (P<0.001). There is no difference between the study groups statistically. (P>0.05). The results were the same for MPO levels. Although definitive cell damage was determinated in the control group by hystopatological evaluation, the damage in the study groups observed was lower in different levels. However, there was no significant difference between the study groups statistically (P>0.05).

CONCLUSION

Either ischeamic preconditioning or pharmacologic preconditioning made by bradykinin reduced the ischemia reperfusion injury at jejunum.

Ischemia With Preconditioning in Wistar Rats Maintains Mitochondrial Respiration, Even With Mild Hepatocellular Disturbance

INTRODUCTION

In hepatectomy or liver transplantation, preconditioning is a procedure indicated to protect the organ from ischemia-reperfusion injury (I-R).

OBJECTIVE

Evaluate the effect of preconditioning after hepatic I-R in Wistar rats, through mitochondrial respiration, liver histology, and profile.

METHOD

Twenty male Wistar rats, weighing on average 307.1 g, were anesthetized with sodium thiopental (25 mg/kg) intravenously and xylazine hydrochloride (30 mg/kg) intramuscularly. The animals were divided into 2 groups: the preconditioning group (PCG), which contained 10 animals, and the hepatic pedicle was isolated and submitted to clamping with microvascular clamp (10 minutes of ischemia and 10 minutes of reperfusion, followed by 30 minutes of ischemia and 30 minutes of reperfusion); and the simulated operation group (SOG), which contained 10 animals submitted to manipulation of the hepatic pedicle and observation for the same length of time, with blood collected for transaminase dosage measurements, and liver biopsy for evaluation of mitochondrial respiration and histologic liver analysis and after sacrificed under anesthesia. The project was approved by the Ethics Committee on Animal Experimentation CEEA/UNICAMP under protocol number 3905-1.

RESULT

The PCG mitochondria showed the same respiration level as the SOG, when stimulated with the addition of adenosine diphosphate or carbonyl cyanide p-trifluoromethoxyphenylhydrazone. In the respiratory control ratio and resting of velocity of respiration the groups behaved in a similar way. The PCG presented high aspartate and alanine transaminases (P < .03) and about 60% of sinusoidal congestion and venous congestion in the histologic analysis when compared with SOG.

CONCLUSION

We found that ischemia with preconditioning in Wistar rats can lead to mild histologic and biochemical dysfunction without leading to impairment of mitochondrial respiration.

Remote Ischemic Preconditioning: A Novel Strategy in Rescuing Older Livers From Ischemia-reperfusion Injury in a Rodent Model

OBJECTIVES

The aim of this study was to determine whether remote ischemic preconditioning (RIPC) protects aged liver against ischemia reperfusion (IR).

SUMMARY OF BACKGROUND DATA

The demands for liver surgery in an aging population are growing. Clamping of vessels to prevent blood loss is integral to liver surgery, but the resulting IR injury (IRI) augments postoperative complications. More so, sensitivity to hepatic IRI increases with age; however, no strategies have been developed that specifically protect old liver. RIPC, a novel protective approach, was performed distant to the surgical site. Whether RIPC may also protect old liver from IRI is unknown.

METHODS

RIPC to the femoral vascular bundle was compared against direct ischemic preconditioning (IPC) and the standard of care intermittent clamping (IC) using a model of partial hepatic ischemia in mice aged 20 to 24 months. Liver injury was measured 6 hours after reperfusion. Protective signaling (serotonin-Vegf-Il10/Mmp8 axis, Kupffer cell polarization) was assessed immediately after preconditioning. Neutralizing antibody was used to test the role of Vegf. Hepatic vasculature was examined by electron microscopy.

RESULTS

RIPC was superior over other strategies in protecting old liver from IRI, with standard IPC approaches being ineffective. RIPC induced the strongest elevations in circulating Vegf, and Vegf inhibition dampened protective signaling and abrogated the protective effects. RIPC was further associated with improvements in vascular functionality.

CONCLUSIONS

RIPC is highly effective in protecting old liver from ischemic insults, mainly owing to its ability to induce circulating Vegf. These findings warrant efforts toward clinical translation.

Ischemic preconditioning and remote ischemic preconditioning provide combined protective effect against ischemia/reperfusion injury

AIMS

Our objective was to compare the protective efficacy of ischemic preconditioning (IPC) and remote ischemic preconditioning (RIPC) against liver ischemia/reperfusion injury (IRI) and to evaluate their combined protective effect in mouse liver transplantation (MLT).

MATERIALS AND METHODS

Mice were randomly allocated to sham, IPC, RIPC, or IPC+RIPC groups. The animals were sacrificed at 2h, 24h, and 3 days after reperfusion. Blood samples were collected to evaluate alanine aminotransferase, TNF-α, and innate immune response. Liver tissue samples were obtained for histological evaluation, terminal deoxynucleotidyltransferased UTP nick end labeling, malondialdehyde (MDA) assay.

KEY FINDINGS

Mice given preconditioning measures had significantly lower increase in transaminase, TNF-α expression, MDA formation, liver injury scores, and apoptosis index at 2h, 24h and 3 days after liver transplantation. The percentages of CD11b(+), CD11b(+)CD16/32(+) and CD11b(+) CD16/32(high) in white blood cells at 3 days after MLT were significantly lower than in the sham group. The results of factorial analysis demonstrated no synergistic effect for IPC and RIPC, except for MDA formation 2h after reperfusion (p=0.038).

SIGNIFICANCE

Based on the synergistic and addictive effect on liver IRI induced by MLT between IPC and RIPC, the study suggested ways in which combined preconditionings could be elicited in patients undergoing planned procedures complicated by IRI to support better outcomes.

How much ischemia can the liver tolerate during resection?

The use of vascular inflow occlusion (VIO, also known as the Pringle maneuver) during liver surgery prevents severe blood loss and the need for blood transfusion. The most commonly used technique for VIO entails clamping of the portal triad, which simultaneously occludes the proper hepatic artery and portal vein. Although VIO is an effective technique to reduce intraoperative blood loss, it also inevitably inflicts hepatic ischemia/reperfusion (I/R) injury as a side effect. I/R injury induces formation of reactive oxygen species that cause oxidative stress and cell death, ultimately leading to a sterile inflammatory response that causes hepatocellular damage and liver dysfunction that can result in acute liver failure in most severe cases. Since the duration of ischemia correlates positively with the severity of liver injury, there is a need to find the balance between preventing severe blood loss and inducing liver damage through the use of VIO. Although research on the maximum duration of hepatic ischemia has intensified since the beginning of the 1980s, there still is no consensus on the tolerable upper limit. Based on the available literature, it is concluded that intermittent and continuous VIO can both be used safely when ischemia times do not exceed 120 min. However, intermittent VIO should be the preferred technique in cases that require >120 min duration of ischemia.

Mitochondrial Dysfunction and Autophagy in Hepatic Ischemia/Reperfusion Injury

Ischemia/reperfusion (I/R) injury remains a major complication of liver resection, transplantation, and hemorrhagic shock. Although the mechanisms that contribute to hepatic I/R are complex and diverse involving the interaction of cell injury in hepatocytes, immune cells, and endothelium, mitochondrial dysfunction is a cardinal event culminating in hepatic reperfusion injury. Mitochondrial autophagy, so-called mitophagy, is a key cellular process that regulates mitochondrial homeostasis and eliminates damaged mitochondria in a timely manner. Growing evidence accumulates that I/R injury is attributed to defective mitophagy. This review aims to summarize the current understanding of autophagy and its role in hepatic I/R injury and highlight the various therapeutic approaches that have been studied to ameliorate injury.

Hepatic cytoprotective effect of ischemic and anesthetic preconditioning before liver resection when using intermittent vascular inflow occlusion: a randomized clinical trial

BACKGROUND

Ischemic preconditioning (IPC) and anesthetic preconditioning (APC) have been reported to attenuate ischemia-reperfusion (IR) injury after liver resection under continuous inflow occlusion. This study evaluates whether these strategies enhance hepatic protection of remnant liver against IR after liver resection with intermittent clamping (INT).

METHODS

A total of 106 patients without underlying liver disease and submitted to liver resection using INT were randomized into 3 groups: IPC (10 minutes of inflow occlusion followed by 10 minutes of reperfusion before liver transection), APC (sevoflurane administration for 20 minutes before liver transection), and INT (no preconditioning). Patients were also stratified according to the extent of the hepatectomy. Cytoprotection was evaluated by comparing hepatocyte and endothelial dysfunction markers, apoptosis, histologic lesions, and postoperative outcome.

RESULTS

No differences were observed in preoperative chemotherapy and steatosis, total warm ischemia time, operative time, or blood loss. Kinetics of transaminases (aspartate aminotransferase, P = .137; alanine aminotransferase, P = .616), bilirubin (P = .980), and hyaluronic acid increase (P = .514) revealed no differences. Significant apoptosis was present in 40% of patients, mild-to-moderate leukocyte infiltration and steatosis in 45% and 55%, respectively, and mild sinusoidal congestion in 65%, with a similar distribution in the 3 groups. When patients were stratified by major versus minor resections, no differences were observed in any of the variables studied. Postoperative clinical outcomes were also similar.

CONCLUSION

These results suggest that these protocols of IPC and APC used in this study do not provide better cytoprotection from IR when INT is used.

Systemic protection through remote ischemic preconditioning is spread by platelet-dependent signaling in mice

Remote ischemic preconditioning (RIPC), the repetitive transient mechanical obstruction of vessels at a limb remote to the operative site, is a novel strategy to mitigate distant organ injury associated with surgery. In the clinic, RIPC has demonstrated efficacy in protecting various organs against ischemia reperfusion (IR), but a common mechanism underlying the systemic protection has not been identified. Here, we reasoned that protection may rely on adaptive physiological responses toward local stress, as is incurred through RIPC. Standardized mouse models of partial hepatic IR and of RIPC to the femoral vascular bundle were applied. The roles of platelets, peripheral serotonin, and circulating vascular endothelial growth factor (Vegf) were studied in thrombocytopenic mice, Tph1(-) (/) (-) mice, and through neutralizing antibodies, respectively. Models of interleukin-10 (Il10) and matrix metalloproteinase 8 (Mmp8) deficiency were used to assess downstream effectors of organ protection. The protection against hepatic IR through RIPC was dependent on platelet-derived serotonin. Downstream of serotonin, systemic protection was spread through up-regulation of circulating Vegf. Both RIPC and serotonin-Vegf induced differential gene expression in target organs, with Il10 and Mmp8 displaying consistent up-regulation across all organs investigated. Concerted inhibition of both molecules abolished the protective effects of RIPC. RIPC was able to mitigate pancreatitis, indicating that it can protect beyond ischemic insults.

CONCLUSIONS

We have identified a platelet-serotonin-Vegf-Il10/Mmp8 axis that mediates the protective effects of RIPC. The systemic action, the conservation of RIPC effects among mice and humans, and the protection beyond ischemic insults suggest that the platelet-dependent axis has evolved as a preemptive response to local stress, priming the body against impending harm.

Ischemic preconditioning versus intermittent clamping of portal triad in liver resection: A meta-analysis of randomized controlled trials

AIM

To compare the clinical outcome of patients undergoing liver resection under ischemic preconditioning (IP) versus intermittent clamping (IC).

METHODS

A systematic published work search was conducted to detect randomized controlled trials (RCT) comparing IP and intermittent clamping of the portal triad. A meta-analysis was conducted to estimate postoperative morbidity and mortality, blood loss, transfusion requirement, and liver injury based on the levels of bilirubin, aspartate aminotransferase (AST) and alanine aminotransferase (ALT). Meta-analysis was performed using either the fixed-effects model or random-effects model.

RESULTS

Five RCT published between 2006 and 2012 containing a total of 403 patients were eligible for final analysis. Meta-analysis of operative time showed it was lower in the IP group than the IC group with weighted mean difference (WMD) of -18.23 (95% confidence interval (CI), -28.58 to -7.87; P = 0.0006). Meta-analysis of ALT levels indicated lower levels in the IP group on postoperative days 3 and 7 (WMD on day 3: -45.27, 95% CI, -49.92 to -40.62; P < 0.00001; I(2)  = 0%; WMD on day 7: -24.33, 95% CI, -28.04 to -20.62; P < 0.00001; I(2)  = 0%). Meta-analyses revealed no significant difference in blood loss, transfusion requirement, mortality, morbidity, ischemic duration, hospital stay, AST and bilirubin levels on postoperative days 1, 3 and 7, and ALT levels on postoperative day 1 between IP and IC groups.

CONCLUSION

On currently available evidence, IP does not offer a satisfying benefit to patients undergoing hepatic resection. However, they have lower operative time and less liver injury after liver resections.

Rodent models of hepatic ischemia-reperfusion injury: time and percentage-related pathophysiological mechanisms

Ischemia and reperfusion (IR) injury remains one of the major problems in liver surgery and transplantation, which determines the viability of the hepatic tissue after resection and of the grafted organ. This review aims to elucidate the mechanisms involved in IR injury of the liver in rodent experimental studies and the preventative methods and pharmacologic agents that have been applied. Many time- and percentage-related liver IR injury rodent models have been used to examine the pathophysiological mechanisms and the parameters implicated with different morbidity, mortality, and pathology findings. The most preferred experimental rodent model of liver IR is the induction of 70% IR for 45 min, which is associated with almost 100% survival. In this model, plasma levels of several parameters such as alanine transaminase, aspartate aminotransferase, gamma-glutamyltransferase, endothelin-1, malonodialdehyde, tumor necrosis factor α, interleukin 1b, inducible nitric oxide synthase, and caspases are increased. The increase of caspases is associated with the initiation of hepatic cellular apoptosis. The main injuries observed 24 h after reperfusion are nuclear pyknosis, cytoplasmic hypereosinophilia, severe necrosis, and loss of intercellular borders. Both ischemic pre- and post-conditioning preventative methods and pharmacologic agents are successfully applied to alleviate the IR injuries. The selection of the time- and percentage-related liver IR injury rodent model and the potential preventative method should be related to the clinical question being answered.

Study of hepatocellular function in the murine model following hepatic artery selective clamping

PURPOSE

To investigate the impact of selective hepatic artery clamping (SHAC) in hepatocellular function.

METHODS

Three groups of Wistar male rats were subjected to SHAC ischemia period of 60min: Group A continuous SHAC were subjected to SHAC ischemia period of 60min, Group B intermittent SHAC of 30min with 5min of reperfusion and Group C intermittent SHAC of 15min with 5min of reperfusion. Animals without SHAC were included-Group D. To evaluate hepatocellular function blood markers and hepatic extraction function (HEF) using 99mTc-mebrofenin were performed before and after surgery. Flow cytometry was used to analyze oxidative stress and cell viability.

RESULTS

A mortality rate of 7.6% in Group A was observed. HEF maintained normal values between the groups. Flow cytometry demonstrated no significant differences between the groups in viability, type of cell death as well as in the production of reactive oxygen species.

CONCLUSIONS

The selective hepatic artery clamping compared to other clamping techniques results on increased cell viability and decreased hepatocyte death. The SHAC is a potential alternative to decrease per-operative bleeding while maintaining hepatocellular function.

Intermittent selective clamping improves rat liver regeneration by attenuating oxidative and endoplasmic reticulum stress

Intermittent clamping of the portal trial is an effective method to avoid excessive blood loss during hepatic resection, but this procedure may cause ischemic damage to liver. Intermittent selective clamping of the lobes to be resected may represent a good alternative as it exposes the remnant liver only to the reperfusion stress. We compared the effect of intermittent total or selective clamping on hepatocellular injury and liver regeneration. Entire hepatic lobes or only lobes to be resected were subjected twice to 10 min of ischemia followed by 5 min of reperfusion before hepatectomy. We provided evidence that the effect of intermittent clamping can be damaging or beneficial depending to its mode of application. Although transaminase levels were similar in all groups, intermittent total clamping impaired liver regeneration and increased apoptosis. In contrast, intermittent selective clamping improved liver protein secretion and hepatocyte proliferation when compared with standard hepatectomy. This beneficial effect was linked to better adenosine-5′-triphosphate (ATP) recovery, nitric oxide production, antioxidant activities and endoplasmic reticulum adaptation leading to limit mitochondrial damage and apoptosis. Interestingly, transient and early chaperone inductions resulted in a controlled activation of the unfolded protein response concomitantly to endothelial nitric oxide synthase, extracellular signal-regulated kinase-1/2 (ERK1/2) and p38 MAPK activation that favors liver regeneration. Endoplasmic reticulum stress is a central target through which intermittent selective clamping exerts its cytoprotective effect and improves liver regeneration. This procedure could be applied as a powerful protective modality in the field of living donor liver transplantation and liver surgery.

[Results after laparoscopic liver resection: an appropriate option in malignant disease]

INTRODUCTION

The laparoscopic approach is not yet widely used in liver surgery, but has proven to be safe and feasible in selected patients even in malignant disease. The experience and results of a hepato-pancreato-biliary (HPB) surgery unit in the treatment of malignant liver disease by laparoscopic approach is presented.

MATERIAL AND METHODS

Between February 2002 and May 2011, 71 laparoscopic liver resections were performed, 43 for malignant disease (only patients with more than one year of follow-up were included). Mean age was 63 years old and 58% of the patients were male. Forty-nine per cent of the lesions were located in segments ii-iii. Thirty segmentectomies were performed, 7 limited resections and 6 major hepatectomies.

RESULTS

The median operative time was 163 min. There were 3 conversions. Five cases (11%) required blood transfusion. The oral intake began at 32 h and the median hospital stay was 6.7 days. There were no reoperations and there was one case of mortality. Nine patients (21%) had postoperative complications. The mean number of resected lesions was 1.2, with an average size of 3.5 cm. All resections were R0. The median survival after resection of colorectal liver metastases (CLM) was 69% and 43.5% at 36 and 60 months, respectively, and 89% and 68% at 36 and 60 months, respectively, in hepatocellular carcinoma (HCC).

CONCLUSION

The laparoscopic liver resection in malignant disease is feasible and safe in selected patients. The same oncological rules as for open surgery should be followed. In selected patients it offers similar long-term oncological results as open surgery.

Remifentanil ameliorates intestinal ischemia-reperfusion injury

Background

Intestinal ischemia-reperfusion injury (IRI) can occur in clinical scenarios such as organ transplantation, trauma and cardio-pulmonary bypass, as well as in neonatal necrotizing enterocolitis or persistent ductus arteriosus. Pharmacological protection by pretreating (“preconditioning”) with opioids attenuates IRI in a number of organs. Remifentanil appears particularly attractive for this purpose because of its ultra-short duration of action and favorable safety profile. To date, little is known about opioid preconditioning of the intestine.

Methods

Young adult C57BL/6J mice were randomly assigned to receive tail vein injections of 1 μg/kg of remifentanil or normal saline and underwent either ischemia-reperfusion of the intestine or a sham laparotomy. Under isoflurane anesthesia, the mice were subjected to intestinal ischemia-reperfusion by occlusion (clamping) of the superior mesenteric artery for 30 min, followed by unclamping and 60 min of reperfusion. After completion of this protocol, tissue injury and lipid peroxidation in jejunum and ileum were analyzed by histology and malondialdehyde (MDA), respectively. Systemic interleukin (IL)-6 was determined in the plasma by ELISA.

Results

Pretreatment with remifentanil markedly reduced intestinal IRI (P < 0.001): In the ileum, we observed a more than 8-fold decrease in injured villi (4% vs 34% in saline-pretreated animals). In fact, the mucosa in the remifentanil group was as healthy as that of sham-operated animals. This protective effect was not as pronounced in the jejunum, but the percentage of damaged villi was still reduced considerably (18% vs 42%). There was up to 3-fold more tissue MDA after intestinal ischemia-reperfusion than after sham laparotomy, but this increase in lipid peroxidation was prevented by preconditioning with remifentanil (P < 0.05). The systemic inflammatory response triggered by intestinal IRI was significantly attenuated in mice pretreated with remifentanil (159 vs 805 pg/ml of IL-6 after saline pretreatment, with 92 pg/ml in the sham groups). After sham operations, no difference was detected between the saline- and remifentanil-pretreatments in any of the parameters investigated.

Conclusion

Preconditioning with remifentanil attenuates intestinal IRI and the subsequent systemic inflammatory response in mice. We therefore suggest that prophylaxis with this ultra-short-acting opioid may be advantageous in various clinical scenarios of human IRI.

Protection of pharmacological postconditioning in liver surgery: results of a prospective randomized controlled trial

OBJECTIVES

: To elucidate the possible organ-protective effect of pharmacological postconditioning in patients undergoing liver resection with inflow occlusion.

BACKGROUND

: Inflow occlusion reduces blood loss during liver transection in selected patients but is potentially harmful due to ischemia-reperfusion injury. Preventive strategies include the use of repetitive short periods of ischemia interrupted by a reperfusion phase (intermittent clamping), application of a short period of ischemia before transection (ischemic preconditioning), or pharmacological preconditioning before transection. Whether intervention after resection (postconditioning) may confer protection is unknown.

METHODS

: A 3 arm, prospective, randomized trial was designed for patients undergoing liver resection with inflow occlusion to compare the effects of pharmacological postconditioning with the volatile anesthetic agent sevoflurane (n = 48), intermittent clamping (n = 50), or no protective intervention (continuous inflow occlusion, n = 17). Endpoints included peak serum aspartate transaminase level, postoperative complications, and hospital stay. All patients were intravenously anesthetized with propofol. In patients with postconditioning, propofol infusion was stopped upon reperfusion and replaced with sevoflurane for 10 minutes.

RESULTS

: Compared with the control group, both postconditioning (P = 0.044) and intermittent clamping (P = 0.015) significantly reduced aspartate transaminase levels. The risk of complications was significantly decreased by postconditioning, odds ratio, 0.08 [95% confidence interval (CI), 0.02-0.36; P = 0.001]) and intermittent clamping, odds ratio, 0.50 [95% CI, 0.26-0.96; P = 0.038], compared with controls. Both interventions reduced length of hospital stay, postconditioning -4 days [95% CI, -6 to -1; P = 0.009], and intermittent clamping -2 days, [95% CI, -4 to 0; P = 0.019].

CONCLUSIONS

: Pharmacological postconditioning reduces organ injury and postoperative complications. This easily applicable strategy should be used in patients with prolonged continuous inflow occlusion.

Intermittent clamping is superior to ischemic preconditioning and its effect is more marked with shorter clamping cycles in the rat liver

BACKGROUND

Intermittent clamping (IC) and ischemic preconditioning (PC) reportedly protect the liver against the ischemia/reperfusion (I/R) injury induced by inflow occlusion during hepatectomy. While IC cycles consisting of 15 min of clamping with 5 min of reperfusion are used empirically, the optimal IC cycle has not been established. We compared the effects of various cycles of IC and PC in the rat liver.

METHODS

Rats subjected to 60 min of inflow occlusion were assigned to the following five groups (n = 8 each): 60 min of continuous ischemia; 4 cycles comprising 15 min of ischemia/5 min of reperfusion; 6 cycles comprising 10 min of ischemia/3.3 min of reperfusion; 12 cycles comprising 5 min of ischemia/1.7 min of reperfusion (the time ratio of ischemia to reperfusion in the IC groups was 3:1); and PC (10/10 min of ischemia/reperfusion) prior to 60 min of ischemia. The severity of liver injury was assessed by determining the serum alanine aminotransferase (ALT) level, bile flow, tissue glutathione content, and induction of apoptosis (terminal deoxynucleotidyl transferase-mediated biotin nick end-labeling [TUNEL] staining and DNA laddering), and by histological examination of areas of severe necrosis.

RESULTS

All the parameters indicated that liver injury was attenuated in the three IC groups compared with the continuous group; furthermore, this effect became increasingly marked with shorter cycles of IC. PC did not exert a protective effect under the present experimental conditions.

CONCLUSION

Various cycles of IC consistently conferred protection against I/R injury, and IC with shorter cycles of ischemia and reperfusion was more effective. No protective effect of PC was evident. IC is a more robust strategy than the PC protocol for liver protection.

Effect of the pringle maneuver on tumor recurrence of hepatocellular carcinoma after curative resection (EPTRH): a randomized, prospective, controlled multicenter trial

BACKGROUND

Hepatic resection is currently still the best choice of therapeutic strategies for liver cancer, but the long-term survival rate after surgery is unsatisfactory. Most patients develop intra- and/or extrahepatic recurrence. The reasons for this high recurrence rate are not entirely clear. Recent studies have indicated that ischemia-reperfusion injury to the liver may be a significant factor promoting tumor recurrence and metastasis in animal models. If this is also true in humans, the effects of the Pringle maneuver, which has been widely used in hepatectomy for the past century, should be examined. To date, there are no reported data or randomized controlled studies examining the relationship between use of the Pringle maneuver and local tumor recurrence. We hypothesize that the long-term prognosis of patients with liver cancer could be worsened by use of the Pringle maneuver due to an increase in the rate of tumor recurrence in the liver remnant. We designed a multicenter, prospective, randomized surgical trial to test this hypothesis.

METHODS

At least 498 eligible patients from five participating centers will be enrolled and randomized into either the Pringle group or the non-Pringle group in a ratio of 1:1 using a permuted-blocks randomization protocol. After the completion of surgical intervention, patients will be included in a 3-year follow-up program.

DISCUSSION

This multicenter surgical trial will examine whether the Pringle maneuver has a negative effect on the long-term outcome of hepatocellular carcinoma patients. The trial will also provide information about prognostic differences, safety, advantages and disadvantages between Pringle and non-Pringle surgical procedures. Ultimately, the results will increase the available information about the effects of ischemia-reperfusion injury on tumor recurrence, which will be of immense benefit to general surgery.

TRIAL REGISTRATION

http://www.clinicaltrials.gov NCT00725335.

Quantitative histological assessment of hepatic ischemia-reperfusion injuries following ischemic pre- and post-conditioning in the rat liver

BACKGROUND

Ischemic preconditioning (IPC) has been shown to protect the liver against ischemia-reperfusion (I/R) injuries. However, ischemic post-conditioning has received little attention. The aim of the present study was to quantify and compare the hepato-protective properties of IPC and IPO, for the first time, using unbiased design-based stereological methods.

METHODS

We divided 67 rats into four groups: sham, liver ischemia (LI), IPC, and IPO. Rats were subjected to 60 min LI, followed by 4- or 24-h reperfusion. We performed quantification of (NVR) and apoptotic cell profile number.

RESULTS

We observed no significant differences in NVR between ischemic groups after 4 h. After 24-h reperfusion, NVR had increased to 70% in the LI group, compared with 51% (P = 0.02) and 49% (P = 0.01) in the IPC and IPO groups, respectively. After 4-h reperfusion, the apoptotic cell number was significantly higher in all ischemic groups than in the sham group; we detected no difference between ischemic groups. After 24-h reperfusion, we detected a significantly lower number of apoptotic cell profiles in the IPC group than in the LI group (P = 0.02). The mean number of apoptotic cell profiles decreased insignificantly in the IPO group (P = 0.06). Liver parameters were at all time comparable between groups.

CONCLUSIONS

After I/R, IPC and IPO reduce the degree of hepatocellular injury. Both methods are equally efficient at preventing hepatocellular necrosis. Furthermore, apoptosis is significantly lower after IPC.

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.

Mangafodipir protects against hepatic ischemia-reperfusion injury in mice

Introduction and Aim

Mangafodipir is a contrast agent used in magnetic resonance imaging that concentrates in the liver and displays pleiotropic antioxidant properties. Since reactive oxygen species are involved in ischemia-reperfusion damages, we hypothesized that the use of mangafodipir could prevent liver lesions in a mouse model of hepatic ischemia reperfusion injury. Mangafodipir (MnDPDP) was compared to ischemic preconditioning and intermittent inflow occlusion for the prevention of hepatic ischemia-reperfusion injury in the mouse.

Methods

Mice were subjected to 70% hepatic ischemia (continuous ischemia) for 90 min. Thirty minutes before the ischemic period, either mangafodipir (10 mg/kg) or saline was injected intraperitoneally. Those experimental groups were compared with one group of mice preconditioned by 10 minutes' ischemia followed by 15 minutes' reperfusion, and one group with intermittent inflow occlusion. Hepatic ischemia-reperfusion injury was evaluated by measurement of serum levels of aspartate aminotransferase (ASAT) activity, histologic analysis of the livers, and determination of hepatocyte apoptosis (cytochrome c release, caspase 3 activity). The effect of mangafodipir on the survival rate of mice was studied in a model of total hepatic ischemia.

Results

Mangafodipir prevented experimental hepatic ischemia-reperfusion injuries in the mouse as indicated by a reduction in serum ASAT activity (P<0.01), in liver tissue damages, in markers of apoptosis (P<0.01), and by higher rates of survival in treated than in untreated animals (P<0.001). The level of protection by mangafodipir was similar to that observed following intermittent inflow occlusion and higher than after ischemic preconditioning.

Conclusions

Mangafodipir is a potential new preventive treatment for hepatic ischemia-reperfusion injury.

Hemihepatic versus total hepatic inflow occlusion during hepatectomy: A systematic review and meta-analysis

AIM: To evaluate the clinical outcomes of patients undergoing hepatectomy with hemihepatic vascular occlusion (HHO) compared with total hepatic inflow occlusion (THO).

METHODS: Randomized controlled trials (RCTs) comparing hemihepatic vascular occlusion and total hepatic inflow occlusion were included by a systematic literature search. Two authors independently assessed the trials for inclusion and extracted the data. A meta-analysis was conducted to estimate blood loss, transfusion requirement, and liver injury based on the levels of aspartate aminotransferase (AST) and alanine aminotransferase (ALT). Either the fixed effects model or random effects model was used.

RESULTS: Four RCTs including 338 patients met the predefined inclusion criteria. A total of 167 patients were treated with THO and 171 with HHO. Meta-analysis of AST levels on postoperative day 1 indicated higher levels in the THO group with weighted mean difference (WMD) 342.27; 95% confidence intervals (CI) 217.28-467.26; P = 0.00 001; I² = 16%. Meta-analysis showed no significant difference between THO group and HHO group on blood loss, transfusion requirement, mortality, morbidity, operating time, ischemic duration, hospital stay, ALT levels on postoperative day 1, 3 and 7 and AST levels on postoperative day 3 and 7.

CONCLUSION: Hemihepatic vascular occlusion does not offer satisfying benefit to the patients undergoing hepatic resection. However, they have less liver injury after liver resections.

Protective effect of intermittent clamping of the portal triad in the rat liver on liver ischemia-reperfusion injury

BACKGROUND

Intermittent clamping (IC) of the portal triad is an effective method of protecting the liver from ischemia-reperfusion injury (IR). In clinical practice, this method is employed during a resection, but its mechanism is still not clear.

OBJECTIVES

To evaluate the effect of IC on rat liver and determine its mechanisms.

MATERIALS AND METHODS

Wistar rats were submitted to 60-min IC (cycles of 12-min clamping followed by 4-min reperfusion), and the samples were collected after 1, 6, and 72 hrs of reperfusion. We determined the serum activity of alanine aminotransferase (ALT), and measured the concentration of TNF-α, malondialdehyde (MDA) and myeloperoxidase (MPO) in liver homogenates. The apoptosis of hepatocytes was evaluated immunohistochemically.

RESULTS

When compared to the IR rats, the activity of ALT decreased in the IC group in all periods of observation (the highest decrease of ~48% after 1 hr of reperfusion). When compared to the IR group, a statistically significant decrease (p < 0.05) in the TNF-α concentration (~33%) in the IC rats occurred only after 1 hr of reperfusion, and it was accompanied by a decrease in the MPO concentration after 1 and 6 hrs of reperfusion. IC reduces the effects of reactive oxygen species (ROS) activity, which has been confirmed by a statistically significant decrease in MDA concentration by 25%-35% in all studied periods. The limitation of hepatocytes apoptosis due to IC occurs in the early (~26%; p < 0.05) and late (~45%; p < 0.01) phases of reperfusion.

CONCLUSIONS

The use of IC in early phase of reperfusion brings about a decrease in TNF-α release, which can be related to liver injury due to neutrophil infiltration and apoptotic cell reduction. It seems that the reduction of lipid peroxidation may also limit the liver injury.

Ischemia/reperfusion injury in liver resection: a review of preconditioning methods

Ischemic preconditioning is one of the therapeutic interventions aiming at preventing ischemia/reperfusion-related injury. Numerous experimental studies and a few clinical series have shown that during liver resections, ischemic preconditioning is a promising strategy for optimizing the postoperative outcome. Moreover, various types of pharmacological intervention as well as different types of preconditioning, such as remote preconditioning, the use of heat shock, and hyperbaric oxygen, have been developed to attenuate the functional impairment accompanying ischemia/reperfusion injury. This review summarizes the various forms of preconditioning, thus suggesting that close cooperation between surgeons and anesthesiologists paves the way to apply novel strategies to improve the outcome of liver resection.

Cell apoptosis and Fas gene expression in liver and renal tissues after ischemia-reperfusion injury in liver transplantation

Ischemia-reperfusion (I/R) injury is an important factor in a nonfunctioning liver graft and acute renal failure. Apoptosis is a cell death mechanism in early stages of I/R injury. In the present study, orthotopic liver transplantation (oLT) using a modified double-cuff method was performed in Wistar rats, with sham-operated rats serving as the control group. Rats in the treatment and control groups were sacrificed at 1, 3, 6, 12, and 24 hours after oLT to obtain liver and kidney tissues. Fas protein expression in apoptotic cells at various times was detected at immunohistochemical staining and flow cytometry, and Fas gene expression was detected using the reverse transcriptase polymerase chain reaction. Apoptosis began in liver and renal cells at 1 hour after oLT, peaking at 12 hours. The reverse transcriptase polymerase chain reaction demonstrated Fas gene expression in liver and renal tissues at 1 hour post-oLT, peaking at 12 hours. Changes in the treatment group were significantly greater than in the control group (P < .05). We conclude that renal cells, like liver cells, undergo apoptosis due to I/R injury after oLT.

Hepatic ischaemia-reperfusion injury from bench to bedside

BACKGROUND

Vascular occlusion to prevent haemorrhage during liver resection causes ischaemia-reperfusion (IR) injury. Insights into the mechanisms of IR injury gathered from experimental models have contributed to the development of therapeutic approaches, some of which have already been tested in randomized clinical trials.

METHODS

The review was based on a PubMed search using the terms 'ischemia AND hepatectomy', 'ischemia AND liver', 'hepatectomy AND drug treatment', 'liver AND intermittent clamping' and 'liver AND ischemic preconditioning'; only randomized controlled trials (RCTs) were included.

RESULTS

Twelve RCTs reported on ischaemic preconditioning and intermittent clamping. Both strategies seem to confer protection and allow extension of ischaemia time. Fourteen RCTs evaluating pharmacological interventions, including antioxidants, anti-inflammatory drugs, vasodilators, pharmacological preconditioning and glucose infusion, were identified.

CONCLUSION

Several strategies to prevent hepatic IR have been developed, but few have been incorporated into clinical practice. Although some pharmacological strategies showed promising results with improved clinical outcome there is not sufficient evidence to recommend them.

Ischemic preconditioning confers antiapoptotic protection during major hepatectomies performed under combined inflow and outflow exclusion of the liver. A randomized clinical trial

BACKGROUND

Extensive experimental studies and a few clinical series have shown that ischemic preconditioning (IPC) attenuates oxidative ischemia/reperfusion (I/R) injuries in liver resections performed under inflow vascular control. Selective hepatic vascular exclusion (SHVE) employed during hepatectomies completely deprives the liver of blood flow, as it entails simultaneous clamping of the portal triad and the main hepatic veins. The aim of the present study was to identify whether IPC can also protect hepatocytes during liver resections performed under SHVE.

METHODS

Patients undergoing major liver resection were randomly assigned to have either only SHVE (control group, n = 43) or SHVE combined with IPC--10 min of ischemia followed by 15 min of reperfusion before SHVE was applied (IPC group, n = 41).

RESULTS

The two groups were comparable with regard to age, liver resection volume, blood loss and transfusions, warm ischemic time, and total operative time. In liver remnant biopsies obtained 60 min post-reperfusion, IPC patients had significantly fewer cells stained positive by TUNEL compared to controls (19% +/- 8% versus 45% +/- 12%; p < 0.05). Also IPC patients had attenuated hepatocyte necrosis, systemic inflammatory response, and oxidative stress as manifested by lower postoperative peak values of aspartate transaminase, interleukin-6, interleukin-8, and malondialdehyde compared to controls. Morbidity was similar for the two groups, as were duration of intensive care unit stay and extent of total hospital stay.

CONCLUSIONS

In major hepatectomies performed under SHVE, ischemic preconditioning appears to attenuate apoptotic response of the liver remnant, possibly through alteration of inflammatory and oxidative pathways.

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.

Up regulation of IL-6 by ischemic preconditioning in normal and fatty rat livers: Association with reduction of oxidative stress

We analyzed the role of IL-6 in the protection that ischemic preconditioning (IP) exerts against hepatic ischemia reperfusion-mediated (I/R) oxidative damage, particularly in fatty livers. IP-related IL-6 up-regulation during reperfusion in steatotic and non-steatotic livers was correlated with reduced indices of liver damage, as also demonstrated by pharmacological modulation of IL-6. IP activated NF-kB and HSF during ischemia (Isc), whereas AP-1 activity was unaffected. IP blunted the activation of STAT3 and stress-responsive genes, such as NF-kB, AP-1 and heme oxygenase (HO-1) during reperfusion. The role of reduced oxidative stress in hepatoprotection of fatty livers was further demonstrated by the fact that: (i) IP prevented the decrease of glutathione levels and the increase of lipid peroxidation; (ii) the anti-oxidant GSH-ester prevented lipid peroxidation and necrosis. In conclusion, IP modulates the activity of transcription factors and triggers IL-6 production; this may prevent hepatic I/R damage in a oxidative stress-dependent way, particularly in fatty livers.

Colorectal liver metastasis surgery: analysis of risk factors predicting postoperative complications in relation to the extent of resection

BACKGROUND/AIMS

Despite advances in diagnosis and treatment, the rate of complications after resection for colorectal liver metastases remains high. An awareness of risk factors is essential for the rates of morbidity and mortality to fall to optimal levels.

MATERIALS AND METHODS

Of the 240 patients who underwent resection for the first manifestation of colorectal liver metastases, 49 patients with lobectomy or extended hepatectomy (major resections) and 58 with wedge resections within only one liver segment (minor resections) form the basis of this report. A total of 16 variables were analyzed to find the risk factors linked to postoperative morbidity and mortality.

RESULTS/FINDINGS

Thirty-four patients (31.8%) suffered postoperative complications, and one patient died during the hospital stay (0.9%). In the major resection group, multivariate analysis showed that neoadjuvant chemotherapy [odds ratio (OR): 2.4; p = 0.005], vascular clamping (OR: 1.4; p = 0.008), and intraoperative blood loss with transfusion of three to six packed red cell units (OR: 1.2; p = 0.029) were significantly associated with postoperative morbidity. Vascular clamping was an independent predictor for biliary fistula (OR: 1.2; p = 0.029). Postoperative temporary liver failure was influenced by neoadjuvant chemotherapy (OR: 3.4; p = 0.010), vascular clamping (OR: 1.5; p = 0.015), and requirement of blood transfusion (OR: 2.1; p = 0.016). After minor resections, only a decreased postoperative serum cholinesterase B level was an independent predictor for complications (OR: 2.2; p = 0.001), as well as for hemorrhage (OR: 1.6; p = 0.023). Postoperative mortality was not predicted by any of the factors that were analyzed.

INTERPRETATION/CONCLUSION

Factors for complications differ depending on the extent of colorectal liver metastasis resection. Only knowledge and particular consideration of these factors may provide for an optimal postoperative outcome for the individual patient.

Bcl-2 upregulation after 3-nitropropionic acid preconditioning in warm rat liver ischemia

We aimed to determine whether 3-nitropropionic acid (3-NPA) preconditioning protects rat livers against warm ischemia/reperfusion injury. We hypothesized that 3-NPA mediates its protective effects by Bcl-2 upregulation. Brown-Norway rats (200 g) were injected with 3-NPA (10 mg/kg intraperitoneally) 24 h before 90 min of selective warm in situ ischemia. In additional experiments, 30-day survival was studied after 90 min of warm liver ischemia and resection of nonischemic liver tissue. We demonstrate increased mRNA and protein levels of Bcl-2 by real-time polymerase chain reaction, immunohistochemistry, and Western blot analysis in 3-NPA-pretreated rats. All treated animals survived, whereas all untreated rats died within 3 days after selective ischemia and resection of the nonischemic tissue. This corresponded well with a significant decrease of caspases 3 and 9 activity at 1 h of reperfusion after preconditioning with 3-NPA as compared with untreated rats. The histological sections showed protection of liver tissue after 3-NPA by reduction of apoptotic and oncotic tissue damage. Lipid peroxidation in liver tissue was reduced after 3-NPA preconditioning. We show that subtoxic doses of the mitochondrial toxin 3-NPA induces tolerance to warm liver ischemia in rats associated by synthesis of Bcl-2. Bcl-2 upregulation might protect against the postischemic burst of reactive oxygen species and therefore reduces apoptotic- and oncotic-related cell death.

A randomized controlled trial on pharmacological preconditioning in liver surgery using a volatile anesthetic

OBJECTIVE

To evaluate the effects of pharmacological preconditioning with a volatile anesthetic in patients undergoing liver resection with inflow occlusion.

BACKGROUND

In liver surgery, ischemic preconditioning and intermittent clamping are the only established protective strategies to reduce tissue damage due to ischemia during inflow occlusion. Preconditioning with volatile anesthetics has provided protection against cardiac and renal ischemic injury in several animal models through NO and HO-1 pathways. But pharmacological preconditioning has never been tested in patients undergoing liver surgery in a randomized trial.

METHODS

Sixty-four patients undergoing liver surgery with inflow occlusion were randomized intraoperatively for preconditioning with sevoflurane or not (ClinicalTrials.gov NCT00516711). Anesthesia was performed intravenously with propofol. Thirty minutes before inflow occlusion propofol was replaced by sevoflurane in the preconditioning group. Primary endpoint was postoperative liver injury assessed by peak values of liver transaminases. Postoperative complications were recorded according to an established scoring system.

RESULTS

Sevoflurane preconditioning significantly limited the postoperative increase of serum transaminase levels by 261 U/L (95% CI, 65 to 458; P = 0.01) for the ALT and by 239 (95% CI, -2 to 480; P = 0.05) for the AST corresponding to decreases of baseline levels of 35% and 31%, respectively. Patients with steatosis had an even better benefit than patients without steatosis. The rates of any complication (risk ratio 0.46; 95% CI, 0.25 to 0.85; P = 0.006) and of severe complications requiring invasive procedures (risk ratio 0.25; 95% CI, 0.06 to 1.08; P = 0.05) were also lowered by preconditioning.

CONCLUSION

This first randomized trial of pharmacological preconditioning in liver surgery in humans showed a protective effect of preconditioning with volatile anesthetics. This strategy may provide a new and easily applicable therapeutic option to protect the liver and to lower complication rates.

The Pringle manoeuvre should be avoided in hepatectomy for cancer patients due to its side effects on tumor recurrence and worse prognosis

Curative hepatectomy is still the best therapeutic strategy for liver cancer treatment up to now. The Pringle manoeuvre has been commonly used to avoid massive blood loss during operation since its advent, which greatly accelerates the advance of liver surgery and oncological surgery. In the past century, more attentions have been paid to different effects of ischemia-reperfusion injury elicited by Pringle manoeuvre. Theses include its impacts on complex metabolic, immunological, and microvascular changes, which altogether might contribute to hepatocellular damage and dysfunction, and contribute to haemodynamic instability. Despite these adverse impacts, the short-term outcome of affected patients under hepatectomy was greatly improved with the advances of surgical techniques and perioperative management in recent years. While the long-term prognosis remains unsatisfactory due to a high incidence of intra/extrahepatic recurrence. The reason for it was not totally elucidated. Furthermore, the effect of the Pringle manoeuvre on the prognosis of oncologic patients and behavior of the tumor cell was not deliberately mentioned. This point was put forward to the front-desk by the specific phenomenon from recent animal studies. It is showed that ischemia-reperfusion injury of the liver remnant may be a significant factor to promote the tumor recurrence and metastasis. If it is a truth in human, there must be a big challenge to the Pringle manoeuvre. So we hypothesized that the long-term prognosis of cancer patients could be worsened by the ischemia-reperfusion injury elicited by Pringle manoeuvre during the hepatectomy and it should be revised, or even, avoided in future hepatectomy for oncologic patients. The less surgical stress including ischemia-reperfusion injury in the hepatic resection without Pringle manoeuvre might contribute to a better prognosis. To get a deeper understanding, prospective randomized clinical trials need to be done. It is surely supposed to provide more important information about the long-term effects of the Pringle manoeuvre, and to our hypothesis.

Ischemic preconditioning in hepatic ischemia and reperfusion

PURPOSE OF REVIEW

Ischemic preconditioning that consists of a short period of hepatic inflow occlusion followed by reperfusion has the potential to increase tolerance to a subsequent prolonged ischemic insult. This review outlines current insight into ischemic preconditioning for hepatic ischemia and reperfusion injury in experimental and clinical settings.

RECENT FINDINGS

Experimental evidence suggests that interleukin-6 signaling and increased phosphorylation of STAT3 (signal transducer and activator of transcription-3) are involved in the protective effects of ischemic preconditioning. The benefit of ischemic preconditioning is restricted, however, by old liver and prolonged ischemic time (>60 min). To overcome this, ascorbic acid or glucose administration combined with ischemic preconditioning potentially can maintain the integrity of hepatic mitochondrial function through signal transduction pathways. The influence of ischemic preconditioning on hepatic regeneration varies with partial hepatectomy or small-for-size liver graft models, and remains controversial. Clinically, ischemic preconditioning in deceased donors protects against ischemia and reperfusion injury, as demonstrated by lowered liver enzyme levels, reduced incidence of primary nonfunction, and increased hepatic hypoxia-induced factor-1alpha concentrations.

SUMMARY

Enhanced understanding of the mechanisms of organ tolerance induced by ischemic preconditioning would strengthen the significance of this potential therapeutic strategy in liver transplantation.

Ischemic preconditioning and intermittent clamping confer protection against ischemic injury in the cirrhotic mouse liver

Surgery on cirrhotic livers is fraught with complications, and many surgeons refrain from operating on patients with cirrhosis. Surgical procedures include temporal occlusion of blood flow resulting in ischemia. The mechanisms of protective strategies to prevent ischemic injury in patients with cirrhosis are not fully understood. The aim of this study was to evaluate how the cirrhotic liver tolerates an ischemic insult, whether mechanisms other than those observed in the normal liver are active, and whether intermittent clamping and preconditioning, which are known as safe surgical strategies in normal and steatotic livers, confer protection to the cirrhotic liver. We applied partial hepatic inflow occlusion to cirrhotic mice fed carbon tetrachloride according to different vascular occlusion protocols: intermittent clamping with 15 or 30 minute cycles of ischemia or ischemic preconditioning prior to 60 or 75 minutes of ischemia. Continuous ischemia (60 or 75 minutes) served as controls. The results showed that the cirrhotic liver was significantly more susceptible to 60 minutes of ischemia than the normal liver. Apoptosis was higher in the normal liver, whereas necrosis was a predominant feature in the cirrhotic liver. Both protocols of intermittent vascular occlusion and ischemic preconditioning dramatically prevented injury compared to continuous occlusion for 60 minutes. This protection was associated with reduced necrosis and apoptosis, and particularly reduced activation of the apoptotic pathway through mitochondria. In conclusion, this study extends the protective effects of ischemic preconditioning and intermittent clamping to the cirrhotic liver, highlighting a diminished apoptotic pathway with dramatic improvement in the development of necrosis.

L-arginine protects from pringle manoeuvere of ischemia-reperfusion induced liver injury

Pringle described a new technique to reduce blood loss during liver surgery. Adult Wistar rats were subjected to 1 h of partial liver ischemia and followed by 3 h reperfusion. Eighteen Wistar rats were divided into sham-operated control group (I) (n=6), ischemia and reperfusion (I/R) group (II) (n=6), L-arginine treated group (100 mg/kg body weight/daily by oral route for 7 d before induced ischemia reperfusion maneuver) (III) (n=6). Ischemic and reperfusion hepatocellular injury occurred as indicated by increased-alanine transaminase (ALT), aspartate transaminase (AST). Pre-treatment with L-arginine significantly decreased serum-ALT, AST after 1 h ischemia followed by 3 h of reperfusion. Nitric oxide production, in hepatocytes was increased 2 fold and MDA levels significantly decreased by L-arginine treatment as compared to I/R rat. Histopathology and TEM studies showed markedly diminished hepatocellular injury in L-arginine pretreated rats during the hepatic I/R, which reached a level comparable to saline-treated rat of sham operated group. Thus, findings it may be concluded that L-arginine afforded significant protection from hepatobiliary function from I/R injury by nitric oxide production.

Systematic review and meta-analysis of the effect of portal triad clamping on outcome after hepatic resection

Background

The effect of portal triad clamping (PTC) on outcome after hepatic resection is uncertain.

Methods

A systematic literature search was conducted to detect randomized controlled trials (RCTs) assessing the effectiveness and safety of PTC alone and of PTC with ischaemic preconditioning (IPC) of the liver. Studies on clamping of the inferior vena cava or hepatic veins were excluded. Endpoints included postoperative overall morbidity and mortality, cardiopulmonary and hepatic morbidity, blood loss, transfusion rates and alanine aminotransferase (ALT) levels. Meta-analyses were performed using a random-effects model.

Results

Eight RCTs published between 1997 and 2006 containing a total of 558 patients were eligible for final analysis. The design of the identified studies varied considerably. Analyses of endpoints revealed no difference between intermittent PTC and no PTC. Meta-analyses of PTC with and without previous IPC revealed no differences, but postoperative ALT levels were significantly lower with IPC.

Conclusion

On currently available evidence, the routine use of PTC does not offer any benefit in perioperative outcome after liver resection. It cannot be recommended as a standard procedure.

Intermittent ischemia but not ischemic preconditioning is effective in restoring bile flow after ischemia reperfusion injury in the livers of aged rats

BACKGROUND/AIMS

Ischemic preconditioning (IPC) and intermittent ischemia (INT) reduce liver injury following ischemia reperfusion in liver resections. Aged livers are at higher risk for ischemia reperfusion injury, but little is known of the effectiveness of IPC and INT in aged livers. The aim of this study was to investigate the effects of IPC and INT on ischemia reperfusion injury in aged livers.

METHODS

A rat model of segmental hepatic ischemia (45 min) and reperfusion (60 min) was used. Bile flow, as an indicator of early hepatocyte damage and dynamic liver function, plasma concentrations of bilirubin, liver marker enzymes, and liver histology were assessed.

RESULTS

In young rats (8-13 weeks), IPC regimes of 10 min clamping and 10 min reperfusion, and 5 min clamping and 30 min reperfusion, restored bile flow to 23 and 42%, respectively, of the initial value, compared to 14 and 88% for continuous clamping and controls, respectively. An INT regime of three cycles of alternating 15 min perfusion and 15 min clamping gave a substantially greater (70%) restoration of bile flow. In aged rats (20-24 months), the IPC regimes did not give any restoration of bile flow. By contrast, the INT regime restored bile flow to 68%. Plasma bilirubin concentrations were lowest in the INT groups, whereas alanine transaminase concentrations for the IPC and INT groups compared with the continuous clamping groups showed no significant differences.

CONCLUSIONS

In young rats, INT is more effective than IPC in restoring the immediate consequences of IP-induced damage to hepatocytes and liver function after ischemia-reperfusion. In aged rats INT, but not IPC, reverses hepatocyte damage and restores liver function. INT may promote better hepatocyte and liver function than IPC following the surgical resection of aged livers.