Donor nutritional status--a determinant of liver preservation injury

ESPEN practical guideline: Clinical nutrition in surgery

Early oral feeding is the preferred mode of nutrition for surgical patients. Avoidance of any nutritional therapy bears the risk of underfeeding during the postoperative course after major surgery. Considering that malnutrition and underfeeding are risk factors for postoperative complications, early enteral feeding is especially relevant for any surgical patient at nutritional risk, especially for those undergoing upper gastrointestinal surgery. The focus of this guideline is to cover both nutritional aspects of the Enhanced Recovery After Surgery (ERAS) concept and the special nutritional needs of patients undergoing major surgery, e.g. for cancer, and of those developing severe complications despite best perioperative care. From a metabolic and nutritional point of view, the key aspects of perioperative care include the integration of nutrition into the overall management of the patient, avoidance of long periods of preoperative fasting, re-establishment of oral feeding as early as possible after surgery, the start of nutritional therapy immediately if a nutritional risk becomes apparent, metabolic control e.g. of blood glucose, reduction of factors which exacerbate stress-related catabolism or impaired gastrointestinal function, minimized time on paralytic agents for ventilator management in the postoperative period, and early mobilization to facilitate protein synthesis and muscle function.

Donor gluconate rescues livers from uncontrolled donation after cardiac death

BACKGROUND

Ischemia from organ preservation or donation causes cells and tissues to swell owing to loss of energy-dependent mechanisms of control of cell volume. These volume changes cause substantial preservation injury, because preventing these changes by adding cell impermeants to preservation solutions decreases preservation injury. The objective of this study was to assess if this effect could be realized early in uncontrolled donation after cardiac death (DCD) livers by systemically loading donors with gluconate immediately after death to prevent accelerated swelling injury during the warm ischemia period before liver retrieval.

METHODS

Uncontrolled DCD rat livers were cold-stored in University of Wisconsin solution for 24 hours and reperfused on an isolated perfused liver (IPL) device for 2 hours or transplanted into a rat as an allograft for 7 days. Donors were pretreated with a solution of the impermeant gluconate or a saline control immediately after cardiac death. Livers were retrieved after 30 minutes.

RESULTS

In vivo, gluconate infusion in donors immediately before or after cardiac death prevented DCD-induced increases in total tissue water, decreased vascular resistance, increased oxygen consumption and synthesis of adenosine triphosphate, increased bile production, decreased lactate dehydrogenase release, and decreased histology injury scores after reperfusion on the IPL relative to saline-treated DCD controls. In the transplant model, donor gluconate pretreatment significantly decreased both alanine aminotransferase the first day after transplantation and total bilirubin the seventh day after transplantation.

CONCLUSION

Cell and tissue swelling plays a key role in preservation injury of uncontrolled DCD livers, which can be mitigated by early administration of gluconate solutions to the donor immediately after death.

Perioperative management in liver transplantation for acute liver failure

Acute liver failure occurs abruptly with rapid progression. Traditional medical treatment and simple non-bioartificial liver support system cannot reverse the prognosis of acute liver failure (ALF), and liver transplantation is the only effective treatment. However, donor liver shortage, the need of a life-long immunosuppressive therapy as well as complex postoperative complications make ALF patients facing a variety of challenges in the perioperative period of liver transplantation, which are directly related to the success rate of surgery and the mortality. This article aims to discuss perioperative difficulties and preventive measures in liver transplantation for ALF by exploring how to extend the lives of patients before liver transplantation and how to deal with postoperative complications.

The genotoxic, hepatotoxic, nephrotoxic, haematotoxic and histopathological effects in rats after aluminium chronic intoxication

Aluminium (Al) is used in water purification and is also present in several manufactured foods and medicines. Al is known to induce a broad range of physiological, biochemical and behavioural dysfunctions in laboratory animals and humans. This investigation was carried out to investigate the effects of subchronic exposure to Al (as AlCl3) in rats. Sprague-Dawley rats were randomly separated into two groups. Group 1 rats treated with sodium chloride served as the control, group 2 rats were treated with Al (as AlCl3, 5 mg/kg body weight) intraperitonally for 10 weeks. Animals were killed and blood samples were analyzed for blood serum alkaline phosphatase (ALP), aspartate aminotransferase (AST), alanine aminotransferase (ALT) and lactate dehydrogenase (LDH) enzyme activities and creatinine, urea (U) and uric acid (UA) levels for evaluating hepatotoxicity and nephrotoxicity. Blood parameters including red blood cells (RBCs), haemoglobin (Hb) concentration, haematocrit (Ht), platelets (PLTs) and white blood cells (WBCs) were compared between control and experimental group to assess haematoxicity. In order to determine the genotoxicity, the number of micronucleated hepatocytes (MNHEPs) was counted in isolated hepatocytes. In addition, histological alterations in liver and kidney samples were investigated. After exposure with Al, the enzymatic activities of ALP, AST, ALT and LDH, and the levels of U and UA significantly increased. RBC, WBC, PLT, Hb and Ht revealed significant decreases in experimental group compared to the control. AlCl3 caused a significant increase in MNHEPs. Furthermore, severe pathological damages were established in both liver and kidney samples. Subchronic exposure to low doses of Al can produce serious dysfunctions in rat blood, liver and kidney, and exposure to this metal can result in greater damages.

Propolis prevents aluminium-induced genetic and hepatic damages in rat liver

Aluminium is present in several manufactured foods and medicines and is also used in water purification. Therefore, the present experiment was undertaken to determine the effectiveness of propolis in modulating the aluminium chloride (AlCl(3)) induced genotoxicity and hepatotoxicity in liver of rats. Animals were assigned to 1 of 4 groups: control; 34 mg AlCl(3)/kg bw; 50mg propolis/kg bw; AlCl(3) (34 mg/kg bw) plus propolis (50mg/kg bw), respectively. Rats were orally administered their respective doses daily for 30 days. At the end of the experiment, rats were anesthetized and hepatocytes (HEP) were isolated for counting the number of micronucleated hepatocytes (MNHEPs). In addition, the levels of serum enzymes and histological alterations in liver were investigated. AlCl(3) caused a significant increase in MNHEPs, alkaline phosphatase, transaminases (AST and ALT) and lactate dehydrogenase (LDH). Furthermore, severe pathological damages such as: sinusoidal dilatation, congestion of central vein, lipid accumulation and lymphocyte infiltration were established in liver. On the contrary, treatment with propolis alone did not cause any adverse effect on above parameters. Moreover, simultaneous treatments with propolis significantly modulated the toxic effects of AlCl(3). It can be concluded that propolis has beneficial influences and could be able to antagonize AlCl(3) toxicity.

The use of preoperative nutritional interventions to protect against hepatic ischemia-reperfusion injury

Preoperative fasting was introduced in the 19th century to reduce the risk of aspiration pneumonia while patients were under general anesthesia. During the last decades, the value of preoperative fasting has been questioned, and more liberal guidelines have been proposed, such as the use of preoperative carbohydrate-rich drinks. Here we review both old and new evidence supporting the view that fasting slightly longer than overnight is beneficial for an entirely different purpose: protection against certain types of stress, such as ischemia-reperfusion injury. We provide a framework to explain these benefits as well as future applications and alternatives that could be used to induce the protection afforded by nutritional interventions.

Intrahepatic complement activation, sinusoidal endothelial injury, and lactic acidosis are associated with initial poor function of the liver after transplantation

BACKGROUND

Changes in glucose metabolism in the liver during transplantation have been recently described using microdialysis. Here, these findings are correlated with histopathologic, immunohistochemical, and ultrastructural changes in liver.

METHODS

Microdialysis catheters were inserted into 15 human livers, which were perfused with isotonic solution, and samples of perfusate were analyzed before harvest, after storage, and after reperfusion. At each stage Menghini needle biopsy samples were taken and each studied using light and electron microscopy.

RESULTS

Six livers showed serum biochemical evidence of initial poor function. These livers had significantly more staining for complement fragment 4d (C4d) of both lobular and periportal hepatocytes. C4d-positive hepatocytes were also found in the liver during cold storage (3 of 15). These periportal hepatocytes also showed evidence of necrosis and were found to have intracellular neutrophils. Hepatocyte rounding in zone III, necrosis, and C4d staining in recipient were also significantly correlated with the degree of lactic acidosis during this phase. Intrahepatic lactic acidosis at all time points was significantly associated with sinusoidal endothelial cell injury after reperfusion. There were no correlations between glucose, pyruvate, and glycerol levels and histopathologic changes in the liver.

DISCUSSION

In the patients studied, the degree of C4d staining correlated with initial poor function and was associated with intrahepatic lactic acidosis in the donor during cold storage and after reperfusion. Complement activity in the liver during cold storage may be after in situ activation. Intrahepatic lactic acidosis is associated with sinusoidal endothelial cell and hepatocyte injury. The role of intrahepatic neutrophils is uncertain and could possibly be in response to cell necrosis.

ESPEN Guidelines on Enteral Nutrition: Surgery including organ transplantation

Enhanced recovery of patients after surgery ("ERAS") has become an important focus of perioperative management. From a metabolic and nutritional point of view, the key aspects of perioperative care include: Enteral nutrition (EN) by means of oral nutritional supplements (ONS) and if necessary tube feeding (TF) offers the possibility of increasing or ensuring nutrient intake in cases where food intake is inadequate. These guidelines are intended to give evidence-based recommendations for the use of ONS and TF in surgical patients. They were developed by an interdisciplinary expert group in accordance with officially accepted standards and are based on all relevant publications since 1980. The guideline was discussed and accepted in a consensus conference. EN is indicated even in patients without obvious undernutrition, if it is anticipated that the patient will be unable to eat for more than 7 days perioperatively. It is also indicated in patients who cannot maintain oral intake above 60% of recommended intake for more than 10 days. In these situations nutritional support should be initiated without delay. Delay of surgery for preoperative EN is recommended for patients at severe nutritional risk, defined by the presence of at least one of the following criteria: weight loss >10-15% within 6 months, BMI<18.5 kg/m(2), Subjective Global Assessment Grade C, serum albumin <30 g/l (with no evidence of hepatic or renal dysfunction). Altogether, it is strongly recommended not to wait until severe undernutrition has developed, but to start EN therapy early, as soon as a nutritional risk becomes apparent.

The nutritional status modulates preservation-reperfusion injury in rat fatty liver

BACKGROUND

Microcirculation disturbances are essential factors of preservation injury in fatty liver. However, hepatocyte injury is also markedly excessive in fatty liver resulting, at least in part, from energy metabolism impairment and oxidative stress. Thus, this study aimed to determine whether nutritional status influences preservation injury in fatty liver and whether energetic substrate supplementation, alone or with a vasodilator, is protective.

MATERIALS AND METHODS

Normal or fatty livers induced by a choline-deficient diet were isolated from fed and fasted rats, preserved in University of Wisconsin solution at 4 degrees C for 18 h, and then reperfused with Krebs-Henseleit solution at 37 degrees C for 120 min. Fasted rats with fatty liver were also treated as follows: (1) Glucose supplementation: rats had access to a glucose solution for 18 h prior procurement; (2) Prostaglandin (PG): alprostadil was continuously infused during reperfusion; (3) Combined treatment: Glucose supplementation + PG.

RESULTS

Fasting-induced liver injury was significantly greater in fatty than normal liver. In fatty livers from fasted rats, all treatments reduced the alanine aminotransaminase release. Hepatic oxygen consumption improved in the glucose and glucose + PG groups, while PG infusion had no effect. Glucose supplementation did not affect portal pressure, which, in contrast, was reduced in livers receiving PG. Finally, all treatments lowered oxidative injury.

CONCLUSIONS

Preservation injury in fatty liver is greatly related to nutritional status. Energetic substrate supplementation may represent a clinically feasible protective strategy and a multistep approach adding vasodilators could offer further benefit by acting on different pathogenetic mechanisms.

Natural resistance to liver cold ischemia-reperfusion injury associated with the hibernation phenotype

The success of liver grafts is currently limited by the length of time organs are cold preserved before transplant. Novel insights to improve viability of cold-stored organs may emerge from studies with animals that naturally experience low body temperatures (T(b)) for extended periods. In this study, we tested whether livers from hibernating ground squirrels tolerate cold ischemia-warm reperfusion (cold I/R) for longer times and with better quality than livers from rats or summer squirrels. Hibernators were used when torpid (T(b) < 10 degrees C) or aroused (T(b) = 37 degrees C). Livers were stored at 4 degrees C in University of Wisconsin solution for 0-72 h and then reperfused with 37 degrees C buffer in vitro. Lactate dehydrogenase (LDH) release after 60 min was increased 37-fold in rat livers after 72 h cold I/R but only 10-fold in summer livers and approximately three- to sixfold in torpid and aroused hibernator livers, despite twofold higher total LDH content in livers from hibernators compared with rats or summer squirrels. Reperfusion for up to 240 min had the least effect on LDH release in livers from hibernators and the greatest effect in rats. Compared with rats or summer squirrels, livers from hibernators after 72 h cold I/R showed better maintenance of mitochondrial respiration, bile production, and sinusoidal lining cell viability, as well as lower vascular resistance and Kupffer cell phagocytosis. These results demonstrate that the hibernation phenotype in ground squirrels confers superior resistance to liver cold I/R injury compared with rats and summer squirrels. Because hibernation-induced protection is not dependent on animals being in the torpid state, the mechanisms responsible for this effect may provide new strategies for liver preservation in humans.

Pattern of ischemia reperfusion injury in a mouse orthotopic liver transplant model

BACKGROUND

The molecular pathways of ischemic injury after liver transplantation are complex and difficult to dissect because of the presence of many variables. Transgenic and genetically deficient strains of mice provide ideal models for the study of the contribution of a single gene product in biological processes in vivo. Although well described in rats, prolonged preservation has not been studied in a mouse model of orthotopic liver transplantation (mOLT). The aim of this study was to establish a model of cold ischemia and reperfusion injury in mOLT and describe the pattern of the regenerative response to various lengths of cold storage.

MATERIALS AND METHODS

mOLT was performed using a syngeneic combination. Grafts were preserved at 4 degrees C in University of Wisconsin (Viaspan) solution for increasing periods of cold preservation. After cold storage, the liver grafts were transplanted and recipient survival was monitored. Hepatocellular injury was determined by histology, and the regenerative response was quantitated by interleukin 6 upregulation and DNA replication.

RESULTS

Long-term survival was 100%, 100%, 88%, and 0% for cold preservation of 1, 4, 8, and 16 h, respectively. Grafts with short preservation times (1 and 4 h) demonstrated limited injury and a weak regenerative response, with slight IL-6 early upregulation and minimal cell division. Eight hours of cold ischemia resulted in prominent injury and an intense regenerative response accompanied by significant IL-6 upregulation and DNA synthesis. Sixteen hours of storage resulted in all recipients succumbing to liver failure, with histology showing extensive hepatic necrosis.

CONCLUSIONS

This study demonstrated the feasibility of using the mOLT model for the study of molecular mechanisms associated with recovery from cold ischemia and reperfusion injury. Increasing lengths of cold ischemia correlate with progressive tissue damage whereas recovery is associated with a regenerative response that correlates with the severity of injury.

Insulin in University of Wisconsin solution exacerbates the ischemic injury and decreases the graft survival rate in rat liver transplantation

BACKGROUND

Insulin keeps the liver in a metabolically vigorous state. However, organ preservation aims to decrease the metabolic rate. The objective of this study was to clarify the effect of insulin used in University of Wisconsin (UW) preservation solution on the liver graft.

METHODS

The liver grafts were preserved by UW solution with or without insulin for 7, 9, and 24 hr, respectively. The influence of insulin was studied by 7-day survival rate, liver function, morphology, and intragraft gene expression 24 hr after transplantation. Morphology was studied on the preserved grafts.

RESULTS

The morphology of the graft in the insulin group showed more severe ischemia-reperfusion injury. The 7-day graft survival rates of the 7-hr subgroups with and without insulin were 55% and 93%, respectively (P=0.02). In the 9-hr subgroups, the survival rates were 0% and 78%, respectively (P=0.002). The serum levels of aspartate aminotransferase (AST) (P=0.008) and alanine aminotransferase (ALT) (P=0.032) were higher in the 7-hr subgroup with insulin. The same trend was found in the 9-hr subgroups (AST, P=0.016; ALT, P=0.016). The expression level of 215 genes were much lower at 24 hr after transplantation in the grafts preserved with insulin than in those preserved without insulin, and most of the genes were related to metabolic activities.

CONCLUSIONS

Insulin in UW solution may exacerbate graft ischemic injury and decrease the graft survival rate in rat liver transplantation. Insulin, in the absence of glucose in UW solution, may exhaust the metabolic activity of the liver graft. It is harmful rather than helpful for isolated rat liver grafts preserved in UW solution.

Repeated fasting stress causes activation of mitogen-activated protein kinases (ERK/JNK) in rat liver

Mitogen-activated protein kinases (MAPK)-signaling pathways play key roles in cytoplasmic-nuclear signal transmission in response to various extracellular stimuli. In this study, we investigated the effect of repeated fasting stress on activation of the 3 members of the MAPK family, the extracellular signal-regulated kinase (ERK), the c-Jun NH(2)-terminal kinase (JNK), and the p38 mitogen-activated protein kinase (p38 kinase), in rat liver. Immunecomplex kinase assays showed that ERK and JNK were significantly activated in the liver extract from fasted rats whereas p38 kinase showed no activation. In an immunohistochemical study, the phosphorylated and activated form of ERK (p-ERK) was abundantly expressed in pericentral hepatocytes of fasted liver compared with those of the control. On the other hand, the phosphorylated and activated form of JNK (p-JNK) was highly expressed in irregular-shaped cells along the sinusoidal lining of fasted liver. A double immunofluorescent study to identify p-JNK immunoreactive cells revealed them to be Kupffer cells, which are the resident hepatic macrophages. In conclusion, ERK and JNK are selectively activated in distinct cell types of rat liver by repeated fasting stress.

Activated Kupffer cells cause a hypermetabolic state after gentle in situ manipulation of liver in rats

Harvesting trauma to the graft dramatically decreases survival after liver transplantation. Since activated Kupffer cells play a role in primary nonfunction, the purpose of this study was to test the hypothesis that organ manipulation activates Kupffer cells. To mimic what occurs with donor hepatectomy, livers from Sprague-Dawley rats underwent dissection with or without gentle organ manipulation in a standardized manner in situ. Perfused livers exhibited normal values for O(2) uptake (105 +/- 5 micromol. g(-1). h(-1)) measured polarigraphically; however, 2 h after organ manipulation, values increased significantly to 160 +/- 8 micromol. g(-1). h(-1) and binding of pimonidazole, a hypoxia marker, increased about threefold (P < 0.05). Moreover, Kupffer cells from manipulated livers produced three- to fourfold more tumor necrosis factor-alpha and PGE(2), whereas intracellular calcium concentration increased twofold after lipopolysaccharide compared with unmanipulated controls (P < 0.05). Gadolinium chloride and glycine prevented both activation of Kupffer cells and effects of organ manipulation. Furthermore, indomethacin given 1 h before manipulation prevented the hypermetabolic state, hypoxia, depletion of glycogen, and release of PGE(2) from Kupffer cells. These data indicate that gentle organ manipulation during surgery activates Kupffer cells, leading to metabolic changes dependent on PGE(2) from Kupffer cells, which most likely impairs liver function. Thus modulation of Kupffer cell function before organ harvest could be beneficial in human liver transplantation and surgery.

Role of hepatocytes and bile duct cells in preservation-reperfusion injury of liver grafts

In liver transplantation, it is currently hypothesized that nonparenchymal cell damage and/or activation is the major cause of preservation-related graft injury. Because parenchymal cells (hepatocytes) appear morphologically well preserved even after extended cold preservation, their injury after warm reperfusion is ascribed to the consequences of nonparenchymal cell damage and/or activation. However, accumulating evidence over the past decade indicated that the current hypothesis cannot fully explain preservation-related liver graft injury. We review data obtained in animal and human liver transplantation and isolated perfused animal livers, as well as isolated cell models to highlight growing evidence of the importance of hepatocyte disturbances in the pathogenesis of normal and fatty graft injury. Particular attention is given to preservation time-dependent decreases in high-energy adenine nucleotide levels in liver cells, a circumstance that (1) sensitizes hepatocytes to various stimuli and insults, (2) correlates well with graft function after liver transplantation, and (3) may also underlie the preservation time-dependent increase in endothelial cell damage. We also review damage to bile duct cells, which is increasingly being recognized as important in the long-lasting phase of reperfusion injury. The role of hydrophobic bile salts in that context is particularly assessed. Finally, a number of avenues aimed at preserving hepatocyte and bile duct cell integrity are discussed in the context of liver transplantation therapy as a complement to reducing nonparenchymal cell damage and/or activation.

Picroliv preconditioning protects the rat liver against ischemia-reperfusion injury

Cell death following ischemia-reperfusion injury is a major concern in clinical issues such as organ transplantation and trauma. The need to identify agents with a potential for preventing such damage has assumed great importance. We have evaluated the efficacy of picroliv, a potent antioxidant derived from the plant Picrorhiza kurrooa, in protecting against hepatic ischemia-reperfusion injury in vivo. Picroliv was fed to male Sprague Dawley rats in a dose of 12 mg/kg once daily by oral gavage for 7 days prior to hepatic ischemia. Ischemia was induced by occluding the hepatic pedicel with a microaneurysm clip for 30 min and reperfusion was allowed thereafter for varying period (15-120 min) by releasing the microaneurysm clip. Picroliv pretreatment resulted in better hepatocyte glycogen preservation and reduced apoptosis. Reduction in apoptosis was associated with decreased mRNA expression of caspase-3 and Fas. Oxidant induced cellular damage as measured by tissue malondialdehyde (MDA) levels was significantly less following picroliv pretreatment. Both a reduction in neutrophil infiltration and an increased level of intracellular antioxidant enzyme superoxide dismutase possibly contributed to the reduction in tissue lipid peroxidation. Tissue inflammatory cytokines level of interleukin-1alpha (IL-1alpha) and interleukin-1beta (IL-1beta) was also lower in picroliv group. Furthermore, picroliv pretreatment resulted in enhanced proliferating cell nuclear antigen (PCNA) immunoreactivity. These studies strongly suggest picroliv to be a promising agent for ameliorating injury following ischemia-reperfusion.

Phospholipid metabolism of hypothermically stored rat hepatocytes

Isolated rat hepatocytes were suspended and stored in either Liebovitz-15 medium (37 degrees C or 4 degrees C) or University of Wisconsin (UW) solution (4 degrees C) containing [(3)H] arachidonic acid (AA). At varying times, membrane phospholipids were separated by thin layer chromatography. AA labeled phospholipids similarly at both 4 degrees C and 37 degrees C. Analysis of the ratios of [(3)H] AA and [(14)C] glycerol incorporated into phosphatidic acid or other phospholipids in dual-labeled cells indicated that the deacylation/reacylation cycle was the major route of AA incorporation at hypothermia. This was supported by showing that blocking phospholipase A(2) (PLA(2)) activity by trifluoperazine suppressed AA incorporation into phospholipids. PLA(2) activity, measured by determining the release of AA, was slow during 48-hour cold storage, but increased significantly when ATP was depleted by inhibition of mitochondria and glycolysis. In the whole rat liver, there was no significant loss of phospholipids during 48-hour storage (total phospholipids [micromol phosphorus/L/mg] : 0.197 +/-. 001 at 0 hours) unless energy blockers were used (0.155 +/-.005 at 48 hours) or glycogen depleted by fasting the rat (0.167 +/-.001 at 48 hours). This study shows that a net PLA(2) stimulated hydrolysis of phospholipids is seen only when ATP is depleted and its generation from anaerobic glycolysis inhibited. Thus, PLA(2) hydrolysis of phospholipids is not a significant cause of liver cell injury during cold storage when livers are obtained in optimal condition. However, conditions affecting the generation of ATP during cold storage could alter PLA(2) leading to membrane damage.

Ischemia-reperfusion injury in rat fatty liver: role of nutritional status

Fatty livers are more sensitive to the deleterious effects of ischemia-reperfusion than normal livers. Nutritional status greatly modulates this injury in normal livers, but its role in the specific setting of fatty liver is unknown. This study aimed to determine the effect of nutritional status on warm ischemia-reperfusion injury in rat fatty livers. Fed and fasted rats with normal or fatty liver induced by a choline deficient diet underwent 1 hour of lobar ischemia and reperfusion. Rat survival was determined for 7 days. Serum transaminases, liver histology and cell ultrastructure were assessed before and after ischemia, and at 30 minutes, 2 hours, 8 hours, and 24 hours after reperfusion. Survival was also determined in fatty fasted rats supplemented with glucose before surgery. The preischemic hepatic glycogen was measured in all groups. Whereas survival was similar in fasted and fed rats with normal liver (90% vs. 100%), fasting dramatically reduced survival in rats with fatty liver (14% vs. 64%, P <.01). Accordingly, fasting and fatty degeneration had a synergistic effect in exacerbating liver injury. Mitochondrial damage was a predominant feature of ultrastructural hepatocyte injury in fasted fatty livers. Glucose supplementation partially prevented the fasting-induced depletion of glycogen and improved the 7-day rat survival to 45%. These data indicate that rat fatty livers exposed to normothermic ischemia-reperfusion injury are much more sensitive to fasting than histologically normal livers. Because glucose supplementation improves both the hepatic glycogen stores and the rat survival, a nutritional repletion procedure may be part of a treatment strategy aimed to prevent ischemia-reperfusion injury in fatty livers.

Hypothermic oscillating liver perfusion stimulates ATP synthesis prior to transplantation

BACKGROUND

ATP and glycogen depletion often have been demonstrated during cold storage of the liver prior to transplantation. Suppression of events that lead to metabolic depression and to lipid peroxidation could contribute to improvement of liver preservation. A new method of liver preservation for transplantation is therefore suggested, an oscillating oxygenated hypothermic liver perfusion.

METHODS

Biochemical analysis of liver tissue samples and perfusate after 10 h of perfusion by the presented oscillating perfusion model were compared with results after continuous liver perfusion for 10 h as well as with data derived from cold-stored livers over a period of 10 h. Particular reference was made to nucleotide metabolites, glycogen content, lipid peroxidation, glutathione content, glycolytic metabolites, and enzyme release before and after preservation.

RESULTS

Glycogen depletion occurred to the same degree in hypothermic storage and machine perfusion (oscillating as well as continuous perfusion), but the energy charge was significantly increased after oxygenated perfusion, whereas cold storage resulted in a significant energy charge depletion. In addition, perfusion by an oscillating technique yielded superior energy charge loading compared to the continuous perfusion technique and diminished the other hand lipid peroxidation.

CONCLUSIONS

Hypothermic oscillating oxygenated perfusion could be important for the improvement of the quality of energy-depleted organs prior to transplantation.

Rat liver preservation by hypothermic oscillating liver perfusion compared to simple cold storage

Rat livers were preserved hypothermically for 10 or 24 h in vitro as if for transplantation. Two methods of preservation were compared using physiological and biochemical parameters: simple storage and oscillating perfusion. By measuring the nucleotides after preservation the calculated energy charge was significantly higher after 10 and 24 h of oscillating perfusion compared to the simple storage group. In addition, a significant energy charge loading was demonstrated by 10 h oscillating perfusion compared to the initial value prior to perfusion. The oscillating, computer-controlled perfusion permits continuous monitoring of perfusate temperature, O2 consumption, pCO2, portal vein pressure, and pH and also automatic sample collection and pH compensation. In addition, the perfusate can be easily exchanged by using two different pumps or be rewarmed by a heat exchanger. For measuring of short-lived metabolites (interleukins, oxygen radicals, prostaglandins) sampling can be performed directly out of the vena cava outflow. pH and temperature stability was maintained by a data acquisition and controlling system. Because of a special designed liver chamber a combination of storage and perfusion with or without substrates was possible. The demonstrated standardized perfusion technique was achieved by a combination of special equipment and computer-aided monitoring and allows further experiments to improve understanding of ischemic and reperfusion injury.

The protective effects of L-arginine after liver ischaemia/reperfusion injury in a pig model

Hepatic ischaemia/reperfusion is characterized by circulatory and metabolic derangement, liver dysfunction, and tissue damage. To evaluate the role of L-arginine, a substrate of nitric oxide, in ischaemia/reperfusion injury, total liver ischaemia was induced for 120 min in 22 Landrace x Large White female pigs, which were randomly assigned to a treatment group (10 animals) or a control group (12 animals). An L-arginine bolus (540 mg/kg i.v.) was administered to the treatment group 1 h before clamping the hepatic hilum, at clamping, at reperfusion, and at 1 and 2 h after reperfusion. The control animals received normal saline and an i.v. infusion. Liver function tests and analysis of serum, erythrocyte, and tissue malondialdehyde contents were performed at commencement of laparotomy, before reperfusion, and at 30 min and 7 days after reperfusion. Liver biopsies were taken at laparotomy, at 30 min, and at 7 days after reperfusion for histological and ultrastructural examination. Assessment of apoptosis included in situ end-labelling analysis and DNA gel electrophoresis. Survival at 7 days was better in the treated animals than in the controls (9/10 vs. 7/12). Tissue malondialdehyde content, aspartate aminotransferase, and lactate dehydrogenase levels were lower in the treatment group, in which morphological changes were significantly less evident than in the controls 30 min after reperfusion. At 7 days, differences between the groups with respect to cell integrity were apparent only on ultrastructural analysis. Glycogen content, 7 days after reperfusion, was higher in the treatment group than in the controls: 70.25 per cent vs. 21.66 per cent positive hepatocytes (score 3 vs. score 1). Multiparametric analysis showed fewer apoptotic cells in the treatment group at all times. Our data show that the administration of L-arginine reduces damage to liver tissue after ischaemia/reperfusion injury in a pig model. This may be explained not only by the known vasodilator, anti-aggregation, and superoxide inactivation effects of increased nitric oxide release, but possibly also by some other action of L-arginine, such as its influence on cellular metabolism.

Liver glycogen in fasted rat livers does not improve outcome of liver transplantation

Controversy exists over how the nutritional condition of the donor liver affects transplant outcome. Some studies suggest that livers from fasted animals (liver glycogen-depleted) are more readily injured than livers from fed animals. Our previous study suggested the opposite, i.e., livers from donors fasted for 4 days were significantly more viable on orthotopic liver transplantation. Fasting may decrease the sensitivity of the liver to an inflammatory response or block Kupffer cell activation following transplantation. Thus, long-term fasting may be beneficial for reasons unrelated to liver glycogen content. In this study we attempted to separate out the roles of fasting and liver glycogen in liver transplant outcome by fasting donors for 2 days and then feeding them only glucose to elevate liver glycogen. Rats (Brown Norway) were fed (standard diet), fasted (4 days), or fasted 2 days and then fed glucose (in water) for 2 days. Livers were preserved for either 30 or 44 h in UW solution and transplanted. Four-day fasting of the donor improved the survival rate in liver transplantation (50%-100% in 30-h cold storage, 29%-83% in 44-h cold storage). However, feeding glucose for 2 days to fasted animals caused a decrease in survival in this series of transplants (40% in 30-h cold storage, 0% in 44-h cold storage). In the glucose-fed group, liver glycogen was 240% of that in the control group. This suggests that the presence of a high concentration of liver glycogen is not beneficial to the preserved and transplanted rat liver.