Reversal of experimental posthepatectomy liver failure in pigs: a new application of hepatocyte bioreactors.

Postoperative liver failure remains a major cause of morbidity and mortality after extensive hepatectomies. This study aims to evaluate the effectiveness of a hepatocyte bioreactor in the treatment of experimental post-hepatectomy liver failure. Our experimental model included a combination of a side-to-side portacaval shunt, occlusion of the hepatoduodenal ligament for 150 min, 70% hepatectomy, and reperfusion. Following the development of liver failure, 12 pigs were randomized into a control group (n = 6) and a treatment group (n = 6). Both groups underwent extracorporeal perfusion through a plasma separation device, a membrane oxygenator, and two parallel bioreactors. In the latter group, the bioreactors were loaded with 10 billion fresh hepatocytes, isolated from a donor pig. Following hepatocyte treatment, all animals were maintained for 24 h under mechanical ventilation, with intravenous fluid and glucose supplementation. Hemodynamic parameters, intracranial pressure, and biochemical parameters were measured. Liver biopsies were obtained during the 24-h autopsy. The extracorporeal circuit was well-tolerated hemodynamically. Treated animals had lower intracranial pressure compared with controls (at 24 h, 15 ± 3.1 vs. 22 ± 3.5 mm Hg, P = 0.006). Plasma ammonia in treated animals was lower compared with controls at 12 h (100 ± 29 vs. 244 ± 131 µmol, P = 0.026). Liver histological study showed decreased necrosis and increased regeneration activity in treated animals compared with controls. Treatment through an extracorporeal hepatocyte bioreactor attenuates brain edema and improves histological and functional parameters of the liver remnant of pigs with posthepatectomy liver failure.

Intestinal preconditioning ameliorates ischemia-reperfusion induced acute lung injury in rats: an experimental study.

BACKGROUND: Phospholipases A(2) (PLA(2)) have been implicated in the pathogenesis of acute respiratory distress syndrome (ARDS) induced by intestinal ischemia-reperfusion (IIR). Intestinal ischemic preconditioning (IIP) has been shown to improve intestinal tolerance to subsequent sustained ischemia and limit the systemic inflammatory response. We tested the effect of IIP on the intestinal ischemia-reperfusion-induced ARDS, with particular focus on PLA(2). METHODS: Rats were randomized into three groups: (1) sham surgery group (sGroup), 45 min sham intestinal ischemia-4 h reperfusion, (2) IIR group (IIRGroup), 45 min intestinal ischemia-4 h reperfusion, (3) IIP group (ipGroup), three cycles of intestinal ischemia for 4 min and reperfusion for 10 min followed by 45 min intestinal ischemia-4 h reperfusion. At the end of each experiment, blood gases were obtained and bronchoalveolar lavage (BAL) followed. Biochemical (total protein, PLA(2), PAF-AcH) and cytological parameters of the BAL fluid were quantified. Plasma MDA was measured as an indicator of systemic oxidative stress. Comparisons between groups were made using one-way ANOVA followed by post hoc comparison with a Tukey test or Mann-Whitney test when appropriate. Differences were considered significant if P < 0.05. RESULTS: Alveolar-arterial O(2) gradient values and wet to dry lung ratio were significantly (P < 0.05) increased in the IIRGroup and this increase was prevented in the ipGroup. Following the same pattern, BAL total protein, PLA(2), and PAF-AcH were significantly lower in the ipGroup. Ischemic preconditioning significantly abolished neutrophil count in BAL fluid. Plasma MDA was significantly lower in the ipGroup. Despite a significant tissue polymorphonuclear reduction, no significant lung or intestinal histologic damage score changes were revealed. CONCLUSIONS: Intestinal preconditioning protects IIR-induced lung injury, partly by modulating the arachidonic acid cascade.

Acute lung injury in a rat model of intestinal ischemia-reperfusion: the potential time depended role of phospholipases A(2).

BACKGROUND: A pivotal role of phospholipase A(2) (PLA(2)) and platelet-activating factor-acetylhydrolase (PAF-AcH) as enzymes involved in lung inflammation has recently been suggested. The objective of this study was to elucidate the role and the time dependence of PLA(2) and PAF-AcH fluctuations in the lung relative to the evolution of intestinal ischemia-reperfusion (IIR). MATERIALS AND METHODS: Rats were randomly allocated to five groups of IIR induced by occlusion of the superior mesenteric artery for 45 min followed by 1 min, 2, 4, and 8 h of reperfusion (expGroups) and five corresponding sham groups (sGroups). Bronchoalveolar lavage fluid was obtained from the right lung and its biochemical (protein, PLA(2), PAF-AcH) and cytological characteristics were determined. Plasma malonyldialdehyde was measured as a marker of lipid peroxidation. The 4 and 8 h reperfusion expGroups had significantly (P < 0.05) elevated alveolar-arterial O(2) gradient values compared with the corresponding controls. Total protein, PLA(2) and PAF-AcH levels significantly (P < 0.05) increased in expGroups compared with the corresponding shams after 4 h of reperfusion. Total bronchoalveolar lavage fluid cells and plasma malonyldialdehyde were significantly (P < 0.05) elevated in expGroups compared with the sGroups after 2 h of reperfusion. CONCLUSIONS: PLA(2) could act synergistically or parallel with the reactive oxygen species produced during IIR, resulting in the induction or even in the exacerbation of the inflammatory reaction in acute respiratory distress syndrome. PAF-AcH could play an anti-inflammatory role by reducing the concentration of PAF.

Norepinephrine in small-for-size liver grafts: an experimental study in pigs.

BACKGROUND: Norepinephrine plasma levels may play a role in small-for-size grafts dysfunction at the early posttransplant period. MATERIALS AND METHODS: The 18 pigs used as recipients were assigned to group 1 (n = 6), group 2 (n = 6), and group 3 (n = 6) and given grafts with graft-to-recipient volume ratios of 1:1, 2:3, and 1:3, respectively. Blood serum norepinephrine was measured by high-performance liquid chromatography with electrochemical detection at the following time points: pre-anhepatic period (baseline); anhepatic period; and 30, 60, 180, and 360 min after reperfusion. Graft arterial and portal vein flows were obtained 30, 60, 180, and 360 min after reperfusion by the aid of an ultrasonic flowmeter. Aspartate transferase (AST) and international normalized ratio (INR) were measured before the procedure (baseline), and at 180 and 360 min after reperfusion. RESULTS: Anhepatic phase was characterized by a significant increase (6- to 8-fold) of norepinephrine in all groups (P < 0.05). In groups 1 and 2 plasma norepinephrine returned to normal values 30 min after reperfusion. In group 3, plasma norepinephrine remained significantly increased at every time point of the study compared to groups 1 and 2 (P < 0.001). Hepatic artery and portal vein flows in group 3 were significantly (P < 0.05) reduced and increased, respectively, compared to groups 1 and 2 at all times measured. Liver function tests (AST and INR) 360 min after reperfusion were significantly higher in group 3 compared to groups 1 and 2. CONCLUSIONS: Norepinephrine levels are increased in very small-for-size grafts and this increase may be associated with early graft dysfunction.

Effects of mannitol in the prevention of lipid peroxidation during liver resection with hepatic vascular exclusion.

STUDY OBJECTIVE: To examine the efficacy of mannitol in the prevention of lipid peroxidation during major liver resections performed during hepatic inflow occlusion. DESIGN: Prospective, randomized, open-label study. SETTING: Aretaieion Hospital, a university-affiliated hospital. PATIENTS: 30 ASA physical status II and III patients, less than 75 years of age, scheduled for elective liver resection. INTERVENTIONS: All patients received combined general and epidural anesthesia. Laparotomy was performed through a bilateral subcostal incision, and hepatectomy was performed by inflow vascular exclusion (Pringle's maneuver). Before this maneuver, and if the patients were hemodynamically stable, they were randomized to receive either mannitol 20% 1.5 mL kg(-1) (group M) or normal saline 1.5 mL kg(-1) (group S) intravenously for 30 minutes. MEASUREMENTS: Venous blood malondialdehyde (MDA) concentration, as an index of lipid peroxidation, was measured spectrophotometrically at selected time points. MAIN RESULTS: Patients in both groups presented with raised MDA values (P < 0.05) for the period starting before the release of vascular occlusion until 6 days postoperatively. In patients receiving mannitol, lower MDA values were observed (P < 0.05) compared with group S at the end of operation. CONCLUSION: Mannitol has an antioxidant activity, but we were unable to confirm a positive impact on the postoperative clinical course.