Hepatectomy In Pigs Research Articles

PERCUTANEOUS RADIOFREQUENCY ASSISTED LIVER PARTITION WITH PORTAL VEIN EMBOLIZATION FOR STAGED HEPATECTOMY (PRALPPS).

ABSTRACTBackground: When a major hepatic resection is necessary, sometimes the future liver remnant is not enough to maintain sufficient liver function and patients are more likely to develop liver failure after surgery. Aim: To test the hypothesis that performing a percutaneous radiofrecuency liver partition plus percutaneous portal vein embolization (PRALPPS) for stage hepatectomy in pigs is feasible. Methods: Four pigs (Sus scrofa domesticus) both sexes with weights between 25 to 35 kg underwent percutaneous portal vein embolization with coils of the left portal vein. By contrasted CT, the difference between the liver parenchyma corresponding to the embolized zone and the normal one was identified. Immediately, using the fusion of images between ultrasound and CT as a guide, radiofrequency needles were placed percutaneouslyand then ablated until the liver partition was complete. Finally, hepatectomy was completed with a laparoscopic approach. Results: All animals have survived the procedures, with no reported complications. The successful portal embolization process was confirmed both by portography and CT. In the macroscopic analysis of the pieces, the depth of the ablation was analyzed. The hepatic hilum was respected. On the other hand, the correct position of the embolization material on the left portal vein could be also observed. Conclusion: “Percutaneous radiofrequency assisted liver partition with portal vein embolization” (PRALLPS) is a feasible procedure.

Chronological Profiling of Plasma Native Peptides after Hepatectomy in Pigs: Toward the Discovery of Human Biomarkers for Liver Regeneration.

Liver regeneration after partial hepatectomy (PHx) is a time-dependent process, which is tightly regulated by multiple signaling cascades. Failure of this complex process leads to posthepatectomy liver failure (PHLF), which is associated with a high rate of mortality. Thus, it is extremely important to establish a useful biomarker of liver regeneration to help prevent PHLF. Here, we hypothesized that alterations in the plasma peptide profile may predict liver regeneration following PHx and hence we set up a diagnostic platform for monitoring posthepatectomy outcome. We chronologically analyzed plasma peptidomic profiles of 5 partially hepatectomized microminipigs using the ClinProtTM system, which consists of magnetic beads and MALDI-TOF/TOF MS. We identified endogenous circulating peptides specific to each phase of the postoperative course after PHx in pigs. Notably, peptide fragments of histones were detected immediately after PHx; the presence of these fragments may trigger liver regeneration in the very acute phase after PHx. An N-terminal fragment of hemoglobin subunit α (3627 m/z) was detected as an acute-phase-specific peptide. In the recovery phase, the short N-terminal fragments of albumin (3028, 3042 m/z) were decreased, whereas the long N-terminal fragment of the protein (8926 m/z) was increased. To further validate and extract phase-specific biomarkers using plasma peptidome after PHx, plasma specimens of 4 patients who underwent PHx were analyzed using the same method as we applied to pigs. It revealed that there was also phase-specificity in peptide profiles, one of which was represented by a fragment of complement C4b (2378 m/z). The strategy described herein is highly efficient for the identification and characterization of peptide biomarkers of liver regeneration in a swine PHx model. This strategy is feasible for application to human biomarker studies and will yield clues for understanding liver regeneration in human clinical trials.

The Use of Erythropoietin in Liver Regeneration in Pigs after Partial Hepatectomy

A partial hepatectomy is a surgical procedure performed during the living-donor liver transplantation and sometimes the only option for patients with hepatocarcinoma. However the remnant liver after the hepatectomy is still a major concern. Therefore, the process of liver regeneration has been a constant theme of study in order to optimize this process. Erythropoietin, a hormone produced by the kidney and involved in protecting organs like heart, liver and kidney itself against injuries can be one of these factors that could accelerate the liver regeneration. This study aims to observe if erythropoietin can accelerate the process of liver regeneration after partial hepatectomy in pigs. Methods: 8 pigs were classified into 2 groups of 4 pigs each: the control group and the test group. The animals in the first group underwent an application of saline solution subcutaneous on the day before the hepatectomy. Instead of saline solution, the test groups received a subcutaneous injection of 200 UI/lg of recombinant erythropoietin also on the day before the surgical procedure. After 7 days since the hepatectomy, in each animal the liver was biopsied in two regions, one next to the hepatectomy section and other far from it. The liver regeneration was analyzed using Ki-67. Results: Pigs from control group presented the following results: Control pig I: 30% of regeneration in the hepatectomy section and 10% in the region far from it; control pig II 24% and 4%; control pig III 27% and 7%. The test group presented no significant liver regeneration since Ki-67 could not identify cell proliferation in neither the biopsied areas. Conclusion: Since the number of pigs was not statistically significant, we could not conclude any further hypothesis. We strong believe that enhancing the number of pigs and testing different doses, we will be able to reach further conclusions.

How to successfully resect 70 % of the liver in pigs to model an extended hepatectomy with an insufficient remnant or liver transplantation with a small-for-size graft

An insufficient remnant in extended hepatectomy and small-for-size graft in liver transplantation are critical matters in the field of liver surgery, and reliable and reproducible animal models that can provide clinically relevant and reliable data are needed. We herein describe our detailed surgical procedures for performing 70 % hepatectomy in pigs, and discuss the critical anatomical features, key techniques and pitfalls based on our experience. The porcine liver is divided into four lobes. The right lateral lobe (RLL) accounts for 30 % of the liver volume. Important points, such as selective temporal clamping of the arterial branch, confirmation of a related demarcation line, a two-step process to skeletonize Glisson's capsules during liver resection and selective ligation of the portal venous branch to the right medial lobe without inducing any subtle injuries to Glisson's capsules from the RLL to common bile duct, are discussed.

Laparoscopic left hepatectomy in swine: a safe and feasible technique.

A purely laparoscopic four-port approach was created for left hepatectomy in pigs. A polyethylene loop was placed on the left two hepatic lobes for traction and lift. Next, penetrating ligation of the lobes using of a double row of silk sutures was performed to control bleeding. A direct hepatic transection was completed using a monopolar hook electrode without meticulous dissection of the left hepatic vein. The raw surface of the liver was coagulated and sealed with fibrin glue. Lobes were retrieved through an enlarged portal. Laparoscopic hepatic lobectomy was completed in all pigs without the use of specialized instruments and with a mean operative time of 179 ± 9 min. No significant perioperative complications were observed. The average weight of each resected lobe was 180 ± 51 g. Complete blood count as well as serum organics and enzyme levels normalized after about 2 weeks. During necropsy, adhesion of the hepatic raw surface to the gastric wall and omentum were observed. No other abnormalities were identified. This minimally invasive left hepatectomy technique in swine could serve as a useful model for investigating liver diseases and regeneration, and offer preclinical information to improve hepatobiliary surgical procedures.

Platelets prevent acute liver damage after extended hepatectomy in pigs

Platelets develop tissue repair and promote liver regeneration. We investigated whether platelets prevented acute liver damage after extended hepatectomy in pigs. Thrombocytosis was induced by the following two methods; afterwards 80% hepatectomy was performed in pigs. In the first method, the pigs received administration of thrombopoietin [TPO (+) group], and they were compared with a control group [TPO (-) group]. In the second method, the pigs received a splenectomy [Sp (+) group], and theywere compared with another control group [Sp (-) group]. Platelet counts, biochemical examination of blood, and histopathological findings of the residual liver were examined. Serum aspartate transaminase (AST), alanine transaminase (ALT), alkaline phosphatase (ALP), and total bilirubin (T-Bil) levels were significantly decreased in the thrombocytotic groups compared with the control groups in the early period after hepatectomy. In the histopathological findings, hemorrhagic necrosis with a bile plug was observed in the control groups, but this phenomenon was not observed in the thrombocytotic groups. On transmission electron microscopy, the sinusoidal endothelial lining was destroyed and detached into the sinusoidal space with enlargement of Disse's spaces in the thrombocytotic groups, but these findings were not observed in the control groups. An increased number of platelets prevents acute liver damage after extended hepatectomy.

Effect of the Portacaval Shunt on Reperfusion Injury after 65% Hepatectomy in Pigs

Background: Portal flow diversion by portacaval shunts (PCS) has been shown to prevent primary graft nonfunction in liver transplantation using small-for-size grafts. In this study, we examine whether PCS can improve reperfusion injury after major hepatectomy in pigs. Materials and Methods: In 14 pigs, a partial PCS was constructed following 65% hepatectomy and 1 h of inflow ischemia. During 24 h of reperfusion, the shunt was either closed (group A, n = 7) or left open (group B, n = 7). Results: 24 h after reperfusion, group A had higher levels of alanine aminotransferase (70 ± 12 IU/l vs. 51 ± 5.9 IU/l; p < 0.05), alanine aminotransferase per gram of liver remnant (0.41 ± 0.07 IU/l/g vs. 0.21 ± 0.05 IU/l/g; p < 0.05), prothrombin time (24.1 ± 2.4 s vs. 14.3 ± 2.9 s; p < 0.05), international normalized ratio (2.11 ± 0.15 vs. 1.29 ± 0.28; p < 0.05), hepatocyte necrosis scores and percentages of nuclei stained for proliferating cell nuclear antigen (52.57 ± 8.9% vs. 36.71 ± 6%; p < 0.05) compared to group B. Conclusions: Partial portal flow diversion appears to attenuate reperfusion injury in a porcine model of major hepatectomy.

A New Surgical Model for Hepatectomy in Pigs

Background: Anhepatic animal models are suitable for simulating acute liver failure. Hepatectomy in pigs includes en bloc resection of the vena cava, and therefore, a temporary extracorporeal bypass and total clamping of the inferior vena cava are needed. These steps cause severe depression of circulation with impaired survival. Methods: Previous to en bloc hepatectomy including retrohepatic vena cava in 20 female pigs, a Y-shaped bypass was implanted starting with end-to-side anastomosis between the vena cava and the portal vein, followed by anastomosis to the intrathoracic vena cava. Results: Blood flow was constant during and after hepatectomy because vessels were only partially clamped. No venous stasis of intestinal organs was observed. Hemodynamic parameters like heart rate, mean arterial pressure, central venous pressure, pulse oximetry and intracranial pressure remained extremely stabile during and after hepatectomy. Postoperative survival time was 100% after 12 h. Maximum survival time was 84.9 h and mean survival time 51.2 ± 18.7 h. All animals died from multiple organ failure. Intracranial pressure remained stable during the surgical procedure and rose continuously until death. The autopsy showed massive brain edema. Conclusions: This new surgical technique is safe and easy to perform and permits total hepatectomy with minimal blood loss under stable circulation without requiring an extracorporeal bypass.

Effect of Portocaval Shunt on Residual Extreme Small Liver after Extended Hepatectomy in Porcine

When residual liver volume is extremely small after extended hepatectomy, postoperative hepatic failure may ensue. The cause of the hepatic failure is likely associated with the portal hypertension after hepatectomy. We investigated the effects of portocaval shunt on portal hypertension in producing sinusoidal microcirculatory injury after extended hepatectomy in pigs. Fourteen pigs were divided into two groups: a group without a shunt, in which extended hepatectomy was carried out (i.e., residual volume was 17% of the whole liver), and a group with a shunt, in which extended hepatectomy was carried out and a portocaval shunt was inserted. The portocaval shunt was placed by side-to-side anastomosis between the portal vein and the inferior vena cava. In the group without a shunt, all pigs died of hepatic failure within postoperative day 3. In the group with a shunt, all pigs were alive for more than 4 days, and 4 pigs survived longer than 7 days. Portal vein pressure after hepatectomy was 15.9 +/- 3.8 mmHg in the group without a shunt and 10.5 +/- 0.6 mmHg in the group with a shunt (P < 0.01). The portal vein flow after 83% hepatectomy in the group without a shunt increased significantly more than at laparotomy and in the group with a shunt (P < 0.01). In the group without a shunt, remarkable destruction of the sinusoidal lining and edema of the portal triad and hydropic change of hepatocytes were observed 1 hour after hepatectomy, but these findings were not observed in the group with a shunt. These results indicate that, after extended hepatectomy, overload of portal flow is one of the most significant risk factors of hepatic failure by sinusoidal microcirculatory injury.

Extra-hepatic factor VIII expression in porcine fulminant hepatic failure

In humans, fulminant hepatic failure (FHF) is frequently associated with increased factor VIII (FVIII) levels, despite widespread liver cell death. The mechanisms leading to increased FVIII levels and cellular sites of this enhanced FVIII production are poorly understood. We studied the effect of total hepatectomy in pigs, a large-animal model of FHF, on the expression of plasma and tissue FVIII during 24-hour follow-up. Tissue FVIII expression was determined before and 24 h after hepatectomy, both at the mRNA level and immunohistochemically. The expression of plasma and tissue von Willebrand factor (VWF), the natural stabilizing carrier protein of FVIII, was also measured. Total hepatectomy elicited a gradual and sustained twofold elevation of circulating FVIII, whereas FVIII mRNA levels in various organs did not increase after hepatectomy. The half-life of FVIII increased from 7.7 to 10.3 h and VWF levels were also elevated in anhepatic pigs. The increase in the half-life of FVIII and increased levels of VWF were not sufficient to explain the rise in plasma FVIII levels. At the protein level, prominent changes in the cellular distribution of FVIII were seen in spleen and kidney. These observations suggest that in this model of FHF the lack of hepatic FVIII synthesis is adequately compensated by other organs, notably spleen and kidneys.

A bioartificial liver support system using primary hepatocytes: a preclinical study in a new porcine hepatectomy model

BackgroundBioartificial liver support systems providing a bridge to transplantation or even a definitive treatment of acute hepatic failure are a current focus of research. Different devices are used, although an impact on patient survival is doubtful for the time being. After developing a new flat membrane bioreactor, further preclinical studies have become necessary. Existing animal models of fulminant hepatic failure show common difficulties in defining a reproducible loss of functional liver tissue while considering systemic side effects. We now present a reproducible model with total hepatectomy in pigs, suitable to test the safety and efficacy of liver support systems. MethodsTwelve pigs underwent total hepatectomy by using silicone tubes and a Y-adapter as vascular prosthesis; intracranial pressure was measured via a subdural probe. Anhepatic pigs were monitored under general anesthesia until death occurred. All were treated with a new flat membrane bioreactor (FMB) that contained porcine hepatocytes in 6 of the 12 cases. ResultsOur hepatectomy technique proved to be successful without requiring venovenous bypass circulation. Mean vascular clamping time was 9 minutes. The mean survival time was longer in animals treated with hepatocyte-equipped bioreactors than in untreated animals (24.8 ± 4.3 vs 16.4 ± 4.7 hours), which already showed increased intracranial pressure after 10 to 12 hours. Serum albumin levels indicated stable cell-specific functions of the FMB. ConclusionsThe described technique of total hepatectomy is a well-reproducible animal model. The presented FMB maintained stable cell-specific functions and is a safe and efficient device.

Decrease in core liver temperature with 10°C by in situ hypothermic perfusion under total hepatic vascular exclusion reduces liver ischemia and reperfusion injury during partial hepatectomy in pigs

Objective We attempted to assess liver ischemia/reperfusion injury under a mild decrease in core liver temperature of 10° C by in situ hypothermic perfusion during ischemia. Methods Liver ischemia was induced in pigs by total hepatic vascular exclusion with concomitant in situ perfusion with hypothermic (4°C) Ringer-glucose (cold perfused group, core liver temperature maintained at 28°C), with normothermic (38°C) Ringer-glucose (warm perfused group) or without in situ perfusion (control group). Results In the cold perfused, warm perfused, and control groups, 24-hour survival was 5/5, 0/5, and 3/5, respectively. Hemodynamic parameters in the cold perfused group remained stable, whereas pigs in both other groups required circulatory support. Plasma AST and interleukin-6 levels were lower in the cold perfused group than in both other groups. Hepatocellular function was best preserved in the cold perfused group as indicated by complete recovery of bile production during reperfusion and no loss of indocyanine green clearance capacity. In both other groups, bile production and indocyanine green clearance capacity were reduced significantly. The hyaluronic acid uptake capacity of pigs in the cold perfused group or control group did not differ, indicating preserved sinusoidal endothelial cell function. Histopathologic injury scores during reperfusion were significantly lower in the cold perfused group when compared to both other groups. Conclusions A mild decrease in core liver temperature of 10°C by in situ hypothermic liver perfusion during ischemia protects the liver from ischemia/reperfusion injury. This protection appears to be related to cooling of the liver rather than to the washout of blood during perfusion.

Blood coagulation in anhepatic pigs: effects of treatment with the AMC-bioartificial liver

The function of a newly devised bioartificial liver (AMC-BAL) based on viable, freshly isolated porcine hepatocytes has been evaluated in anhepatic pigs. The aim of this study was to assess the contribution of BAL treatment on blood coagulation parameters. Pigs were anesthetized and a total hepatectomy was performed (n = 15). The infrahepatic caval vein and the portal vein were connected to the subdiaphragmatic caval vein using a three-way prosthesis. Animals received standard intensive care (control, n= 5), treatment with an empty BAL (device control, n= 5) or with a cell-loaded BAL (BAL-treatment, n= 5) for a period of 24 h starting 24 h after hepatectomy. Coagulation parameters studied concerned prothrombin time (PT), platelet count, the procoagulant system (factors (F)II, FV, FVII, FVIII and fibrinogen), anticoagulant system (AT III), fibrinolytic system (t-PA, PAI-1) as well as markers of coagulation factor activation (TAT complexes, prothrombin fragment F1 + 2). FII, FV, FVII, AT III and fibrinogen rapidly decreased after total hepatectomy in pigs in accordance with the anhepatic state of the animals. FVIII levels were not influenced by the hepatectomy. A mild drop in platelet count was seen in all groups. Treatment of anhepatic pigs with the cell-loaded BAL did not restore PT or clotting factor levels. TAT and F1 + 2 complexes, however, were significantly increased in this group. Levels of t-PA and PAI-1 were not influenced by cell-loaded BAL treatment. Treatment of anhepatic pigs with the AMC-BAL based on freshly isolated porcine hepatocytes does not result in an improved coagulation state due to extensive consumption of clotting factors. However, increased levels of TAT complexes and prothrombin fragments F1 + 2 during treatment of anhepatic pigs indicate synthesis and direct activation of coagulation factors, leading to thrombin generation. This demonstrates that this bioartificial liver is capable of synthesizing coagulation factors.

Decrease in core liver temperature with 10 °C by in situ hypothermic perfusion under total hepatic vascular occlusion reduces liver ischemia and reperfusion injury during partial hepatectomy in pigs.

Decrease in core liver temperature with 10 °C by in situ hypothermic perfusion under total hepatic vascular occlusion reduces liver ischemia and reperfusion injury during partial hepatectomy in pigs.

Decresse in core liver temperature with 10°C by in situ hypothermic perfusion under tetal hepatic vaseular occlusion reduces liver ischemia and reperfusion injury during partial hepatectomy in pigs

Decresse in core liver temperature with 10°C by in situ hypothermic perfusion under tetal hepatic vaseular occlusion reduces liver ischemia and reperfusion injury during partial hepatectomy in pigs

Decresse in core liver temperature with 10°C by in situ hypothermic perfusion under tetal hepatic vaseular occlusion reduces liver ischemia and reperfusion injury during partial hepatectomy in pigs

Decresse in core liver temperature with 10°C by in situ hypothermic perfusion under tetal hepatic vaseular occlusion reduces liver ischemia and reperfusion injury during partial hepatectomy in pigs

Partial hepatectomy and liver regeneration in pigs—The response to different resection sizes

Liver regeneration has been extensively studied in the rat and dog models but pigs have seldom been used. They resemble man closely in their omnivorous diet and their gastroenterological and endocrinological responses. This paper describes techniques of 15, 50, 65, and 70% partial hepatectomy in the pig. Thymidine kinase activity and mitotic index were used as indices of liver regeneration. The timing and events of the regenerative response in the pig compared favorably with other animal models and the maximum regenerative response occurred on the third postoperative day, irrespective of the size of the partial hepatectomy. The 15% partial hepatectomy, which shows a minimal response to resection, provides a suitable “primed” model for the study of stimulatory substances.

Aspects of anaesthetic management of heterologous extracorporeal hepatic support in patients with acute liver failure.

Some anaesthetic aspects of heterologous extracorporeal hepatic support for patients with acute liver failure have been investigated in animals and men. Two types of anaesthesia during hepatectomy in pigs were performed in 20 experiments divided into two groups. A convenient anaesthetic technique was found to be the combined use of neuroleptanalgesics, gamma-OH, small doses of thiopental sodium and nitrous oxide--oxygen mixture. The necessity for care in the procedure of temporary liver support for 'poor-risk' patients is outlined. A minimal use of drugs which are metabolized by the liver, and avoidance of potent analgesics, narcotics, hypotension and hypoxia are the main principles for safe extracorporeal hepatic assistance to critically ill patients.