Ex vivo liver perfusion with arterial blood from a pig with ischemic liver failure

Dynamic metabonomic analysis of BALB/c mice with different outcomes after D-galactosamine/lipopolysaccharide-induced fulminant hepatic failure

Fulminant hepatic failure (FHF) is one of the most challenging gastrointestinal emergencies encountered in clinical practice. Early identification of patients with FHF who need liver transplantation is very important. To construct a prediction model for the early diagnosis and prognosis of FHF, we studied the dynamics of metabolic intermediates and metabolic profiles with a D-galactosamine (GalN)/lipopolysaccharide (LPS)-treated BALB/c mouse model of FHF. Levels of plasma metabolites were quantified with gas chromatography/time-of-flight mass spectrometry, and data were processed with partial least squares discriminant analysis (PLS-DA). Distinct clustering differences were observed 5 and 6 hours after GalN/LPS treatment between mice that survived and those that died, but there were no differences between these groups 4 hours after treatment. Five hours after treatment, plasma levels of some metabolites differed significantly between the survival, dead, and control groups. Ketogenesis and the tricarboxylic acid cycle were inhibited in both the survival and dead groups, but in the dead group, the urea cycle was also inhibited, and glycolysis was elevated. PLS-DA indicated that principal component weighting was greatest for plasma levels of phosphate, beta-hydroxybutyrate, urea, glucose, and lactate. The Y-predicted scatter plot in the partial least squares (PLS) model assigned samples to the survival or dead groups with an a priori cutoff of 0.10 with 100% sensitivity and specificity. Similar results were observed in 11 FHF patients with different outcomes. In conclusion, the PLS model based on metabonomic analysis can be used to predict outcomes well, and plasma levels of phosphate, beta-hydroxybutyrate, urea, glucose, and lactate may constitute a set of markers for the early diagnosis and prognosis of FHF.

The Functional Integrity of a Normothermic Perfusion System Using Artificial Blood in Pig Liver

BACKGROUND

We have reported already that we succeeded in developing a normothermic liver perfusion system consisting of purely artificial products such as artificial blood. The aim of this study was to ascertain the metabolic functional integrity of the liver perfused in this system.

MATERIALS AND METHODS

A liver graft from a female pig weighing 20 kg was harvested in the usual manner. The perfusion solution consisted of artificial blood, L-15 medium, distilled water, bovine serum albumin, NaHCO3, NaOH, KCl, human regular insulin, 50% glucose solution, and dexamethasone. The isolated liver was perfused with this oxygenated perfusate through the portal vein at a rate of 300 ml/min for 9 h. We analyzed the changes of amino acids, ammonia, and urea concentrations in five livers, which showed high oxygen consumption (over 8 ml-O2/min during perfusion).

RESULTS

Although urea did not exist in the perfusate at first, an extremely high level of the urea concentration appeared during the perfusion. On the other hand, the ammonia concentration was only slightly elevated during the perfusion. Arginine vanished from the perfusate with increases of citrulline and ornithine. Taurine was elevated with the disappearance of methionine. Alanine, glutamine, serine, histidine, and threonine concentrations decreased with an increase of the glucose concentration. Numerous liver cells exhibited PAS-positive cytoplasmic glycogen deposits not exhibited before perfusion. The ratios of branched-chain amino acids/aromatic amino acids were elevated during the perfusion.

CONCLUSION

Normothermic liver perfusion using artificial blood could sufficiently maintain the functional integrity of the liver.

Intrasplenic transplantation of encapsulated hepatocytes decreases mortality and improves liver functions in fulminant hepatic failure from 90% partial hepatectomy in rats

BACKGROUND

Encapsulated cell therapy might be a promising approach to enable cell transplantation without immunosuppression. This study investigates the viability and hepatic function of hepatocytes encapsulated with alginate/poly-L-lysine in vitro and the effect of the intrasplenic transplantation of cultured encapsulated hepatocytes on survival in 90% hepatectomized rats as a preliminary step toward allogeneic hepatocyte transplantation without immunosuppression.

MATERIALS AND METHODS

Rat hepatocytes were isolated and encapsulated using alginate/poly-L-lysine. Encapsulated hepatocytes were cultured for 28 days to measure cell viability, liver function, and morphology. Rats were treated with a 90% partial hepatectomy and then immediately underwent the intrasplenic transplantation of the cultured encapsulated hepatocytes, the capsule alone, or the allogeneic hepatocytes without the capsule. The survival rate, liver function, and cell morphology were assessed after transplantation.

RESULTS

The cultured encapsulated hepatocytes maintained their viability and showed better metabolic activity than day 0 cultured encapsulated hepatocytes. The encapsulated cells strongly expressed albumin and were positive for periodic acid-Schiff staining. Electron microscopy demonstrated that the microencapsulated hepatocytes retained the structural elements of hepatic cytoplasm and nuclei. Intrasplenic transplantation of the encapsulated hepatocytes increased the survival rate and improved the hepatic function. Encapsulated hepatocytes transplanted into rat spleen survived well and retained their hepatic function. Moreover, dramatic liver regeneration was observed 48 hr after transplantation in the group that received intrasplenic transplantations of encapsulated hepatocytes.

CONCLUSIONS

The intrasplenic transplantation of cultured encapsulated hepatocytes improved the survival rate of an acute liver failure rat model induced by a 90% partial hepatectomy.

Liver Function During Extracorporeal Whole Liver Perfusion in a Pig Model of Acute Ischemic Liver Failure

The shortage of livers for transplant has renewed interest in the potential of temporary liver support such as extra corporeal whole liver perfusion. In an ischemic induced liver failure model we perfused an extra corporeal liver through only a portal vein and assessed the function of this ex vivo liver by using hepatic tests to estimate elimination as well as synthesis capacities. Acute liver failure was performed in five control pigs by a hepatic devascularization associated to an end to side portocaval shunt. In a treated group, 5 to 6 h after this hepatic devascularization, animals were connected to an extra corporeal liver perfused via the portal vein with blood withdrawn from the ischemic liver animal from its portal vein. Devascularization of the liver induced an increase in liver enzymes and ammonia, a drop in the ratio of branched chain amino acids to aromatic amino acids, and a decrease in blood urea and indocyanine green and galactose clearances. In treated animals, urea, amino acid ratio, and clearances increased after the ex vivo liver perfusion. In this group, mean bile production and mean liver oxygen consumption were 13.7 +/- 3.6 ml/h and 16.1 +/- 7.7 ml/min, respectively. In an acute ischemic liver failure pig model, an extra corporeal whole liver perfusion demonstrated detoxification properties as well as synthesis capacities.

Successful ex vivo normothermic liver perfusion with purely artificial products using artificial blood

We tried to make an ex vivo functioning liver with an artificial perfusate that consisted of artificial blood in the pig liver. A liver graft from a female pig weighing 20 kg was harvested in the usual manner. The perfusion solution consisted of artificial blood, L-15 medium, distilled water, bovine serum albumin, NaHCO3, NaOH, KCl, human regular insulin, 50% glucose solution, and dexamethasone. The isolated liver was perfused with this oxygenated perfusate through the portal vein at a rate of 300 ml/min for 9 hours. Seven livers were perfused for 9 hours in this system. Five of the livers showed mean oxygen consumption of over 8 ml-O2/min during perfusion. Histological findings showed that the hepatic architecture was almost completely preserved and numerous hepatocytes exhibited PAS-positive cytoplasmic glycogen deposits in these livers. These observations indicate that we have succeeded in developing an ex vivo functioning liver with an artificial perfusate employing artificial blood.