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Background. Hepatocyte transplantation is an attractive treatment for various liver diseases. The intraportal route of transplantation is favored, but little information is available on the possible adverse effects in this technique. We investigated the influence of intraportal loads of hepatocytes on portal, pulmonary, and systemic hemodynamics in 13 pigs. Methods. Under general anesthesia, pigs were provided with an arterial line, a Swan-Ganz catheter, and two intraportal catheters, one for cell infusion and one for heparin infusion and portal pressure measurement. Pig hepatocytes were infused at a rate of 25 million cells/min. Results. The first six animals were used to develop the infusion technique. In the last seven animals, portal pressure increased linearly with cell load upon infusion of 400–2400×106 hepatocytes (r2=0.704;P 40 mmHg. Pulmonary arterial pressure increased by 11–62%. AST increased up to 10-fold, and platelets decreased by 22–58%. Hepatocytes-containing thrombi were present in segmental and in smaller portal branches. Hepatocytes were always identified in lung sinusoids 48 hr after infusion, and a small basal pulmonary infarction was found in one animal. Conclusions. These data suggest that up to 2.4% of total hepatocyte mass can be infused in this large animal model. However, the risk of significant thrombotic complications should be considered for clinical applications.

Background and aims: Reversible Ischemia/Reperfusion liver injury was used to induce engraftment and hepatic parenchymal differentiation of exogenous β2-microglubulin -/ Thy1+ bone marrow-derived cells. This method of hepatic parenchymal repopulation, theoretically applicable to clinical practice, was further tested to correct the metabolic disorder in a rat model of congenital hyperbilirubinemia. Methods and results: Analysis by confocal laser microscopy of fluorescence-labelled cells and by immunohistochemistry for β2-microglubulin, 72 hours after intraportal delivery, demonstrated engraftment of infused cells in liver parenchyma of rats with Ischemia/Reperfusion, but not in control animals with non-injured liver. Transplantation of bone marrow-derived cells obtained from GFP-transgenic rats into Lewis rats resulted in the presence of up to 20% of GFP-positive hepatocytes in Ischemia/Reperfusion liver lobes after one month. The repopulation rate was proportional to the number of transplanted cells. Infusion of GFP-negative bone marrow-derived cells into GFP-positive transgenic rats resulted in the appearance of GFP-negative hepatocytes, suggesting that the main mechanism underlying parenchymal repopulation was differentiation rather than cell fusion. Transplantation of wild type bone marrow-derived cells into hyperbilirubinemic Gunn rats with deficient bilirubin conjugation after Ischemia/Reperfusion damage resulted in 30% decrease of serum bilirubin, in the appearance of bilirubin conjugates in bile and in the expression of normal UDP-glucuronyltransferase enzyme evaluated by PCR. Conclusions: Ischemia/Reperfusion injury induced hepatic parenchymal engraftment and differentiation into hepatocyte-like cells of bone marrow-derived cells. Transplantation of bone marrow-derived cells from non-affected animals resulted in the partial correction of hyperbilirubinemia in the Gunn rat.

Background and aims: Hydrophobic bile acids contribute to hepatocellular injury in cholestasis and rapidly induce apoptosis in vitro; however, unlike Fas agonists, cholestasis does not cause extensive hepatocyte apoptosis. As antioxidants provide protection against bile acid induced liver injury, our premise was that bilirubin, a free radical scavenger with increased plasma levels in the presence of liver disease, could protect hepatocytes against bile acid induced apoptosis. Methods: Freshly isolated rat hepatocytes were incubated for four hours with 100 μmol/l glycochenodeoxycholate (GCDC) alone or with increasing concentrations of unconjugated (UCB) or conjugated (CB) bilirubin. Results: Both UCB and CB inhibited GCDC induced apoptosis in a dose dependent fashion and suppressed the generation of reactive oxygen species by hepatocytes. Conclusions: The antiapoptotic effect of bilirubin associated with its antioxidant properties indicates that hyperbilirubinaemia may have a protective role in liver disease.