Evidence for Galα(1-3)Gal expression on primary porcine hepatocytes:: implications for bioartificial liver systems

Background/Aims: To bridge acute liver failure (ALF) patients to orthotopic liver transplantation, several bioartificial liver (BAL) systems have been developed. The bio-component of most BAL systems consists mainly of porcine hepatocytes. Plasma or blood of ALF patients is perfused through the BAL thereby contacting porcine hepatocytes. Xenogeneic BAL systems may suffer from hyperacute rejection similar to whole-organ xenotransplants. Hyperacute rejection is mediated by antibodies directed against Gal alpha(1-3)Gal, a carbohydrate structure present on most mammalian cells. Gal alpha(1-3)Gal is produced by the enzyme alpha 1,3-galactosyltansferase (alpha Gal-T). Conflicting data have been published concerning Gal alpha(1-3)Gal expression on hepatocytes in intact porcine liver. We investigated whether isolated porcine hepatocytes express Gal alpha(1-3)Gal. Methods: Immunofluorescence, flow cytometry, RT-PCR and enzyme activity assays were performed on freshly isolated and cultured porcine hepatocytes and liver biopsies. Anti-Gal alpha(1-3)Gal antibodies were measured in plasma from patients treated with BAL by ELISA. Results: Isolated porcine hepatocytes express (alpha Gal-T) at low levels and Gal alpha(1-3)Gal is present in low quantities on these cells, in contrast to hepatocytes in situ. Furthermore, IgG and IgM anti-Gal alpha(1-3)Gal are depleted from the plasma of ALF patients during BAL treatment. Conclusions: Isolation and culture of porcine hepatocytes induce Gal alpha(1-3)Gal expression, which may elicit immunological responses potentially compromising BAL functionality. (C) 2005 European Association for the Study of the Liver. Published by Elsevier B.V. All rights reserved.