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 Galα(1–3)Gal, a carbohydrate structure present on most mammalian cells. Galα(1–3)Gal is produced by the enzyme α1,3-galactosyltansferase (αGal-T). Conflicting data have been published concerning Galα(1–3)Gal expression on hepatocytes in intact porcine liver. We investigated whether isolated porcine hepatocytes express Galα(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-Galα(1–3)Gal antibodies were measured in plasma from patients treated with BAL by ELISA. Results Isolated porcine hepatocytes express (αGal-T) at low levels and Galα(1–3)Gal is present in low quantities on these cells, in contrast to hepatocytes in situ. Furthermore, IgG and IgM anti-Galα(1–3)Gal are depleted from the plasma of ALF patients during BAL treatment. Conclusions Isolation and culture of porcine hepatocytes induce Galα(1–3)Gal expression, which may elicit immunological responses potentially compromising BAL functionality.