Evidence for Galalpha(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 Galalpha(1-3)Gal, a carbohydrate structure present on most mammalian cells. Galalpha(1-3)Gal is produced by the enzyme alpha1,3-galactosyltansferase (alphaGal-T). Conflicting data have been published concerning Galalpha(1-3)Gal expression on hepatocytes in intact porcine liver. We investigated whether isolated porcine hepatocytes express Galalpha(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-Galalpha(1-3)Gal antibodies were measured in plasma from patients treated with BAL by ELISA.

RESULTS

Isolated porcine hepatocytes express (alphaGal-T) at low levels and Galalpha(1-3)Gal is present in low quantities on these cells, in contrast to hepatocytes in situ. Furthermore, IgG and IgM anti-Galalpha(1-3)Gal are depleted from the plasma of ALF patients during BAL treatment.

CONCLUSIONS

Isolation and culture of porcine hepatocytes induce Galalpha(1-3)Gal expression, which may elicit immunological responses potentially compromising BAL functionality.