Effects of plasma exposure on cultured hepatocytes: Implications for bioartificial liver support

Abstract

In order to examine their potential for use in a bioartificial liver, hepatocytes maintained in a collagen sandwich configuration were cultured for 9 days in heparinized rat plasma. The cells exhibited a progressive accumulation of cytoplasmic lipid droplets which proved to be mainly triglyceride (TG). The rate of TG accumulation correlated with the free fatty acid (FFA) content of the plasma. Removal of FFA and TG from plasma by ether extraction significantly reduced the rate and extent of TG accumulation. A smaller reduction in the rate and extent of TG accumulation was observed when cells were maintained in an oxygen enriched environment. The lipid accumulation suppressed urea synthesis, but clearance of the drug diazepam, although constitutively depressed in plasma, appeared unaffected by the accumulation. The functional and morphological effects of plasma exposure could be fully reversed after at least 6 days of plasma exposure by returning the cells to culture medium.The results indicate that elevated FFA in plasma induces lipid accumulation, which inhibits urea synthesis in cultured hepatocytes. This suggests that estimates of the cell number needed for effective liver support should not be based upon function measurements conducted in culture media. Furthermore, optimization of bioartificial liver support device use may have to be governed by the need to limit the plasma exposure of cultured hepatocytes. However, the highly responsive nature of these cultures and the reversibility of the plasma effects suggest that the collagen sandwich culture system is a promising foundation for the development of an effective bioartificial liver support system. (c) 1996 John Wiley & Sons, Inc.