EFFECTS OF PLASMA EXPOSURE ON CULTURED-HEPATOCYTES - IMPLICATIONS FORBIOARTIFICIAL LIVER SUPPORT

In order to examine their potential for use in a bioartificial liver, hepatocytes maintained in a collagen sandwich configuration were cultu red for 9 days in heparinized rat plasma. The cells exhibited a progre ssive accumulation of cytoplasmic lipid droplets which proved to be ma inly triglyceride (TG). The rate of TG accumulation correlated with th e free fatty acid (FFA) content of the plasma. Removal of FFA and TG f rom plasma by ether extraction significantly reduced the rate and exte nt of TG accumulation. A smaller reduction in the rate and extent of T G accumulation was observed when cells were maintained in an oxygen en riched 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 afte r at least 6 days of plasma exposure by returning the cells to culture medium. The results indicate that elevated FFA in plasma induces lipi d 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 su pport device use may have to be governed by the need to limit the plas ma exposure of cultured hepatocytes. However, the highly responsive na ture of these cultures and the reversibility of the plasma effects sug gest that the collagen sandwich culture system is a promising foundati on for the development of an effective bioartificial liver support sys tem. (C) 1996 John Wiley & Sons, Inc.