Comparative study of metabolic activity of liver bioreactor with perfused liver

摘要

The aim of this study si to compare the metabolic activity of hollow fibre bioreactor with a perused liver. A special construction of a fibre bioreactor was made using freshly isolated rat liver. After isolation, hepatocytes were incubated in the bioreactor for 3 hours and was subjected to the following conditions: 100 ml medium Hanks balances Salts solution supplemented with 4% albumin, 2 nM ornithine, 10 mM ammonium chloride and 6 mM ethanol. The medium was perfused in a circulated sysytem for 25 ml/min, samples of the medium were taken to estimate ammonia, urea, glucose, lactate, ethanol, AST and ALT activity before and after 5 minutes and every 15 minutes of perfusion time. Utilization of ammonia was different in both systems and amounted to 8.89 and 5.23 micro mol/h/g hepatocytes in the bioreactor and perfused liver respectively. Urea production was 2.35 and 8.22 micro mol/h/g hepatocytes, respectively. The largest difference among the two systems was observed from the glucose and lactate metabolism. The bioreactor did not release glucose and lactate during the entire time of perfusion. In contrast perfused liver intensively released glucose (31.32 micro mol/hr/g cells) and produced lactate (29.42 micro mol/hr/g cells). However no significant difference on the rate of ethanol metabolism was observed from the two systems. The results indicate that a bioreactor with freshly isolated hepatocytes is not bioequivalent to a perfused liver if estimation was based on the basis of ureogenesis and/or glucose utilization. However ethanol utilization gives evidence that the metabolic activity of the bioreactor is comparable with a perfused liver. On the basis of the obtained results it can be concluded that the difference in metabolic activity of the bioreactor and perfused liver is connected with catabolic state and disturbances of energy metabolism in freshly isolated hepatocytes. In such a system a condition HBSS is not the proper medium for the recovery of homeostasis. To estimate the metabolic activity of freshly isolated hepatocytes cultivated in various in vitro systems such as a marker of model usefulness it is suggested to use the activity of inducible enzymes but not constituent enzymes.