Isolation and Culture of Pig Hepatocyte in Large Scale for the Application of Bioartificial Liver System / 대한간학회지

BACKGROUND/AIMS: Acute hepatic failure is a serious problem. Its mortality reaches up to 80%. Only liver transplantation has been accepted as a definite treatment for patients with hepatic failure but shortage of donor organs is the main obstacle of this approach. A possible solution to this problem is a bioartificial liver system, perfusion of patients blood to isolated hepatocyte. In this study, we performed the isolation and culture of pig hepatocyte in large scale for the application of bioartificial liver system. METHODS: Hepatocyte isolation was performed by two-step collagenase method via portal vein perfusion in 10kg female pigs. After that, we compared the functional differences of the spheroid culture to the monolayer culture of hepatocyte. The viability and the function of hepatocyte were assessed using trypan-blue exclusion test and the measurement of the rate of ureagenesis and ammonia removal. RESULTS: The average viability and yield of hepatocyte were 86.8 +/- 8.0 % and 7.8 +/- 5.4 X 10(9), respectively. The spheroid culture was superior to the monolayer culture in functional aspect of hepatocyte, and their differences, especially for ammonia removal, were more apparent in parallel with culture time. CONCLUSIONS: For hepatocyte isolation, we obtained sufficient viability and yield of hepatocyte for clinical usage of bioartificial liver system. The function of hepatocyte seems to be better in the spheroid culture than in the monolayer culture. Further studies are needed for application of bioartificial liver system in clinical setting.

Effect of metabolic inhibition on inward rectifier K current in single rabbit ventricular myocytes

In the present study, we have investigated the effect of metabolic inhibition on the inward rectifer K current (IK1). Using whole cell patch clamp technique we applied voltage ramp from +80 mV to -140 mV at a holding potential of -30 mV and recorded the whole cell current in single ventricular myocytes isolated from the rabbit heart. The current-voltage relationship showed N-shape (a large inward current and little outward current with a negative slope) which is a characteristic of IK1. Application of 0.2 mM dinitrophenol (DNP, an uncoupler of oxidative phosphorylation as a tool for chemical hypoxia) to the bathing solution with the pipette solution containing 5 mM ATP, produced a gradual increase of outward current followed by a gradual decrease of inward current with little change in the reversal potential (-80 mV). The increase of outward current was reversed by glibenclamide (10 muM), suggesting that it is caused by the activation of KATP. When DNP and glibenclamide were applied at the same time or glibenclamide was pretreated, DNP produced same degree of reduction in the magnitude of the inward current. These results show that metabolic inhibition induces not only the increase of KATP channel but also the decrease of IK1. Perfusing the cell with ATP-free pipette solution induced the changes very similar to those observed using DNP. Long exposure of DNP (30 min) or ATP-free pipette solution produced a marked decrease of both inward and outward current with a significant change in the reversal potential. Above results suggest that the decrease of IK1 may contribute to the depolarization of membrane potential during metabolic inhibition.