Effects of hepatocyte growth factor on viability and biotransformation functions of hepatocytes in gel entrapped and monolayer culture

Objectives: An extracorporeal bioartificial liver device must maintain viability and differentiated function of hepatocytes cultivated at high cell density. Growth factors, such as hepatocyte growth factor, found in high concentrations in the plasma of patients with fulminant hepatic failure, have the potential to promote hepatocyte dedifferentiation and thus, decrease function. We tested the hypothesis that hepatocyte growth factor would improve viable cell density and decrease biotransformation functions of liver cells in monolayer culture and in hepatocytes entrapped in collagen cylindrical gel 'noodles' as found in the extracorporeal bioartificial liver. Design: In vitro, controlled study. Setting: University research laboratory. Subjects: Adult Sprague Dawley Rats. Interventions: Hepatocytes were harvested by a two-step collagenase technique. Harvested hepatocytes were plated onto type I collagen coated plates or entrapped in type 1 collagen cylindrical gels and cultured in different concentrations of hepatocyte growth factor. Interval measurements of ³H-thymidine incorporation, albumin synthesis, biotransformation functions, and viability were made. Measurements and Main Results: In monolayer culture, the addition of hepatocyte growth factor caused a dramatic increase in ³H-thymidine incorporation. This increase was accompanied by a decrease in the appearance of the lidocaine metabolite, monoethyglycinexylidide. Albumin production was unchanged. In cylindrical gel entrapment cultures, hepatocyte growth factor caused a significant increase in 2-day viability but had no effect on the metabolite appearance of lidocaine or 4-methyl umbelliferone or albumin production. Conclusions: Hepatocyte growth factor induces dedifferentiation of hepatocytes in monolayer culture. Collagen matrix entrapment appears to abrogate this effect and improve liver cell viability. There may be reciprocal regulation of hepatocyte reproductive and differentiated functions, such as biotransformation, which can be influenced by the entrapment of hepatocytes in an extracellular type 1 collagen matrix.