Alteration of expression of liver-enriched transcription factors in the transition between growth and differentiation of primary cultured rat hepatocytes

The current status of primary hepatocyte culture

Recently, there have been significant advances toward the development of culture conditions that promote proliferation of primary rodent hepatocytes. There are two major methods for the multiplication of hepatocytes in vitro: one is the use of nicotinamide, the other is the use of a nutrient-rich medium. In the medium containing a high concentration of nicotinamide and a growth factor, primary hepatocytes can proliferate well. In this culture condition small mononucleate cells, which are named small hepatocytes, appear and form colonies. Small hepatocytes have a high potential to proliferate while maintaining hepatic characteristics, and can differentiate into mature ones. On the other hand, combining the nutrient-rich medium with 2% DMSO, the proliferated hepatocytes can recover the hepatic differentiated functions and maintain them for a long time. In this review I describe the culture conditions for the proliferation and differentiation of primary hepatocytes and discuss the small hepatocytes, especially their roles in liver growth.

Growth and differentiation of rat hepatocytes: changes in transcription factors HNF-3, HNF-4, STAT-3, and STAT-5

The liver enriched transcription factors HNF-3 and HNF-4 are known to play major roles in development and differentiation of hepatocytes. STAT-3 and STAT-5 are signaling peptides activated by a variety of cytokines and growth factors including HGF and EGF. Their role in hepatocyte growth and differentiation is yet to be determined. We examined protein expression and DNA binding activities of these transcription factors in a hepatocyte culture system in which the hepatocytes first de-differentiate and proliferate. Overlaying proliferating hepatocytes with EHS-matrix led to an increase in HNF-4 protein and DNA-binding activity. STAT-5 DNA binding activity was only slightly effected by EHS-matrix. HNF-3 and STAT-3 DNA-binding activities were reduced in the presence of EHS-matrix. This is consistent with the role of HNF-3 as the major initiating transcription factor involved in embryonic liver development and suggests, that STAT-3 might also play a role in growth and differentiation of hepatocytes.