Growth stimulation of adult rat hepatocytes in a primary culture by soluble factor(s) secreted from nonparenchymal liver cell.

Cocultures of adult rat hepatocytes with nonparenchymal liver cells (NPC) resulted in stimulation of DNA synthesis of hepatocytes and their survival for more than one month. These cells were found capable of synthesizing albumin and 3-methylcholanthrene-inducing cytochrome P-450. A conditioned medium obtained by culturing NPC was effective to the same degree as the coculture with NPC for stimulating DNA synthesis in hepatocytes. The factor(s) responsible for this was inactivated by heating or trypsin treatment, but it was not capable of passing through a cellulose tubing. It is thus evident that soluble proteinaceous substance (s) secreted from NPC stimulates the growth of hepatocytes in a primary culture.