Proliferation of fetal rat hepatocytes in response to growth factors and hormones in primary culture

Fetal rat hepatocytes multiply in primary culture in arginine-free, hydrocortisone-containing chemically defined medium MX-82 supplemented either with epidermal growth factor or insulin or both. In contrast, hepatocytes did not multiply under similar culture conditions using Dulbecco's minimum essential medium. Cells underwent two divisions within 10 days in cultures maintained in MX-82 medium without a medium change, and cells grew to increased final cell densities when the medium was renewed every third day. When the medium MX-82 was enriched by the addition of lipids, intermediary metabolites, and trace metals, cells grew to higher densities. In the absence of the growth factors, cells became quiescent and subsequently could be induced to synthesize DNA in response to EGF. With the increasing numbers of cells per dish, the growth response of the hepatocytes diminished. Levels of hepatocyte-specific albumin and -fetoprotein mRNAs at day O were similar to those observed at day 10 in p rimary fetal rat hepatocyte cultures and were maintained at higher levels in medium MX-83 than in medium MX-82.