Effect of epidermal growth factor in collagen gel cultures of rat hepatocytes

Collagen gel cultures of hepatocytes represent a promising in vitro model in pharmaco-toxicology. Epidermal growth factor (EGF) is usually added to the culture medium, although one could question its value in a culture model aiming at maintaining a maximum of differentiated functional capacities. In this study, the effects of EGF (20 ng/ml) on albumin secretion, morphology and pentoxyresorufin O-depentylase (PROD), ethoxyresorufin O-deethylase (EROD) and glutathione S-transferase (GST) activities have been examined in both collagen gel sandwich and immobilization gel cultures of adult rat hepatocytes. Transmission electron microscopy did not show an obvious influence of epidermal growth factor (EGF) on the intracellular organization of organelles of the rat hepatocytes. It was found that EGF addition had no effect on albumin secretion in both culture models. On the contrary, the presence of EGF in the culture medium provoked in collagen gel sandwich cultures, after 7 days, significant decreases of 66% and 25% in EROD and PROD activities, respectively. On GST activities, no effect of EGF could be observed in both collagen gel cultures. Removal of EGF from the culture medium seemed to have a positive effect on the maintenance of the phase 1 biotransformation capacity of rat hepatocytes. Its addition should therefore be avoided in collagen gel cultures used in pharmaco-toxicology.