Three-dimensional cell culture systems stabilise the differentiation of hepatocyte cell lines

The suitability of a hepatocyte cell line for in vitro toxicity and drug metabolism largely depends in the expression of hepatic differentiated functions. In the present study the activity of phase I enzymes was examined in a long-term run using immobilised (Cultispher GH) and aggregates of hepatocyte cell lines derived fr-om Sprague-Dawley male rats. With that purpose the metabolic profile of testosterone was followed as the oxidative metabolism of this hormone is catalysed, with a high degree of regio- and stereoselectivity, by different cytochrome P450 families (1A, 2A, 2B, 2C and 3A). The results revealed that the cytochrome P450 activities were maintained for higher periods of time in three-dimensional cell systems then monolayer (conventional) cell cultures. Conventional cultures showed a rapid loss of cytochrome P450, which were undetectable after few passages. In contrast, some isoenzymes assayed were measurable in three-dimensional cell cultures systems for as long as 4 months. The beneficial effects of three-dimensional systems seemed to be attributed to the cell-cell contacts that will promote their phenotypic stability or to the retention of globular cell structure.