Human hepatocyte - A model for toxicological studies. Functional and biochemical characterization

Isolated human hepatocytes (HH) are an accepted model for in vitro experime nts for testing liver function and xenobiotic metabolism. Preferred over mo re traditional animal hepatocyte model used in toxicological studies, it is the model of choice when substances undergoing biotransformation in man ar e investigated. The aim of this study was to optimize isolation and culture conditions for HH primary culture with regard to cell yield, viability, an d metabolic activity, and to evaluate the suitability of donor samples for toxicology experiments. Cell viability, total cytochrome P450 (CYP) content , CYP3A4, CYP1A2 activity, and finally mixed ethoxycoumarin-O-deethylase (E COD) activity were parameters measured in order to characterize the isolate d HH. The duality of the primary cultures, stable and functional for a seve n-day period following 24 hour stabilization, was assessed by lactate dehyd rogenase (LDH) leakage and response to the model to,, tert-butylhydroperoxi de (tBH) and to silybinin, a model cytoprotective substance. Based on KH ob tained from livers of five multiorgan donors (average age 44.8 years, three males and two females), the individual variability of donors needs to be c onsidered in evaluating cultures focussing on clinical liver tests. Greater sensitivity to toxins and silybinin was found in the hepatocyte culture fr om one donor with higher aminotransferase activity. In another case, higher serum bilirubin appeared to be linked to higher ECOD activity. Our conclus ion is that values of clinical liver tests ought to suggest a healthy organ thus eliminating previous hepatocyte damage, the crucial factor of primary culture stability and functioning.