In vitro test models may reduce the time and resources required for pre-clinical toxicology studies, as well as decrease the number of laboratory animals needed to assess toxicity of drugs. Several models and toxicity assays have been evaluated at GE Healthcare, e.g. using rat liver slices, but the viability of slices has not been optimal and the results inconclusive.
The aims of this study were to test a new incubator and improve the viability of rat liver slices; evaluate various in vitro assays for toxicity; and evaluate the in vitro toxicity of menadione and iron (II) sulphate on rat liver slices.
Exsanguinous rat livers were cut in slices of 8 mm diameter and 250 µm thickness and incubated in William’s medium E with menadione or iron (II) sulphate for various time periods. The slices were analysed for weight, mitochondrial viability (MTT test), enzyme leakage (ALAT, ASAT, GLDH, LDH), and iron and potassium content.
Leakage of certain enzymes (ASAT, GLDH), and reduced potassium content, indicated less viability of liver slices treated with iron (II) sulphate than negative controls. Of the assays studied here, GLDH leakage seemed to be the most predictive of iron (II) sulphate toxicity. The MTT test, LDH leakage, and reduced potassium content indicated less viability of liver slices treated with menadione than negative controls.
More practical training of personnel in using the equipment is required to improve the performance of the rat liver slice model. Isolated hepatocytes may be easier to culture and use for toxicity screening.