Gene expression analysis of precision cut human liver slices indicate stable expression of ADME-Tox related genes

In the process of drug development it is of high importance to test the safety of new drugs with predictive value for human toxicity. Currently, for toxicity studies toxicogenomic analysis of changes in gene expression profile of the liver is increasingly applied. Toxicity screening based on animal liver cells cannot be directly extrapolated to humans due to species differences. For the prediction of human specific toxicity, including metabolism and transport, we developed an in vitro method with precision cut human liver slices. The liver slices contain all cell types of the liver in their natural architecture. This is important since drug-induced toxicity often is a multi-cellular process, involving not only hepatocytes but also Kupffer, stellate and endothelial cells. Previously we showed that toxicogenomic analysis of rat liver slices is highly predictive for rat in vivo toxicity. For the use of human liver slices as a model system it is a prerequisite that the basic gene expression of the proteins involved in metabolism, transport and toxicity does not change to a large extend during incubation. In this study we investigated the basic levels of gene expression during incubation up to 24 h with Affymetrix microarray technology. The analysis was mainly focused on genes related to stress and toxicity, phase-I and phase-II metabolizing enzymes and drug transporters. From the total amount of probe sets analyzed (54,675) the expression of only about 2% changed significantly during incubation (FC > 2, p < 0.05). According to Metacore™ analysis, maps concerning cytoskeleton remodeling, extracellular matrix and cell adhesion were most significantly affected. Particularly in the categories stress and toxicity pathways, drug transporters and metabolic enzymes, changes were minimal. These results indicate that precision cuthumanliver slices are relatively stable during 24 h of incubation and represent a valuable model for human in vitro ADME-Tox testing.