S1: The Resolution of Concentration Response: High Throughput Transcriptomics
Importance of Cell Culture Configuration on Hepatocyte Functionality & the Resolving Power to Distinguish ‘Safer’ Case Study Analogues & Liver Injury Compounds
National Toxicology Program
As part of Phase III of the Tox21 Program, we are developing improved approaches to investigate chemical safety/toxicity potential in humans. Initial efforts have focused on developing and integrating organotypic in vitro liver screening models (2D & 3D) and high dimensional assay systems (i.e., high throughput transcriptomics (HTT), morphological imaging, cell health assays). In this presentation, we describe our findings with a panel of 24 compounds designed to probe the impact of cell culture configuration (HepaRG cells) on cellular differentiation (i.e., xenobiotic metabolism, hepatic receptor pathway functionality, modeling of metabolically-activated biological responses (i.e., toxicity), and the power of broad-range concentration response evaluations to discriminate ‘therapeutic’ vs. ‘off-target’ or toxic responses to chemical exposures. The study highlights the major limitations of proliferating cell culture models, even with highly differentiated cells such as HepaRG, to mimic tissue-like responses to compounds (i.e., phenobarbital, fenofibric acid, chenodeoxycholic acid, rosiglitazone), the impact of proliferating status on baseline xenobiotic metabolism competence, the potential to model metabolically-activated toxicity (e.g., cyclophosphamide, troglitazone, acetaminophen, aflatoxin B1), and the promising utility to distinguish ‘case study’ liver injury compounds from less hepatotoxic analogues via increased propensities for increased/pleiotropic transcript perturbations. The approach, coupled with quantitative in vitro to in vivo extrapolation methods, provides a data-rich and cost-effective solution to rapidly survey biological response space, in a potency-driven framework, to more effectively evaluate chemical-induced biological perturbations in humans.