Development and Validation of Organotypic In Vitro Models of the Liver for Toxicity Testing

Edward LeCluyse and Melvin Andersen. The Hamner Institutes for Health Sciences.

Over the past five years, there has been a broad-based discussion on the future direction of toxicology and how safety testing is performed. This discussion has spawned multiple research efforts looking to use high- and medium-throughput in vitro screening data in identifying chemical hazards. For industrial and agricultural chemicals, research efforts in United States and Europe have characterized the in vitro biological activity of chemicals using multiple in vitro assays and technologies in order to predict in vivo toxicity and prioritize compounds for conventional toxicity testing. The efforts in the United States and Europe are now several years old and a significant amount of data has been collected, which has provided an excellent opportunity to evaluate the ability of high-throughput in vitro screening assays to predict in vivo toxic endpoints.

A broad based analysis of the U.S. Environmental Protection Agency's ToxCast Phase I dataset has been performed using a suite of different predictive modeling methods. The predictors include the results from the more than 600 in vitro cell-based and biochemical assays. The in vivo effects to be predicted included 60 endpoints from the ToxRef database. The results demonstrated that the ToxCast in vitro assays provided limited ability to predict in vivo toxic responses which restricts their applicability for in vivo hazard prediction and prioritization. There are multiple reasons for the lack of predictive performance from the ToxCast Phase I in vitro assays, but primarily, the current suite of in vitro ToxCast assays may not represent the biochemical and cellular responses in the in vivo tissues with adequate fidelity. This lack of representation may include cellular properties such as metabolic competence and transporter expression or more complex cell-cell interactions such as the interactions between immune cells and epithelial cells following cytotoxicity.

The main goals of this project are to identify and develop organotypic, human and rat liver culture systems that are amenable to some degree of automation to evaluate and model several prototypical toxicity pathways. In 2011, the Hamner evaluated multiple commercially available organotypic liver systems to identify which systems maintained their hepatic phenotype for up to a month. In 2012-2014, these systems will be further developed and validated to identify the key mechanisms that underlie chemically-induced liver toxicity. The systems will then be tested against a panel of known hepatotoxic chemicals to assess its predictive capacity and whether the organotypic assays designed for a specific purpose in this study are more accurate than the in vitro assays employed in the ToxCast Phase I effort.

Implications
 
The development of human and rat organotypic liver culture systems in these studies should provide a more predictive model for in vivo hepatotoxicity by incorporating elements that are currently lacking in the in vitro test systems. Since the liver accounts for a large percentage of endpoints used in risk assessments, building better and more predictive models of hepatotoxicity should provide a useful tool in the evaluation of chemical safety. Further, the development of both human and rat organotypic liver culture systems will provide a means to evaluate potential cross-species differences in toxicity and understand the mechanisms that underlie those differences. 

Keywords

organotypic liver culture models, hepatocytes, in vitro, toxicity testing

Project Start and End Dates

January 2010 – December 2014

Project ID

MTH1002-02

Peer-reviewed Publication(s)

Andersen, M. E., Al-Zoughool, M., Croteau, M., Westphal, M., and Krewski, D. (2010). The future of toxicity testing. Journal of Toxicology and Environmental Health, Part B: Critical Reviews 13:163-196.

Andersen, M. E. and Krewski, D. B. (2010). The vision of toxicity testing in the 21st century: Moving from discussion to action. Toxicological Sciences 117:17-24.

Andersen, M. E. (2010). Calling on science: Making “alternatives” the new gold standard. Alternatives to Animal Experimentation 27:135-143.

Boekelheide, K. and Andersen, M. E. (2010). A mechanistic re-definition of adverse effects – A key step in the toxicity testing paradigm shift. Alternatives to Animal Experimentation 4:243-252.

Krewski, D., Westphal, M., Al-Zoughool, M., Croteau, M., and Andersen, M. E. (2011). New directions in toxicity testing. Annual Review of Public Health 32:161-178.

LeCluyse, E. L., Witek, R. P., Andersen, M. E., and Powers, M. J. Organotypic liver culture models: Meeting the future challenges in toxicity testing. Critical Reviews in Toxicology. (Submitted).

Watanabe, K. H., Andersen, M. E., Basu, N., Carvan, M. J., III, Crofton, K. M., King, K. A., Sunol., C., Tiffany-Castiglioni, E., and Schultz, I. R. (2010). Development of computational models of known adverse outcome pathways: Domoic acid and neuronal signaling as a case study. Environmental Toxicology and Chemistry 30:9-21.

Zhang, Q., Bhattacharya, S., Andersen, M. E., and Conolly, R. B. (2010). Computational systems biology and dose response modeling in relation to new directions in toxicity testing. Journal of Toxicology and Environmental Health, Part B: Critical Reviews 13:253-276.

Other Publication(s)

Woods, C. G., Yarborough, K. M., Pluta, L. J., Pi, J., Thomas, R. S., and Andersen, M. E. (2011). Constructing a PPARα-mediated transcriptional network in primary human and rat hepatocytes. The Toxicologist 120:78.

Woods, C. G., Yarbourough, K. M., Zhang, H., Hou, Y., Fu, J., Pluta, L. J., Thomas, R. S., Pi, J., and Andersen, M. E. Temporal analysis of PPARa-mediated transcriptional regulation in primary human hepatoctyes. (In preparation).

Woods, C. G., Yarbourough, K. M., Zhang, H., Hou, Y., Fu, J., Pluta, L. J., Thomas, R. S., Pi, J., and Andersen, M. E. Dose response analysis of PPARa-mediated transcriptional regulation by GW7647 in primary human hepatocytes. (In preparation).

Abstract Revision Date

January 2012

*This abstract was prepared by the principal investigator for the project.

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