In vitro assays are currently the best alternative to costly animal testing. Such assays are mainly used in product testing for pharmacological and toxicological purposes. However, they present many disadvantages in terms of key performance characteristics and are associated with low reliability and with poor validation often caused by the lack of adequate quality control and standards.
This project aimed to address some of these issues using chronic hepatotoxicity as an important and relevant case study. This assay is of prime importance to industry as it is used to investigate the damage caused to the liver by long-term administration of novel drugs. The current model involves rat hepatocytes, but these tend to lose their functionality in culture within a few days, making them of questionable value for chronic study.
As part of the project a series of biomarkers, genomic and biochemical, were developed to test the fitness for purpose and functionality of hepatocytes. Specifically, four important enzymes (CYP2A2, CYP3A2, CYP2B1 AND CYP2C11) were measured and proved to be good markers of cell activity making them appropriate for quality control purposes.
Two different culture conditions were also investigated (traditional collagen coat and novel collagen gel), as well as a proprietary storage matrix, to assess methods for maintaining the long-term functionality of cells. These proved suitable for maintaining the cells for a few days, however refinements must be sought if hepatocytes are to be used appropriately in models for chronic hepatotoxicity.
As an addition to the practical study, a report was prepared highlighting current issues in cell-based testing and recommending areas of research. This was compiled through literature review and in consultation with appropriate stakeholders. It was concluded that further work is required in the area of in vitro validation area, especially to improve reproducibility of measurements and to support improved in vitro/in vivo correlation.