Better in vitro dosing

The nominal concentration, i.e. the theoretical concentration based on amount of test chemical added to culture medium, is generally used to express concentration-effect relationships in in vitro toxicity tests. However, for instable, volatile, highly plastic and plasma protein bound chemicals, the nominal concentration does not represent the concentration responsible for the observed effect at the target site in cells.

We aim to develop tools that account and control for the degradation, evaporation and binding of chemicals to the in vitro system setup. These tools include exposing cells in sealed glass vials and microtiter plates dosed through polymers loaded with test chemicals (i.e. partition-controlled dosing).
In vitro assays form the cornerstone of toxicity testing in the twenty-first century, refining, reducing and ultimately replacing animal testing in toxicology. Their widespread use in regulatory toxicology is largely dependent on their inclusion in regulatory documents such as OECD test guidelines.

For these assays to be accepted by regulatory bodies, they should, among others, yield consistent and robust readouts across laboratories and reliably estimate in vivo toxic doses. The Good In Vitro Method Practices (GIVIMP) guidance document of the OECD describes the factors that need to be considered by assays developers. One of these factors is the control and monitoring of the exact test chemical exposure.

The work of this project will give in-depth practical guidance on which method for chemical dosing to apply in vitro to control exposures in vitro and thus improve the reliability and robustness of in vitro assay readouts for quantitative in vitro-in vivo extrapolations (QIVIVE).
A webtool with a decision tree will be designed to allow researchers to determine whether the use of each of these tools is necessary and applicable for the chemical and in vitro biomarker they wish to test.
  • A framework to better dose and assess chemical exposures in in vitro assays for difficult-to test chemicals
  • In vitro-in vivo extrapolations (QIVIVE)
  • Coupling dosing and analytical measurements technologies with computational models
  • Interdisciplinary approach for testing and assessment (IATA) of chemicals
  • Tested in high-throughput assays in vitro assays with human-relevant cell systems
  • Reliable adverse outcome pathway (AOP) development relevant for human chemical safety assessment
  • Determine physicochemical cut-offs for test chemicals where standard dosing does not provide stable free concentrations in vitro
  • Detailed experimental protocols to ease their regulatory acceptance