- By integrating sexual dimorphism into in vitro liver models, the project will enhance the prediction of chemical-induced liver injury across sexes, which addresses a major limitation in current safety testing.
- The project will generate sex-specific mechanistic data that support regulatory acceptance of NAMs. These findings align with ongoing efforts by EU and OECD bodies, contributing to the development of sex-aware IATAs, particularly for NGTX carcinogens and endocrine disruptors.
- By addressing the historical underrepresentation of female biology in in vitro studies, the project supports equitable health outcomes. The development of sex-aware liver models ensures that both men and women are equally protected from chemical-induced liver toxicity, promoting fairness in safety assessments and fulfilling ethical and regulatory commitments to gender-inclusive research.
Key messages
To address current gaps in test strategies for chemical-induced liver toxicity, this project will support regulatory assessments by integrating sex-specific biological differences into in vitro liver models:
- to improve mechanistic understanding of sex-specific mechanisms of liver toxicity;
- to enhance human relevance and equity of chemical safety assessments through improved NAMs ↗ that can predict male and female chemical-induced hepatotoxic responses.
Overview
Sexual dimorphism plays a key role in hepatic metabolism, influencing how men and women process xenobiotics, amino acids, and lipids. These biological differences impact susceptibility to chemical exposures. For instance, women account for 70% of acute liver failure cases, yet current in vitro models do not reflect sex-specific variations. In contrast, in vivo animal studies can account for sex differences by selecting the most sensitive sex, which highlights the urgent need to adapt in vitro methodologies accordingly.
This project aims to enhance current in vitro methods for evaluating hepatotoxicity by integrating parameters of sexual dimorphism into multiple hepatic cell models, including primary human hepatocytes, HepaRG, and liver cells derived from multipotent and induced pluripotent stem cells (mSCs and iPSCs).
By doing so, the project will provide insights into sex-specific mechanisms of liver toxicity and contribute to the regulatory advancement of New Approach Methodologies (NAMs).
The work supports ongoing efforts in EU and OECD initiatives. It complements activities within the OECD ↗ expert group on non-genotoxic carcinogens (NGTXs) and endocrine disruptors, which is currently developing an Integrated Approach to Testing and Assessment (IATA ↗) for NGTXs. By generating mechanistic data and enhancing assay relevance, the project will contribute to identifying and characterising NGTX mechanisms in a sex-specific manner. This effort not only advances scientific understanding but also aligns with the broader objective of improving chemical safety assessments in a sex-aware and human-relevant manner.
Policy relevance
The relevance of this work is multi-dimensional and should finally be aligned with regulatory and policy frameworks.
- Supports implementation of gender-inclusive regulatory standards. The project addresses long-standing gender bias in toxicological testing by integrating sexual dimorphism into in vitro liver models. This directly supports EU policy objectives on gender equality in research and innovation, including those outlined in the Horizon Europe Strategic Plan and Gender Equality Strategy 2020–2025 ↗. It helps ensure that sex-specific differences are accounted for in health risk assessment and regulatory decision-making.
- Contributes to the regulatory acceptance of NAMs. By providing robust, human-relevant, and sex-aware mechanistic data, this project advances the regulatory maturity of NAMs, aligning with the OECD’s work on IATA and the European Chemicals Agency (ECHA ↗)’s efforts to reduce reliance on animal testing under REACH ↗. It helps fulfil the EU’s commitment to the 3Rs (Replacement, Reduction, Refinement) principles in toxicological testing.
- Informs evidence-based chemical safety policies. The improved predictive power of these models for chemical-induced liver injury, especially across sexes, enables more accurate human health risk assessments. This supports policy development related to chemical safety assessment (e.g. of endocrine disruptors); hereby enhancing consumer protection and public health in accordance with the EU Chemicals Strategy for Sustainability ↗ and Green Deal ↗ objectives.