Recently, the need for developmental neurotoxicity (DNT) testing has been moving into the focus of the scientific community including regulatory scientists. Several initiatives promoted by EFSA, the OECD, and the International STakeholder NETwork (ISTNET) for DNT highlighted the most urgent needs for DNT evaluation (Lanzoni et al. 2019; Lupu et al. 2020; Fritsche et al. 2018; Bal-Price et al. 2015). The amount and quality of DNT data generated to date are not sufficient to provide confidence in the safety of the thousands of untested chemicals to which pregnant women, infants, and children may be exposed (Paparella et al. 2020). Moreover, there is an urgent need for a problem formulation-driven, fit-for-purpose testing paradigm to supply data for risk assessment and to support management decisions (Paparella et al. 2020). To tackle these issues, the OECD and EFSA in collaboration with the Danish- and US-EPA (Environmental Protection Agency) as well as the US national toxicology program have been harmonizing a screening effort. Several laboratories and stakeholders joined forces to define a DNT testing battery based on already available tests. A first application has been the comprehensive screen of 119 chemicals supplied by EFSA and the US EPA (Masjosthusmann et al. 2020). The outcome of this effort will contribute to an OECD guidance document on DNT in vitro evaluation. Despite its broad coverage of neurodevelopmental key events, the current DNT in vitro battery mainly focuses on neurons and oligodendrocytes. It fails to cover important radial glia, astrocyte, or microglia endpoints.
This project envisions the establishment of an expanded DNT in vitro test battery including radial glia (RG)-, astrocyte (AC)- and microglia (MG)-based/enhanced test systems. It will then assess the performance of the enhanced battery compared to the standard DNT in vitro test battery.
For this purpose, the project will focus on the following main objectives:
(1) set-up and characterize test methods to detect chemical interference with human RG differentiation and functionality;
(2) set-up and characterize test methods to detect chemical interference with AC maturation and with neuronal function in astrocyte-neuron co-culture models;
(3) set-up and characterize complex co-cultures of neurons, astrocytes, and MG to assess chemical-induced DNT under inflammatory and basic conditions.
Importantly, by comparison of data derived from rodent and human in vitro models and by identification of molecular biomarkers, the project aims to improve the transparency and in vivo transferability of the DNT test battery results from rodents to humans.