A test strategy to detect developmental toxicants that affect neural development using human embryonic stem cells

Abstract

Developmental neurotoxicity (DNT) is caused by exposure to toxicants during sensitive periods of neurodevelopment and can lead to cognitive, sensory or behavioural deficits, persisting long after removal of the original stimulus. However, information on developmental neurotoxic effects of most chemicals is still very sparse and not much is known on the mode of action of known toxicants. To address these issues, we are working on test systems based on human pluripotent cells with the potential to differentiate towards neural cells. To test the earliest phase of neurodevelopment, we used human embryonic stem cells, which were differentiated to Pax6-positive neural precursor cells. The transcriptional changes were examined in this system by whole genome chip analysis to select suitable markers. Chromatin changes were determined by immunostaining of histone modifications and confocal analysis. In this system we investigated the role of various signalling pathways for neural differentiation and how toxicants might interfere with those pathways. The cells were exposed either to chemicals targeting specific pathways, to epigenetic modulaters or to known developmental neurotoxicants during various differentiation periods. As read-out, we used mRNA expression levels of markers specific for certain neurodevelopmental stages and flow cytometry. A list of test compounds suitable for system characterization will be presented.