Integrating biokinetics and in vitro studies to evaluate developmental neurotoxicity induced by chlorpyrifos in human iPSC-derived neural stem cells undergoing differentiation towards neuronal and glial cells

For some complex toxicological endpoints, chemical safety assessment has conventionally relied on animal testing. Apart from the ethical issues, also scientific considerations have been raised concerning the traditional approach, highlighting the importance for considering real life exposure scenario (i.e., repeated low dose exposure). Implementation of flexible testing strategies, integrating multiple sources of information, including in vitro reliable test methods and in vitro biokinetics, critical to extrapolate to the real in vivo situations, would enhance the relevance of the obtained results. Such an approach could be pivotal in the evaluation of developmental neurotoxicity (DNT), especially when applied to human cell based models, mimicking key neurodevelopmental processes, relevant to human brain development. Here, we integrated the kinetic behaviour with the toxicodynamic alterations of chlorpyrifos (CPF) and in vitro endpoints specific for developmental neurotoxicity (DNT) evaluation after repeated exposure during differentiation of human neural stem cells into a mix population of neuronal/glial cells. The upregulation of some cytochrome P450s (e.g., CYP-2B6, -3A5, -1A1 and -2C8) and glutathione S-transferase genes during neuronal differentiation and the formation of the two major CPF metabolites (due to bioactivation and detoxification) supported the metabolic competence of the used in vitro model. The alterations in the number of synapses, neurite outgrowth, brain derived neurotrophic factor, the proportion of neurons and astrocytes, as well as spontaneous electrical activity correlated well with the CPF ability to enter the cells and be bioactivated to CPF-oxon. Overall, our results confirm that combining biokinetics and human cell-based in vitro assays to evaluate chemical effects on neurodevelopmental endpoints should be regarded as a key strategy for a quantitative characterization of DNT effects.

DI CONSIGLIO Emma;  PISTOLLATO Francesca;  MENDOZA Emilio;  PRICE Anna;  TESTAI Emanuela; 

2020-12-11

PERGAMON-ELSEVIER SCIENCE LTD

JRC121578

0890-6238 (online),   

https://doi.org/10.1016/j.reprotox.2020.09.010,    https://publications.jrc.ec.europa.eu/repository/handle/JRC121578,   

10.1016/j.reprotox.2020.09.010 (online),