Markers of murine embryonic and neural stem cells, neurons and astrocytes: reference points for developmental neurotoxicity testing

Abstract

Developmental neurotoxicity (DNT) testing is an important area for the safety of human beings. Animal-based models cannot reliably predict human hazard, and test capacities are limited. Embryonic stem cells (ESC) that differentiate to neural cells recapitulate all developmental steps known from the development of the nervous system. At present, protocols for the differentiation of murine ESC (mESC) are most rapid and robust. Different approaches towards the use of mESC for DNT assays are discussed here, especially in the context of a modern mechanism- and pathway-based toxicology. Transcriptional profiling is presented as sensitive endpoint that can be scaled up to relatively high throughput, but still gives rich information on underlying mechanisms of toxicity. As a basis for test system development and validations, mRNA marker lists for mESC (n=41), for neural stem cells (n=74), for mapping out the balance between different cell types (n=57), and for astrocytes as examples of terminally-differentiated cells (n=25) have been compiled here, based on literature and data bank searches and extensive filtering. The compilation is discussed in the context of a new generation of alternative assays (embryonic stem cell based DNT testing = ESDNT V2.0), that are not designed for 1:1 replacement of animal experiments, but are rather based on independent scientific principles to directly solve problems of human risk assessment.