[Microcinematographic studies on neurodifferentiation and neurotoxicity in vitro using mouse embryonic stem cells]

The ontogeny of the mammalian nervous system remains largely unknown, mainly because of the lack of experimental systems that will allow identification of cellular mechanism involved in neuronal maturation. Recently the succesful differentiation of neurons from embryonic stem cells of the BLC-6 cell line has been shown by our group, and these cells are able to form complex neuronal networks with typical electrophysiological characteristica including postsynaptic potentials, comparable to the situation in vivo. Further characterization of neuronal cells revealed characteristic phenotypes, equipped with various neurotransmitters, e.g. glutamate. This excitatory neurotransmitter is reported to be involved in ischemia dependent neurological disorders. As the investigation of toxic effects during neuronal maturation in the embryo is usually rather difficult, due to the limited isolation of early embryonic neurons, the ES cell line seems to be an appropriate model to study effects of neurotoxicological substances. Because of the well known effect of glutamate on dendritic outgrowth and neuronal survival, the in vitro system of embryonic stem cells was applied to study the effect of glutamate intoxication by the receptor agonist NMDA during early neuronal development using videomicroscopic time lapse studies. The results point out that the NMDA induced neurotoxicity correlates with the degree of neuronal differentiation. Despite the existence of NMDA receptors in apolar, bipolar and multipolar neurons, the latter two populations were affected more dramatically than undifferentiated apolar neurons.