EMBRYONIC STEM-CELLS EXPRESS NEURONAL PROPERTIES IN-VITRO

Mouse embryonic stem (ES) cells cultured as aggregates and exposed to retinoic acid are induced to express multiple phenotypes normally asso ciated with neurons. A large percentage of treated aggregates produce a rich neuritic outgrowth. Dissociating the induced aggregates with tr ypsin and plating the cells as a monolayer results in cultures in whic h a sizable percentage of the cells have a neuronal appearance. These neuron-like cells express class III beta-tubulin and the neurofilament M subunit. Induced cultures express transcripts for neural-associated genes including the neurofilament L subunit, glutamate receptor subun its, the transcription factor Brn-3, and GFAP. Levels of neurofilament L and GAD(67) and GAD(65) transcripts rise dramatically upon inductio n. Physiological studies show that the neuron-like cells generate acti on potentials and express TTX-sensitive sodium channels, as well as vo ltage-gated potassium channels and calcium channels. We conclude that a complex system of neuronal gene expression can be activated in cultu red ES cells. This system should be favorable for investigating some o f the mechanisms that regulate neuronal differentiation. (C) 1995 Acad emic Press, Inc.