Human spinal cord neurons in dissociated monolayer cultures: morphological, biochemical, and electrophysiological properties.

The preparation of dissociated monolayer cultures from embryonic human spinal cord is described. Optimal survival was achieved with embryonic tissue between the eighth and ninth week. The neurons survive for as long as 7 weeks in culture and they grow in a standard tissue culture medium which contains 13% decomplemented human serum. The neurons have been identified by indirect immunofluorescence techniques using antibodies to tetanus toxin and neurofilament protein. Our biochemical studies demonstrate the presence of cholinergic and GABAergic neurons. Cholinergic neurons develop in culture and are more numerous in the cultures prepared from the anterior part of the spinal cord as compared to those from the posterior part. Therefore, it is possible that a large part of the cholinergic neurons derive from the motoneuron pool. Electrical membrane properties were studied with patch electrodes using the whole cell recording technique. Neurons had short duration action potentials that could be blocked by tetrodotoxin (TTX). Voltage clamp experiments combined with the use of pharmacological blocking agents revealed the presence of several voltage- and time-dependent currents: a sodium current sensitive to TTX, a potassium current made up of two components, sensitive to tetraethylammonium and 4-aminopyridine, and a calcium current sensitive to cobalt. From a biochemical and electrophysiological point of view the properties of human spinal cord neurons in culture closely resemble the properties of spinal cord neurons from other species.