Electrophysiological properties of mitogen-expanded adult rat spinal cord and subventricular zone neural precursor cells

Growth factor-expanded neural precursor cells isolated from the mammalian c entral nervous system can differentiate into neurons and glia. Although the morphological and neurochemical development of these neural precursor cell s has been investigated, little attention has been paid to their electrophy siology. This study examined the electrophysiological properties of neurons and glia derived from neural precursor cells isolated from the adult rat s pinal cord (SC) and subventricular zone (SVZ). Cells were cultured in mediu m containing epidermal growth factor and/or fibroblast growth factor-2. Aft er at least two passages, spheres of neural precursor cells were plated on coated coverslips and maintained in culture for up to 6 weeks. Whole-cell p atch recordings were made using standard current clamp techniques. Immature action potentials were observed within hours of plating for both SC and SV Z cells. Input resistance and time constants decreased over the first week after plating and no further changes were found at later times. At similar times following plating, however, SVZ cells had a lower input resistance an d shorter time constant compared to SC cells. SVZ cells also had higher res ting membrane potentials and smaller after hyperpolarizations than those of SC cells, despite no significant difference in the amplitude of action pot entials. Neither the SC nor the SVZ cells were capable of eliciting more th an a single action potential in response to injected current. While all SC cells tested were depolarized by glutamate, the response of SVZ cells to gl utamate varied considerably. This study revealed that neural precursor cell s from SC and SVZ differ in both active and passive membrane properties. It appears also that the electrophysiological development of SC and SVZ precu rsor-derived neurons is incomplete under the conditions used. These observa tions suggest that the neural precursor cells from different anatomical loc ations may be physiologically diverse and may exhibit some differences in c ommitment toward neuronal or glial phenotypes. (C) 1999 Academic Press.