Human neural stem cells: electrophysiological properties of voltage-gated ion channels

We have characterized the profile of membrane currents in an immortalized human neural stem cell line, HBI.F3 cells, using whole-cell patch clamp technique. Human neural stem cell line generated from primary cell cultures of embryonic human telencephalon using a replication-incompetent retroviral vector containing v-myc expresses nestin, a cell type-specific marker for neural stem cells. The human neural stem cells expressed both outward and inward K+ currents with no evidence for Na+ currents. The density of the outward, delayed rectifying type K+ current was 1.8+/-0.015 nA/pF, and that of the inwardly rectifying K+ current was 0.37+/-0.012 nA/pF (at 30 mM of [K+](o)). In order to induce neuronal differentiation of the neural stem cells, a full-length coding region of NeuroD, a neurogenic transcription factor, was transfected into HBI.F3 cells. Introduction of NeuroD induced expression of Na+ currents with the current density of 0.042+/-0.011 nA/pF. The presence of two types of K+ currents and expression of Na+ currents induced by NeuroD appear to reflect the characteristic physiological features of human neural stem cells.