Characterizing Human Ion Channels in Induced Pluripotent Stem Cell–Derived Neurons

Neurons derived from human-induced pluripotent stem cells were characterized using manual and automated patch-clamp recordings. These cells expressed voltage-gated Na+ (Nav), Ca2+ (Cav), and K+ (Kv) channels as expected from excitable cells. The Nav current was TTX sensitive, IC50 = 12 ± 6 nM ( n = 5). About 50% of the Cav current was blocked by 10 µM of the L-type channel blocker nifedipine. Two populations of the Kv channel were present in different proportions: an inactivating (A-type) and a noninactivating type. The A-type current was sensitive to 4-AP and TEA (IC50 = 163 ± 93 µM; n = 3). Application of γ-aminobutyric acid (GABA) activated a current sensitive to the GABAA receptor antagonist bicuculline, IC50 = 632 ± 149 nM ( n = 5). In both devices, comparable action potentials were generated in the current clamp. With unbiased, automated patch clamp, about 40% of the cells expressed Nav currents, whereas visual guidance in manual patch clamp provided almost a 100% success rate of patching “excitable cells.” These results show high potential for pluripotent stem cell–derived neurons as a useful model for drug discovery, in combination with automated patch-clamp recordings for high-throughput and high-quality drug assessments at human neuronal ion channels in their correct cellular background.