Figure 5
hCBiPSCs maturated into functional neurons in vitro . All functional analyses were conducted with the hCBiPSC line K2. (A-C) Voltage-activated sodium and potassium currents were recorded in the whole-cell voltage-clamp mode by increasing depolarizing steps of 10 mV from a holding potential of -70 to 40 mV. (A) Cells showed potassium outward currents (IK) that were inhibited by application of tetraethylammonium (TEA, 10 mM, n = 18). (B) Sodium inward currents (INa) could be completely blocked by tetrodotoxin (TTX, 1 μM, n = 8). (C) The current-voltage plot indicates the activation of IK between -30 and -20 mV. INa were activated between -40 and -20 mV with a current peak at -10 to 0 mV. Current amplitudes were normalized for cell capacitances and are calculated as means ± SEM. (D) Action potentials were elicited by a depolarizing current step of 100 pA in current-clamp mode and inhibited by application of 1 μM TTX (n = 7). Voltage-gated ion channel, passive membrane and action potential properties are summarized in Table 1. hCBiPSC, human cord blood induced pluripotent stem cells; SEM, standard error of the mean.