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. Author manuscript; available in PMC: 2013 Oct 21.
Published in final edited form as: Cell Stem Cell. 2012 Jun 28;11(2):264–278. doi: 10.1016/j.stem.2012.04.027

Figure 3. iPSCs can be Differentiated into Mature, Electrophysiologically Active Neurons Susceptible to Glutamate Toxicity.

Figure 3

(A) HD180i, HD60i and HD33i lines differentiated for 14 days were positive for MAP2a/b and GABA (Scale bar 50µm). (B) Current density (pA.pF−1) versus voltage (mV) relationships for the outward, voltage-activated currents of the exemplar conventional whole-cell recording shown in the inset in normal extracellular solution (ECS) and after isoosmotic addition of 20 mM tetraethylammonium chloride (TEA). Holding potential = −70 mV. (C) Current density (pA.pF−1) versus voltage (mV) relationships for the inward, voltage-activated currents of the same cell as in (B) in the presence of ECS and after isoosmotic replacement of Na+ with N-methyl D glutamine (NMDG). The exemplar family of Na+ currents in the inset was recorded in the presence of 20 mM TEA and is displayed on a fast time base. Holding potential = −70 mV. (D) Current (pA) versus voltage (mV) relationships, evoked using a voltage-ramp protocol, for currents carried by Ba2+ (27 mM, isoosmotic replacement of NaCl, Ba2+) in the absence and presence of 2 mM of the Ltype Ca2+ channel blocker, nifedipine (Ba2+ + Nif). Holding potential = −110 mV. (E) Current density (pA.pF−1) versus voltage (mV) relationship for Cl− currents activated by 300 mM GABA. The inset shows a family of GABA-activated currents recorded at the voltages shown in the main panel; GABA application is indicated by the bar above the traces shown and the voltage was stepped from −60mV to the voltages indicated in the main panel at the point indicated by the arrow. Holding potential = −70 mV. (F) Typical evoked action potential (upper trace) recorded under current-clamp in the conventional whole-cell patch-clamp configuration during the current injection shown in the lower trace (from 0 to + 120 pA). (G) Example of spontaneous action potential activity recorded under current-clamp (I = 0 mV) in the conventional whole-cell patch-camp configuration. (H,I) Staining for cleaved caspase 3 revealed increased apoptotic death in the HD180i.5 line over time compared with the control line HD33i.8 (p< 0.05, Students t-test).