FIG. 6.

Electrophysiological profile of differentiated cells derived from iPSCs. Using the nystatin configuration of the patch-clamp electrophysiology method, both inward and outward currents were recorded in differentiated cells. In some cells, a distinct inward current starting at −30 mV and terminating around −10 mV (A) was observed. Inset depicts a typical current profile of voltage steps from −100 mV to +80 mV. During current-clamp studies, neuronal-like cells were observed to have reversible depolarizing transients that were sensitive to bath application of the voltage sensitive Na+ channel blocker tetrodotoxin (TTX 0.5 mM) (B). After electrophysiological experiments, the cells were backfilled with Lucifer yellow [(C) green) and cells were found to be immunopositive for the neuronal marker β-3 tubulin (red). In contrast, glial cells did not exhibit any inward current profile, although they did show current/voltage relationships typical for oligodendroglial precursor cells [OPC; (D)], mature oligodendrocytes (E), and astrocytes (F). After electrophysiological recordings, cells were backfilled with Lucifer yellow (LY; green). Cells were identified as being OPCs when stained positive for PDGFα-R [(D); red), as mature oligodendrocytes when positive for myelin basic protein [(E); MBP; red], or astrocytes when positive for GFAP [(E); red]. Table (G) summarizes the electrophysiological profile of the above cells indicating resting membrane potential (Em in mV), input resistance (MΩ), membrane capacitance (pF), and number of cells recorded (N).