Fig. 4.

Electrophysiology and in vivo grafting of CB-derived neurons. (A) Representative fluorescence micrograph of CB-derived neurons in culture expressing Synapsin::DsRed. (Scale bar, 10 μm.) (B and C) Whole-cell recordings obtained in vitro. (B) Transient Na⁺ currents and sustained K⁺ currents in response to voltage step (cell voltage-clamped at −70 mV while transient steps at 5-mV increments were applied). The trace highlighted in red was obtained in response to a step of +45 mV from resting −70 mV. (C) Action potentials evoked by somatic current injections (cell current-clamped at approximately −70 mV, currents from 50 to 150 pA at 50-pA steps). (D) Spontaneous action potentials when the cell was current-clamped at −60 mV. (E) CD133⁺ cells grafted in the hippocampus, as controls, did not integrate into the host tissue and did not express the neuronal markers TUJ-1 (arrow). (F) Representative image of CB-derived neurons 4 wk after transplantation show increase in colocalization with the mature neuronal marker NEUN (arrow). (Scale bars, 50 μm.) (G) Quantification of percentage of CB-derived neurons positive for TUJ-1 and NEUN 4 wk after transplantation. (H) Detail of a GFP⁺ CB-derived neuron 3 mo after transplantation shows extensive arborization and colocalization with the mature neuronal marker NEUN. (Scale bar, 50 μm.) (I–K) Whole-cell recordings obtained from a GFP⁺ CB-derived neuron 3 mo after its transplantation in a young mouse hippocampus from cell represented in I demonstrate that CB-derived neural progenitors can develop into functional neurons and survive in the mouse brain. (J) Action potentials evoked by somatic current injections [cell current-clamped at approximately −70 mV (−2 pA) while increments of 2 pA were applied]. (K) Transient Na⁺ currents and sustained K⁺ currents in response to voltage step (cell voltage-clamped at −70 mV while transient steps at 5-mV increments were applied). The traces highlighted in red were obtained in response to steps of +20 pA (J) or +45 mV (K).