Figure 2. Electrophysiological analysis of EGFP⁺NG2⁺ cells after spinal cord injury indicates an OPC-like phenotype.

A. Immunostaining for NG2 and PDGFα R identifies EGFP⁺ OPC-like cells. Expression of PDGFαR was observed on NG2 cells, but was weak and limited to the cell body. After electrophysiological analysis, cells were filled with biocytin (red) for post-hoc immunocytochemical analysis to distinguish between EGFP⁺NG2⁺ (blue, top panels) and EGFP⁺O4⁺ (blue, bottom panels) stage cells, and to confirm identification of EGFP⁺NG2⁺ cells.

B. Proliferative electrophysiological phenotype of EGFP⁺NG2⁺ cells in the rostral spinal cord of uninjured and injured animals at 3 DPI. Representative traces from EGFP⁺NG2⁺ cells depicting total outward current (K_A + K_DR, top panel), isolated K_DR (middle panel) and isolated K_A (bottom panels) for control (left panels) and 3-day injured (right panels) cells.

C. Current-voltage curves constructed from a series of depolarizing voltage steps from −70mV to 70 mV; 10mV increments. Holding potential was −60mV. For isolation of K_A, K_DR amplitude was digitally subtracted from the total outward current. For K_DR, this followed a pre-pulse to −40mV to inactivate K_A. All values are after junction potential correction. N = 32 cells for control, and 32 cells for injured. Prior to recording, series resistance compensation to at least 75% was performed. Symbols represent mean ± SEM.