Fig. 3
Current generation by mHCN2-expressing cells and their electrical coupling. Human mesenchymal stem cells (hMSCs) expressing mHCN2 (green) abutted (a) and connected through tunneling nanotubes (TNTs) (b, c). (inset c) GJ-based electrical coupling between cells also could be achieved by intersection of lamellipodia extensions. d and inset d TNTs between hMSCs containing F-actin, and Cx43-based GJs between hMSC-1 and the lamellipodium of hMSC-2. I f current was measured in mHCN2-expressing hMSCs (e, lower panel) by hyperpolarizing the cells from Vh = −40 mV for 5 s to voltages between −50 and −140 mV in 10 mV increments (e, upper panel). I f current was absent in non-transfected or transfected with empty vector hMSCs (e, middle panel). f Typical experiment showing the measurement of electrical coupling between two hMSCs connected through TNT (shown in b). gT/VT plot (f, lower panel) was obtained by measuring the Ij response (f, middle panel) in the hMSC-2 to the voltage ramp of negative polarity from 0 to −120 mV (f, upper panel) applied to the hMSC-1 with its symmetric counterpart at positive Vjs. The co-culture of mHCN2-transfected (green fluorescence) and non-transfected hMSCs (not fluorescent) was investigated