Figure 1.

EFs induce collective electrotaxis of large epithelial sheets that maintain cell-cell junctions

(A) Phase contrast image of a square cell sheet. Scale bar = 500 μm.

(B and C) Collective electrotaxis demonstrated by contour assay showing color-coded edge position of cell sheets. Color coding from blue (0 h) to yellow (6 h). Arrows indicate overall edge migration direction and distance. An EF guided directional migration of the cell sheet downward (C), whereas a control cell sheet without EF expanded in all directions (B). Polarity and strength of the field as shown.

(D–G) Collective electrotaxis of whole cell sheets is shown by the trajectories of the geometric center (centroid) of cell sheets (n = 6) (D, E). Y axis displacement (F), directionality along the field line (G), as a function of time. Directionality is calculated as cosθ, where θ is the angle between each centroid trajectory and the electric field line. Data are represented as mean ± SEM from 6 independent experiments. A positive value of cosθ indicates migration to the anode; negative to the cathode, and zero indicates random direction.

(H–K) EFs maintained cell sheet geometry by suppressing the dispersal of cells. Quantification of area increase (H-I), y axis expansion (J), and x axis expansion (K). (∗∗p < 0.01). Data are represented as mean ± SEM from 6 independent experiments. See also Figure S1 and Video S1.