Applied Electric Fields Polarize Initiation and Growth of Endothelial Sprouts

Figure 5

DC EFs polarize endothelial sprouts. (a1–e1) Superimposed sprout tracings display increasing anodal polarization with EF strength (origin = white disk). Insets display the relative distribution of all sprouts for each 30° region of each condition. C: cathode; A: anode. (a2) Regional comparison of relative sprout distribution in the absence of EFs (100 • Σ sprout length per region/Σ sprout length for all regions). (b2–e2) Relative distribution of EF-exposed sprouts (red) normalized to the relative sprout distribution determined in the absence of EFs (black) for each condition. (a3) The average sprout length (μm) remains the same for all regions in the absence of EFs. (b3–e3) EFs decrease average relative sprout length (red) compared to sprouts grown simultaneously in the absence of EFs (black). (a4) Sprouts were traced using the line segment tool in ImageJ and used to determine the values between the initial segment () and the final segment () of each sprout. (b4–e4) Relative average turning of EF-exposed sprouts (red) normalized to sprout turning determined in the absence of EFs (black). Cathodal turning (<1), no net turning (=1), anodal turning (>1). One-tailed t-tests were used to assess statistical significance for increased () or decreased (∘) growth or turning (one symbol, ; two symbols, ; three symbols, ).