Effects of Dll4 overexpression on endothelial cell migration and extracellular matrix-dependent cord formation. (A) VEGF-A (100 ng/mL)- and bFGF (100 ng/mL)-induced transwell migration of control and Dll4-overexpressing HUVECs (5 × 105 cells/well) over 16 to 20 hours of incubation. The results reflect the mean fold increase (± SEM) in cell migration compared with medium alone in 3 experiments performed in triplicate. (B) Representative images reflecting cord formation by control and Dll4-overexpressing HUVECs (4-7.5 × 104 cells/well) plated in complete culture medium on matrigel-coated wells (24-well plate) and incubated 16 to 18 hours. Phase-contrast microscopy (original magnification, × 10). (C) Quantitative analysis of matrigel-induced cord formation in control and Dll4-overexpressing HUVECs. Cord formation was measured as a function of the number of cord angles per visual field (phase-contrast microscopy, 4 × magnification). The results represent the mean (± SD) from 8 independent experiments. *P = .001.
