Figure 2.

Kaempferol promotes VEGF-mediated endothelial cell proliferation, cell migration, and tube formation. (A) Different concentrations of kaempferol were applied onto endothelial cells for 48 h, and MTT assay and LDH cytotoxicity assay were determined. (B) HUVECs were seeded onto a 96-well plate at 5,000 cells/well and treated with kaempferol for 48 h with or without VEGF. (C) In cell migration assay, HUVECs at 20 × 10⁴ cells/well were plated onto a 12-well plate. A wounded endothelial cell monolayer was created manually at the bottom of wells, and images representing recovery of wounds were taken at 0 and 8 h, separately, by a phase-contrast microscope. HUVECs were incubated with VEGF, with or without kaempferol or Avastin. In tube formation assay, endothelial cells were seeded onto a 12-well plate at 20 × 10⁴ per well. The well was pre-coated with matrigel. VEGF, together with or without kaempferol, was applied to treat cells for 8 h. To quantify the images of tube formation, three fields in one photo were randomly selected, and branching points were determined manually. In all experiments, VEGF was at a concentration of 5 ng/ml, and Avastin (a positive control) was set at 200 μg/ml. Data are demonstrated as mean ± SEM of the percentage of change as compared to control group, where n = 4; p < 0.05 *p < 0.01 **p < 0.001 (***) vs VEGF-treated group. Bar = 40 μm. MTT, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide; HUVEC, human umbilical vein endothelial cell.