Fig. 2

Alkaloid extract of YHS inhibited migration, sprouting and tube formation of HUVECs (a) Representative images from a time-lapse sequence (0, 12 and 24 h) of HUVECs migrating to heal a wound scratched in a monolayer following the treatment of various concentrations of alkaloid extract of YHS in the presence of VEGF, scale bar: 250 μm. b Quantification of HUVEC horizontal migration. The migration of cells toward the wounds represents percentage of wound width. Wound width at time zero (t = 0 h) was set as 100%. Data are presented as mean ± SEM. **, P < 0.01; *, P < 0.05, paired t-test. c Representative images of vertical migration of HUVECs after exposure to (a) 0 μg/ml; (b) 10 μg/ml; (c) 50 μg/ml; (d) 100 μg/ml of alkaloid extract of YHS. Migrated cells stained with crystal violet were imaged with an inverted bright field microscopy, scale bar: 100 μm. d Quantification of HUVEC vertical migration by quantifying the number of migrated cells. Relative migrated cell number of HUVECs treated with 0 μg/ml alkaloid extract of YHS was set as 100%. Data are presented as mean ± SEM. **, P < 0.01; *, P < 0.05, paired t-test. e Representative images of spheroid formed by HUVECs after exposure to (a) 0 μg/ml; (b) 10 μg/ml; (c) 50 μg/ml; (d) 100 μg/ml of alkaloid extract of YHS in the presence of VEGF, scale bar: 100 μm. f Quantitative analysis of the number of sprouts. Data are presented as mean ± SEM. **, P < 0.01; *, P < 0.05, paired t-test. g Quantification of cumulative sprouts length. Data are presented as mean ± SEM. **, P < 0.01; *, P < 0.05, paired t-test. h Representative images of HUVEC tube formation after exposure to (a) 0 μg/ml; (b) 10 μg/ml; (c) 50 μg/ml; (d) 100 μg/ml of alkaloid extract of YHS, scale bar: 100 μm. i Quantitative analysis of tube length. Relative tube length of HUVECs treated with 0 μg/ml alkaloid extract of YHS was set as 100%. Data are presented as mean ± SEM. ****, P < 0.0001; *, P < 0.05, paired t-test