PGE2 promotes angiogenesis. (A-B) PGE2 promotes the in vitro tube formation. HMVECs were seeded on growth factor–reduced Matrigel-coated wells in the absence or presence of PGE2 or VEGF. The tube formation images at 50× magnification in the central field of the well were taken 6 hours later (A), and the branching points were counted with ImageJ software (National Institutes of Health). (B) Each point represents the mean ± SEM of 3 experiments performed in triplicate. (C-D) PGE2 promotes angiogenesis. Fertilized chicken eggs were incubated for 10 days, and CAMs were treated with PGE2 (1μM) or VEGF (100 ng/mL) twice per day for a total of 3 days. Blood vessel images at a 50× magnification were photographed (C), and branching points quantified with the ImageJ software (National Institutes of Health; D). The experiments were initiated with 12 eggs for each group and were culminated with 4-6 evaluable CAMs. Each point represents the mean ± SEM of 3 independent experiments. (E-F) PGE2 promotes aortic ring vessel outgrowth. Mouse thoracic aorta were sectioned into 1-mm rings and placed into growth factor–reduced Matrigel-coated wells. The rings were treated daily with PGE2 (100nM) or VEGF (50 ng/mL) for a total of 6 days, and 50× magnification images were recorded. The area of the cell outgrowth was quantified with the ImageJ (National Institutes of Health). (F) Two rings per aorta from a total of 4 aortas were used for each group, and the assay was repeated 3 times. Each point represents the mean ± SEM of 5 evaluable outgrowths. (B,D,F) *P < .05 and **P < .01 versus vehicle groups.