Fucoidan inhibits angiogenesis in vivo. (A,B) Effects of dextran and fucoidan on VEGF-induced angiogenesis in Matrigel plugs. Mice bearing Matrigel plugs containing VEGF plus heparin or PBS alone were injected daily intraperitoneally for 6 days with dextran or fucoidan (1 mg/mouse per day). After the plugs were fixed and immunostained for CD31/PECAM, endothelial cell density was evaluated microscopically (Nikon Eclipse E600) equipped with a DIC M 20×/0.75 Nikon lens (Nikon, Tokyo, Japan). Images were imported into IPLab software, and the area occupied by CD31⁺ cells was quantified. The results are expressed as mean (± SD) surface areas (μm²) occupied by CD31⁺ cells within a unit area (10⁶ μm²). In panel A, the 2 groups consisted of 5 C57BL/6J 7-week-old female mice; in panel B, the 4 groups consisted 6 BALB/cAnNCr 6-week-old female mice. (C,D) Effects of dextran and fucoidan on tumor growth in mice. Mean (± SEM) (C) tumor size (expressed in square millimeters) and (D) tumor weight (expressed in grams) in the 2 groups of 15 female BALB/cAnNCr 6-week-old mice inoculated subcutaneously with 10⁷ MOPC315 tumor cells and subsequently treated daily for 7 days with dextran or fucoidan. (E) Vascular infiltration in tumor tissues from mice treated with dextran or fucoidan was quantified using IPLab software after immunohistochemical staining for CD31. The results are expressed as the mean (± SD) surface areas occupied by CD31⁺ cells within a unit area (μm²/10⁶ μm²). (F) Representative images reflecting CD31/PECAM immunostaining of tumor tissues from mice treated with dextran (left panel) or fucoidan (middle and right panel). CD31 is displayed in red; DAPI nuclear staining in blue. Original magnification 20×.