Mast cells and their secretory granules are angiogenic in the chick embryo chorioallantoic membrane

Background Many data suggest that the density of mast cells is highly correlated with the extent of both normal and pathological angiogenesis. Objective In this study we have compared in an in vivo assay, the chick embryo chorioallantoic membrane, the angiogenic potential of mast cell suspensions isolated from rats, degranulated mast cells and their secretory granules. Methods Gelatin sponges adsorbed with cell suspensions of rat mast cells, degranulated mast cells and their secretory granules were implanted on the top of the chorioallantoic membrane at day 8 of incubation. At day 12 the angiogenic response was evaluated macroscopically, microscopically and by a morphometric method of 'point counting'. Results Isolated mast cells and their secretory granules, but not degranulated mast cells, induced an angiogenic response in the chorioallantoic membrane. The addition of antifibroblast growth factor-2 or antivascular endothelial growth factor antibodies reduced the angiogenic response of both mast cells and their secretory granules by 50% and 30%, respectively. Conclusion These data support the evidence that the angiogenic properties of mast cells depend on the angiogenic molecules contained in their secretory granules and indicate that fibroblast growth factor-2 and vascular endothelial growth factor are the angiogenic cytokines primarily and perhaps synergistically responsible for this vasoproliferative activity.