VASCULAR ENDOTHELIAL GROWTH-FACTOR EXPRESSION IN EXPANDED TISSUE - A POSSIBLE MECHANISM OF ANGIOGENESIS IN TISSUE EXPANSION

Vascular endothelial growth factor (VEGF) is a major angiogenic growth factor. Angiogenesis stimulated by VEGF occurs in several important c linical contexts, including myocardial ischemia, retinal disease, and tumor growth. The level of VEGF is increased in several skin disorders and is stimulated by ischemia. Tissue expansion has been shown to ind uce angiogenesis and ischemia on the overlying skin. We therefore inve stigated the hypothesis that VEGF was expressed in expanded tissue. Th ree samples of skin were obtained from five patients who sustained rec onstruction with tissue expansion. One sample was taken on the implant ation site of the expander before implantation. Two samples were taken at the time of removal, respectively, one on the nonexpanded skill ad jacent to the expanded area and one on the expanded skin on the site o f expansion. On these samples we performed immunolocalization of VEGF. Mouse monoclonal antibody was used, recognized with rabbit anti-mouse immunoglobulin alkaline phosphatase-anti-alkaline phosphatase (APAAP) complex conjugated and revealed with naphthol red. Our results showed clearly an increased number of cells that fixated VEGF antibody on th e site of expansion. Cell counts revealed that the numbers of cells ex pressing VEGF were statistically higher in expanded tissue than in non expanded tissue. Before expansion skin specimens did not express VEGF. These findings are the first to show the presence of a growth factor in expanded tissue. They open a new field of research on the biologica l explanation of tissue-expanded angiogenesis.