ANGIOGENIC ROLE OF ENDOGENOUS BASIC FIBROBLAST GROWTH-FACTOR RELEASEDBY RAT AORTA AFTER INJURY

The autocrine role of basic fibroblast growth factor (bFGF) in angioge nesis was studied in the rat aortic ring-collagen gel model using seru m-free culture conditions. Immunohistochemical staining of the rat aor ta showed bFGF in the cytoplasm of endothelial and smooth muscle cells . Aortic rings mechanically injured during the dissection procedure re leased bFGF, which was demonstrated in the conditioned medium by slot and Western blot analysis. bFGF-containing aorta-conditioned medium an d purified bFGF increased both the number and length of microvessels s prouting from the explants. This effect was particularly evident durin g the second week of culture, when the release of endogenous bFGF was minimaL Neutralizing anti-bFGF antibodies induced a 40% reduction of a ngiogenesis. Regression of microvessels, which regularly occurred towa rd the end of the second week, was prevented by purified bFGF. These d ata support the idea that bFGF released by vascular cells plays an imp ortant role in the autoregulation of angiogenesis after injury.