Basic fibroblast growth factor increases tissue factor expression in circulating monocytes and in vascular wall

Background-Basic fibroblast growth factor (bFGF) promotes vascular repair a nd angiogenesis and can induce in vitro tissue factor (TF), a potent agent initiating thrombogenesis, which probably plays a role in angiogenesis. We investigated whether bFGF administration induced TF expression by monocytes and vascular cells. Methods and Results-We studied TF expression in normally fed (n=16) and cho lesterol-fed (2% for 6 weeks, n=16) rabbits. Animals were then randomized t o receive intravenous bFGF (2.5 mu g twice weekly for 3 weeks) or saline in jections. TF expression was evaluated in mononuclear cells from arterial bl ood and in aortic sections by an immunohistochemical assay using a monoclon al anti-rabbit TF antibody (activator protein 1). Monocyte TF expression wa s increased by bFGF administration in both normal and hypercholesterolemic rabbits (129+/-45 versus 19+/-3 mU TF/1000 monocytes, P<0.05, and 31+/-12 v ersus 7+/-1 mU TF/1000 monocytes, P<0.005, respectively) and was further in creased by stimulation of monocytes by endotoxin in vitro. TF expression wa s lower in hypercholesterolemic rabbits than in normal rabbits. In the medi a of the vascular wall, bFGF induced strong TF expression in normal rabbits and only weak TF expression in hypercholesterolemic ones. Conclusions-This study demonstrates that systemic administration of bFGF in duces an impressive increase of TF expression in circulating monocytes and in the vascular wall in normal and to a lower extent in hypercholesterolemi c rabbits. The significance of this observation in terms of inducing thromb osis in vivo needs clarification.