The effect of growth factors, cytokines, and extracellular matrix proteinson fibronectin production in human vascular smooth muscle cells

Purpose: Although 60% to 80% of the mature intimal hyperplastic plaque is c omposed of extracellular matrix (ECM) proteins, little is known about the f actors that stimulate smooth muscle cells (SMCs) to produce these proteins. A major component of the ECM protein is fibronectin. Thus we studied fibro nectin production and its response to various growth factors, cytokines, an d other ECM proteins that are released at the time of vascular injury. Methods: Quiescent cultured human SMCs were stimulated for varying interval s with increasing concentrations of agonist. Fibronectin in the cell medium was assayed by immunoblotting with a fibronectin-specific antibody. Results: After 72 hours of stimulation, transforming growth factor-beta (10 ng/mL) had the most profound effect on fibronectin production (9.6- +/- 2. 1-fold; P < .05), followed by epidermal growth factor (100 ng/mL; 5.0- +/- 0.1-fold; P < .05, for both). Surprisingly, the platelet-derived growth fac tors (AA, AB, and BE) and fibroblast growth factor did not stimulate fibron ectin production. Among the matrix proteins studied, only collagen type I ( 20 mu g/mL) stimulated fibronectin production (1.9- +/- 0.1-fold; P < .05), whereas collagen type TV and laminin had no effect. The contractile protei n angiotensin II (100 ng/mL) was a weak stimulant of fibronectin (1.6- +/- 0.2-fold; P < .05). Time course studies of fibronectin production up to 72 hours revealed kinetics that varied with each agonist. Transforming growth factor-p stimulated significant early production of fibronectin, whereas fi bronectin production in response to epidermal growth factor and collagen ty pe I was initially modest but increased with time. The effect of angiotensi n II did not become evident until 72 hours. Conclusion: Cytokines, growth factors, and matrix proteins have varying qua ntitative effects on ECM protein production by human vascular SMCs. Knowled ge of the factors that influence ECM protein production may allow for the d esign of specific inhibitors that can prevent intimal hyperplasia.