Stimulation of human monocyte/macrophage-derived growth factor (MDGF) production by plasma fibronectin

Culture supernatants from human peripheral blood monocytes, isolated free of platelet contamination and cultured in the absence of serum, stimulate DNA synthesis and cell growth in Balb/c 3T3 fibroblasts and bovine aortic smooth-muscle cells. Monocytes cultured in serum-free medium for 24 hours with plasma fibronectin, added as either a surface-attached or soluble molecule, secrete significantly increased amounts of growth-promoting activity. Fibronectin also stimulates an increase in intracellular growth factor content and in protein synthesis by monocytes. Both the enhanced growth-promoting activity and protein synthesis are inhibited by cycloheximide. Thus, fibronectin-monocyte interactions may influence the production of growth-promoting activity by monocytes and contribute to fibroblast and smooth-muscle replication in wound healing, chronic inflammation and atherosclerosis.