HAPTOTACTIC AND GROWTH-STIMULATORY EFFECTS OF FIBRIN(OGEN) AND THROMBIN ON CULTURED FIBROBLASTS

We tested the ability of purified, ultraviolet C virally inactivated c omponents of human fibrin sealant (FS) to modulate the chemotaxis, adh erence, and proliferation of cultured cells. A fibrin clot formed on a near-confluent layer of human fibroblasts (HFs) recruited cells from the surrounding area. Thrombin (Thr) enhanced HF proliferation by a fa ctor of 1.5 to 1.8, whereas fibrinogen (Fib) exerted only a minimal pr oliferative effect. We developed a new cell haptotactic/attachment ass ay by using Thr and Fib covalently bound to Sepharose beads (SBs). The kinetics of cell binding were approximately equivalent for beads coat ed with either protein. Uncoated SBs or fibrinogen-bound SBs (Fib-SB) pretreated with plasmin did not attract HFs. alpha Thr-SB induced a po sitive migratory response that was not affected by blocking its proteo lytic site, whereas gamma Thr-SB elicited no response. X irradiation o f HFs at a dose of 6 Gy showed that the migratory response of HF is in dependent of proliferation, as confirmed by a bromodeoxyuridine uptake assay. Several types of cultured cells (murine fibroblasts, smooth mu scle cells, aortic endothelial cells, and murine mammary carcinoma cel ls) also attached to Fib-SB. By contrast, human keratinocytes, human o varian carcinoma cells, murine macrophage-like cells, leukemic cells, and murine mast cells did not attach, Our results provide some mechani stic insights into the haptotactic and proliferative effects of Fib an d Thr on different cells.