Haptotactic and growth stimulatory effects of fibrin(ogen) and thrombin on cultured fibroblasts

We tested the ability of purified, ultraviolet C virally inactivated components of human fibrin sealant (FS) to modulate the chemotaxis, adherence, 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 factor of 1.5 to 1.8, whereas fibrinogen (Fib) exerted only a minimal proliferative effect. We developed a new cell haptotactic/attachment assay by using Thr and Fib covalently bound to Sepharose beads (SBs). The kinetics of cell binding were approximately equivalent for beads coated with either protein. Uncoated SBs or fibrinogen-bound SBs (Fib-SB) pretreated with plasmin did not attract HFs. alpha Thr-SB induced a positive migratory response that was not affected by blocking its proteolytic site, whereas gamma Thr-SB elicited no response. X irradiation of HFs at a dose of 6 Gy showed that the migratory response of HF is independent of proliferation, as confirmed by a bromodeoxyuridine uptake assay. Several types of cultured cells (murine fibroblasts, smooth muscle cells, aortic endothelial cells, and murine mammary carcinoma cells) also attached to Fib-SB. By contrast, human keratinocytes, human ovarian carcinoma cells, murine macrophage-like cells, leukemic cells, and murine mast cells did not attach, Our results provide some mechanistic insights into the haptotactic and proliferative effects of Fib and Thr on different cells.