Summary
Fucoidan, a sulfated polysaccharide extracted from brown seaweeds, has antithrombotic
properties, the mechanism of which is not yet completely understood. Tissue factor
pathway inhibitor (TFPI), which regulates the tissue factor-dependent pathway of blood
coagulation, is released from the endothelium by heparin, a mechanism contributing
to its antithrombotic activity. In this study, we demonstrated that fucoidan, as heparin,
induces TFPI release from cultured human umbilical vein endothelial cells (HUVEC).
The TFPI accumulation in the HUVEC supernatants depends on the incubation time and
polysaccharide concentration. After 30 to 60 minutes of incubation, TFPI concentration
(total antigen level) was twice higher in the presence of both polysaccharides than
in their absence. After one hour of incubation, in the presence of increasing concentrations
of each polysaccharide, an optimal stimulation was observed for 0.5 μg/ml of fucoidan
and 5 μg/ml of heparin, as evidenced by a raise of the basal TFPI level: a 2-fold
increase for the total antigen and a 3-fold increase for the free antigen. These data
suggest that TFPI released from vascular endothelial cells may contribute to the antithrombotic
effect of fucoidan.
