Rheological studies on blood coagulation and network formation of fibrin

Formation of fibrin gel in fibrinogen-thrombin system: static and dynamic light scattering study

The dynamics of thrombin-induced fibrin gel formation was investigated by means of static and dynamic light scattering. The decay time distribution function, obtained by the dynamic light scattering, clearly revealed a stepwise gelation process: the formation of fibrin and protofibril from fibrinogen followed by the lateral aggregation of protofibrils to form fibrin fibers and the formation of a three-dimensional network consisting of fibers. This conversion process was correlated with the angular dependence of the scattered light intensity (static light scattering). The correlation function of dynamic light scattering was analyzed in terms of sol-gel transition and gel structure. The correlation function showed a stretched exponential type behavior before the sol to gel transition point, and it showed a power law behavior at the gelation point.

Antithrombogenicity of cultured endothelial cell-detached surface

To examine the antithrombogenicity of cultured endothelial cell-detached surface, a simple hybrid vascular model tube consisting of a glass tube and endothelial cells was constructed. To detach the endothelial cells from the inner surface of the model tube, a steady shear stress of 2 or 8 N m(-2) was imposed onto the surface of endothelial cell monolayer by means of a coaxial double cylinder rotational-type apparatus. Coagulation of blood in contact with the endothelial cell-detached surface was examined using a damped oscillation rheometer. Coagulation of whole blood in the cell-detached tube occurred at about 40 min, which was almost the same as that in the endothelial cell-coated tube. A few platelets without shape change adhered to the endothelial cell-detached surface. These data suggest that the endothelial cell-detached surface may exhibit antithrombogenic and anticoagulant surfaces. Biochemical analyses showed that the glass surface, where endothelial cell was detached, was covered with components such as collagen type IV that is considered to be produced from the endothelial cells on the glass surface.