Effect of factor VIII on tissue factor-initiated spatial clot growth.

Using time-lapse videomicroscopy, we studied the role of coagulation factor VIII (fVIII) in tissue factor-initiated spatial clot growth on fibroblast monolayers in a thin layer of non-stirred recalcified plasma from healthy donors or patients with severe Haemophilia A. Analysis of temporal evolution of light-scattering profiles from a growing clot revealed existence of two phases in the clot growth-initiation phase in a narrow (0.2 mm) zone adjacent to activator surface and elongation phase in plasma volume.

Hemophilia A and B are associated with abnormal spatial dynamics of clot growth.

To gain greater insight into the nature of the bleeding tendency in hemophilia, we compared the spatial dynamics of clotting in platelet-free plasma from healthy donors and from patients with severe hemophilia A or B (factor VIII:C or IX:C<1%). Clotting was initiated via the intrinsic or extrinsic pathway in a thin layer of nonstirred plasma by bringing it in contact with the glass or fibroblast monolayer surface. The results suggest that clot growth is a process consisting of two distinct phases, initiation and elongation.