The role of recombinant factor VIIa(FVIIa) in fibrin structure in the absence of FVIII/FIX

Research output: Contribution to journalArticle


Patients with hemophilia have an impaired thrombin Generation and therefore form loose fibrin hemostatic plugs that are easily dissolved by fibrinolysis. This prevents maintained hemostasis in these patients, resulting in a severe bleeding disorder. Recombinant (F)VIIa has been shown to enhance thrombin generation on already thrombin-activated platelets in the absence of FVIII and FIX. An efficacy rate of 80-90% has been found in hemophilia patients with inhibitors against FVIII or FIX both in association with major surgery and in the treatment of serious bleedings. In a model measuring fibrin clot permeability in a platelet-containing system described by Blomback et at. (1994) this was demonstrated to be dependent on the concentration of FVIII and FIX. The addition of rFVIIa in concentrations of 1.9. 4.8 and 9.6 mug mL (-1) normalized fibrin clot permeability. The concentration of 1.9 mug mL (-1) of rFVIIa normalized clot permeability in this system and the higher concentrations of rFVIIa added only slightly to the effect. No further decrease in clot permeability was found when rFVIIa in a concentration of 1.9 mug mL (-1) was added to a sample with a normal concentration (100%) of FVIII or FIX. Higher concentrations of rFVIIa added to the plasma containing 100% of FVIII or FIX induced only a slight further decrease of fibrin permeability constant, arguing against any unwanted effect of extra rFVIIa on clot permeability in the case of a normal hemostasis. Furthermore, the fibrin network was studied with 3D microscopy and the loose network found in the absence of FVIII or FIX increased in density with increasing FVIII or FIX concentrations. The addition of rFVIIa to FVIII- or FIX-deficient systems altered the network structure, making the fibers thinner and more tightly packed.


  • S He
  • M Blomback
  • GJ Ekman
  • Ulla Hedner
Research areas and keywords

Subject classification (UKÄ) – MANDATORY

  • Cardiac and Cardiovascular Systems


  • FVII, FIX, fibrin permeability, fibrin structure, FVIII, hemophilia, NovoSeven
Original languageEnglish
Pages (from-to)1215-1219
JournalJournal of Thrombosis and Haemostasis
Issue number6
Publication statusPublished - 2003
Publication categoryResearch

Bibliographic note

The information about affiliations in this record was updated in December 2015. The record was previously connected to the following departments: Emergency medicine/Medicine/Surgery (013240200)