Antithrombotic efficacy of inactivated active site recombinant factor VIIa is shear dependent in human blood.

Abstract

Several studies have indicated a profound role for factor VII(a) [FVII(a)] in venous and arterial thrombogenesis. In the present study, we quantified the inhibitory efficacy of dansyl-glutamyl-glycyl-arginyl-recombinant FVIIa (DEGR-rFVIIa) on acute thrombus formation. Thrombus formation was elicited by immobilized tissue factor (TF) in a parallel-plate perfusion chamber device at blood flow conditions characterized by wall shear rates of 100 S-1 (veins) and 650 S-1 (medium-sized healthy arteries). Native human blood was drawn directly from an antecubital vein by a pump into a heparin-coated mixing device in which DEGR-rFVIIa (0.09 to 880 nmol/L final plasma concentration) or buffer was mixed homogeneously with flowing blood. Subsequently, the blood was passed over a plastic coverslip coated with TF and phospholipids in the parallel-plate perfusion chamber. Fibrin deposition, platelet-fibrin adhesion, and platelet thrombus volume triggered by this surface were measured by morphometry. DEGR-rFVIIa inhibited thrombus formation in a dose-dependent manner, but the efficacy was shear rate dependent. At a wall shear rate of 100 S-1, the IC50 (50% inhibition) was 30 nmol/L, whereas at 650 S-1, the IC50 was 0.6 nmol/L. Binding studies to immobilized TF under flow conditions using surface plasmon resonance revealed a significantly higher on-rate for DEGR-rFVIIa and FVIIa than for FVII, 2.8 x 10(5), 2.6 x 10(5), and 1.8 x 10(5) M-1 S-1, respectively. This indicates that a contributing factor to the shear-dependent efficacy may be a differential importance of on-rates at arterial and venous blood flow conditions.

• Authors: U Orvim, R M Barstad, L Orning, L B Petersen, M Ezban, U Hedner, K S Sakariassen
• Journal: Arteriosclerosis, thrombosis, and vascular biology (Arterioscler Thromb Vasc Biol) Vol. 17 Issue 11 Pg. 3049-56 (Nov 1997) ISSN: 1079-5642 [Print] United States
• PMID: 9409292 (Publication Type: Journal Article)

Chemical References

• Chromogenic Compounds
• Dansyl Compounds
• Fibrinolytic Agents
• Oligopeptides
• Phospholipids
• Recombinant Fusion Proteins
• dansyl-glutamyl-glycyl-arginyl-factor VIIa
• isoleucyl-prolyl-arginine-4-nitroanilide
• Fibrin
• Thromboplastin
• Factor VIIa

Topics

• Binding Sites
• Blood Coagulation (drug effects)
• Chromogenic Compounds (metabolism)
• Dansyl Compounds (pharmacology)
• Factor VIIa (pharmacology)
• Fibrin (metabolism)
• Fibrinolytic Agents (pharmacology)
• Hemorheology
• Humans
• Mutagenesis, Site-Directed
• Oligopeptides (metabolism)
• Phospholipids (metabolism)
• Platelet Adhesiveness (drug effects)
• Recombinant Fusion Proteins (pharmacology)
• Thromboplastin (metabolism)