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A Uniform Shear Assay for Human Platelet and Cell Surface Receptors via Cone-plate Viscometry
Published on: June 5, 2019
Platelets interact with tissue factor immobilized on surfaces: effects of shear rate
R Tonda1, I Lopez-Vilchez, F Navalon
1Service of Hemotherapy-Hemostasis, Hospital Clinic, CDB, IDIBAPS, UB, Barcelona, Spain.
European Journal of Clinical Investigation
|January 5, 2008
Summary
Tissue Factor (TF) acts as an adhesive surface for platelets, potentially mediated by von Willebrand factor. Recombinant activated FVIIa (rFVIIa) boosts TF’s procoagulant effect at lower shear rates.
Area of Science:
- Hematology
- Biochemistry
- Biomaterials Science
Background:
- Tissue Factor (TF) is known for its procoagulant roles.
- Its potential pro-adhesive properties for platelets remain under-investigated.
Purpose of the Study:
- To investigate the adhesive properties of human Tissue Factor (hTF) for platelets.
- To evaluate the influence of shear rates and recombinant activated FVIIa (rFVIIa) on hTF-mediated platelet interactions and coagulation.
Main Methods:
- Platelet interaction with hTF immobilized on PVDF surfaces was studied under varying shear rates (250, 600, and 5000 s⁻¹).
- Platelet and fibrin deposition were assessed using morphometric, immunocytochemical, and ultrastructural analyses.
- Prothrombin fragment 1 + 2 levels and PFA-100 closure times were measured, with and without rFVIIa.
Main Results:
- hTF surfaces showed significant platelet deposition at 250 and 600 s⁻¹.
- Fibrin formation was higher at 250 s⁻¹ compared to 600 s⁻¹.
- rFVIIa increased fibrin formation and thrombin generation but did not affect platelet deposition; it also shortened PFA-100 closure times at high shear rates.
Conclusions:
- Human Tissue Factor (hTF) functions as a platelet-adhesive substrate, potentially via von Willebrand factor.
- rFVIIa enhances the procoagulant activity of hTF at low to intermediate shear rates, but not at very high shear rates.
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