Abstract Number: PB1660
Meeting: ISTH 2020 Congress
Theme: Platelets and Megakaryocytes » Platelet Function and Interactions
Background: Immunoglobulin receptor GPVI is involved in platelet activation and has recently been implicated in thrombus growth and stability.
Aims: To determine the effects of GPVI on clot structure and identify how this contributes to the GPVI-deficient phenotype.
Methods: Clots from purified fibrinogen were analyzed by turbidity with 0-10 µM GPVI-monomer/dimer. Clot pore size was determined by permeation ± 2.5 µM of GPVI-monomer/dimer, and the mechanical properties of the clot ± 5 µM GPVI were investigated using magnetic tweezers. Clotting/lysis was analyzed by ROTEM using whole blood from WT and GPVI-/- mice. Platelet-rich plasma (PRP) clots were used to determine clot pore size by permeation, and fiber density/size by confocal and scanning electron microscopy (SEM).
Results: Turbidity analysis showed an increase in clotting lag phase (18-23% GPVI-monomer;
11-38% GPVI-dimer, p< 0.05), suggesting impaired protofibril formation, and increased MaxOD
(4-12% GPVI-monomer; 16-17% GPVI-dimer, p< 0.05), suggesting thicker fibres, in the presence of GPVI. Fibrin-clots containing GPVI showed a reduced elastic modulus (G') (2.1-fold GPVI-monomer, p< 0.001; 0.8-fold GPVI-dimer, ns) and larger pore size (1.95-fold GPVI-monomer; 1.91-fold GPVI-dimer, p< 0.05). There were no differences in clotting/lysis or fiber density between WT and GPVI-/- mice clots, although a small reduction in pore size was observed in clots from GPVI-/- mice. SEM showed no changes in fiber size/number or platelet number between both groups, however, a clear reduction in the number of procoagulant platelets was observed in GPVI-/- mice compared to WT (1:2 procoagulant:non-procoagulant ratio for GPVI-/- vs 1:1 for WT, p≤0.05).
Conclusions: Our data indicate that clots are more porous, less stiff, and composed of thicker fibers in the presence of GPVI. Less procoagulant platelets were observed in PRP clots from GPVI-/- mice. These findings support GPVI as a possible therapeutic target to reduce thrombosis.
To cite this abstract in AMA style:
Gauer JS, Duval C, Baker S, Xu R-, Slater A, Martin E, Watson SP, Ariëns RAS. Effects of GPVI on Clot Structure: Reduction in Procoagulant Platelets in GPVI-Deficient Clots [abstract]. Res Pract Thromb Haemost. 2020; 4 (Suppl 1). https://abstracts.isth.org/abstract/effects-of-gpvi-on-clot-structure-reduction-in-procoagulant-platelets-in-gpvi-deficient-clots/. Accessed March 21, 2024.« Back to ISTH 2020 Congress
ISTH Congress Abstracts - https://abstracts.isth.org/abstract/effects-of-gpvi-on-clot-structure-reduction-in-procoagulant-platelets-in-gpvi-deficient-clots/