Abstract Number: PB0890
Meeting: ISTH 2022 Congress
Background: Proteoglycans are a heterogeneous family of proteins with covalently bound sulfated glycosaminoglycans. Perlecan, a matrix heparan sulfate proteoglycan secreted by endothelial cells and smooth muscle cells, has been proved to bind to the platelet and megakaryocyte-specific ITIM receptor G6bB, regulating glycoprotein VI (GPVI) signaling. Contrastingly its C-term fragment can enhance collagen induced platelet adhesion via the integrin α2β1.
Aims: We investigated the potential dual role of perlecan to induce platelet adhesion and to regulate GPVI mediated thrombus formation.
Methods: Platelet degranulation and integrin αIIbβ3 activation was measured by flow cytometry following pre-incubation with proteoglycans and dose-dependent activation with suboptimal concentrations of collagen-related peptide (CRP-XL). In spreading assays, platelets were allowed to interact with collagen and perlecan for 45 minutes. Whole blood thrombus formation under flow was measured on CRP-XL surfaces with(out) perlecan. After perfusion the formed thrombi were stained for P-Selectin.
Results: Perlecan enhanced CRP-XL-induced platelet degranulation and integrin αIIbβ3 activation in a time and concentration-dependent manner. Immobilised perlecan supported platelet adhesion and spreading. However, in combination with collagen, perlecan reduced the platelet spreading. In whole blood perfusion over a combination of CRP-XL and von Willebrand factor (VWF), co-immobilised perlecan reduced the buildup of thrombi, but simultaneously changed the thrombus structure. Morphological analyses indicated smaller, denser and more regularly shaped thrombi, with increased P-selectin exposure when perlecan was present. Perfusion onto perlecan alone resulted in a monolayer of platelets without multilayered thrombus formation.
Conclusion(s): Perlecan enhanced adhesion and GPVI-mediated platelet activation. However, when co-immobilised, it suppressed GPVI-mediated spreading and thrombus formation, while still enhancing local platelet activation. Whether this is due to a slower kinetic of platelet deposition or to an enhanced thrombus contractility remains unclear. These findings reflect the intrinsic structural features of perlecan, acting as a ligand for platelets and simultaneously competing with GPVI ligands.
To cite this abstract in AMA style:Provenzale I, Gibbins J, Heemskerk J, van der meijden P, Jones C. The heparan sulfate proteoglycan perlecan induces conflicting patterns of thrombus formation upon activation of GPVI: a novel role in thrombus stability? [abstract]. https://abstracts.isth.org/abstract/the-heparan-sulfate-proteoglycan-perlecan-induces-conflicting-patterns-of-thrombus-formation-upon-activation-of-gpvi-a-novel-role-in-thrombus-stability/. Accessed March 4, 2024.
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ISTH Congress Abstracts - https://abstracts.isth.org/abstract/the-heparan-sulfate-proteoglycan-perlecan-induces-conflicting-patterns-of-thrombus-formation-upon-activation-of-gpvi-a-novel-role-in-thrombus-stability/