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Updated: Sep 26, 2026

Platelet Adhesion and Aggregation Under Flow using Microfluidic Flow Cells
Published on: October 27, 2009
A PLC gamma 2-independent platelet collagen aggregation requiring functional association of GPVI and integrin
1INSERM U.311, Etablissement Français du Sang-Alsace, 10 rue Spielmann, BP 36, 67065 Strasbourg Cedex, France.
Abstract:
The role of the phospholipase C (PLC)gamma 2 isotype in platelet activation was evaluated by studying PLC gamma 2 -/- mice. These mice have a prolonged bleeding time but their platelets respond normally to non-collagenous agonists. PLC gamma 2-null platelets show residual aggregation response to collagen fibres (6% versus 74% for wild-type) with minimal granule secretion and no shape change. A delayed shape change is observed at later aggregation times. Specific activation by glycoprotein (GP)VI agonists (convulxin, collagen-related peptide and GPVI crosslinking) is, however, abolished. Antibodies against integrin alpha(2)beta(1) and GPVI each inhibit the residual collagen response, implying a role of alpha(2)beta(1) in platelet activation and a functional association with GPVI. These responses are also prevented by blocking integrin alpha(IIb)beta(3) and phosphoinositide 3-kinase, whereas aspirin treatment and ADP receptor blockade only inhibit shape change. These results provide evidence for a PLC gamma 2-independent collagen activation pathway requiring cooperation between GPVI and alpha(2)beta(1) leading to alpha(IIb)beta(3)-dependent aggregation and shape change by released ADP and thromboxane A(2).
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