Effect of shear stress on platelet activation via the glycoprotein VI receptor

Cardiovascular diseases are the nation´s leading cause of death. Such diseases are caused by platelet response to collagen especially in the event of vascular injury leading to thrombosis. One of the platelet receptors known to bind to the collagen ligand is glycoprotein VI (GPVI) with co-receptor Fc receptor gamma chain (FcRγ). By stably expressing the GPVI receptor in rat basophilic leukemia cells (RBL-2H3), which abundantly express FcRγ, but endogenously lack GPVI, studies have shown that GPVI-FcRγ is sufficient to confer adhesion as well as signaling responses to collagen as long as the receptor density is equivalent to that found on human platelets. While those investigations confirm that the GPVI receptor mediate binding to collagen under static conditions, they do not provide information on how the GPVI receptor interacts with collagen under dynamic conditions. In the present study we have used the GPVI-expressing RBL-2H3 cells to observe the kinetics of adhesion to collagen under hydrodynamic flow conditions in vitro using a parallel plate flow chamber coupled with video microscopy. We demonstrate that these cells do adhere to the surface at a low shear rate and do so at a greater adherent cell density than wild-type RBL-2H3 (WT-RBL) cells.