Platelets in ischemic stroke

Abstract

Ischemic stroke is among the leading causes of mortality and permanent disability worldwide. Treatment approaches in acute stroke patients aim at rapid recanalization of occluded extra- and intracranial vessels. However, progressive stroke can still develop in patients despite successful recanalization, a process termed "reperfusion injury". It has long been recognized that pathological platelet activity essentially contributes to initiation and progression of ischemic stroke. However, the exact mechanisms and signaling pathways governing the detrimental effects of platelets in reperfusion injury have remained elusive. This chapter summarizes recent experimental data which have revealed that the pathophysiology of ischemic stroke critically depends on the activity of the von Willebrand factor receptor glycoprotein (GP)Ib and the major collagen receptor GPVI which are both involved in early platelet adhesion and activation. By contrast, interference with GPIIb/IIIa-dependent platelet aggregation and thrombus formation does not improve the outcome of acute brain ischemia and dramatically increases the susceptibility to intracranial hemorrhage. Furthermore, this chapter focuses on recent experimental data documenting a complex cascade of pathological events, involving interactions between platelets, immune cells, endothelial cells and the contact activation system in ischemic stroke progression. The potential translational impact of several key findings is briefly discussed.