Platelet-derived VWF in the stroke spotlight.

In this issue of Blood, Verhenne et al present data showing the role of platelet-derived von Willebrand factor (VWF) in mediating ischemic stroke injury using a murine model. They created mice with either endothelial VWF or platelet-derived VWF and examined each phenotype for bleeding and thrombosis. Their intriguing findings were that mice lacking platelet-derived VWF, but with adequate endothelial VWF stores, demonstrated normal hemostasis in a tail bleeding model and normal carotid artery thrombosis. Mice with only platelet-derived VWF had defective hemostasis and defective carotid artery thrombosis, but experienced significant cerebral infarction using a stroke model with middle cerebral artery occlusion (see figure). In contrast, minimal infarcts were seen for VWF-deficient mice. These data suggest that platelet-derived VWF plays a specific role in stroke pathology.