No abstract

Background and Purpose: Von Willebrand factor (VWF) strings mediate spontaneous platelet adhesion in the vascular lumen, which may lead to microthrombi formation and contribute to stroke pathology. However, the mechanism of VWF string attachment at the endothelial surface is unknown. We tested the novel hypothesis that VWF strings are tethered to the endothelial surface through an interaction between extracellular vimentin and the A2 domain of VWF. We further explored the translational value of blocking this interaction in a model of ischemic stroke. Methods: Human endothelial cells (EC) and pressurized cerebral arteries were stimulated with histamine to elicit VWF string formation. Recombinant proteins and antibodies were employed to block VWF string formation. Mice underwent transient middle cerebral artery occlusion (MCAO) with reperfusion. Just prior to recanalization, mice were given either vehicle or A2 protein (recombinant VWF A2 domain) to disrupt the vimentin/VWF interaction. Laser speckle contrast imaging was used to monitor cortical perfusion. Results: Pressurized cerebral arteries produced VWF strings following histamine stimulation, which were reduced in arteries from vimentin knockout mice. VWF string formation was significantly reduced in EC incubated with A2 protein or anti-vimentin antibodies. Lastly, A2 protein treatment significantly improved cortical reperfusion following MCAO. Conclusions: We provide the first direct evidence of cerebral VWF strings and demonstrate that extracellular vimentin significantly contributes to VWF string formation via A2 domain binding. Lastly, we show that pharmacologically targeting the vimentin/VWF interaction through the A2 domain can promote improved reperfusion following ischemic stroke. Together, these studies demonstrate the critical role of VWF strings in stroke pathology and offer new therapeutic targets for treatment of ischemic stroke.

Pain management is challenging for patients with sickle cell disease (SCD) who present in vaso‐occlusive crisis (VOC). Opioid therapy is highly effective, nevertheless undesirable side effects can hinder their effectiveness. Regional anesthesia with deposition of perineural anesthetic offers nociceptive blockade, local vasodilatation, and reduces the inflammatory response. Among pediatric patients, continuous peripheral nerve block (CPNB) for perioperative adjunctive analgesia is safe. Herein, we describe the trajectory of a cohort of pediatric SCD patients with opioid‐refractory upper‐extremity VOC following placement of CPNBs for analgesia; highlighting reduced opioid consumption, improved pain scores, and decreased length of hospitalization.