Recombinant ADAMTS13 Attenuates Cerebral Hemorrhage Caused By TPA After Cerebral Ischemia

Background and purpose:Stroke is a leading cause of adult morbidity and mortality. Ischemic stroke is the most common form of stroke and occurs when there is an abrupt interruption of blood flow to the brain. Until recently, there are no specific drug therapies for it. Tissue-type plasminogen activator is a highly specific serine protease that can benefit patients with acute ischemic stroke by lysing clots when it is applied within3hours after symptom onset. And it is the only thrombolytic agent in clinical practice to date. However, it has been recognized that tPA has neurotoxic effects and promotes the formation of brain edema. Hemorrhagic transformation is a major complication associated with tPA therapy for ischemic stroke. Accumulating evidence suggest that von Willebrand factor (vWF) plays a pivotal role in thrombus formation and microcirculatory disturbances after ischemic stroke. By cleaving VWF, ADAMTS13(a disintegrin-like and metalloprotease with thrombospondin type I repeats-13) protects mice from cerebral ischemia. Therefore, The major aim of the present study was to investigate the hypothesis that recombinant ADAMTS13(rADAMTS13) could increase the safety of tPA thrombolysis in stroke.Methods:Transient focal cerebral ischemia and reperfusion mice animal model was established by unilateral middle cerebral artery occlusion (MCAO) for45minutes. Wortmannin and fasudil used as tools medicine. We examined BBB permeability after intraventricular injection of tPA, VWF, VWF or rADAMTS13in combination with tPA in non-ischemic mice. Then, We investigated the role of rADAMTS13on reducing tPA-induced BBB dysfunction and cerebral hemorrhage in a mouse stroke model. The analyse of westen blotting was used to detect the expressions of molecules related with intracerebral hemorrhage24hours after stroke in mice treated with vehicle, tPA, tPA+rADAMTS13(rATS), and rADAMTS13. The immunostaining was used to detect the expression and situation of VEGF after cerebral ischemia-reperfusion. Results:Intraventricular injection of tPA or VWF under nonischemic conditions resulted in significant increases in BBB permeability. In contrast, rADAMTS13blocked tPA-induced BBB opening. BBB disruption following stroke was exacerbated by intravenous administration of tPA, but this was attenuated by injection of rADAMTS13. Correspondingly, tPA-associated hemorrhage and neurological deficits after stroke were significantly reduced by rADAMTS13. We also showed that rADAMTS13inhibited tPA-mediated upregulation of vascular endothelial growth factor (VEGF) in vascular endothelium after stroke. The upregulation of VEGF was suppressed by either a Rho kinase inhibitor fasudil or an Akt inhibitor wortmannin. Furthermore, rADAMTS13downregulated tPA-induced activation of RhoA and phosphorylated Akt.Conclusions:The study found that tPA treatment could induce cerebral hemorrhage after stroke by disrupting integrity of BBB. rADAMTS13blocked tPA-induced loss of cerebrovascular integrity, consequently decreased tPA-mediated cerebral hemorrhage, and suggest that this effect may occur through the RhoA/Akt mediated VEGF pathways. These findings may provide a new approach to increase the safety of tPA thrombolysis in ischemic stroke.