Edaravone, a Synthetic Free Radical Scavenger, Enhances Alteplase‐Mediated Thrombolysis

Abstract

The combination of alteplase, a recombinant tissue plasminogen activator, and edaravone, an antioxidant, reportedly enhances recanalization after acute ischemic stroke. We examined the influence of edaravone on the thrombolytic efficacy of alteplase by measuring thrombolysis using a newly developed microchip-based flow-chamber assay. Rat models of embolic cerebral ischemia were treated with either alteplase or alteplase-edaravone combination therapy. The combination therapy significantly reduced the infarct volume and improved neurological deficits. Human blood samples from healthy volunteers were exposed to edaravone, alteplase, or a combination of alteplase and edaravone or hydrogen peroxide. Whole blood was perfused over a collagen- and thromboplastin-coated microchip; capillary occlusion was monitored with a video microscope and flow-pressure sensor. The area under the curve (extent of thrombogenesis or thrombolysis) at 30 minutes was 69.9% lower in the edaravone-alteplase- than alteplase-treated group. The thrombolytic effect of alteplase was significantly attenuated in the presence of hydrogen peroxide, suggesting that oxidative stress might hinder thrombolysis. D-dimers were measured to evaluate these effects in human platelet-poor plasma samples. Although hydrogen peroxide significantly decreased the elevation of D-dimers by alteplase, edaravone significantly inhibited the decrease. Edaravone enhances alteplase-mediated thrombolysis, likely by preventing oxidative stress, which inhibits fibrinolysis by alteplase in thrombi.

Uric acid enhances alteplase-mediated thrombolysis as an antioxidant

“…We did not use a CBF monitor as previously reported 14 . The neurological score of all rats after awakening was 3 or 4, and the differences among the three groups of rats assigned to the different treatments were not statistically significant (Fig.…”

“…In the experiments using whole blood and PRP samples, we selected the final concentration of alteplase (500 IU/ml) based on half the maximum concentration after administration to Japanese patients with AIS 14 . Patients in the UA group received 1000 mg of UA in the URICO-ICTUS trial 5 .…”

“…In the experiments using PPP samples, we selected the final concentration of alteplase (100 IU/ml) based on the findings of a preliminary experiment 14 . The final concentration of H 2 O 2 (100 µM) (Sigma-Aldrich Japan, Tokyo, Japan) was based on a previous report 14 , recognizing that it is difficult to estimate the local concentration of reactive oxygen species (ROS) around intravascular thrombi during AIS 26 . The total volume of the agents or vehicle in the blood sample was 5%.…”

“…Thromboembolic ischemia of the middle and posterior cerebral arteries was induced by homologous blood clot in 8-week-old male Sprague–Dawley rats (KBT Oriental Co., LTD, Tosu, Japan) weighing 290 to 310 g as previously described by our group 14 . Anaesthesia was induced and maintained with 2.5% to 3.0% isoflurane inhalation.…”

“…Anaesthesia was induced and maintained with 2.5% to 3.0% isoflurane inhalation. The left internal carotid artery was isolated, a 24-gauge catheter (SURFLO Flash®; Terumo Co.) was inserted in the internal carotid artery, and a 5-mm clot (volume of 3.6 mm 3 ) was pushed into the artery via the catheter 14 . The catheter containing the clot was hooked up to a syringe containing physiological saline.…”