A Snake Venom‐Derived Hemocoagulase Modified with Factor Xa Restores Hemostasis in Heparin‐Treated, Hypocoagulant Mice

Abstract

BackgroundExcessive, post‐traumatic bleeding is the leading cause of potentially preventable death in the United States. Nearly one‐third of trauma patients present with coagulopathy upon hospital admission, which significantly increases the incidence of multiple organ failure and death when compared with healthy patients with similar injuries. A hemocoagulase, such as batroxobin, is a thrombin‐like serine protease that is derived from the venom of either the Bothrops Jararaca or Bothops atrox snake and has the ability to convert fibrinogen to fibrin, thus enhancing clot formation and ultimately reducing blood loss in hemorrhagic injuries. Slounase is a modified hemocoagulase combined with Factor Xa (FXa) which may have better hemostatic efficacy in hypocoagulant conditions compared to batroxobin alone. However, the effects of this modified hemocoagulase in the presence of a coagulopathy has not been well characterized in vivo due to lack of reliable hemostasis models.AimTo determine the hemostatic efficacy of slounase compared to both batroxobin and FXa in hypocoagulant murine models using real‐time intravital microscopy.MethodsThe effects of slounase, batroxobin, and Fxa, at doses of both 1 U and 0.1 U, were assessed in vivo by laser ablation of arterioles in the cremaster muscle under real‐time microscopy. Prior to injury, mice were intravenously injected with 25 U heparin to induce hypocoagulant conditions.ResultsIntravenous injection of 25 U heparin inhibited clot formation, significantly increasing bleeding time in untreated, hypocoagulant mice. Injection of slounase, FXa, and Batroxobin did not cause platelet activation in absence of injury. After arteriole injury, FXa did not have a significant effect on clot formation, as FXa alone is inhibited by heparin. Batroxobin‐treated mice had some fibrin formation, however, there was no noticeable change in platelet recruitment. Slounase, at both 0.1 U and 1 U, resulted in a significant enhancement of platelet‐fibrin content, restored clot formation, and significantly shortened bleeding time.ConclusionsThis in vivo study clearly demonstrated that slounase restores hemostasis in hypocoagulant mice by enhancing both platelet activation and fibrin formation, while batroxobin alone only enhances formation of fibrin. Our data strongly suggests that slounase has a better hemostatic efficacy in heparin‐induced hypocoagulant conditions than hemocoagulase alone.Support or Funding InformationThis work was funded by LEE'S PHARM and in part through the National Institutes of Health grants: R01 GM105671 (MH), R01 HL114405 (MH), and R01 MD007880 (MH)This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.