| 研究実績の概要 |
We have reported that both exposing PS platelets and generated fibrin were localized only in the core of the intravascular thrombus. In this project, we also observed the accumulation of exogenously infused Alexa-labeled Glu-plasminogen (Glu-plg) in the center of the microthrombus, which was attenuated by EACA and carboxypeptidase B, suggesting that the binding was dependent on lysine binding sites. Aprotinin, a plasmin inhibitor, significantly reduced the accumulation of Glu-plg, suggesting that endogenously generated plasmin activity is a prerequisite for the accumulation. Taken together, fibrinolysis is endogenously activated at a site of platelet activation at an early phase of thrombus formation (Brzoska et al., PloS ONE 2015). To further analyze the mechanism for closely regulated activation of both coagulation and fibrinolysis on activated platelets, we designed an experiment, in which fibrin network formation and its following lysis can be analyzed with the employment of diluted platelet-rich plasma with fluorescently labeled coagulation- and fibrinolytic- factors using Confocal Laser Microscopy. The structure of the fibrin network formed by supplemented tissue factor was uneven and denser at the sites of coagulation initiation regions (CIRs) on PS-exposing platelets. When tPA was supplemented, labeled plg as well as tPA accumulated at CIRs, from where fibrinolysis started and gradually expanded to the peripheries. By these we successfully demonstrated the detail of crosstalk between coagulation and fibrinolysis, which takes place on activated platelets’ surface.
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