Pre-administration of a carboxypeptidase inhibitor enhances tPA-induced thrombolysis in mouse microthrombi: Evidence from intravital imaging analysis.

INTRODUCTION: Thrombolysis using recombinant tissue-type plasminogen activator (rt-PA) is the pharmacological treatment of choice in acute thrombotic events. However, a narrow therapeutic window and bleeding complications limit its use. We describe the role of carboxypeptidase inhibitor from potato tuber (PTCI), an inhibitor of activated thrombin-activatable fibrinolysis inhibitor (TAFIa), on Glu-plasminogen accumulation and microthrombus dynamics in vivo and demonstrate its influence on rt-PA-mediated thrombolysis. MATERIALS AND METHODS: In conjunction with real-time intravital two-photon excitation fluorescence microscopy, we produced and imaged laser-induced microthrombi in the mesenteric venules of Green Fluorescent Protein (GFP)-expressing mice. We examined microthrombus dynamics and thrombolysis patterns in vivo by measuring the changes in the fluorescence intensity of labeled Glu-plasminogen following administration of epsilon aminocaproic acid (EACA), PTCI, and rt-PA. RESULTS: PTCI enhanced Glu-plasminogen accumulation at the core of the thrombus by inhibiting TAFIa, while EACA inhibited this process. Exogenous rt-PA effectively triggered Glu-plasminogen activation within the thrombus and promoted thrombolysis. Administration of PTCI and rt-PA together showed no significant benefit on thrombolysis compared to rt-PA administration alone. However, early-phase systemic administration of PTCI before thrombolytic therapy by rt-PA expedited clot lysis as evidenced by significantly faster time to reach peak Glu-plasminogen fluorescence intensity and shorter time to achieve near-complete clot lysis (P = 0.014 and P = 0.003, respectively). CONCLUSIONS: PTCI potentiates rt-PA-mediated thrombolysis when administered early in acute thrombotic events. Further studies are warranted to explore the potential of TAFI inhibitors as adjunct agents in thrombolysis or thromboprophylaxis.

Comparación de la activación y la cinética de laplasmina bufalina con la humana / Ativação e cinética comparativa da plasmina bufalina e a humana / Comparative activation and kinetic of plasmin bufaline with the human one

El plasminógeno es el zimógeno de la plasmina, enzima activada a nivel fisiológico por el activadortisular del plasminógeno y la urokinasa, la plasmina es la enzima encargada de disolver el coágulosanguíneo. En este estudio se compararon la plasmina humana con la bufalina en su forma de activación dezimógeno a enzima y en la afinidad hacia el sustrato cromogénico. Los plasminógenos fueron purificadospor el mismo método de cromatografías de afinidad y cambio iónico. De igual manera las activaciones sehicieron utilizando urokinasa humana en ambos casos. La plasmina bufalina demostró mayor activacióny afinidad (1.35mM) que la plasmina humana (2.16 mM), siendo la bufalina 1.5 veces mas afin al sustratocromogénico que la humana. Este estudio demuestra que el método de purificación de los plasminógenospuede ser el mismo para muchas especies, se demuestra una vez más que las plasminas animales al parecerson más eficientes en la disolución del coágulo o degradación de sustratos, que la plasmina humana.Este estudio indica que la plasmina bufalina puede ser utilizada en los parámetros que se determinanclínicamente en pacientes con problemas cardiovasculares, reduciendo el tiempo de determinación de estosparámetros fibrinolíticos, que pueden dar al médico un margen de tiempo superior para actuar.

The Plasminogen is the zymogene of the Plasmin, enzyme which physiologically is activated by twodifferent enzymes, the tissue plasminogen activator and the urokinase, the plasmin is the enzyme that dissolves blood clots. In this study the human plasmin was compared to the bufaline plasmin, in theactivation from the zymogene to the enzyme form as well as in the affinity to the chromogenic substrate.The two plasminogens were purified by the same chromatographies methods: affinity and ion-exchange.Furthermore, both plasminogens were activated by human urokinase. The bufaline plasmin showed moreactivation and affinity (1.35 mM) that the human plasmin (2.16 mM), in addition, the bufaline plasmindemonstrated a 1.5 times more affinity to the chromogenic substrate that the human plasmin. This studydemonstrated that the plasminogens of several species can be purified by this method. Besides, one moretime the animal’s plasmins probably to be more efficient in the dissolution of blood clots or degradation ofsubstrates than the human plasmin. More over this study indicated that the bufaline plasmin can be usedin clinical determinations of patients with cardiovascular diseases. This also reduces the determinationtime of fibrinolytic parameters that physicians can give, having more time to take appropriate treatment.

O plasminogênio é o zymogen da plasmina, enzima ativada a nivel fisiológico pelo ativador tissulardo plasminogênio e uroquinase, plasmina é a enzima responsável de dissolver o coágulo de sanguíneo.neste estudo foi comparada a plasmina humana com a plasmina búbalina em seu modo de ativaçãode zymogen a enzima e na afinidade substrato cromogênico. Os plasminogênio foram purificados como mesmo método de cromatografia de afinidade e de troca iônica, e as ativações foram feitas usandouroquinase humana nos dois casos. A Búfalo plasmina mostrou maior ativação e afinidade (1.35 mM)que a plasmina humana (2.16 mM), sendo a bufalina 1.5 vezes mais afim ao substrato Cromogênico quea humana. Este estudo mostrou que o método de purificação do plasminogênios pode ser o mesmo paramuitas espécies, alem disso, que as plasminas animais são mais eficientes na dissolução do coáguloo degradação de substratos que a plasmina humana. Este estudo indicou que a plasmina búfalo podeser utilizada nos parâmetros determinados clínicamente em pacientes com problemas cardiovasculares,diminuindo o tempo de determinação destes parâmetros fibrinolíticos, que podem dar ao médico umintervalo de maior tempo para atuar.