Highly stable plasminogen activator inhibitor type one (VLHL PAI-1) protects fibrin clots from tissue plasminogen activator-mediated fibrinolysis

• Published in: International journal of molecular medicine Vol. 20; no. 5; pp. 683 - 687
• Main Authors: Jankun, Jerzy, Aleem, Ansari, Selman, Steven, Skrzypczak-Jankun, Ewa, Lysiak-Szydlowska, Wieslawa, Grafos, Nicholas, Fryer, Hugh, Greenfield, Robert
• Format: Journal Article
• Language: English
• Published: Greece D.A. Spandidos 01-11-2007
• Subjects: Blood Coagulation - drug effects; Electrophoresis, Polyacrylamide Gel; Fibrin - metabolism; Fibrinolysis - drug effects; Half-Life; Humans; Plasminogen Activator Inhibitor 1 - isolation & purification; Plasminogen Activator Inhibitor 1 - pharmacology; Recombinant Proteins - pharmacology; Spectrophotometry; Thermodynamics; Tissue Plasminogen Activator - pharmacology
• ISSN: 1107-3756; 1791-244X
• DOI: 10.3892/ijmm.20.5.683

Plasminogen activator inhibitor-1 (PAI-1) is the major specific inhibitor
of tissue-type plasminogen activator (tPA) which mediates fibrin clot lysis through
activation of plasminogen. Wild-type-PAI-1 (wPAI-1) is rapidly converted to the
latent form (half-life of ≈2 h) and loses its ability to inhibit tPA. We developed
a very long half-life PAI-1 (VLHL PAI-1), a recombinant protein with a half-life
>700 h compared with wPAI-1. In this study, VLHL PAI-1 was assessed for its
ability to inhibit clot lysis in vitro. Clot formation was initiated in normal
plasma supplemented with tPA by the addition of either tissue factor or human
recombinant FVIIa. Clot lysis time, monitored turbidimetrically in a microtiter
plate reader, was determined at various concentrations of wPAI-1 and VLHL PAI-1.
Both wPAI-1 and VLHL PAI-1 caused a significant increase in clot lysis time, although
the latter was somewhat less effective at lower concentrations. The VLHL PAI-1,
but not wPAI-1, maintained its anti-fibrinolytic activity after preincubation
overnight at 37°. These studies demonstrate that VLHL PAI-1 is an effective inhibitor
of fibrin clot degradation. Due to the high stability of VLHL PAI-1 compared with
wPAI-1, this novel inhibitor of tPA-mediated fibrinolysis may have therapeutic
applications for treating surgical and trauma patients when used directly or in
conjunction with the procoagulant recombinant FVIIa.