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B. Devcic-Kuhar:
"Ultrasound induced distribution of fibrinolytic enzymes in blood clots";
Vortrag: Ultrasonic Standing Wave Network Scientific Meeting, Cardiff / UK (eingeladen); 26.01.2005.

The exchange of lysis reactants plays an important role in the process of plasminogen activator (rt-PA) induced clot lysis, as it occurs during thrombolytic therapy. Diffusion limited clot lysis is a very slow process but it can be accelerated when taking place in an ultrasound field (sonothrombolysis). The aim of our study was to prove the assumption that ultrasound enhances thrombolysis in vitro by promoting the penetration of rt-PA into the clot. We developed a new technique of visual detection of fibrinolytic reactants within the blood clot. By using gel immobilization technique and immunohistochemistry, we were able to localize plasminogen and rt-PA within the clot. The spatial distributions of these fibrinolytic components showed clearly that ultrasound of 2 MHz frequency and 1.2 W/cm2 acoustic intensity, promoted penetration of rt-PA into thrombi significantly, and broadened zone of lysis from 9 µm to 21 µm on average. Several mechanisms such as acoustic radiation force, acoustic streaming and bubble associated phenomena have been suggested to be responsible for this effect. We conclude that ultrasound facilitates transport of rt-PA from the surrounding medium into the clot. Deeper penetration of enzyme into the thrombus results in an enhanced thrombolysis.