Ultrasound affects distribution of plasminogen and tissuetype plasminogen activator in whole blood clots in vitro

Summary

Ultrasound of 2 MHz frequency and 1.2 W/cm2 acoustic intensity was applied to examine the effect of sonication on recombinant tissue-type plasminogen activator (rt-PA)-induced thrombolysis as well as on the distribution of plasminogen and t-PA within whole blood clots in vitro. Thrombolysis was evaluated quantitatively by measuring clot weight reduction and the level of fibrin degradation product D-dimer (FDP-DD) in the supernatant. Weight reduction in the group of clots treated both with ultrasound and rt-PA was 35.2% ± 6.9% which is significantly higher (p<0.0001) than in the group of clots treated with rt-PA only (19.9% ± 4.3%). FDP-DD level in the supernatants of the group treated with ultrasound and rt-PA increased sevenfold compared to the group treated with rt-PA alone, (14895 ± 2513 ng/ml vs. 2364 ± 725 ng/ml). Localization of fibrinolytic components within the clots was accomplished by using gel-entrapping technique and immunohistochemistry. Spatial distributions of t-PA and plasminogen showed clearly that ultrasound promoted the penetration of rt-PA into thrombi significantly (p<0.0001), and broadened the zone of lysis from 8.9 ± 2.6 µm to 21.2 ± 7.2 µm. We speculate that ultrasound enhances thrombolysis by affecting the distribution of rt-PA within the clot.

Keywords

Thrombolysis - ultrasound - sonothrombolysis - immunohistochemistry - fibrinolytic enzymes

^* BDK and SP contributed equally to this study

^‡ JW and MGW contributed equally to this study

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