Locally delivered plasmin: why should it be superior to plasminogen activators for direct thrombolysis?

With advances in the field of thrombolytic therapy, whereby clots are routinely treated locally via a catheter, traditional systemic thrombolytics such as plasminogen activators might not be the best drugs for this task. Plasmin represents a new class of thrombolytic agents that exhibit direct fibrinolytic activity, without the need for either plasminogen or a plasminogen activator. In contrast to plasminogen activators, this independence from plasminogen allows plasmin to efficiently dissolve long, retracted blood clots that are inherently deficient in plasminogen.