Protective effects of bifunctional platelet GPIIIa49-66 ligand on myocardial ischemia-reperfusion injury in rats

Current antiplatelet drugs mainly focus on prevention rather than the more clinically relevant issue of clearance of an existing thrombus. We recently described a novel and effective therapeutic strategy for dissolution of preexisting platelet thrombus in a murine ischemic stroke model with a bifunctional platelet GPIIIa49-66 ligand (Single-chain antibody Linked first Kringle 1 of plasminogen, named SLK), which homes to newly deposited fibrin strands tangled of platelet thrombus and induces aggregated platelet fragmentation. In this study, we perform in-depth analysis of the effect of SLK on myocardial ischemia-reperfusion (IR) injury in rats. We show that SLK dose-dependently reduces lactate dehydrogenase (LDH) release as well as mean infarction size of left ventricle. Histological observation demonstrates that the arterial thrombi in coronary arteries of rat almost disappear after SLK injection. Optimal dose of SLK (37.5 μg/ individual) provides the myocardial protection at 2 hours post-infusion. However, there are no significant protective effects if SLK was given at 4 or 8 hours post-infusion. The combined application of SLK and urokinase (UK) demonstrates greater myocardial protection than UK alone at 2 hours post-infusion. Thus, SLK could be used as a thrombolytic alternative in other arterial vascular beds associated with thrombosis to enhance fibrinolysis.