Activated protein C (APC) is a critical regulator of thrombin formation and thereby protects against thrombosis. On the other hand, overwhelming formation of APC increases the risk of bleeding such as in trauma-induced coagulopathy. Thus, pharmacological inhibition of APC activity may improve blood clottability in certain clinical situations. In this study, we demonstrate that the DNA aptamer HS02-52G binds with fast onset (1.118 ± 0.013 × 105 M-1 s-1) to APC and possesses a long residence time of 13.5 min within the aptamer-APC complex. Functional analysis revealed HS02-52G as a highly potent and specific inhibitor of APC in plasma and whole blood with IC50 values ≤30 nM, whose activity can be readily neutralized by the short complementary DNA molecule AD22. These features qualify the novel aptamer-antidote pair as a candidate treatment option for acute APC-related bleedings.
Keywords: activated protein C (APC); antidote; aptamer; hemophilia; inhibitor; trauma-induced coagulopathy (TIC).