Regular Article THROMBOSIS AND HEMOSTASIS Selective depletion of factor XI or factor XII with antisense oligonucleotides attenuates catheter thrombosis in rabbits

• Antisense oligonucleotides reduce levels of target hepatic mRNA and protein and decrease clotting activity in rabbits. • Selective depletion of factors XI and XII in rabbits attenuates catheter thrombosis, whereas factor VII depletion does not. Central venous catheter thrombosis can cause venous obstruction and pulmonary embolism. To determine the extent to which catheter thrombosis is triggered by the contact or extrinsic pathway of coagulation, we used antisense oligonucleotides (ASOs) to selectively knock down factor (f)XII, fXI, or high-molecular-weight kininogen (HK), key components of the contact pathway, or fVII, which is essential for the extrinsic pathway. Knockdown of contact pathway components prolonged the activated partial thromboplastin time and decreased target protein activity levels by over 90%, whereas fVII knockdown prolonged the prothrombin time and reduced fVII activity to a similar extent. Using a rabbit model of catheter thrombosis, catheters implanted in the jugular veinwere assessed daily until they occluded, up to a maximum of 35 days. Compared with control, fXII and fXI ASO treatment prolonged the time to catheter occlusion by 2.2and 2.3-fold, respectively. In contrast, both HK and fVII knockdown did not significantly prolong the time to occlusion, and dual treatment with fVIIand fXI-directed ASOs produced a time to occlusion similar to that with the fXI ASO alone. These findings suggest that catheter thrombosis is triggered via the contact pathway and identify fXII and fXI as potential targets to attenuate this complication. (Blood. 2014;123(13):2102-2107)