Effect of recombinant factor IX mutants at 5% plasma levels on the time to occlusion (TTO) after FeCl3-induced saphenous vein injury in the hemophilia B mouse.Factor IX gene–ablated C57B6 mice were infused with recombinant factor IX wild-type, R170A, or R233A at doses calculated to result in 5% normal plasma levels before undergoing FeCl3-induced saphenous vein injury as described in “Saphenous vein hemostasis and thrombosis models.” Saphenous vein flow was monitored by Doppler probe up to 45 minutes or until loss of flow was observed for 60 seconds to determine the time to occlusion (TTO). Median TTO (solid lines) was 15.7 minutes for factor IX wild-type, 9.1 minutes for factor IX R170A, and more than 45 minutes for factor IX R233A (P ≤ .003, Mann-Whitney).
