Survival after line h38 platelets or pFVIII-expressing iMKs and rFVIIa infusion in the tail-clip exsanguination assay. (A-B) Tail-clip exsanguination assay with expiration assessed 16 hours post–tail clip. In both panels, on the left, WT, FVIII^null, and line h38 mice underwent tail-clip exsanguination. Percentage of animals surviving of 5 animals per arm is shown. Dashed gray line is 100% survival. (A) On the right, FVIII^null mice were infused to ∼15% line h38 platelets and then underwent tail-clip exsanguination at 1 to 72 hours postinfusion. (B) On the right, mice were infused with 0.25, 1, and 4 mg/kg of rFVIIa retroorbitally 15 minutes before tail resection; additional mice were studied at 4 mg/kg of rFVIIa 1.5 hours postinfusion.