In vivo assessment of VWF:CB variants using a ferric chloride-induced cremasteric arteriolar injury model. (A) Evaluation of thrombus size in the ferric chloride injury model. The cremaster muscle was exteriorized and platelets were labeled by the injection of rhodamine 6G via the catheter placed in the jugular vein. Thrombosis was induced by the application of 10% ferric chloride for 3 minutes. The injured area was observed for 40 minutes. Representative images of indicated group at 30 minutes after injury were shown. Scale bar, 50 μm. (B) Occlusion time course of collagen-binding VWF variants. Intravital microscopy was performed with the VWF^−/− mice expressing WT or collagen-binding mutant-mVWF via hydrodynamic injection. The p.L1757A gain-of-function mutant showed enhanced thrombus generation. In contrast, the p.H1786D loss-of-function mutant showed decreased thrombus generation. Thrombus generation was most reduced in the VWF^−/− mice. However, even in these animals, residual thrombus activity of ∼25% occlusions were documented (n > 6). Scale bar, 50 μm.