Assessment of the biological hemostatic properties in VWF^2N mice whole blood. Blood samples were collected from the vena cava (terminal experiment) using 3.8% sodium citrate as an anticoagulant (vol/vol 1:10) and analyzed by nonactivated ROTEM analysis and nWB-TGA. (A) ROTEM analysis of whole blood. ROTEM standard cups were preloaded with 21 µL of 0.2M CaCl_2, and then 300 µL of whole blood was added. Clot formation was recorded using the NATEM measurement until maximum clot firmness reached its peak. (B) nWB-TGA analysis of whole blood. Fifteen microliters of whole blood was recalcified in the presence of a rhodamine-based, thrombin-cleavable, fluorescent substrate and added in duplicate to filter paper placed within the wells of a black 96-well plate. Change in fluorescence was measured over time and converted to thrombin generation. Conversions were calculated from a curve generated during a calibration experiment using a thrombin standard. C57BL/6J and VWF^−/− mice served as controls. *P < .05; **P < .01; ***P < .001. These data demonstrate that functional hemostatic properties in VWF^2N/2N whole blood are defective.