Endogenous α-defs accelerate coagulation and impair fibrinolysis in whole blood. (A) Blood was drawn from WT and Def⁺⁺ mice. Clotting initiated by adding kaolin and calcium chloride was monitored by thromboelastography. “1” and “2” denote the time until the first evidence of clot formation was detected in WT and Def⁺⁺ mice, respectively. “3” and “4” depict lysis in WT and Def⁺⁺ mice, respectively. One experiment representative of 3 is shown. (B) Blood was drawn from a healthy human donor. Clotting was initiated and monitored as in panel A. Results show the comparability of the thromboelastography tracing in human blood and blood from Def⁺⁺ mice expressing α-Def-1. One experiment representative of 3 is shown. (C) Formation of IVC thrombi in Def⁺⁺ mice. Partial occlusion of the IVC was induced in Def⁺⁺ and WT mice. Arrows denote the direction of blood flow and the size of the clot. (D) Three days later, clots were removed. The weights of clots extracted from Def⁺⁺ and WT mice are shown. (E) The segment of the IVC containing the blood clot was excised. The clots were embedded in paraffin, sectioned, and stained with hematoxylin and eosin, and the results are shown at original magnification ×50. Panels C-E are representative of results in 12 mice. *P < .001. (F) Effect of α-def-1 on the structure of mouse IVC thrombi. Scanning electron microscopy of thrombi within the IVC of Def⁺⁺ and WT mice. a and c show the clot surface, and b and d show the clot interior. Fibrin fibrils elements are identified with red arrowheads; representative compressed red blood cells (polyhedrocytes) are identified with blue arrowheads. The fibrin meshwork on the surface of the clot in Def⁺⁺ is more dense (a), and many more polyhedrocytes are seen within the clot (c) than within thrombi from WT mice (b and d, respectively). Scale bars represent 10 μm (a and b) and 30 μm (c and d).