Fig. 4: Thromboprotection of FXII900 in mice and effect on bleeding.
a Intravital fluorescence microscopy images showing mesenteric arterioles in which thrombosis was induced by topical application of FeCl3 (7.5%, 1 min). Platelets were fluorescently labeled with Rhodamine 6G for visualization. Representative images are shown for two mice, one treated with FXII900 (upper panels) and one treated with inactive control peptide FXII901 (lower panels) 15 min before the application of ferric chloride (5 mg kg−1, subcutaneous injection). Vessel walls at the FeCl3 application site are indicated with yellow markers. Three distinct morphological changes, (1) a characteristic speckled pattern, (2) clot formation, (3) and vessel occlusion, are indicated. Scale bar: 200 μm. b The percentage of mice showing either clot formation or full occlusion at different time points after ferric chloride application is indicated over time (inhibitor FXII900: 5 mg kg−1, n = 9; 25 mg kg−1, n = 8; neg. control FXII901: 5 mg kg−1, n = 8, 25 mg kg−1, n = 9; heparin: n = 10). Clot formation was defined as the appearance of an aggregate with a diameter larger than 10 μm. Full occlusion of the blood vessel was defined as a blood clot having the same diameter as the blood vessel. c Blood loss and bleeding time of mice with 2 mm tail transections. Mice were treated 5 min before clipping the tail tips with the vehicle (PBS, IV, n = 6), heparin (200 IU kg−1, IV, n = 10), FXII900 (25 mg kg−1, SC, n = 6) or FXII901 (25 mg kg−1, SC, n = 6). Mean values and standard deviations are indicated. The significance for a prolonged bleeding time was assessed with an unpaired, one-tailed t-test. The p value is indicated for significant results and n.s. stands for not significant. Mice treated with heparin showed either a small or medium-to-large loss of blood, and a mean value is thus not indicated.
