TSP-1 deficiency delays thrombus formation and prolongs bleeding time. (A) Representative immunoblot of TSP-1 from lysates of WT and TSP-1^−/− platelets. (B) Animals were counted after cessation of bleeding for 1 minute. Data are presented as scatter plot; every dot represents an individual animal, and the black line indicates mean. N = 7 for WT and N = 8 for TSP-1^−/− mice (P < .02). (C) In vivo thrombus formation following ferric chloride injury of the carotid artery of WT mice was compared with that of TSP-1^−/− mice (supplemental Videos). Platelets were labeled with Dylight488-conjugated rat anti-CD42b antibody. (i) Representative images of thrombus accrual at indicated times, (ii) representative graph of continuous monitoring of real-time thrombus formation (WT = black line and TSP-1^−/− = gray line), and (iii) time to peak thrombus size expressed as mean ± standard deviation of N = 8 WT (black bar) and N = 8 TSP-1^−/− (gray bar) mice (*P < .01). (D) Plasma TSP-1 pull-down from noninjured mice and from mice 30 minutes after ferric chloride injury examined by immunoblotting. Representative of 5 mice. (E) Peak thrombus size analysis (20 minutes’ postinjury) after transfusion of WT or TSP-1^−/− donor platelets into TSP-1^−/− recipient mice followed by ferric chloride injury. Data are presented as mean ± standard deviation and represent N = 5 (*P < .02).