VWF KO mice do not show significant thrombocytopenia, experience a level of P-selectin expression but do not form platelet leukocyte aggregates following adenovirus administration. (A) Platelet counts were assessed at 1 hour, 5 hours, 24 hours, and 1 week following intravenous administration in WT and VWF^−/−C57BL/6 mice showing nonsignificant thrombocytopenia in VWF^−/− following adenovirus (n = 6, P = .002 in WT versus P = .06 in VWF KO mice). (B) Similar to VWF^+/+ mice, platelets from VWF^−/− mice show significant P-selectin expression at 1 hour after adenovirus injection (n = 3, P < .001) compared to preinjection expression but significantly lower when compared to WT (P = .01). (C) Graph showing nonsignificant platelet leukocyte aggregates at 1 hour following virus administration to VWF KO mice compared to the preinjection level (n = 3, P = .12 in KO versus P = .007 in WT mice)