VWF is essential for PNA formation in the process of arteriogenesis. Following induction of arteriogenesis at day 1, whole blood was drawn from wild-type mice treated with saline or RNase A (A) or with DMSO or semaxanib (B) or from VWF-deficient (VWF KO) mice and their respective controls (C) and analyzed using flow cytometry. The scatter plots show the percentage of PNAs relative to the total number of neutrophils. Platelets were detected by a CD41 antibody, and neutrophils were identified by CD11b and Gr-1 antibodies. The dashed horizontal line indicates the mean sham value. For comparison, blood neutrophils (D) and platelets (E) were quantified in wild-type mice treated with saline, RNase A, DMSO, or semaxanib, as well as in VWF-deficient (VWF KO) mice and untreated wild-type mice (Control). Data are mean ± SEM. n = 6 per group (A-C), n = 3 per group (D-E). *P < .05, unpaired Student t test.