FXII stimulates angiogenesis in matrigel plugs. Matrigel plugs were prepared with FGF + VEGF, FXII, or nothing and implanted in C57BL6 mice as indicated in “Methods.” All plugs did contain heparin. (A) Representative histology with an antibody to VWF detected with immunoperoxidase. The panel labeled IgG (immunoglobulin G) is an isotype-specific control antibody to the antibody to VWF detected with immunoperoxidase. “Neg” represents matrigel plugs with no growth factor stimulation; “FXII” represents matrigel plugs treated with FXII, and “FGF + VEGF” represents vessel formation stimulated by these combined growth factors. (B) The bar graph represents the means ± SDs of 10 high-power field of new vessel formation stimulated by FGF + VEGF, unstimulated (Neg), or FXII. (C) Represents the means ± SDs (n = 10 plugs) hemoglobin content/g of matrigel under each of the conditions: FGF + VEGF–treated plugs, untreated plugs (Neg), or FXII-treated plugs. (B-C) The asterisk indicates that there is a significant (P < .05) increase in the cells/field of view or hemoglobin content, respectively, compared with control in the FXII-treated samples. (D) Photographs of excised representative matrigel plugs placed in wild-type (WT) or uPAR KO mice that were not stimulated (Neg), treated with FXII (FXII), or treated with FGF + VEGF. The bottom row is anti-CD31 staining of representative sections from an untreated (Neg), FXII-treated (FXII), or FGF + VEGF-treated matrigel plugs that were placed into uPAR KO mice. (E) Represents the means ± SDs (n ≥ 3 plugs) hemoglobin content/g of matrigel under each of the conditions: Neg, no treatment; FXII, FXII treatment; FGF + VEGF, FGF + VEGF treatment in wild-type (WT) or uPAR KO (KO) mice. The significance between conditions is shown on the figure.