CCM lesions are procoagulant in vivo. (A) Representative images of the cerebellum of wild-type (upper panel) and Ccm3-iECKO (lower panel) P8 mice stained with fibrin-fibrinogen (green), fibronectin (red), and isolectin (magenta). Colocalization of fibrin-fibrinogen and fibronectin is highlighted with an arrow. (B) Quantification of fibrin-fibrinogen in the cerebellum (cb) of wild-type and Ccm3-iECKO mice (P = .0556). (C) Quantification of fibronectin in the cerebellum (cb) of wild-type and Ccm3-iECKO mice (P = .0079). (D) Representative images of the cerebellum of wild-type (upper panel) and Ccm3-iECKO (lower panel) P8 mice stained with isolectin (green), VWF (red), and DAPI (blue). A magnified image is shown in the right panel and the asterisks highlight secreted VWF. (E) Quantification of VWF in the cerebellum (cb) of wild-type and Ccm3-iECKO mice (P = .0159). (F) A tile scan of a sporadic CCM patient biopsy with multiple lesions. DAPI (blue) highlights the nuclei of cells, fibrin-fibrinogen (green) highlights leakage and clots and VWF (magenta) outlines the vasculature and fills clots. A selected region (dashed box) is shown to the right and it demonstrates a large clot filled fibrin (green) and VWF (magenta). Fibrin and VWF colocalize in the clot (merged panel on the top right). (G) Confluent HBECs (shScramble, left and shCCM3, right) stained for VWF (green) VE-cadherin (red), and DAPI (blue). High magnification (zoom) images on the right side of each condition. Arrows represent VWF strings. In all graphs, each data point represents 1 biological replicate (n = 4-8 mice per group), the bar indicates the mean of each group, and the error bars represent the standard deviation. A Mann-Whitney U test was used to compare wild-type mice with Ccm3-iECKO mice; the corresponding P values are indicated on each graph.