Interruption of fibrinolysis blocks retinal neoangiogenesis during OIR. (A) Clot lysis curves representative of ≥ 3 assays (n = 4 for each) performed with plasma from P17 Anxa2^+/+ mice treated with or without TA. (B) Representative cross-sections (magnification ×40) of retinas from P17 oxygen-treated Anxa2^+/+ mice treated with or without TA and stained with DAPI (blue), isolectin B4 (green), and anti-fibrinogen (red). Close-up views of the peripheral retina (magnification ×200) are also shown. Fibrin deposition is indicated by arrowheads. S indicates sclera; V, vitreous body. Scale bars 500 and 100 μm for magnification ×40 and ×200, respectively. (C) Representative immunoblot of fibrin in retinas from P17 oxygen-treated Anxa2^+/+ mice treated with or without TA. (D) Representative images from P17 oxygen-treated Anxa2^+/+ mice treated with or without TA, showing total retinal area and regions of VO and NV. Pixel number corresponding to each compartment is indicated below each image. Scale bars, 200 μm (magnification ×50). (E) Ratios of VO to total retinal area (19.8% ± 1.3% vs 22.2% ± 3.3%) and NV to total area (11.4% ± 0.9% vs 4.6% ± 0.3%) in retinas from P17 oxygen-treated Anxa2^+/+ mice treated with or without TA (n = 4; NS indicates no significant difference, ***P < .001). (F) Enumeration of neovascular nuclei in retinas from P17 oxygen-treated Anxa2^+/+ mice treated with (92 ± 4.0; n = 5) or without TA (207 ± 5.9; n = 3; ***P < .001). The data are representative of 5 (B) or 3 (C) independent experiments.