Figure 8.

Endothelial regeneration and vascular repair after endotoxemia-induced injury is also HIF-1α dependent. A: Pulmonary transvascular Evans Blue Dye–conjugated albumin (EBA) flux assay demonstrating defective vascular repair in Hif1a^f/f/Tie2Cre⁺ (CKO) mouse lungs after lipopolysaccharide (LPS) challenge (2.5 mg/kg, intraperitoneally). B: Lung wet/dry weight ratio analysis revealing lung edema in Hif1a^f/f/Tie2Cre⁺ mice at 72 hours after LPS.C: Time course of lung myeloperoxidase (MPO) activity after LPS challenge. D: Representative micrographs of hematoxylin and eosin staining of lung sections showing perivascular leukocyte sequestration in Hif1a^f/f/Tie2Cre⁺ mouse lungs at 72 hours after LPS. The boxed areas are shown at higher magnification in the insets in the left lower corners. E: Real-time quantitative RT-PCR analysis showing increased expression of proinflammatory mediators in Hif1a^f/f/Tie2Cre⁺ mouse lungs at 72 hours after LPS. F: Representative micrographs showing endothelial cell (EC) proliferation. Cryosections of lungs (5 μm thick) collected at 72 hours after LPS were immunostained with anti–5-bromo-2-deoxyuridine (BrdU) antibody to identify proliferating cells (green) and with anti-CD31/von Willebrand factor (vWF) antibodies to identify ECs (red). Arrows indicate proliferating Ecs. The boxed areas in the top panels are shown at higher magnification in the three bottom panels. G: Quantification of cell proliferation in mouse lungs. Three consecutive cryosections from each mouse lung were examined, and the average number of BrdU⁺ nuclei was used for each mouse. Data are expressed as means (A and C) or means ± SD (B, E, and G). n = 5 mice per group (B); n = 4 (E and G). ^∗∗P < 0.01 (t-test). Scale bars = 50 μm (D and F). B, basal; Br, bronchiole; Icam-1, intercellular adhesion molecule 1; Nos-2, inducible nitric oxide synthase; Tnf-α, tumor necrosis factor–α; V, vessel; WT, wild type.