Figure 8

Deficits in vessel function in mammary tumors in NG2 null mice. A-C. Leakage from Py8119 tumor vessels was evaluated using intravenously-administered FITC-dextran. Tissue sections were immunolabeled for CD31 (red) to allow image analysis of FITC-dextran (green) located external to tumor vessels in wild type (A) versus NG2 null (B) tissues. Arrowheads in merged images A and B show sites with extravascular FITC-dextran. Confocal z-stacks were used to quantify the percentage of FITC pixels external to CD31-positive vessel walls (C). Data were collected from six tumors per genotype, evaluating four sections per tumor. D-H. Tumor hypoxia was evaluated in mice injected intravenously with pimonidazole hypoxia probe. Immunostaining of wild type (D, F) and NG2 null (E, G) tissue sections for CD31 (red, D, E) and pimonidazole (green, F, G) allowed visualization of hypoxic areas relative to tumor vasculature. Image analysis was used to determine the extent of hypoxia as a percentage of total tumor area (H). Data were collected from six tumors per genotype, evaluating four sections per tumor. Scale bars = 100 μm. * P = 0.05; ** P = 0.003. FITC, fluorescein isothiocyanate; NG2, nerve-glial antigen 2.