Figure 2.

Capillary histochemical affinity staining indicates lack of an ischemia-induced angiogenic response in MMP-9^−/− mice. Examination of tissue cross-sections stained with endothelial specific Griffonia simplicifolia lectin (green) indicates that capillary density increases in WT, but not in MMP-9^−/− tissues in response to ischemia (scale bar=20 μm). All nuclei counterstained with Hoechst (blue). Insets illustrate in addition BrdU-positive (red) immunodetection of proliferating cells (pink, due to localization to nuclei counterstained in blue) with capillary staining (green), as well as a negative control with no primary antibody (“No 1⁰”). Proliferating cells were found only in ischemic WT tissues supporting the presence of a robust angiogenic response. Quantification of capillary density displays a significant increase in capillary number within WT but not within MMP-9^−/− ischemic tissues (n=4 for each point, *P<0.05 vs MMP-9^−/−), supporting MMP-9 role in ischemia-induced angiogenic response.