Abstract 865: Impaired Angiogenesis In Response To Hindlimb Ischemia In CuZnSOD-deficient Mice
Background: We have previously shown that several risk factors for cardiovascular diseases are also associated with reduced neovascularization in response to ischemia. A common feature of all cardiovascular risk factors is increased generation of reactive oxygen species, particularly superoxide. Accordingly, here we investigated the role of superoxide dismutase (SOD) in postnatal neovascularization following hindlimb ischemia.
Methods and Results: Two groups of mice were studied: homozygous CuZnSOD-deficient (CuZnSOD−/ −) mice and wild-type (CuZnSOD+/+) littermates. Hindlimb ischemia was surgically induced by femoral artery removal, and blood flow perfusion was then evaluated by serial Laser Doppler perfusion imager measurements. We found that CuZnSOD−/ − mice had a significant reduction of blood flow recovery when compared to CuZnSOD+/+mice, as assessed by Doppler Flow Ratios (DFR) between the ischemic and normal hindlimbs at day 21 after surgery (0.67±0.04 vs. 0.78±0.04, p<0.05). At the microvascular level, CuZnSOD−/ −mice showed a statistically significant reduction in capillary density in ischemic muscles compared to control mice, as assessed by CD31 immunohistochemistry (300±11 vs. 360±17 capillaries per mm2, p<0.05). The impaired angiogenic response in CuZnSOD−/ − mice was associated with increased oxidative stress in ischemic tissues (nitrotyrosine staining). We also found that the number of endothelial progenitor cells (EPCs) isolated from the bone marrow (40.6±3.0 vs. 70.5±5.0, p<0.001) or the spleen (0.29±0.06 vs. 0.54± 0.11, p<0.05) was significantly reduced in CuZnSOD−/ − compared to CuZnSOD+/+mice. Moreover, the functional activities of EPCs (cellular migration, adhesion, and integration into tubules) were significantly impaired in SOD deficient mice.
Conclusions: CuZnSOD deficiency is associated with impaired angiogenesis in response to ischemia. Our data suggest that increased oxidative stress could contribute to explain the previously described EPC dysfunction and impaired neovascularization associated with cardiovascular risk factors.