Effects of aging on time course of neovascularization-related gene expression following acute hindlimb ischemia in mice.

BACKGROUND: Molecular analysis of neovascularization related genes by time course in response to ischemia has not been described in the context of aging. We aimed to provide a progressively deeper understanding of how aging compromises neovascularization. METHODS: Young (3-month) and old (18-month) C57Bl mice were subjected to left hindlimb ischemia. Necrosis score was evaluated in calf muscles. Calf muscles, peripheral blood, bone marrow were harvested at different time points. The expressions of matrix metalloproteiniase-9 (MMP9), endothelial nitric oxide synthase (eNOS), vascular endothelial growth factor (VEGF), stromal derived growth factor-1 (SDF1), hypoxia inducible factor-1α (HIF1α), VEGF receptor-1 (Flt1), VEGF receptor-2 (Flk1), angiopoietin-1 (Ang1), CD133, CD26 were detected by RT-PCR or Western blotting. White blood cells were counted in the peripheral blood. Gene expression data were compared by two-way analysis of variance. RESULTS: MMP9, HIF-1α and SDF-1 were more upregulated during acute ischemia in old vs. young mice, reflecting increased ischemia in aging mice. However VEGF and eNOS exhibited lower expression in old vs. young mice, despite greater ischemia intensity. Ang1 and Flk1 showed similar expression in old vs. young mice. MMP9 peaked earlier in peripheral blood in young vs. old mice. Concurrent decreasing CD26 and increasing CD133 expression in aging bone marrow suggest aging impairs progenitor cell mobilization, CONCLUSIONS: Our results indicate that a complex array of defects occur with aging that interfere with optimal neovascularization. These include potential impaired mobilization of progenitor cells to ischemic tissue, decreased levels of eNOS and VEGF and delayed responses to ischemia.

Metallothionein enhances angiogenesis and arteriogenesis by modulating smooth muscle cell and macrophage function.

OBJECTIVE: In a previous study we identified metallothionein (MT) as a candidate gene potentially influencing collaterogenesis. In this investigation, we determined the effect of MT on collaterogenesis and examined the mechanisms contributing to the effects we found. METHODS AND RESULTS: Collateral blood flow recovery was assessed using laser Doppler perfusion imaging, and angiogenesis was measured using a Matrigel plug assay. Smooth muscle cells were isolated from MT knockout (KO) mice for functional assays. Gene expression of matrix metalloproteinase-9, platelet-derived growth factor, vascular endothelial growth factor, and Fat cadherin in smooth muscle cells was measured by real-time polymerase chain reaction, and protein levels of vascular endothelial growth factor and matrix metalloproteinase-9 were determined using enzyme-linked immunosorbent assay and Western blot. CD11b(+) macrophages were tested for invasiveness using a real-time impedance assay. Both flow recovery and angiogenesis were impaired in MT KO mice. Proliferation, migration, and invasion were decreased in MT KO smooth muscle cells, and matrix metalloproteinase-9, platelet-derived growth factor, and vascular endothelial growth factor expression were also decreased, whereas FAT-1 cadherin expression was elevated. MT KO CD11b(+) cells were more invasive than wild-type cells. CONCLUSIONS: MT plays an important role in collateral flow recovery and angiogenesis, an activity that appears to be mediated, in part, by the effects of MT on the functionality of 3 cell types essential for these processes: endothelial cells, smooth muscle cells, and macrophages.

Cross-sectional associations of resistin, coronary heart disease, and insulin resistance.

CONTEXT: Recently, resistin was found to be present in atherosclerotic lesions in apoE(-/-) mice. Resistin may be associated with inflammation and atherosclerosis in humans; however, the role of resistin in human disease remains controversial. OBJECTIVE: This study assesses cross-sectional relationships of resistin with coronary heart disease (CHD). DESIGN, SETTING, AND PARTICIPANTS: Blood samples from the third examination of the Strong Heart Study (SHS)--the largest study of CHD in American Indians--were used. Cases who had suffered previous myocardial infarction (n = 100) were selected randomly from the three SHS sites and matched for study site and sex with controls who had no history of cardiovascular disease (CHD or stroke) (n = 100). MAIN OUTCOME MEASURE: Resistin levels by enzyme-linked immunosorbent assay method in cases and controls was the main outcome measure. RESULTS: Resistin levels were higher in cases than controls [median (interquartile range): 3.4 (2.5-4.7) vs. 2.8 (2.1-4.0) ng/ml; P = 0.003] and had univariate correlations with age (Spearman r = 0.21; P < 0.002), fasting insulin (r = 0.21; P = 0.003), insulin resistance by homeostasis model (r = 0.22; P = 0.04), albumin to creatinine ratio (r = 0.19; P = 0.01), and fibrinogen (r = 0.34; P < 0.0001). Cases were more likely to have diabetes (cases 67%; controls 41%; P < 0.0001) but had similar body mass index (cases 31.4 +/- 5.4; controls 30.7 +/- 6.3; P = 0.85). Resistin levels were higher in participants with established nephropathy (albumin to creatinine ratio >300 mg/g, n = 26) compared with those with normo- (n = 122) or microalbuminuria (n = 42). In multivariate analysis, nephropathy (P = 0.0013) but not previous myocardial infarction (P = 0.12) was significantly associated with resistin. CONCLUSIONS: Resistin is not independently associated with CHD. Resistin is elevated in survivors of myocardial infarction; however, this reflects a novel association of raised resistin with diabetic nephropathy.