T. Cooper Woods

Elevation of miR-221 and -222 in the internal mammary arteries of diabetic subjects and normalization with metformin.

Diabetes is a major risk factor for cardiovascular disease and is associated with increased intimal thickening and accelerated vascular smooth muscle cell (VSMC) proliferation. We measured the expression of two microRNAs that promote intimal thickening, miR-221/222, and mRNA encoding a downstream target, p27(Kip1), in internal mammary artery (IMA) segments collected from 37 subjects undergoing coronary artery bypass grafting. The segments were stratified into three groups: non-diabetic subjects (ND), diabetic subjects not on metformin (DMMet-), and diabetic subjects on metformin (DMMet+). The DMMet- group exhibited a significant increase in miR-221/222 and decrease in p27(Kip1) mRNA compared to both the ND and DMMet+ groups. miR-221/222 levels inversely correlated with metformin dose. VSMCs isolated from the IMAs of the DMMet- group proliferate at a faster rate than those of the ND and DMMet+ groups. Further studies into the importance of miR-221/222 in the increased intimal thickening observed in diabetic subjects is warranted.

Circulating inflammation-resolving lipid mediators RvD1 and DHA are decreased in patients with acutely symptomatic carotid disease

BACKGROUND Efficient biomarkers for early prediction and diagnosis of an acutely symptomatic carotid plaque rupture event are currently lacking, impairing the ability to diagnose and treat patients with an acute plaque rupture events in a timely fashion. Resolvins are endogenous inflammation-resolving lipid mediators that are induced by inflammatory insults. We hypothesized that resolvin and other lipid profiles in sera likely mark the process towards plaque rupture. METHODS Circulating lipids associated with plaque rupture events were quantitatively profiled via targeted mediator-lipidomics using ultraperformance liquid chromatography tandem mass spectrometry in patients with acutely symptomatic and asymptomatic carotid disease. RESULTS Resolvin D1 (RvD1, 82 ± 11pM vs. 152 ± 17pM, p = 0.001) and docosahexaenoic acid (DHA) (0.052 ± 0.007µM versus 0.076 ± 0.008µM, p = 0.025) levels are decreased in the sera of patients presenting with an acutely symptomatic carotid plaque rupture event (n = 21) compared to patients with asymptomatic (n = 24) high-grade carotid stenosis. Circulating arachidonic acid (AA) levels, however, were higher (0.429 ± 0.046µM versus 0.257 ± 0.035µM, p < 0.01) in acutely symptomatic compared to asymptomatic carotid patients. ROC curve analysis demonstrates that the serum ratio AA:RvD1 (AUC 0.84, sensitivity 0.71, specificity 0.92) and AA:DHA (AUC 0.86, sensitivity 0.90, specificity 0.71) are biomarkers for the risk of atherosclerotic plaque rupture. CONCLUSIONS A circulating pro-inflammatory lipid profile, characterized by high AA:RvD1 and AA:DHA, is associated with acutely symptomatic carotid disease and stroke.

Upregulation of miR-221 and -222 in response to increased extracellular signal-regulated kinases 1/2 activity exacerbates neointimal hyperplasia in diabetes mellitus

BACKGROUND AND AIMS Diabetes is associated with accelerated arterial intimal thickening that contributes to the increased cardiovascular disease seen in this population. In healthy arteries, intimal thickening is inhibited by elevated levels of the cyclin-dependent kinase inhibitor, p27Kip1, and intimal thickening is promoted by activation of the mammalian Target of Rapamycin to promote degradation of p27Kip1 protein. Recently, we reported that two microRNAs, miR-221 and -222, which promote intimal thickening via down-regulation of mRNA encoding p27Kip1, are elevated in the arteries of diabetic patients. To determine if these miRNAs are critical to the increased intimal thickening under diabetic conditions, we examined the regulation of p27Kip1in a mouse model of diabetes. METHODS Comparisons of p27Kip1 signaling in NONcNZO10 mice fed a diabetogenic versus control diet were performed using immunochemistry and real-time PCR. RESULTS Vascular smooth muscle cells and arteries of diabetic mice exhibited decreased levels of p27Kip1 that derived from destabilization of p27Kip1 mRNA in an extracellular signal response kinase-1/2 (ERK-1/2) dependent manner. The activity of ERK-1/2 is increased in the arteries of diabetic mice and promotes an increase in miR-221 and -222. Inhibition of miR-221 and -222 restores normal levels of p27Kip1 mRNA and protein in the arteries of diabetic mice and reduces intimal thickening following wire injury. CONCLUSIONS These data suggest diabetes is accompanied by increases in arterial miR-221 and -222 expression that promotes intimal thickening. Inhibition of the increased miR-221 and -222 may be efficacious in the prevention of the cardiovascular complications of diabetes.

PC212 Role of Circulating miRNAs in Carotid Atherosclerotic Plaque Vulnerability: Implications for Stroke

Objectives: Each year, >35,000 children are born in the United States with congenital heart defects. A vascular conduit is commonly used in the surgical repair of these defects. However, no currently available vascular conduit provides the potential for growth. For children with congenital heart diseases, this means having to undergo repeated operations due to the limitations of current vascular conduits. Pediatric patients with congenital cardiovascular defects would benefit greatly from an expandable conduit. To address this issue, PECA Labs has developed a novel expanded polytetrafluoroethylene vascular conduit with the capability of being radially expanded via balloon catheterization. We have shown previously that this novel expanded polytetrafluoroethylene material maintains its mechanical properties after expansion (Fig). Methods: In the described study, a systematic biocompatibility and chemical characterization was conducted to investigate the clinical viability of this novel expandable conduit material. The material is also undergoing proof-of-concept testing in a large-animal aortic replacement model. Pyrogenicity was tested in a rabbit model to determine the levels of chemical pyrogens in the material. New Zealand White rabbits were injected with the material extracts, and their temperature was monitored for 3 hours. Cytotoxicity was evaluated in vitro by culturing mouse fibroblast CCL-1 cells with the material and quantifying cell viability after 24 hours. Hemocompatibility was determined with a hemolysis test using rabbit blood. Whole rabbit blood was cultured with material extracts for 3 hours. Samples were then centrifuged to collect the supernatant to test for free hemoglobin. Additional testing, including irritation testing, the genotoxicity, and hemodynamics is currently ongoing. Implantation of the material in a 14-day rabbit implantation study is ongoing to determine the systemic toxicity of the material. Results: The results from testing have thus far have illustrated the biocompatibility of this expandable conduit material. The expandable material is considered nonpyrogenic and meets the requirements of the Pyrogen Test, ISO 10993-11 guidelines. The material also meets the requirements to be nonhemolytic according to ASTM F756 guidelines and is not considered to have a cytotoxic potential based on ISO 10993-5 guidelines. Large-animal proof-of-concept testing and chemical characterization testing is currently underway, and results will be collected over the next 2 months. Conclusions: Thus far, this study represents successful safety verification of this material and is a critical step toward clinical translation,