Background: S100A6 is a small calcium-binding protein that is important in managing calcium storage and myocyte contractility. This protein has a low basal cardiac expression and is upregulated following Myocardial Infarction (MI). Previous experiments have demonstrated that S100A6 gene transfer improves left ventricular function after acute ischemia/reperfusion injury. Hypothesis: Delivery of S100A6 by Ultrasound-Targeted Microbubble Destruction (UTMD) after established MI model results in improved left ventricular function and prevention of adverse ventricular remodeling. Aim: Assess the impact of UTMD delivery of S100A6 on cardiac function following experimental MI. Methods: MI was induced through permanent left anterior descending (LAD) coronary artery ligation in 8-week-Spragues Dawley (SD) male rats on day 0. On day 28, by using UTMD methods, we delivered microbubbles (1×109) coupled with either 200 μg of human S100A6 mini-circle DNA or empty minicircles to the left ventricle (LV), while control animals received no therapy. The three groups were monitored weekly for four weeks post-gene delivery using serial echocardiography to follow LV function, followed by tissue collection from various regions of the myocardium. Results: At day 28 post-MI, all groups showed reduced LV ejection fraction (LVEF) and fractional shortening (FS), with LVEF and FS values of 39.47±1.49% and 19.75±2.38%, respectively. Meanwhile, healthy animals showed LVEF and FS values of (63.75±2.38% and 36.20±1.29% (p<0.001). Four weeks after the UTMD delivery of the S100A6, LVEF increased to 51.14±3.7% and FS increased to 29.66±3.2% (p<0.05). In contrast, the empty minicircle and control groups showed no significant improvement (38.35±2.6% and 20.66±5.2%, p<0.05). The S100A6-treated group at 28 days post-treatment showed a 2.7±1.2-fold increase in the expression level of S100A6 in the border zones. Interestingly, the peri-infarct zone of S100A6-treated myocardium also had a lower expression level of the hypertrophic marker, β-MHC (0.77±0.7-fold), as compared to those of the control groups (2.48±1.63-fold). S100A6 transfection reduced infarct size (24.75±3.3%); vs control (36±4.58%), p<0.05 and decreased collagen content in viable myocardium compared to the control and empty minicircle group, p<0.01. Conclusion: S100A6 overexpression in the peri-infarct zone decreased both hypertrophy and fibrosis and was beneficial to the preservation of cardiac function in a model of chronic MI.

Introduction: MiRNAs play crucial regulatory roles in multiple pathways involved in cardiovascular diseases. RUNX3, a post-transcriptional factor, induces apoptosis in various cells. Hypothesis: We...

Background: B vitamin deficiency has been previously reported to be prevalent in patients with heart failure.However, clinical trials investigating the potential of B vitamin supplementation have failed to show benefit and have suggested some evidence of harm.Negative findings have been hypothesized to be the result of an anti-angiogenic effect associated with B vitamin supplementation.Objective: The current study aimed to determine the impact of vitamin B6 supplementation alone or in combination with folate and B12 on the angiogenic response in a rodent model of hind limb ischemia.Methods: Rats were divided randomly into three groups and fed one of three diets: control diet (CON), high B6 diet (HB6) or high B6+folate+B12 diet (TV).Following five weeks of diet therapy, ischemia was surgically induced in the hind limb.Changes in perfusion and markers of the angiogenic response were studied at either 5 (early) or 10 (late) weeks.Result: Circulating EPCs were reduced in HB6 animals, a finding that reached significance for the TV animals.Quantitative polymerase chain reaction analysis revealed a decline in VEGF and eNOS expression in HB6 and TV groups at week 10.Contrast enhanced ultrasound of the hind limb revealed a significant reduction in perfusion in HB6 and TV animals in comparison to CON at 10 weeks.B vitamin supplementation had no impact on EPC apoptosis or differentiation. Conclusion:Taken together, these results support a negative impact of B vitamin supplementation on the recovery of perfusion following ischemic injury which may be the result of a down-regulation of chemotactic gene expression, leading to lowered EPC recruitment from the bone marrow to the site of ischemic injury.

Introduction: Noncoding RNAs have emerged as important regulators of cardiac development and cardiovascular diseases. The Runt-related transcription factor 3 (RUNX3) is downregulated in cancer cell...

BackgroundCardiomyocyte‐specific transgenic mice overexpressing S100A6, a member of the family of EF‐hand calcium‐binding proteins, develop less cardiac hypertrophy, interstitial fibrosis, and myocyte apoptosis after permanent coronary ligation, findings that support S100A6 as a potential therapeutic target after acute myocardial infarction. Our purpose was to investigate S100A6 gene therapy for acute myocardial ischemia‐reperfusion. Methods and ResultsWe first performed in vitro studies to examine the effects of S100A6 overexpression and knockdown in rat neonatal cardiomyocytes. S100A6 overexpression improved calcium transients and protected against apoptosis induced by hypoxia‐reoxygenation via enhanced calcineurin activity, whereas knockdown of S100A6 had detrimental effects. For in vivo studies, human S100A6 plasmid or empty plasmid was delivered to the left ventricular myocardium by ultrasound‐targeted microbubble destruction in Fischer‐344 rats 2 days prior to a 30‐minute ligation of the left anterior descending coronary artery followed by reperfusion. Control animals received no therapy. Pretreatment with S100A6 gene therapy yielded a survival advantage compared to empty‐plasmid and nontreated controls. S100A6‐pretreated animals had reduced infarct size and improved left ventricular systolic function, with less myocyte apoptosis, attenuated cardiac hypertrophy, and less cardiac fibrosis. ConclusionsS100A6 overexpression by ultrasound‐targeted microbubble destruction helps ameliorate myocardial ischemia‐reperfusion, resulting in lower mortality and improved left ventricular systolic function post–ischemia‐reperfusion via attenuation of apoptosis, reduction in cardiac hypertrophy, and reduced infarct size. Our results indicate that S100A6 is a potential therapeutic target for acute myocardial infarction.

INTRODUCTION:The field of regenerative medicine has evolved over the years, investigating gene and stem/progenitor cell therapies to help address the increasing burden of cardiovascular disease (CVD). While the lack of success of gene therapy in clinical trials has dampened enthusiasm, the search continues for a successful and translatable gene therapy strategy for CVD. Ultrasound-mediated gene delivery (UMGD) is a non-invasive technique for gene delivery that utilizes gene-bearing carrier microbubbles and high power ultrasound to facilitate transfection in vivo. Many pre-clinical studies have shown benefit in animal models of CVD, but this has yet to be translated to human applications.AREAS COVERED:In this review, the basic principles of UMGD will be examined along with an overview of pre-clinical studies to date in CVD, focusing on cardiac and vascular applications and key findings. In addition, the potential path to the clinical translation of UMGD is discussed.EXPERT OPINION:Ultrasound-mediated gene delivery holds promise as a non-invasive technique for gene delivery in CVD, with the ability to deliver multiple genes with repeated deliveries over time. If the substantial hurdles to clinical translation can be overcome, UMGD may prove to be a key aspect in the success of cardiovascular gene therapy in the future.

Pancreatic ductal adenocarcinoma (PDAC) is characterized by an intense fibrotic reaction termed tumor desmoplasia, which is in part responsible for its aggressiveness. Endothelial cells have been shown to display cellular plasticity in the form of endothelial-to-mesenchymal transition (EndMT) that serves as an important source of fibroblasts in pathological disorders, including cancer. Angiogenic co-receptor, neuropilin-1 (NRP- 1) actively binds TGFβ1, the primary mediator of EndMT and is involved in oncogenic processes like epithelial-to-mesenchymal transition (EMT). NRP-1 and TGFβ1 signaling have been shown to be aberrantly up-regulated in PDAC. We report herein a positive correlation between NRP-1 levels, EndMT and fibrosis in human PDAC xenografts. Loss of NRP-1 in HUVECs limited TGFβ1-induced EndMT as demonstrated by gain of endothelial and loss of mesenchymal markers, while maintaining endothelial cell architecture. Knockdown of NRP-1 down-regulated TGFβ canonical signaling (pSMAD2) and associated pro-fibrotic genes. Overexpression of NRP-1 exacerbated TGFβ1-induced EndMT and up-regulated TGFβ signaling and expression of pro-fibrotic genes. In vivo, loss of NRP-1 attenuated tumor perfusion and size, accompanied by reduction in EndMT and fibrosis. This study defines a previously unrecognized role of NRP-1 in regulating TGFβ1-induced EndMT and fibrosis, and advocates NRP-1 as a therapeutic target to reduce tumor fibrosis and PDAC progression.

Background & aims: Secondary prevention can improve outcomes in high risk patients. This study investigated the magnitude of cardiovascular risk reduction associated with consumption of a modified portfolio diet in parallel with medical management.Design: 30 patients with type II diabetes, 6 weeks post bypass surgery received dietary counseling on a Modified Portfolio Diet (MPD) (low fat, 8 g/1000 kcal viscous fibres, 17 g/1000 kcal soy protein and 22 g/1000 kcal almonds). Lipid profiles, endothelial function and markers of glycemic control, oxidative stress and inflammation were measured at baseline and following two and four weeks of intervention. Seven patients with no diet therapy served as time controls.Results: Consumption of the MPD resulted in a 19% relative reduction in LDL (1.9 +/- 0.8 vs 1.6 +/- 0.6 mmol/L, p < 0.001) with no change in HDL cholesterol. Homocysteine levels dropped significantly (10.1 +/- 2.7 vs 7.9 +/- 4 mu mol/L, p = 0.006) over the study period. Flow mediated dilatation increased significantly in treated patients (3.8 +/- 3.8% to 6.5 +/- 3.6%, p = 0.004) while remaining constant in controls (p = 0.6). Endothelial progenitor cells numbers (CD34+, CD 133+ and UEA-1+) increased significantly following MPD consumption (p < 0.02) with no difference in migratory capacity. In contrast, time controls showed no significant changes.Conclusion: Dietary intervention in medically managed, high risk patients resulted in important reductions in risk factors. (C) 2014 Elsevier Ltd and European Society for Clinical Nutrition and Metabolism. All rights reserved.

Objective—MicroRNAs are involved in many critical functions, including angiogenesis. Ultrasound-targeted microbubble destruction (UTMD) is a noninvasive technique for targeted vascular transfection of plasmid DNA and may be well suited for proangiogenic microRNA delivery. We aimed to investigate UTMD of miR-126-3p for therapeutic angiogenesis in chronic ischemia. Approach and Results—The angiogenic potential of miR-126-3p was tested in human umbilical vein endothelial cells in vitro. UTMD of miR-126-3p was tested in vivo in Fischer-344 rats before and after chronic left femoral artery ligation, evaluating target knockdown, miR-126-3p and miR-126-5p expression, phosphorylated Tie2 levels, microvascular perfusion, and vessel density. In vitro, miR-126-3p–transfected human umbilical vein endothelial cells showed repression of sprouty-related protein-1 and phosphatidylinositol-3-kinase regulatory subunit 2, negative regulators of vascular endothelial growth factor and angiopoietin-1 signaling, increased phosphorylated Tie2 mediated by knockdown of phosphatidylinositol-3-kinase regulatory subunit 2 and greater angiogenic potential mediated by both vascular endothelial growth factor/vascular endothelial growth factor R2 and angiopoietin-1/Tie2 effects. UTMD of miR-126-3p resulted in targeted vascular transfection, peaking early after delivery and lasting for >3 days, and resulting in inhibition of sprouty-related protein-1 and phosphatidylinositol-3-kinase regulatory subunit 2, with minimal uptake in remote organs. Finally, UTMD of miR-126-3p to chronic ischemic hindlimb muscle resulted in improved perfusion, vessel density, enhanced arteriolar formation, pericyte coverage, and phosphorylated Tie2 levels, without affecting miR-126-5p or delta-like 1 homolog levels. Conclusions—UTMD of miR-126 results in improved tissue perfusion and vascular density in the setting of chronic ischemia by repressing sprouty-related protein-1 and phosphatidylinositol-3-kinase regulatory subunit 2 and enhancing vascular endothelial growth factor and angiopoietin-1 signaling, with no effect on miR-126-5p. UTMD is a promising platform for microRNA delivery, with applications for therapeutic angiogenesis.

Background: Left ventricular hypertrophy (LVH) is commonly found in chronic dialysis (CD) recipients, and is associated with impaired microvascular cardiac perfusion and heart failure. In response to LVH and cardiac ischemia, early outgrowth pro-angiogenic cellS(EPCs) mobilize from the bone marrow to facilitate angiogenesis and endothelial repair. In the general population, EPC number and function correlate inversely with cardiovascular risk. In end-stage renal disease (ESRD), EPC number and function are generally reduced. Objectives: To test whether left ventricular abnormalities retain their potent ability to promote EPC reparative responses in the setting of ESRD. Design: Cross-sectional study. Setting: St. Michael's Hospital, Toronto, Ontario, Canada. Patients: 47 prevalent chronic dialysis recipients. Measurements: (1) circulating CD34 + and CD133 + EPC number, (2) cultured EPC migratory ability, in vitro differentiation potential, and apoptosis rate, and (3) cardiac magnetic resonance-measured LV mass, volume and ejection fraction. Methods: Bivariate correlation analysis was performed with Spearman's rho test. Results: Of the 47 patients (mean age: 54 ± 13 years), the mean delivered urea reduction was 74 ± 10 %. Mean LV mass was 123 ± 38 g. Circulating CD34 + and CD133 + EPCs represented 0.14 % (IQR: 0.05 – 0.29 %) and 0.05 % (IQR: 0.01 – 0.10 %) of peripheral blood mononuclear cells. There were no significant correlations between any EPC parameter and measures of LV mass or ejection fraction. Limitations: Lack of a non-ESRD control population, and the inability to measure all parameters of EPC function due to limitations in blood sampling. Our inability to measure cardiac VEGF expression prevented an assessment of changes in cardiac EPC mobilization signals. Conclusions: These data suggest that in ESRD, the reparative EPC response to cardiac hypertrophy may be blunted. Further investigation of the effects of uremia on EPC physiology and its relationship to cardiac injury are required.

Hereditary hemorrhagic telangiectasia (HHT) is an autosomal dominant vascular disorder. Circulating angiogenic cells (CACs) play an important role in vascular repair and regeneration. This study was designed to examine the function of CACs derived from patients with HHT. Peripheral blood mononuclear cells (PBMNCs) isolated from patients with HHT and age- and gender-matched healthy volunteers were assessed for expression of CD34, CD133 and VEGF receptor 2 by flow cytometry. PBMNCs were cultured to procure early outgrowth CACs. Development of endothelial cell (EC) phenotype in CACs was analyzed by fluorescence microscopy. CAC apoptosis was assayed with Annexin V staining, and CAC migration assessed by a modified Boyden chamber assay. mRNA expression of endoglin (ENG), activin receptor-like kinase-1 (ACVLR1 or ALK1) and endothelial nitric oxide synthase (eNOS) in CACs was measured by real time RT-PCR. The percentage of CD34+ cells in PBMNCs from HHT patients was significantly higher than in PBMNCs of healthy controls. CACs derived from patients with HHT not only showed a significant reduction in EC-selective surface markers following 7-day culture, but also a significant increase in the rate of basal apoptosis and blunted migration in response to vascular endothelial growth factor and stromal cell-derived factor-1. CACs from HHT patients expressed significantly lower levels of ENG, ALK1 and eNOS mRNAs. In conclusion, CACs from patients with HHT exhibited various functional impairments, suggesting a reduced regenerative capacity of CACs to repair the vascular lesions seen in HHT patients.

Background: Perlecan is a heparan sulfate proteoglycan (HSPG) constituent of the extracellular matrix with roles in cell growth, differentiation, and angiogenesis. The role of the HS side chains in regulating in vivo angiogenesis after hind-limb ischemia is unknown.Methods: Heparan sulfate (HS)-deficient perlecan (Hspg2(Delta 3/Delta 3)) mice (n = 35), containing normal perlecan core protein but deficient in HS side chains, and wild-type (n = 33) littermates underwent surgical induction of hind-limb ischemia. Laser Doppler perfusion imaging (LDPI) and contrast-enhanced ultrasonography (CEU) provided serial assessment of hind-limb perfusion. Harvested muscles underwent immunostaining for endothelial cell density (CD31), real-time reverse transcription polymerase chain reaction RT-PCR for vascular endothelial growth factor (VEGF) mRNA expression and western blot analysis for VEGF and fibroblast growth factor (FGF) 2 protein expression at days 2 and 28.Results: Serial LDPI showed significantly greater perfusion recovery in ischemic limbs of wild-type compared with Hspg2(Delta 3/Delta 3) mice. CEU showed that normalized microvascular perfusion was increased in wild-type compared with Hspg2(Delta 3/Delta 3) mice at day 28 (0.67 +/- 0.12 vs 0.26 +/- 0.08; P = 0.001). CD31-positive cell counts were significantly higher in wild-type compared with Hspg2(Delta 3/Delta 3) mice on day 28 (122 +/- 30 cells vs 84 +/- 34 cells per high-power field [HPF]; P < 0.05). Endogenous VEGF mRNA expression (P < 0.05) and VEGF protein expression (P < 0.002) were significantly decreased in the ischemic limbs of Hspg2(Delta 3/Delta 3) mice compared with wild-type mice at day 2 and day 28, respectively. FGF2 protein expression showed no significant differences.Conclusions: These results suggest that the HS side chains in perlecan are important mediators of the angiogenic response to ischemia through a mechanism that involves upregulation of VEGF expression.

Background: MicroRNA (miR)-126 is an endothelial cell specific microRNA that regulates angiogenesis by blocking Sprouty-related protein (SPRED1) and phosphoinositol-3 kinase (PI3K) two endogenous i...

Background: Ultrasound-targeted microbubble destruction (UTMD) is a non-invasive gene transfection technique using carrier microbubbles and targeted high power ultrasound, primarily used to deliver plasmid DNA (pDNA). Minicircle-DNA (mcDNA) is a novel gene vector, which has recently been shown to have an improved and persistent transfection, compared to conventional pDNA. Hypothesis: We hypothesized that UTMD of mcDNA in a hind-limb model would exhibit a more potent and prolonged gene expression compared to conventional pDNA. Methods: In vitro , HUVECs, fibroblasts (3T3) and neonatal cardiomyocytes were transfected with molar equivalents of GFP-minicircle and GFP-plasmid. GFP expression was measured by RT-PCR and fluorescent microscopy for 28 days. We then performed a comparison of bubble binding capacities of both vectors to cationic lipid microbubbles. In vivo , for UTMD to the left proximal hind-limb adductor muscle, 500μg and 214μg of GFP-plasmid and GFP-minicircle respectively were charge-coupled with 1x10 9 cationic microbubbles and delivered via UMGD into Sprague-Dawley rats (n=30). The animals were followed for 28 days with GFP measured by RT-PCR and immunohistochemistry. Results: In vitro results showed greater GFP expression by mcDNA across all cell lines, with 7-10 fold transfection efficacy compared to pDNA. mcDNA demonstrated greater binding capacity to cationic microbubbles compared to pDNA. For plasmid and minicircle DNA, binding saturations were reached at ~6000 copies per microbubble, and ~20000 copies per microbubble respectively, suggesting a higher minicircle bubble binding efficiency. In vivo results showed higher GFP levels as early as 6 hours post minicircle UTMD, demonstrating minicircle to be a faster acting therapeutic agent over conventional plasmid. A significantly greater (p<0.01) expression of GFP was also evident at day 28 in minicircle UTMD-treated group, proving mcDNA to be a better choice for longer-term gene expression. Conclusions: In summary, UTMD using mcDNA results in more rapid and sustained transfection compared to conventional pDNA, and may be a more effective vector for translational studies of UTMD.

Introduction: The endothelial specific microRNA-126 (miR-126) regulates angiogenesis primarily by blocking endogenous inhibitors of VEGF, Sprouty-related protein and phosphoinositol-3 kinase regulatory subunit 2. We hypothesized that ultrasound-mediated delivery of miR-126 contributes to neovascularization through VEGFR-2 and Tie2 pathway at an early and late stage respectively in chronic ischemia. Methods: F-344 rats (n=4) were delivered with fluorescently labeled miR by ultrasound-mediated gene delivery (UMGD) to determine the miR cellular localization. Unilateral hindlimb ischemia was created by left femoral artery ligation (n=92). At day 14 post-ligation, microvascular blood flow (MBF) was assessed by contrast-enhanced ultrasound (CEU). UMGD of miR-126 (n=35) or scrambled miR (n=25) was performed, with control animals (n=32) receiving no treatment. Perfusion was re-assessed and Tie2 and pTie2 levels were quantified by western blotting at day 28. For in vitro studies, human umbilical vascular endotheli...

Background: Diabetes mellitus is a chronic metabolic disease associated with various vascular complications. Various strategies to promote therapeutic angiogenesis in ischemic tissue including delivery of pro-angiogenic growth factors have shown disappointing results. Risk factors, such as diabetes, may adversely impact the response to angiogenic strategies and limit efficacy in vivo. We assessed the hypothesis that temporally separated delivery of multiple pro-angiogenic growth factors will improve the efficacy of the angiogenic response in the setting of both diabetes and non-diabetes in vitro. Methods: 96-well tissue culture plates were coated with 60 μL growth factor reduced Matrigel. After gelation, non-diabetic human dermal microvascular endothelial cells (HMVECs) and type-II diabetic cells (D-HMVECs) were plated at 1x104 cells/well with 100 μL basal media EBM-2 with 0.1% bovine serum, and incubated at 37°C. Combinations of growth factors including recombinant human VEGF (50 ng/mL), angiopoietin (Ang)-1 and -2 (250 ng/mL) were administrated at start of the assay and/or at 6 hours into the assay. Images were taken at 3, 6, 9, 12, 18 and 24 hours and used for tube formation quantification by Inverted Microscope at 10x magnification. Results: In untreated control, D-HVECs showed reduced tube formation in compared to HMVECs (n=12; p<0.001). Growth factors combination ‘VEGF and Ang-2 at start of the assay and Ang-1 at 6 hours showed the most significantly increased of tube formation when compared to single growth factor (to VEGF, Ang-1, 2; p<0.001) or growth factors combination without temporally separated delivery (to VEGF/Ang-1, VEGF/Ang-2; p<0.001) in both HMVEC and D-HMVEC. Conclusion: Diabetic endothelial cells showed impaired angiogenesis compared to non-diabetic endothelial cells. Combinations of temporally separated pro-angiogenic growth factors were able to optimize the angiogenic effects and yield the most significant efficacy in the setting of both diabetes and non-diabetes. Future studies will focus on in vivo temporally separated combinations of multiple growth factors.

Aims The aim of this study was to investigate anti-apoptotic gene therapy using ultrasound-mediated plasmid delivery of survivin, an inhibitor of apoptosis protein, to prevent apoptosis and to attenuate left ventricular (LV) systolic dysfunction in a model of heart failure induced by doxorubicin.Methods and results Effect of survivin transduction was investigated in vitro in rat cardiomyoblasts. After survivin transduction, survivin protein was detected in cell culture supernate confirming secretion of extracellular survivin. Under doxorubicin stimulation, survivin-transduced cells had significantly reduced apoptosis; however, incubation with survivin-conditioned media also showed reduced apoptosis that was absent with null-conditioned media. Doxorubicin-induced cardiomyopathy was established in Fischer rats. Subsets of animals underwent ultrasound-mediated survivin gene delivery or empty vector gene delivery at Week 3. Control rats received doxorubicin alone. Animals were studied using PCR, immunohistochemistry, echocardiography, and invasive haemodynamic studies out to Week 6. By Week 6, LV% fractional shortening by echocardiography and systolic function by pressure-volume loops were greater in survivin treated when compared with control-and empty-treated animals. There was reduced apoptosis by TUNEL and caspase activity in survivin-treated animals compared with control and empty treated at Week 4, with reduced interstitial fibrosis at Week 6.Conclusion Survivin gene therapy can attenuate the progression of LV systolic dysfunction in doxorubicin cardiomyopathy. This effect can be attributed to decreased myocyte apoptosis and prevention of maladaptive LV remodelling, by both direct myocyte transfection and potentially by paracrine mechanisms.