Coronary Infusion Research Articles

Mixing properties of coronary infusion catheters assessed by in vitro experiments and computational fluid dynamics.

Continuous infusion thermodilution is an established technique for the assessment of absolute coronary blood flow and microvascular resistance due to its proven accuracy and reproducibility. However, for this technique to yield reliable measurements, direct and homogenous mixing of injected saline and blood is mandatory. This study aimed to assess and compare the mixing properties of two different microcatheters, namely the Rayflow® (with sideholes for infusion) and the Finecross® catheter (single end-hole for infusion), which are commonly used in the catheterization laboratory. The study employed three different methods to evaluate the mixing properties of the catheters. Firstly, a qualitative assessment of mixing was performed using ink injections in an in vitro bench model of a coronary artery. Secondly, in analogy to the human catheterization laboratory, mixing properties over the length of the coronary artery were assessed semi-quantitatively by temperature measurements in the bench model. Lastly, a quantitative assessment was performed by 3D computational fluid dynamics, where the standard deviation and entropy ratio of the temperature over the cross-section in the coronary artery model were calculated for both catheters. All three evaluation methods demonstrated that the Rayflow catheter's specific design leads to a more optimal, homogeneous mixture of blood and saline over both the cross-section and length of a coronary vessel, as compared with the standard end-hole catheter.

Abstract 1125: Percutaneous Optofluidic Catheter-guided Photo-triggered Nanogoldsomes Reduce Infarct Size And Mitigate Myocardial Dysfunction In A Swine Model Of Acute Myocardial Infarction

Introduction: S-nitrosoglutathione (GSNO) is an endogenous S-nitrosothiol that plays important roles in nitric oxide (NO) generation and signaling. We previously designed an Au-polymersomes/GSNO nanoparticle (nanogoldsome) that can be triggered by laser or ultrasound to accelerate the release of NO, which effectively dilates the arteries of the target organ and induces anti-apoptotic protection against ischemia-reperfusion injury. In this study we integrated an optofluidic coronary catheter with the photo-triggered nanogoldsomes, and investigate their roles in mitigating the infarct size in a swine model of acute myocardial infarction (AMI). Methods: In a swine AMI model of 90 min coronary artery (CA) occlusion, nanogoldsomes (0.145 mg Au and 3.66 μg GSNO/kg) were administered 5 min after balloon-off using a percutaneous coronary optofluidic catheter with 532 nm laser stimulation at the tip. The CA diameter was measured at baseline and at 0 and 15 min of reperfusion. Left ventricular (LV) function (max dp/dt) were measured at baseline, and 1 h and 7 days after reperfusion. The infarct area was determined at day 7 using triphenyltetrazolium chloride stain with the infarct fraction calculated in reference to the area at risk stained by Evan’s blue coronary infusion with balloon occlusion at the same site. Results: Compared to AMI group, the CA diameter showed significant dilatation 10 min after nanogoldsome/laser treatment (1.22 vs. 0.98 folds, P < 0.05), while systemic blood pressure showed no significant drop. The infarct fraction was significantly reduced (49% vs. 73%, P < 0.05) and LV function markedly better 7 days after AMI. By contrast, no significant differences were noted in the control groups of GSNO (3.66 μg/kg) and nanogoldsomes without laser stimulation. Conclusion: Percutaneous optofluidic catheter-guided infusion of nanogoldsomes at coronary orifice with simultaneous tip laser stimulation in the first minutes of AMI reperfusion magnified NO release in the most critical reperfusion period. This instantly dilated coronary arteries, and reduced infarct area and mitigated LV dysfunction 7 days after AMI. With large animal experiments showing pathophysiological benefits, further translation to pre-clinical studies is encouraged.

Sex-Based Differences in LPS-induced Rapid Myocardial Dysfunction

Background: Previous studies have indicated better myocardial responses with preserved cardiac function in female animals compared to males after LPS challenge; however, the mechanisms remain incompletely understood. Our published studies have revealed that TNFa substantially increased in heart tissue and serum following LPS. Females experienced less cardiac dysfunction than males during equivalent dose of TNFa infusion. Therefore, sex-related disparities in myocardial impairment could be due to an indirect/secondary outcome from LPS-induced inflammatory cytokines, like TNFa. To dissect the potential mechanism underlying myocardial reactions between males and females, we aim to determine any sex differences in LPS-caused direct effects on cardiac function using coronary infusion of LPS.
 
 Methods: Isolated hearts from aged-matched adult male and female mice were subjected to LPS infusion via Langendorff after >20-min equilibration (Eq), with left ventricular developed pressure (LVDP) continuously recorded. Dose responsive experiments with LPS at 2.5, 5.0, and 7.5 mg/kg of body weight were performed in male hearts. Significant depression of LVDP (>20% drop) after LPS infusion was considered rapid response to LPS. Female estrous cycle was determined via vaginal smear.
 
 Results: Male hearts infused with 5.0 and 7.5 mg/kg of LPS demonstrated significant depression of LV function. Males also experienced worse outcomes of LV function than females following 5.0 mg/kg of LPS infusion. A trend of earlier response to LPS occurred in male hearts compared to females. However, there were no significant differences in cardiac function between female groups in different estrous phases.
 
 Conclusion and Potential Impact: Our data demonstrates that male hearts exhibit higher sensitivity to LPS-induced rapid cardiac dysfunction compared to females, but estrogen may have little influence on LPS-induced rapid functional depression. The insight from our data can be used to better understand the differences between male and female outcomes to cardiac pathologies and insult.

Three-vessel coronary infusion of cardiosphere-derived cells for the treatment of heart failure with preserved ejection fraction in a pre-clinical pig model.

Heart failure with preserved ejection fraction (HFpEF) is a major public health concern. Its outcome is poor and, as of today, barely any treatments have been able to decrease its morbidity or mortality. Cardiosphere-derived cells (CDCs) are heart cell products with anti-fibrotic, anti-inflammatory and angiogenic properties. Here, we tested the efficacy of CDCs in improving left ventricular (LV) structure and function in pigs with HFpEF. Fourteen chronically instrumented pigs received continuous angiotensin II infusion for 5weeks. LV function was investigated through hemodynamic measurements and echocardiography at baseline, after 3weeks of angiotensin II infusion before three-vessel intra-coronary CDC (n = 6) or placebo (n = 8) administration and 2weeks after treatment (i.e., at completion of the protocol). As expected, arterial pressure was significantly and similarly increased in both groups. This was accompanied by LV hypertrophy that was not affected by CDCs. LV systolic function remained similarly preserved during the whole protocol in both groups. In contrast, LV diastolic function was impaired (increases in Tau, LV end-diastolic pressure as well as E/A, E/E'septal and E/E'lateral ratios) but CDC treatment significantly improved all of these parameters. The beneficial effect of CDCs on LV diastolic function was not explained by reduced LV hypertrophy or increased arteriolar density; however, interstitial fibrosis was markedly reduced. Three-vessel intra-coronary administration of CDCs improves LV diastolic function and reduces LV fibrosis in this hypertensive model of HFpEF.

Abstract 12366: Intracoronary Delivery of E06 Antibody Directed to Oxidized Phospholipids Decreases Infarct Size in a Porcine Model of Ischemia/Reperfusion Injury

Introduction: Myocardial ischemia/reperfusion injury (IRI) results in additional myocardial cell loss post reperfusion. Oxidized phosphocholine(PC)-containing phospholipids (OxPL) have been shown to result in cardiomyocyte cell death during IRI. E06 is a natural murine monoclonal IgM antibody which binds to the PC headgroup of OxPL. Transgenic mice expressing a single-chain Fv E06 fragment have recently been shown to have smaller infarct sizes post myocardial IRI. The objective of this study was to determine if directly infused E06 IgM reduced IRI in a porcine model of reperfusion injury that more closely reflects human physiology. Methods: Male pigs, 45 to 50 kg, were randomized equally to IRI in two groups: 1) control with saline coronary infusion (n=7). 2) IgM E06 coronary infusion over 1 hour (n=7). The left anterior descending (LAD) artery was occluded distal to the second diagonal branch for 60 minutes using an angioplasty balloon. Following balloon deflation, saline or IgM E06 was infused over 60 min through a microcatheter. Following 120 min of total reperfusion, the area at risk (AAR) and infarct size (IS) were determined by triphenyltetrazolium chloride staining technique (TTC), and myocardial salvage index determined. Results: All animals survived post reperfusion and no differences were present in hemodynamics at the baseline and 2 h post reperfusion between groups. A 51.3% reduction in infarct size was noted in animals receiving intracoronary E06 compared to controls (IS/AAR 21.7% ± 3.4 vs 42.3% ± 3.7 p<0.0005). IS/LV size (7.7 ± 3.2 vs 11.9 ± 1.2 p<0.004) and myocardial salvage index (82.6% vs 57.6% in controls) were significantly improved in animals receiving E06 compared to controls. Conclusion: Intracoronary delivery of E06 antibody at the time of reperfusion leads to a significant reduction in infarct size, suggesting that generation of OxPL during reperfusion leads to cardiomyocyte cell death. Translation of this approach using humanized anti-OxPL antibodies may allow a novel approach to treat myocardial IRI in humans.

Gastrin exerts a protective effect against myocardial infarction via promoting angiogenesis

BackgroundIt is known that increased gastrin concentration is negatively correlated with cardiovascular mortality, and plasma gastrin levels are increased in patients after myocardial infarction (MI). However, whether gastrin can play a protective role in MI remains unknown.MethodsAdult C57BL/6 mice were subjected to ligation of the left anterior descending coronary artery (LAD) and subcutaneous infusion of gastrin (120 μg/Kg body weight/day, 100 μL in the pump) for 28 days after MI. Plasma gastrin concentrations were measured through an ELISA detection kit. Mice were analyzed by echocardiography after surgery. CD31 and VEGF expression were quantified using immunofluorescence staining or/and western blot to assess the angiogenesis in peri-infarct myocardium. Capillary-like tube formation and cell migration assays were performed to detect gastrin-induced angiogenesis.ResultsWe found that gastrin administration significantly ameliorated MI-induced cardiac dysfunction and reduced fibrosis at 28 days in post-MI hearts. Additionally, gastrin treatment significantly decreased cardiomyocyte apoptosis and increased angiogenesis in the infarct border zone without influencing cardiomyocyte proliferation. In vitro results revealed that gastrin up-regulated the PI3K/Akt/vascular endothelial growth factor (VEGF) signaling pathway and promoted migration and tube formation of human coronary artery endothelial cells (HCAECs). Cholecystokinin 2 receptor (CCK2R) mediated the protective effect of gastrin since the CCK2R blocker CI988 attenuated the gastrin-mediated angiogenesis and cardiac function protection.ConclusionOur data revealed that gastrin promoted angiogenesis and improved cardiac function in post-MI mice, highlighting its potential as a therapeutic target candidate.

Thermodilution-derived resting coronary flow measurement: “a reverse dose finding study”

Abstract Background Hyperemic absolute coronary blood flow (in mL/min) can be safely and reproducibly measured with intracoronary continuous thermodilution of saline at room temperature at an infusion rate of 20 mL/min. This study aims at assessing the best infusion rate to measure resting flow by thermodilution, i.e. low enough to avoid microvascular dilation but high enough to allow reliable thermodilution tracings Methods and results In 26 coronary arteries (24 patients) with angiographic non-significant stenoses, absolute flow was assessed by continuous saline thermodilution at infusion rates of 10 mL/min and 20 mL/min using a pressure/temperature sensored guide wire, a dedicated infusion catheter and a dedicated software. Average peak velocity (APV) was measured simultaneously using an intracoronary Doppler-wire. In addition, in a subgroup of 10 arteries, absolute flow and APV were also measured during saline infusion at 6 ml/min and 8 ml/min. In 26 coronary arteries there was no significance difference in the Pd/Pa and in the APV at baseline and during the infusion of saline at 10 ml/min (Pd/Pa: 0.94±0.057 vs 0.94±0.059, p=0.82; APV: 22.2±8.40 vs 23.2±8.39 cm/s, p=0.63). In contrast, at an infusion rate of 20 mL/min, we observed a significant decrease in Pd/Pa compared to baseline (0.85±0.089 vs 0.95±0.053 vs, respectively, p<0.001) and a significant increase in APV (22.2±8.4 cm/s to 57.8±25.5 cm/s, respectively, p<0.001). The coronary flow reserve (CFR) evaluated by Doppler and intracoronary continuous thermodilution correlated well (r=0.87, 95% CI = 0.72–0.94, p<0.001) and Bland-Altman analysis documented a mean bias of −0.003 (limit of agreement −1.05 to 1.04) thus indicating the presence of resting coronary blood flow during the infusion of 10 mL/min of saline. In 10 coronary arteries saline infusions at 6 and 8 ml/min did not produce any significant changes in the Pd/Pa and in the APV compared to baseline and both Doppler and Thermodilution derived CFR correlated well at each infusion rate (6 ml/min: r=0.71, 95% CI 0.14–0.92, p=0.02; 8ml/min: r=0.78, 95% CI=0.31–0.95, p=0.007). However, with an infusion rate of 6 mL/min, an unstable thermodilution tracing was observed. Accordingly, Bland-Altman analysis showed a significantly larger dispersion of the CFR values when 6 ml/min was used to measure resting coronary flow (as compared with 8 m/min): mean bias at 6 ml/min: −0.53, limits of agreement: −2.25 to 1.20: mean bias at 8 ml/min: 0.004, limits of agreement: −0.72 to 0.73. Conclusion Absolute resting coronary flow can be measured by intracoronary continuous thermodilution of saline at infusion rate of 8–10 ml/min. Funding Acknowledgement Type of funding source: None

Abstract 27: Loss of GATA4 in Kit Lineage-derived Endothelium Leads to Vascular Permeability and Increased Heterotypic Fusion

The treatment of cardiac ischemic injury using heart-derived c-Kit stem cells showed promising results in clinical trials with scar reduction and improved ejection fraction following coronary infusion. We previously developed a c-Kit lineage tracing mouse model showing that these cells very rarely convert into de novo cardiomyocytes and most lineage-derived cardiomyocytes are due to fusion. To potentially reduce this de novo rate to zero, and unequivocally evaluate the cellular fusion process in vivo , we deleted the essential cardiomyogenic transcription factor Gata4 in c-Kit cells using a Cre-loxP approach (Kit-Gata4 KO). Mice with the tamoxifen inducible Kit-MerCreMer allele crossed into a Gata4 homozygous LoxP targeted background with the Rosa26-eGFP reporter were fed tamoxifen at weaning to delete Gata4 in all c-Kit expressing cells and show them and their progeny as eGFP + . Unexpectedly, we observed a greater than 10-fold increase in Kit lineage-traced cardiomyocytes in Kit-Gata4 KO mice compared to Kit only controls with up to 4 months of tamoxifen treatment (90% v. 81% fusion in Kit-Gata4 KO v. controls). A 6-fold increase in leukocyte (CD45 + ) infiltration was observed suggesting the possibility for greater rates of fusion in the heart. However, bone marrow transplant studies revealed that Kit-Gata4 KO bone marrow does not exhibit increased cardiac infiltration or heterotypic fusion with cardiomyocytes. The reciprocal experiment, donating control bone marrow to recipient mice with Kit-Gata4 KO hearts, showed a 4-fold increase in fusion of control bone marrow showing that increases in fusion was intrinsic to the cells within the heart. Analysis of cardiac endothelial cells in Kit-Gata4 KO mice revealed that total CD31 + cells were increased by 30% with 2 months of tamoxifen treatment with a parallel increase in endothelial progenitor cells (CD133 + ) in the bone marrow. This endothelial phenotype was corroborated using endothelial-specific deletion of Gata4 in a Tie2-CreER mouse which showed a 5-fold increase in both CD31 + cells and vascular permeability after 1 month of tamoxifen. Currently, studies are underway to assess the mechanism of altered endothelial integrity and expansion in the absence of Gata4 in c-kit hemoangioblast progenitors.

In This Issue

HomeCirculation ResearchVol. 120, No. 2In This Issue Free AccessResearch ArticlePDF/EPUBAboutView PDFView EPUBSections ToolsAdd to favoritesDownload citationsTrack citationsPermissions ShareShare onFacebookTwitterLinked InMendeleyReddit Jump toFree AccessResearch ArticlePDF/EPUBIn This Issue Ruth Williams Ruth WilliamsRuth Williams Search for more papers by this author Originally published20 Jan 2017https://doi.org/10.1161/RES.0000000000000134Circulation Research. 2017;120:245SMC Reprogramming to Resident Progenitor Cells (p 296)Download figureDownload PowerPointMajesky et al discover an unexpected origin of vascular progenitor cells.The adventitia, which forms the outer layer of blood vessels, is a collagen-rich tissue that has been traditionally thought to provide only structural support to the vessel. But recent research has shown that the adventitia contains a variety of dynamic cell types, such as the vascular progenitor cells. The origin of these progenitors was unclear, but Majesky and colleagues have now discovered, quite by accident, the source of at a least a subpopulation of these cells in mice. The team was studying how, after injury, the smooth muscle cells (SMCs) within the medial layer of blood vessels dedifferentiate and migrate to the innermost intimal layer. Unexpectedly, the team observed that SMCs also migrate to the adventitia, where they lost their SMC characteristics and gained stem cell markers. Further fate-mapping experiments confirmed that SMCs do indeed give rise to a subpopulation of adventitia-residing progenitors. These SMC-derived progenitors were multipotent, giving rise to several cell types in vitro and in matrigel implants in mice. The team also found that the transition from SMC to progenitor was regulated by the transcription factor Klf4. Further studies are required to assess how these SMC-derived progenitors contribute to vascular homeostasis and pathology and how these cells could be targeted to treat vascular diseases, say the authors.CD34+ Cells for Post STEMI LV Dysfunction (p 324)Download figureDownload PowerPointQuyyumi et al report the results of a phase II stem cell trial for treating myocardial infarction.Nearly 20% of patients aged 45 and over who suffer a heart attack die within a year. Treatments to improve outcomes are desperately needed, and one possible therapeutic approach that has received much recent attention is coronary infusion of bone marrow-derived cells. Indeed, over 2600 patients have received autologous bone marrow cells in a variety of trials, but the outcomes have been inconsistent. It has been suggested that such unpredictable results may be due to variable bone marrow cell constituents, and that enriching for cells that express the stem cell marker CD34 may provide cell populations with greater clinical benefit. Indeed, a phase I trial of treatment with autologous CD34-positive bone marrow cells improved outcomes in heart attack victims. Now, Quyyumi and colleagues report that some patients enrolled in a randomized, double-blind phase II trial of CD34 cells also fared better than control subjects—with improved ejection fractions and reduced infarct sizes after 6 months. Improvement was seen in patients who were given a high-dose of cells (over 20 million), but low-dose recipients were indistinguishable from controls. The results confirm the safety of autologous CD34+ cell infusions and suggest that high doses of these cells may have some clinical benefit. Based on these results, the authors suggest that further randomized controlled trials should be performed to examine the efficacy of bone marrow-derived CD34+ cells.Mesenchymal Stem Cells for Heart Failure (p 332)Download figureDownload PowerPointButler et al present the results of an intravenous stem cell therapy trial for nonischemic cardiomyopathy.Nonischemic cardiomyopathy is a contractile dysfunction not caused by coronary artery disease (CAD) or myocardial infarction (MI). Nevertheless, as with CAD- or MI-induced heart failure, patients with nonischemic cardiomyopathy could potentially benefit from stem cell therapy. To date, cell therapies for any form of heart failure have been administered directly to the heart—because cell engraftment was considered necessary for clinical effect. However, some effects may derive from secreted factors, such as the anti-inflammatory factors produced by mesenchymal stem cells (MSCs). Butler and colleagues have, therefore, performed the first trial of intravenously administered stem cells for heart failure, giving 22 patients with nonischemic cardiomyopathy infusions of allogenic MSCs. While the team noted no difference in the occurrence of death or hospitalization between test and control subjects, patients receiving the MSCs had reduced systemic inflammation and could walk greater distances after 3 months. An inverse association between inflammation and left ventricle ejection fraction was also noted. These promising early results now pave the way for further follow up trials, say the authors. Previous Back to top Next FiguresReferencesRelatedDetails January 20, 2017Vol 120, Issue 2 Advertisement Article InformationMetrics © 2017 American Heart Association, Inc.https://doi.org/10.1161/RES.0000000000000134PMID: 30520342 Originally publishedJanuary 20, 2017 PDF download Advertisement

GW27-e0778 Combined Retrograde Coronary Venous Infusion of Fibroblast Growth Factor 2 and Bone Marrow Mesenchymal Stem Cells Restores Cardiac Function After Myocardial Infarction in Dogs

Retrograde coronary venous infusion provides both increased regional fibroblast growth factor 2 (FGF-2) concentrations and homogeneous dissemination of bone marrow mesenchymal stem cells (MSCs) across the myocardium. We determined the effects of retrograde delivery of combined FGF-2 and MSCs on

Abstract 362: Deletion of Gata4 and Gata6 in the c-Kit Lineage Augments Cellular Fusion in vivo

Cell therapy for treatment of ischemic heart disease has been under rigorous evaluation in recent years. Heart-derived c-Kit cells showed promising results in clinical trials with scar reduction and improved ejection fraction following coronary infusion. We previously developed a c-Kit lineage tracing model showing that these cells very rarely convert into de novo cardiomyocytes. To potentially reduce this rate to zero, and unequivocally evaluate cellular fusion processes in vivo, we deleted the cardiogenic transcription factors Gata4 and Gata6 in c-Kit cells using a Cre-loxP approach (Kit-Gata4/6 KO). We used the tamoxifen inducible Kit-MerCreMer allele crossed into Gata4/6 homozygous LoxP targeted background and the Rosa26-eGFP reporter, which were given tamoxifen at weaning to delete Gata4 and Gata6 in all c-Kit expressing cells and show them and their progeny as eGFP positive. Unexpectedly, we observed a greater than 10-fold increase in Kit lineage-traced cardiomyocytes in some Kit-Gata4/6 KO mice compared to Kit only controls with up to 4 months of treatment. Exploration of other tissues revealed a dramatic increase in presumed Kit-lineage traced skeletal muscle fibers in Kit-Gata4/6 KO mice as well. However, investigation of this effect suggested that this increase in presumed Kit-lineage traced cardiomyocytes and skeletal muscle fibers was due to an alteration in the immune cell compartment of these mice that generated greater rates of fusion. Indeed, analysis of Kit-derived hematopoietic lineages present in the heart showed a 6-fold increase in leukocyte infiltration (CD45 + ) and a 60-fold increase in dendritic cells (CD11c + ) from Kit-Gata4/6 KO mice. Kit-eGFP + bone marrow was also transplanted into mice expressing a membrane tomato reporter. Kit-Gata4/6 KO bone marrow showed a 3-fold increase in Kit-eGFP cells, although all these myocytes had the membrane tomato tag indicting that these events were all due to fusion. Hence, alterations in c-Kit cell activity likely impacts the activity of the immune system and the fusigenic activity of derived cells.

Lack of correlation between the optimal glycaemic control and coronary micro vascular dysfunction in patients with diabetes mellitus: a cross sectional study.

BackgroundCoronary microvascular dysfunction (CMD) is associated with cardiovascular events in type 2 diabetes mellitus (T2DM). Optimal glycaemic control does not always preclude future events. We sought to assess the effect of the current target of HBA1c level on the coronary microcirculatory function and identify predictive factors for CMD in T2DM patients.MethodsWe studied 100 patients with T2DM and 214 patients without T2DM. All of them with a history of chest pain, non-obstructive angiograms and a direct assessment of coronary blood flow increase in response to adenosine and acetylcholine coronary infusion, for evaluation of endothelial independent and dependent CMD. Patients with T2DM were categorized as having optimal (HbA1c < 7 %) vs. suboptimal (HbA1c ≥ 7 %) glycaemic control at the time of catheterization.ResultsBaseline characteristics and coronary endothelial function parameters differed significantly between T2DM patients and control group. The prevalence of endothelial independent CMD (29.8 vs. 39.6 %, p = 0.40) and dependent CMD (61.7 vs. 62.2 %, p = 1.00) were similar in patients with optimal vs. suboptimal glycaemic control. Age (OR 1.10; CI 95 % 1.04–1.18; p < 0.001) and female gender (OR 3.87; CI 95 % 1.45–11.4; p < 0.01) were significantly associated with endothelial independent CMD whereas glomerular filtrate (OR 0.97; CI 95 % 0.95–0.99; p < 0.05) was significantly associated with endothelial dependent CMD. The optimal glycaemic control was not associated with endothelial independent (OR 0.60, CI 95 % 0.23–1.46; p 0.26) or dependent CMD (OR 0.99, CI 95 % 0.43–2.24; p = 0.98).ConclusionsThe current target of HBA1c level does not predict a better coronary microcirculatory function in T2DM patients. The appropriate strategy for prevention of CMD in T2DM patients remains to be addressed.

Cardiac AAV9 Gene Delivery Strategies in Adult Canines: Assessment by Long-term Serial SPECT Imaging of Sodium Iodide Symporter Expression

Heart failure is a leading cause of morbidity and mortality, and cardiac gene delivery has the potential to provide novel therapeutic approaches. Adeno-associated virus serotype 9 (AAV9) transduces the rodent heart efficiently, but cardiotropism, immune tolerance, and optimal delivery strategies in large animals are unclear. In this study, an AAV9 vector encoding canine sodium iodide symporter (NIS) was administered to adult immunocompetent dogs via epicardial injection, coronary infusion without and with cardiac recirculation, or endocardial injection via a novel catheter with curved needle and both end- and side-holes. As NIS mediates cellular uptake of clinical radioisotopes, expression was tracked by single-photon emission computerized tomography (SPECT) imaging in addition to Western blot and immunohistochemistry. Direct epicardial or endocardial injection resulted in strong cardiac expression, whereas expression after intracoronary infusion or cardiac recirculation was undetectable. A threshold myocardial injection dose that provides robust nonimmunogenic expression was identified. The extent of transmural myocardial expression was greater with the novel catheter versus straight end-hole needle delivery. Furthermore, the authors demonstrate that cardiac NIS reporter gene expression and duration can be quantified using serial noninvasive SPECT imaging up to 1 year after vector administration. These data are relevant to efforts to develop cardiac gene delivery as heart failure therapy.

Ribonucleotide reductase-mediated increase in dATP improves cardiac performance via myosin activation in a large animal model of heart failure.

Heart failure remains a leading cause of morbidity, hospitalizations, and deaths. We previously showed that overexpression of the enzyme ribonucleotide reductase (RNR) in cardiomyocytes increased levels of the myosin activator, 2-deoxy-ATP, catalysed enhanced contraction, and improved cardiac performance in rodent hearts. Here we used a swine model of myocardial infarction (MI) to test preliminarily a novel gene therapy for heart failure based on delivery of the human RNR enzyme complex under the control of a cardiac-specific promoter via an adeno-associated virus serotype 6 vector--designated as BB-R12. We induced heart failure following MI in Yucatan minipigs by balloon occlusion of the left anterior descending artery. Two weeks, later, pigs received BB-R12 at one of three doses via antegrade coronary infusion. At 2 months post-treatment, LVEF and systolic LV dimension (measured by echocardiography) improved significantly in the high-dose group, despite further deterioration in the saline controls. Haemodynamic parameters including LV end-diastolic pressure, +dP/dt, and -dP/dt all trended towards improvement in the high-dose group. We observed no difference in the histopathological appearance of hearts or other organs from treated animals vs. controls, nor did we encounter any safety or tolerability concerns following BB-R12 delivery. These pilot results suggest cardiac-specific gene therapy using BB-R12 may reverse cardiac dysfunction by myosin activation in a large-animal heart failure model with no observed safety concerns. Thus further research into the therapeutic potential of BB-R12 for patients with chronic heart failure appears warranted.

Wrestling with heart failure: SUMO-1 to the rescue.

SUMO-1 Gene Transfer Improves Cardiac Function in a Large-Animal Model of Heart Failure Tilemann et al Sci Transl Med . 2013;5:211ra159. A small ubiquitin-like protein was shown to be beneficial to the failing heart through enhancing sarcoplasmic reticulum Ca 2+ ATPase 2a (SERCA2a) stability and activity in a large animal model of heart failure. Dysregulation of calcium cycling in cardiomyocytes has been recognized as a major molecular mechanism of heart failure. SERCA2a plays a pivotal role in regulating calcium homeostasis, and reduction of SERCA2a activity has been recognized as a hallmark of heart failure. Hajjar and his colleagues1 reported that the activity of SERCA2a is regulated by conjugation of small ubiquitin-like modifier-1 (SUMO-1) to SERCA2a. They also demonstrated that SUMO-1 gene delivery can restore SERCA2a expression and activity in the failing heart in a mouse model. Based on these findings, they postulated that SUMO modification (SUMOylation) is a critical regulator of SERCA2a function, which led to the design of SUMO-1 gene therapy in a swine ischemia–reperfusion heart failure model.2 The authors performed a temporary balloon occlusion of the proximal left anterior descending artery to create myocardial infarction. One month later, 31 survived pigs were randomized to receive via antegrade coronary infusion either saline or adeno-associated vector type 1 (AAV1) loaded with SUMO-1 (low and high dose), SERCA2a , or both. They showed that both SUMO-1 and SERCA2a levels were increased in the pigs that received AAV1. SUMO-1 with or without AAV1. SERCA2a 2 months later. However, the changes in left ventricular ejection fraction (EF) were not statistically significant in all treated groups. Statistically significant changes were demonstrated in the maximal rate of pressure rise [d P /d t (max)] in the groups that received high-dose SUMO-1 , SERCA2a , or both. Furthermore, the treated groups have less left …

TCTAP A-157 Retrograde Coronary Vein Infusion Achieves Targeted Cell Engraftment into Infarcted Myocardium for Cardiac Repair

TCTAP A-157 Retrograde Coronary Vein Infusion Achieves Targeted Cell Engraftment into Infarcted Myocardium for Cardiac Repair

Abstract 131: C-kit+ Cells Generated From Failed Heart Do Not Improve Failed Heart Function

A pilot clinical study using autologous c-Kit+ cells showed improvement in cardiac functions in congestive heart failure (CHF), however, it is unclear if c-Kit+ cells isolated from CHF hearts are equally as potent as cells from controls. To test the potency of CHF c-Kit+ cells, myocardial infarction (MI) was created by permanent ligation of the left anterior descending coronary artery. Six weeks after MI, animals with left ventricle end-diastolic pressure (LVEDP) ≥20 mmHg and scar size ≥30% of left ventricle (LV) were designated as CHF rats. We found that CHF atrial explants generated less c-Kit+ cells compared to shams (15.7% vs. 11% sham vs. CHF). CHF c-Kit+ cells exhibited elevated levels of epicardial to mesenchymal transition markers, including Snail (2.5 fold) and Pai1 (3 fold), while the expression level of epithelial marker, E-cadherin was 3 fold lower in CHF c-Kit+ cells. Moreover, CHF c-Kit+ cells exhibited reduced gene expressions of pluripotency markers; 2.1 fold decrease in Nanog and 4.5 fold decrease in Sox 2 compared to sham cells. To evaluate the potency of the c-Kit+ cells, 1 x 10 6 cells isolated from CHFs or shams were delivered to 3 weeks post-MI CHF hearts. Cells were pre-labeled with GFP to enable their tracing in vivo and delivered to the infarcted myocardium via left coronary vein by a retrograde coronary sinus cell infusion (RCI). RCI delivery resulted in a cell distribution of LV (30%), right atrium (30%) and right ventricle (20%), while only 10% of cells were found in a left atrium. Three weeks after cells delivery, rats transplanted with sham c-Kit+ cells showed improved LVEDP (29.4 ± 6 vs. 11.7 ± 3.5 mmHg, CHF vs. CHF+ sham c-Kit+ cells) and a rise in peak rate of pressure (dPdt max) (3988 ± 520 vs. 5333 ± 597 mmHg/s). In contrast, no functional improvement was detected in rats transplanted with CHF c-Kit+ cells. Histological analysis demonstrated that transplanted c-Kit+/GFP+ cells were mostly incorporated into blood vessels and co-localized with endothelial marker vWf, and α-smooth muscle actin. Our results showed that left coronary vein is an efficient route for c-Kit+ cell delivery and that c-Kit+ cells isolated from CHF rats are less potent when transplanted in chronic heart failure rat model compared to those isolated from control.

AAV9.I-1c Delivered via Direct Coronary Infusion in a Porcine Model of Heart Failure Improves Contractility and Mitigates Adverse Remodeling

AAV9.I-1c Delivered via Direct Coronary Infusion in a Porcine Model of Heart Failure Improves Contractility and Mitigates Adverse Remodeling

AAV9.I-1c Delivered via Direct Coronary Infusion in a Porcine Model of Heart Failure Improves Contractility and Mitigates Adverse Remodeling

Heart failure is characterized by impaired function and disturbed Ca2+ homeostasis. Transgenic increases in inhibitor-1 activity have been shown to improve Ca2 cycling and preserve cardiac performance in the failing heart. The aim of this study was to evaluate the effect of activating the inhibitor (I-1c) of protein phosphatase 1 (I-1) through gene transfer on cardiac function in a porcine model of heart failure induced by myocardial infarction. Myocardial infarction was created by a percutaneous, permanent left anterior descending artery occlusion in Yorkshire Landrace swine (n=16). One month after myocardial infarction, pigs underwent intracoronary delivery of either recombinant adeno-associated virus type 9 carrying I-1c (n=8) or saline (n=6) as control. One month after myocardial infarction was created, animals exhibited severe heart failure demonstrated by decreased ejection fraction (46.4±7.0% versus sham 69.7±8.5%) and impaired (dP/dt)max and (dP/dt)min. Intracoronary injection of AAV9.I-1c prevented further deterioration of cardiac function and led to a decrease in scar size. In this preclinical model of heart failure, overexpression of I-1c by intracoronary in vivo gene transfer preserved cardiac function and reduced the scar size.

Different cardiac tissue plasminogen activator release patterns by local stimulation of the endothelium and sympathetic nerves in pigs

Myocardial ischemia induces cardiac tissue plasminogen activator (tPA) release, declining by repeated periods of ischemia. However, the mechanisms and cellular sources are unknown. Sympathetic nerve stimulation (SS) and bradykinin (BK), an endogenous inducer of endothelial tPA release, may play roles, potentially involving different sources or mechanisms revealed by different release patterns. Therefore, we compared the cardiac tPA release patterns during repeated coronary BK infusions and SS, both with an ensuing period of local myocardial ischemia/reperfusion (I/R). Nine pigs were subjected to four periods of coronary BK infusion (4 min) and another nine animals to four periods of SS (4 min). Finally, 10 min of I/R was induced in both groups. The single-peaked BK-induced tPA release declined toward baseline by repeated infusions, but tPA release reappeared during I/R. In contrast, total tPA release during repeated SS and subsequent I/R was more stable, and SS-induced total tPA and norepinephrine (NE) releases were strongly correlated. Surprisingly, the instantaneous SS-induced tPA release was biphasic with a stable first peak, and a second peak declining toward baseline by repeated stimulations. The fluctuations in cardiac release of plasminogen activator inhibitor-1 and the endogenous BK inhibitor angiotensin-converting enzyme, could not explain the diverging tPA release patterns. Different tPA release patterns were demonstrated during SS and BK stimulation, as well as diverging responses to repeated stimulations and subsequent I/R. This study demonstrates strong association between tPA and NE during SS and possibly two different sources or mechanisms for SS-induced tPA release.