Preservation of Contractile Reserve and Diastolic Function by Inhibiting the NLRP3 Inflammasome with OLT1177® (Dapansutrile) in a Mouse Model of Severe Ischemic Cardiomyopathy Due to Non-Reperfused Anterior Wall Myocardial Infarction.

Interleukin-1ß (IL-1ß), a product of the NLRP3 inflammasome, modulates cardiac contractility and diastolic function. We proposed that OLT1177® (dapansutrile), a novel NLRP3 inhibitor, could preserve contractile reserve and diastolic function after myocardial infarction (MI). We used an experimental murine model of severe ischemic cardiomyopathy through the ligation of the left coronary artery without reperfusion, and after 7 days randomly assigned mice showing large anterior MI (>4 akinetic segments), increased left ventricular (LV) dimensions ([LVEDD] > 4.4 mm), and reduced function (LV ejection fraction < 40%) to a diet that was enriched with OLT1177® admixed with the chow in the diet at 3.75 g/kg (Group 1 [n = 10]) or 7.5 g/kg (Group 2 [n = 9]), or a standard diet as the no-treatment control group (Group 3 [n = 10]) for 9 weeks. We measured the cardiac function and contractile reserve with an isoproterenol challenge, and the diastolic function with cardiac catheterization at 10 weeks following the MI surgery. When compared with the control (Group 3), the mice treated with OLT1177 (Group 1 and 2) showed significantly greater preservation of their contractile reserve (the percent increase in the left ventricular ejection fraction [LVEF] after the isoproterenol challenge was +33 ± 11% and +40 ± 6% vs. +9 ± 7% in the standard diet; p < 0.05 and p < 0.005 for Group 1 and 2, respectively) and of diastolic function measured as the lower left ventricular end-diastolic pressure (3.2 ± 0.5 mmHg or 4.5 ± 0.5 mmHg vs. 10.0 ± 1.6 mmHg; p < 0.005 and p < 0.009 respectively). No differences were noted between the resting LVEF of the MI groups. These effects were independent of the effects on the ventricular remodeling after MI. NLRP3 inflammasome inhibition with OLT1177® can preserve ß-adrenergic responsiveness and prevent left ventricular diastolic dysfunction in a large non-reperfused anterior MI mouse model. OLT1177® could therefore be used to prevent the development of heart failure in patients with ischemic cardiomyopathy.

Anti-inflammatory activities of hepatocyte growth factor in post-ischemic heart failure.

Hepatocyte growth factor (HGF) alleviates acute and chronic inflammation in experimental inflammatory bowel disease, glomerulonephritis, and airway inflammation. However, the anti-inflammatory effects of HGF on myocardial infarction are not defined. The current study assessed the anti-inflammatory effects of HGF in post-ischemic heart failure. The left anterior descending coronary artery was ligated in rats, and adenovirus containing human HGF (Ad-HGF) or control virus (Ad-GFP) was administered intramyocardially. The quantity of proinflammatory cytokines secreted by cardiomyocytes, such as tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), and IL-1ß, was evaluated. Cardiac function and LV remodeling were assessed using echocardiography and collagen deposition, respectively. Left ventricular fractional shortening (LVFS) and left ventricular ejection fraction (LVEF) four weeks after injection were significantly increased in Ad-HGF-treated animals compared to the Ad-GFP group. HGF gene therapy improved ventricular geometry with a significantly decreased left ventricular end-diastolic diameter (LVEDD) and markedly reduced myocardial collagen deposition. Treatment with Ad-HGF significantly decreased the mRNA levels of TNF-α, IL-6, and IL-1ß in the non-infarcted region four weeks after injection. Changes of the TNF-α, IL-6, and IL-1ß levels in the non-infarcted region positively correlated with the LVEDD 4 weeks after infarction. Treatment of acute myocardial infarction (AMI) with Ad-HGF in the early stage of MI reduced the pro-inflammatory cytokine levels and preserved cardiac function. These findings indicated that Ad-HGF gene therapy alleviated ventricular remodeling after infarction by reducing inflammation.

Cardiac αVß3 integrin expression following acute myocardial infarction in humans.

OBJECTIVE: Maladaptive repair contributes towards the development of heart failure following myocardial infarction (MI). The αvß3 integrin receptor is a key mediator and determinant of cardiac repair. We aimed to establish whether αvß3 integrin expression determines myocardial recovery following MI. METHODS: 18F-Fluciclatide (a novel αvß3-selective radiotracer) positron emission tomography (PET) and CT imaging and gadolinium-enhanced MRI (CMR) were performed in 21 patients 2 weeks after ST-segment elevation MI (anterior, n=16; lateral, n=4; inferior, n=1). CMR was repeated 9 months after MI. 7 stable patients with chronic total occlusion (CTO) of a major coronary vessel and nine healthy volunteers underwent a single PET/CT and CMR. RESULTS: 18F-Fluciclatide uptake was increased at sites of acute infarction compared with remote myocardium (tissue-to-background ratio (TBRmean) 1.34±0.22 vs 0.85±0.17; p<0.001) and myocardium of healthy volunteers (TBRmean 1.34±0.22 vs 0.70±0.03; p<0.001). There was no 18F-fluciclatide uptake at sites of established prior infarction in patients with CTO, with activity similar to the myocardium of healthy volunteers (TBRmean 0.71±0.06 vs 0.70±0.03, p=0.83). 18F-Fluciclatide uptake occurred at sites of regional wall hypokinesia (wall motion index≥1 vs 0; TBRmean 0.93±0.31 vs 0.80±0.26 respectively, p<0.001) and subendocardial infarction. Importantly, although there was no correlation with infarct size (r=0.03, p=0.90) or inflammation (C reactive protein, r=-0.20, p=0.38), 18F-fluciclatide uptake was increased in segments displaying functional recovery (TBRmean 0.95±0.33 vs 0.81±0.27, p=0.002) and associated with increase in probability of regional recovery. CONCLUSION: 18F-Fluciclatide uptake is increased at sites of recent MI acting as a biomarker of cardiac repair and predicting regions of recovery. TRIAL REGISTRATION NUMBER: NCT01813045; Post-results.

Relationship between site of myocardial infarction, left ventricular function and cytokine levels in patients undergoing coronary artery surgery.

BACKGROUND: The purpose of this study was to examine the relationship between left ventricular (LV) function, cytokine levels and site of myocardial infarction (MI) in patients undergoing coronary artery bypass grafting (CABG). METHODS: Sixty patients undergoing CABG were divided into three groups (n = 20) according to their history of site of myocardial infarction (MI): no previous MI, anterior MI and posterior/inferior MI. In the pre-operative period, detailed analysis of LV function was done by transthoracic echocardiography. The levels of adrenomedullin, interleukin-1-beta, interleukin-6, tumour necrosis factor-alpha (TNF-α) and angiotensin-II in both peripheral blood samples and pericardial fluid were also measured. RESULTS: Echocardiographic analyses showed that the anterior MI group had significantly worse LV function than both the group with no previous MI and the posterior/inferior MI group (p < 0.05 for LV end-systolic diameter, fractional shortening, LV end-systolic volume, LV end-systolic volume index and ejection fraction). In the anterior MI group, both plasma and pericardial fluid levels of adrenomedullin and and pericardial fluid levels of interleukin-6 and interleukin- 1-beta were significantly higher than those in the group with no previous MI (p < 0.05), and pericardial fluid levels of adrenomedullin, interleukin-6 and interleukin-1-beta were significantly higher than those in the posterior/inferior MI group (p < 0.05). CONCLUSIONS: The results of this study indicate that (1) patients with an anterior MI had worse LV function than patients with no previous MI and those with a posterior/inferior MI, and (2) cytokine levels in the plasma and pericardial fluid in patients with anterior MI were increased compared to patients with no previous MI.

Cardiac Stem Cell Hybrids Enhance Myocardial Repair.

RATIONALE: Dual cell transplantation of cardiac progenitor cells (CPCs) and mesenchymal stem cells (MSCs) after infarction improves myocardial repair and performance in large animal models relative to delivery of either cell population. OBJECTIVE: To demonstrate that CardioChimeras (CCs) formed by fusion between CPCs and MSCs have enhanced reparative potential in a mouse model of myocardial infarction relative to individual stem cells or combined cell delivery. METHODS AND RESULTS: Two distinct and clonally derived CCs, CC1 and CC2, were used for this study. CCs improved left ventricular anterior wall thickness at 4 weeks post injury, but only CC1 treatment preserved anterior wall thickness at 18 weeks. Ejection fraction was enhanced at 6 weeks in CCs, and functional improvements were maintained in CCs and CPC+MSC groups at 18 weeks. Infarct size was decreased in CCs, whereas CPC+MSC and CPC parent groups remained unchanged at 12 weeks. CCs exhibited increased persistence, engraftment, and expression of early commitment markers within the border zone relative to combinatorial and individual cell population-injected groups. CCs increased capillary density and preserved cardiomyocyte size in the infarcted regions suggesting CCs role in protective paracrine secretion. CONCLUSIONS: CCs merge the application of distinct cells into a single entity for cellular therapeutic intervention in the progression of heart failure. CCs are a novel cell therapy that improves on combinatorial cell approaches to support myocardial regeneration.

Transplantation of adipose tissue-derived stem cells overexpressing heme oxygenase-1 improves functions and remodeling of infarcted myocardium in rabbits.

Adipose tissue-derived stem cells (ADSCs) are a promising source of autologous stem cells that are used for regeneration and repair of infracted heart. However, the efficiency of their transplantation is under debate. One of the possible reasons for marginal improvement in ADSCs transplantation is the significant cell death rate of implanted cells after being grafted into injured heart. Therefore, overcoming the poor survival rate of implanted cells may improve stem cell therapy. Due to limited improvement concerning direct stem cell therapy, gene-transfer methods are used to enhance cellular cardiomyoplasty efficacy. Heme oxygenase-1 (HO-1) can provide various types of cells with protection against oxidative injury and apoptosis. However, exact effects of autologous ADSCs combined with HO-1 on cardiac performance remains unknown. In this study, rabbits were treated with ADSCs transduced with HO-1 (HO-1-ADSCs), treated with non-transduced ADSCs, or injected with phosphate buffered saline 14 days after experimental myocardial infarction was induced, when autologous ADSCs were obtained simultaneously. Four weeks after injection, echocardiography showed significant improvements for cardiac functions and left ventricular dimensions in HO-1-ADSCs-treated animals. Structural consequences of transplantation were determined by detailed histological analysis, which showed differentiation of HO-1-ADSCs to cardiomyocyte-like tissues and lumen-like structure organizations. Apart from improvement in angiogenesis and scar areas, more connexin 43-positive gap junction and greater tyrosine hydroxylase-positive cardiac sympathetic nerves sprouting were observed in the HO-1-ADSCs-treated group compared with ADSCs group. These data suggest that the transplantation of autologous ADSCs combined with HO-1 transduction is a feasible and efficacious method for improving infarcted myocardium.

A novel approach to transplanting bone marrow stem cells to repair human myocardial infarction: delivery via a noninfarct-relative artery.

Bone marrow stem cells are able to repair infarcted human myocardium following intracoronary transplantation via the infarct-relative artery. However, traditional reperfusion strategies fail to open the artery in some patients, making effective delivery impossible. Our previous study demonstrated a safe and efficient approach to delivering bone marrow stem cells via a noninfarcted artery in an animal myocardial infarction model. The objective of the present study was to evaluate the safety and feasibility of autologous bone marrow mesenchymal stem cell transplantation via such an approach in patients with acute myocardial infarction (AMI). Sixteen patients with anterior AMI who had successfully undergone percutaneous coronary intervention (PCI) were enrolled in this pilot, randomized study. Three weeks after PCI, cultured bone marrow mesenchymal stem cells were injected into the myocardium via either the infarct-relative artery (left anterior descending branch artery, LAD) or a noninfarct-relative artery (right coronary artery, RCA). The safety and feasibility of the cell infusion were evaluated during the procedure and during 6 months of follow-up. In addition, 2D echocardiography, technetium-99m methoxyisobutylisonitrile (99mTc-MIBI) and 18F-deoxyglucose single photon emission computed tomography were employed to examine cardiac function, myocardial perfusion, and viable cardiomyocytes, respectively, at day 4 after PCI and 6 months after the cell infusion. There were no arrhythmia and any other side-effects, including infections, allergic reactions or adverse clinical events, during, immediately after, or 6 months after cell transplantation. Cardiac function and myocardial perfusion had improved 6 months after PCI/bone marrow stem cells transplantation. Viable cardiomyocytes metabolism was detected in the infarcted areas in both groups after the cell infusion, as demonstrated by 18F-deoxyglucose. Intracoronary infusion of autologous bone marrow mesenchymal stem cells via a noninfarct-relative artery appears safe and feasible in the treatment of patients with AMI.