A2A and A3, Adenosine receptors mRNA are overexpressed in an experimental animal model of myocardial infarction

Background: Adenosine, a purine nucleoside and a "retaliatory metabolite" in ischemia, is ubiquitous in the body, and increases 100-fold during ischemia. Its biological actions are mediated by four adenosine receptors (ARs): A1 and A3, coupled to Gi/o, and the high-affinity A2A and low-affinity A2B, coupled to Gs. Because A1R and A3R are distributed mainly in myocardial cells and A2 are on coronary vascular smooth cells in the heart, adenosine may substantially modulate cardiac function as a whole. Aim: To determine possible myocardial alterations in the expression of ARs, in an experimental animal model of myocardial infarction (MI). Materials and Methods: Left ventricular (LV) tissue was collected from male adult minipigs with MI (n=5), induced by permanent surgical legation of the left anterior descending coronary artery and from 5 healthy pigs. mRNA expression of A1R, A2AR, A2BR,A3R was determined by semi-quantitative RT-PCR in tissue sampled collected from border (BZ) and remote zones (RZ) of infarcted area. Results: Transmural infarction affected about 15% of the LV wall mass. After 4 weeks, mRNA expression was higher in infarct regions than in control for A1R (controls=2.0?1.0, BZ=2.4?0.4, RZ=1.2?0.1), A2AR (controls=0.6?0.3, BZ=1.9?0.2, RZ=1.3?0.04 p=0.002, p=0.04, controls vs. BZ and RZ), A2BR (controls=1.1?0.5, BZ=1.2?0.2, RZ=0.5?0.04) and A3R (controls=0.2?0.07, BZ=2.4?0.7, RZ=0.7?0.07, p=0.006, p=0.002, controls vs. BZ and RZ). Conclusion: All adenosine receptors, and expecially A2A and A3, are overexpressed in the BZ of MI, consistently with an adaptative retaliatory anti-ischemic adenosinergic changes of post-infarcted heart

Myocardial infarction activates the expression of cardiometabolic biomarkers in the heart: study in a swine model.

Purpose. Inflammation, extra-cellular matrix (ECM) remodeling and adipokine system activation represent essential processes of molecular response to cardiac injury. The aim of this study was to evaluate the cardiac expression of biomarkers involved in the inflammation, ECM remodeling and adiponectin system in an experimental animal model of myocardial infarction (AMI). Methods. Left ventricular (LV) tissue was collected from male adult pigs with AMI (n=6), induced by permanent surgical ligation of the left anterior descending coronary artery and from 6 healthy pigs. mRNA expression was determined by RT-PCR in tissue samples collected from border (BZ) and remote zones (RZ) of infarcted area. Proinflammatory cytokines (IL-6, TNF-&#945;), matrix metalloproteinases (MMP)-2, -9, their tissue inhibitors (TIMP)-1, -2 and collagen (COL3&#945;) were evaluated. In addition, adiponectin and its receptors, adipo-R1 and adipo-R2, were evaluated, owing its anti-inflammatory actions. Results. This surgical approach resulted in a permanent transmural infarction affecting 10-15% of the LV wall mass and after 4 weeks the mRNA expression of biomarkers, normalized on the respective GAPDH, was significantly higher in infarcted regions than in controls (MMP-9: 7.09?4.31; 1.18?0.28; 0.72?0.11, respectively for BZ, RZ and controls, p<0.05 BZ vs. RZ and controls; TIMP-1: 2.41?1.20; 0.28?0.04; 0.33?0.05, p=0.01; TIMP-2: 2.75?1.51; 0.53?0.04; 0.38?0.03, p<0.05; COL3&#945;: 4.28?1.11; 0.87?0.13; 0.61?0.18, p<0.0004). Inflammatory indices were increased in AMI, both BZ and RZ. Adiponectin was significantly increased with respect to controls (BZ: 2.95?1.69; RZ: 0.93?0.33; controls: 0.52?0.12, p<0.05 BZ vs controls) as well as the Adipo-R1 (BZ: 1.40?0.31, RZ: 1.26?0.20, controls: 0.63?0.07; p<0.05 BZ and RZ vs controls). Conclusions. The inflammatory and ECM remodelling processes are activated after myocardial injury together with the system of adiponectin, confirming its involvement in the process of cardiac remodelling/repair. The knowledge of the interaction between the various mediators of the complex response to cardiac damage could represent an important target for new therapies. Reference. Shibata R et al, Cardiovasc Res. 2007 Jun 1;74(3):471-9

Transthoracic Sensor for Noninvasive Assessment of Left Ventricular Contractility: Validation in A Minipig Model of Chronic Heart Failure.

Background:Invasively measured left ventricular (LV) dP/dt is the accepted standard for measuring acute and chronic directional changes in LV contractility. Recently, we developed a noninvasive force sensor based on an accelerometer positioned on the chest, which measures the vibrations generated by isovolumic myocardial contraction. The aim of this paper was to compare noninvasive (accelerometer) versus invasive (LV dP/dt) indices of myocardial contractility in a chronic minipig model of pacing-induced heart failure (HF). Comparative assessment was performed both at rest and following dobutamine infusion. Methods:In adult male minipigs (n = 6), LV contractility was simultaneously assessed both invasively (LV dP/dt, Millar catheter) and noninvasively (accelerometer) at rest and following dobutamine (up to 7.5 mcg/kg/min), both before and after development of HF by pacing the LV at 180 beats/min for 3 weeks. Results:Invasive and noninvasive assessments were obtained in 24 conditions (12 at rest and 12 after dobutamine infusion). Sensor-based cardiac force changes were significantly related to positive peak LV dP/dt(max) changes following dobutamine infusion both in normal (r = 0.88, P < 0.001) and failing heart (r = 0.89, P < 0.001). The force-frequency relation showed a tight correlation between invasive and noninvasive assessment (r = 0.68, P = 0.02). Conclusions:The force-frequency relation can be assessed noninvasively by a transthoracic sensor based on an accelerometer. The method can efficiently detect the development of resting dysfunction and the contractile reserve at different HF steps, with potential for wearable HF monitoring

Severe mechanical dyssynchrony causes regional hibernation-like changes in pigs with nonischemic heart failure.

BACKGROUND: Sustained left ventricular (LV) dyssynchrony can lead to heart failure (HF) in the absence of coronary artery stenosis. We tested whether myocardial hibernation underlies the LV functional impairment caused by high-frequency pacing, an established model of nonischemic dilated cardiomyopathy. METHODS AND RESULTS: Regional LV contractile and perfusion reserve were assessed by magnetic resonance imaging, respectively, as end-systolic wall thickening (LVESWT) and myocardial perfusion reserve index (MPRI) at rest and during low-dose dobutamine stress (LDDS, 10 microg.kg.min intravenously for 10minutes) in failing minipigs (n=8). LV tissue was analyzed for glycogen deposits and other molecular hallmarks of hibernation. LDDS caused a marked increase in LVESWT (27+/-2.98 vs. 7.15+/-3 %, P < .05) and MPRI (2.1+/-0.5 vs. 1.3+/-0.3 P < .05) in the region that was activated first (pacing site) compared with the opposite region. Myocardial glycogen content was markedly increased in the pacing site (P < .05 vs. opposite region). In addition, gene expression of glycogen phosphorylase was reduced in pacing site compared with opposite regions (0.71+/-0.1 vs. 1.03+/-0.3, P < .05), whereas that of hexokinase type II was globally reduced by 83%. CONCLUSIONS: The combination of high heart rate and sustained dyssynchronous LV contraction causes asymmetrical myocardial hibernation, in absence of coronary artery stenosis

Ferritin as a reporter gene for in vivo tracking of stem cells by 1.5T cardiac MRI in a rat model of myocardial infarction

The methods currently utilized to track stem cells by cardiac MRI are affected by important limitations, and new solutions are needed. We tested human ferritin heavy chain (hFTH) as a reporter gene for in vivo tracking of stem cells by cardiac MRI. Swine cardiac stem/progenitor cells were transduced with a lentiviral vector to overexpress hFTH and cultured to obtain cardiospheres (Cs). Myocardial infarction was induced in rats, and, after 45 min, the animals were subjected to intramyocardial injection of ∼200 hFTH-Cs or nontransduced Cs or saline solution in the border zone. By employing clinical standard 1.5-Tesla MRI scanner and a multiecho T2* gradient echo sequence, we localized iron-accumulating tissue only in hearts treated with hFTH-Cs. This signal was detectable at 1 wk after infarction, and its size did not change significantly after 4 wk (6.33 ± 3.05 vs. 4.41 ± 4.38 mm(2)). Cs transduction did not affect their cardioreparative potential, as indicated by the significantly better preserved left ventricular global and regional function and the 36% reduction in infarct size in both groups that received Cs compared with control infarcts. Prussian blue staining confirmed the presence of differentiated, iron-accumulating cells containing mitochondria of porcine origin. Cs-derived cells displayed CD31, α-smooth muscle, and α-sarcomeric actin antigens, indicating that the differentiation into endothelial, smooth muscle and cardiac muscle lineage was not affected by ferritin overexpression. In conclusion, hFTH can be used as a MRI reporter gene to track dividing/differentiating stem cells in the beating heart, while simultaneously monitoring cardiac morpho-functional changes

Cardiac metabolism with hyperpolarized [1-¹³c]pyruvate: a feasibility study in mini-pig with a large dose injection

ss Open Acce Technologist presentation Cardiac metabolism with hyperpolarized [1-13c]pyruvate: a feasibility study in mini-pig with a large dose injection Luca Menichetti1, Francesca Frijia2, Vincenzo Lionetti3, Maria Filomena Santarelli1, Jan Henrik Ardenkjaer Larsen4, Giulio Giovannetti1, Vincenzo Positano*2, Daniele De Marchi2, Giovanni Aquaro2, Manuela Campan3, Valentina Hartwig5, Matteo Milanesi2, Fabio A Recchia6, Luigi Landini2 and Massimo Lombardi

Experimental approaches to cardiac imaging with hyperpolarized [1-13c]pyruvate: a feasibility study in rats with a 3T clincal scanner

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Placental stem cells pre-treated with hyaluronan-butyric-retinoic ester to cure infarcted pig hearts: a multimodal study.

AIMS: Pre-treating placenta-derived human mesenchymal stem cells (FMhMSCs) with a hyaluronan mixed ester of butyric and retinoic acid (HBR) potentiates their reparative capacity in rodent hearts. Our aim was to test FMhMSCs in a large-animal model by employing a novel combination of in vivo and ex vivo analyses. METHODS AND RESULTS: Matched regional quantifications of myocardial function and viability were performed by magnetic resonance imaging (MRI) and positron emission tomography (PET) 4weeks after myocardial infarction combined with intramyocardial injection of FMhMSCs (n = 7), or HBR-pre-treated FMhMSCs (HBR-FMhMSCs, n = 6), or saline solution (PBS, n = 7). Sham-operated pigs (n = 4) were used as control animals. Despite no differences in the ejection fraction and haemodynamics, regional MRI revealed, in pigs treated with HBR-FMhMSCs compared with the other infarcted groups, a 40% smaller infarct scar size and a significant improvement of the end-systolic wall thickening and circumferential shortening of the infarct border zone. Consistently, PET showed that myocardial perfusion and glucose uptake were, respectively, 35 and 23% higher in the border zone of pigs treated with HBR-FMhMSCs compared with the other infarcted groups. Histology supported in vivo imaging; the delivery of HBR-FMhMSCs significantly enhanced capillary density and decreased fibrous tissue by approximately 68%. Moreover, proteomic analysis of the border zone in the HBR-FMhMSCs group and the FMhMSCs group indicated, respectively, 45 and 30% phenotypic homology with healthy tissue, while this homology was only 26% in the border zone of the PBS group