Regulation of gene expression with thyorid hormone in rats with myocardial infarction
ABSTRACT: Thyroid hormone improves left ventricular remodeling and cardiac performance after myocardial infarction (MI), but the molecular basis is unknown. This study was designed to detect gene expression changes in left ventricular non-infarcted areas at 4 weeks following myocardial infarction with and without thyroid hormone treatment. The results suggest that altered expression of genes for molecular function and biological process may be involved in the beneficial effects of thyroid hormone treatment following myocardial infarction in rats. MI was produced by ligation of the left anterior descending coronary artery in female SD rats. Rats were divided into the following groups: (1) Sham MI, (2) MI, and (3) MI+T4 treatment (T4 pellet 3.3mg, 60 days release, implanted subcutaneously immediately following MI). Four weeks after surgery, total RNA was isolated from left ventricular non-infarcted areas for microarray analysis using the Illumina RatRef-12 Expression BeadChip Platform.
Project description:Thyroid hormone improves left ventricular remodeling and cardiac performance after myocardial infarction (MI), but the molecular basis is unknown. This study was designed to detect gene expression changes in left ventricular non-infarcted areas at 4 weeks following myocardial infarction with and without thyroid hormone treatment. The results suggest that altered expression of genes for molecular function and biological process may be involved in the beneficial effects of thyroid hormone treatment following myocardial infarction in rats. MI was produced by ligation of the left anterior descending coronary artery in female SD rats. Rats were divided into the following groups: (1) Sham MI, (2) MI, and (3) MI+T4 treatment (T4 pellet 3.3mg, 60 days release, implanted subcutaneously immediately following MI). Four weeks after surgery, total RNA was isolated from left ventricular non-infarcted areas for microarray analysis using the Illumina RatRef-12 Expression BeadChip Platform.
Project description:<h4>Introduction</h4>The expression of hundreds of genes is altered in response to left ventricular (LV) remodeling following large transmural myocardial infarction (MI). Thyroid hormone (TH) improves LV remodeling and cardiac performance after MI. However, the molecular basis is unknown.<h4>Methods</h4>MI was produced by ligation of the left anterior descending coronary artery in female SD rats. Rats were divided into the following groups: (1) Sham MI, (2) MI, and (3) MI+T4 treatment (T4 pellet 3.3 mg, 60 days release, implanted subcutaneously immediately following MI). Four weeks after surgery, total RNA was isolated from LV non-infarcted areas for microarray analysis using the Illumina RatRef-12 Expression BeadChip Platform.<h4>Results</h4>Signals were detected in 13,188 genes (out of 22,523), of which the expression of 154 genes were decreased and the expression of 200 genes were increased in MI rats compared with Sham MI rats (false discovery rate (FDR) <0.05). Compared to MI rats, T4 treatment decreased expression of 27 genes and increased expression of 28 genes. In particular, 6 genes down-regulated by MI and 12 genes up-regulated by MI were reversed by T4. Most of the 55 genes altered by T4 treatment are in the category of molecular function under binding (24) and biological processes which includes immune system process (9), multi-organism process (5) and biological regulation (19) nonexclusively.<h4>Conclusions</h4>These results suggest that altered expression of genes for molecular function and biological process may be involved in the beneficial effects of thyroid hormone treatment following MI in rats.
Project description:Myocardial infarction (MI) often results in left ventricular (LV) remodeling followed by heart failure (HF). It is of great clinical importance to understand the molecular mechanisms that trigger transition from compensated LV injury to HF and to identify relevant diagnostic biomarkers. In this study, we performed transcriptional profiling of LVs in rats with a wide range of experimentally induced infarct sizes and of peripheral blood mononuclear cells (PBMCs) in animals that developed HF. We used microarrays to investigate gene expression in the left ventricle (LV) accompanying myocardial infarction and concomitant heart failure (HF) in a well validated model of post-infarcted heart failure and to evaluate their reflection in peripheral blood mononuclear cells (PBMCs) Myocardial infarction (MI) was induced in male Wistar rats by ligation of the proximal left coronary artery. The sham-operated group (control group) was subjected to the same protocol, except that the suture was not tied around the proximal left coronary artery. Sham-operated rats (n=6) and rats with small (n=6), moderate (n=6), and large (n=5) MI size were included into the experiment two months after the operation. Then, left ventricules and blood samples were obtained for RNA extraction and hybridization on Affymetrix microarrays. Microarrays were used to compare the LV and PBMCs transcriptomes of control and experimental animals. The development of heart failure was estimated by echocardiography and catheterization.
Project description:Purpose. To evaluate whether 3T clinical MRI with a small-animal coil and gradient-echo (GE) sequence could be used to characterize long-term left ventricular remodelling (LVR) following nonreperfused myocardial infarction (MI) using semi-automatic segmentation software (SASS) in a rat model. Materials and Methods. 5 healthy rats were used to validate left ventricular mass (LVM) measured by MRI with postmortem values. 5 sham and 7 infarcted rats were scanned at 2 and 4 weeks after surgery to allow for functional and structural analysis of the heart. Measurements included ejection fraction (EF), end-diastolic volume (EDV), end-systolic volume (ESV), and LVM. Changes in different regions of the heart were quantified using wall thickness analyses. Results. LVM validation in healthy rats demonstrated high correlation between MR and postmortem values. Functional assessment at 4 weeks after MI revealed considerable reduction in EF, increases in ESV, EDV, and LVM, and contractile dysfunction in infarcted and noninfarcted regions. Conclusion. Clinical 3T MRI with a small animal coil and GE sequence generated images in a rat heart with adequate signal-to-noise ratio (SNR) for successful semiautomatic segmentation to accurately and rapidly evaluate long-term LVR after MI.
Project description:<h4>Unlabelled</h4>Stromal cell-derived factor 1 alpha (SDF-1) is not only a major chemotactic factor, but also an inducer of angiogenesis. The effects of SDF-1 alpha on the left ventricular remodeling in a rat myocardial infarction (MI) model were analyzed. Myocardial infarction was induced by ligation of the left coronary artery in rats. 0.5 x 10(10) pfu/ml AdV-SDF-1 or 0.5 x 10(10) pfu/ml Adv-LacZ were immediately injected into the infarcted myocardium, 120 microl cell-free PBS were injected into the infarcted region or the myocardial wall in control, and sham group, respectively. We found that AdV-SDF-1 group had higher LVSP and +/-dP/dt(max), lower LVEDP compared to control or Adv-LacZ group. The number of c-Kit(+) stem cells, and gene expression of SDF-1, VEGF and bFGF were obviously increased, which was associated with reduced infarct size, thicker left ventricle wall, greater vascular density and cardiocytes density in infarcted hearts of AdV-SDF-1 group. Furthermore, the expression of collagen type I and type III mRNA, and collagen accumulation in the infarcted area was lower, which was associated with decreased TGF-beta1, TIMP-1 and TIMP-2 expression in AdV-SDF-1 group.<h4>Conclusion</h4>SDF-1 alpha could improve cardiac structure and function after Myocardial infarction through angiogenic and anti-fibrotic actions.
Project description:BACKGROUND:There is increasing need for better therapies to prevent the development of heart failure after myocardial infarction (MI). An injectable hydrogel derived from decellularized porcine ventricular myocardium has been shown to halt the post-infarction progression of negative left ventricular remodeling and decline in cardiac function in both small and large animal models. OBJECTIVES:This study sought to elucidate the tissue-level mechanisms underlying the therapeutic benefits of myocardial matrix injection. METHODS:Myocardial matrix or saline was injected into infarcted myocardium 1 week after ischemia-reperfusion in Sprague-Dawley rats. Cardiac function was evaluated by magnetic resonance imaging and hemodynamic measurements at 5 weeks after injection. Whole transcriptome microarrays were performed on RNA isolated from the infarct at 3 days and 1 week after injection. Quantitative polymerase chain reaction and histologic quantification confirmed expression of key genes and their activation in altered pathways. RESULTS:Principal component analysis of the transcriptomes showed that samples collected from myocardial matrix-injected infarcts are distinct and cluster separately from saline-injected control subjects. Pathway analysis indicated that these differences are due to changes in several tissue processes that may contribute to improved cardiac healing after MI. Matrix-injected infarcted myocardium exhibits an altered inflammatory response, reduced cardiomyocyte apoptosis, enhanced infarct neovascularization, diminished cardiac hypertrophy and fibrosis, altered metabolic enzyme expression, increased cardiac transcription factor expression, and progenitor cell recruitment, along with improvements in global cardiac function and hemodynamics. CONCLUSIONS:These results indicate that the myocardial matrix alters several key pathways after MI creating a pro-regenerative environment, further demonstrating its promise as a potential post-MI therapy.
Project description:Aldosterone receptor antagonism reduces mortality and improves post-myocardial infarction (MI) remodeling. Because aldosterone and estrogen signaling pathways interact, we hypothesized that aldosterone blockade is sex-specific. Therefore, we investigated the impact of eplerenone on left ventricular (LV) remodeling and gene expression of male infarcted rats versus female infarcted rats. MI and Sham animals were randomized to receive eplerenone (100 mg/kg/day) or placebo 3 days post-surgery for 4 weeks and assessed by echocardiography. In the MI placebo group, left ventricular end-diastolic dimension (LVEDD) increased from 7.3 +/- 0.4 mm to 10.2 +/- 1.0 mm (p < 0.05) and ejection fraction (EF) decreased from 82.3 +/- 4% to 45.5 +/- 11% (p < 0.05) in both sexes (p = NS between groups). Eplerenone attenuated LVEDD enlargement more effectively in females (8.8 +/- 0.2 mm, p < 0.05 vs. placebo) than in males (9.7 +/- 0.2 mm, p = NS vs. placebo) and improved EF in females (56.7 +/- 3%, p < 0.05 vs. placebo) but not in males (50.6 +/- 3%, p = NS vs. placebo). Transcriptomic analysis using Rat_230-2.0 microarrays (Affymetrix) revealed that in females 19% of downregulated genes and 44% of upregulated genes post-MI were restored to normal by eplerenone. In contrast, eplerenone only restored 4% of overexpressed genes in males. Together, these data suggest that aldosterone blockade reduces MI-induced cardiac remodeling and phenotypic alterations of gene expression preferentially in females than in males. The use of transcriptomic signatures to detect greater benefit of eplerenone in females has potential implications for personalized medicine.
Project description:BACKGROUND AND PURPOSE: Mitogen-activated protein kinases (MAPK) are centrally involved in several mechanisms important for heart failure such as apoptosis, activation of inflammatory responses and cell proliferation. We therefore evaluated the effect of the selective p38 MAPK inhibitor SB 239063 on progression of left ventricular remodelling after myocardial infarction (MI) in rats. EXPERIMENTAL APPROACH: Rats were treated for 9 weeks with placebo or SB 239063 by gavage (15 mg kg(-1)) twice daily starting 7 days after ligation of the left anterior descending artery. Serial transthoracic echocardiography was performed at days 7, 36 and 70. KEY RESULTS: Over the 9 weeks, mortality was not different between the groups. On echocardiography, animals after myocardial infarction exhibited significant left ventricular dilatation as expected (week 10, end-systolic diameter, placebo sham 5.21+/- 0.34 vs. placebo MI 8.44+/- 0.57 mm). However, there was no difference between placebo and SB 239063-treated rats (week 10, end-systolic diameter, SB MI 7.76+/- 0.74 mm, not significantly different from placebo MI). Haemodynamics changed accordingly. Moreover, SB 239063 had no effect on left ventricular hypertrophy. Treatment with SB 239063 significantly reduced cytokine expression of tumour necrosis factor and interleukin-1beta after myocardial infarction. However, collagen content was not influenced by the treatment. CONCLUSION: Despite a reduction of inflammation, treatment with the p38 inhibitor SB 239063 does not affect cardiac remodelling and cardiac function when treatment is started 7 days after myocardial infarction.
Project description:To investigate the transcriotome alteration in myocardial infarction (MI)-associated cells, we performed RNA sequcening analysis with single cells derived from mouse infarcted cardiac tissues or normal left ventricle (LV). Particularly, cardiac endothelial cells (ECs) were traced using a Cdh5-Cre;LSL-tdTomatom system. Overall design: Myocardial infarction (MI) was induced Cdh5-CreERT2;Rosa-LSL-tdTomato mice. 0, 1, 2, 3 weeks after the surgery, infarcted tissues or normal left ventricle (LV) were harvested. Single-cell suspensions were analyzed by RNA sequencing.
Project description:Acellular cardiac patches made of various biomaterials have shown to improve heart function after myocardial infarction (MI). Extracellular matrix scaffold derived from a decellularized tissue has unique advantages to serve as an acellular cardiac patch due to its biomimetic nature. In this study, we examined the therapeutic outcomes of using a decellularized porcine myocardium slice (dPMS) as an acellular patch in a rat acute MI model. dPMSs with two different thicknesses (300 and 600 ?m) were patched to the infarcted area of the rat myocardium, and their effects on cardiac function and host interactions were assessed. We found that the implanted dPMS firmly attached to host myocardium after implantation and prevented thinning of the left ventricular (LV) wall after an MI. A large number of host cells were identified to infiltrate into the implanted dPMS, and a significant number of vessel structures was observed in the dPMS and infarcted area. We detected a significantly higher density of M2 macrophages in the groups treated with dPMSs as compared to the MI group. Contraction of the LV wall and cardiac functional parameters (left ventricular ejection fraction and fractional shortening) was significantly improved in the treatment groups (300 and 600 ?m dPMS) 4 weeks after surgery. Our results proved the therapeutic benefits of using dPMS as an acellular cardiac patch for the treatment of acute myocardial infarction.