Left ventricular remodeling in swine after myocardial infarction: a transcriptional genomics approach

The microtubule signature in cardiac disease: etiology, disease stage, and age dependency

Employing animal models to study heart failure (HF) has become indispensable to discover and test novel therapies, but their translatability remains challenging. Although cytoskeletal alterations are linked to HF, the tubulin signature of common experimental models has been incompletely defined. Here, we assessed the tubulin signature in a large set of human cardiac samples and myocardium of animal models with cardiac remodeling caused by pressure overload, myocardial infarction or a gene defect. We studied levels of total, acetylated, and detyrosinated α-tubulin and desmin in cardiac tissue from hypertrophic (HCM) and dilated cardiomyopathy (DCM) patients with an idiopathic (n = 7), ischemic (n = 7) or genetic origin (n = 59), and in a pressure-overload concentric hypertrophic pig model (n = 32), pigs with a myocardial infarction (n = 28), mature pigs (n = 6), and mice (n = 15) carrying the HCM-associated MYBPC32373insG mutation. In the human samples, detyrosinated α-tubulin was increased 4-fold in end-stage HCM and 14-fold in pediatric DCM patients. Acetylated α-tubulin was increased twofold in ischemic patients. Across different animal models, the tubulin signature remained mostly unaltered. Only mature pigs were characterized by a 0.5-fold decrease in levels of total, acetylated, and detyrosinated α-tubulin. Moreover, we showed increased desmin levels in biopsies from NYHA class II HCM patients (2.5-fold) and the pressure-overload pig model (0.2-0.3-fold). Together, our data suggest that desmin levels increase early on in concentric hypertrophy and that animal models only partially recapitulate the proliferated and modified tubulin signature observed clinically. Our data warrant careful consideration when studying maladaptive responses to changes in the tubulin content in animal models.

Corticosteroid Receptors in Cardiac Health and Disease

Nuclear receptors play a central role in both energy metabolism and cardiomyocyte death and survival in the heart. Recent evidence suggests they may also influence cardiomyocyte endowment. Although several members of the nuclear receptor family play key roles in heart maturation (including thyroid hormone receptors) and cardiac metabolism, here, the focus will be on the corticosteroid receptors, the glucocorticoid receptor (GR) and mineralocorticoid receptor (MR). The heart is an important target for the actions of corticosteroids, yet the homeostatic role of GR and MR in the healthy heart has been elusive. However, MR antagonists are important in the treatment of heart failure, a condition associated with mitochondrial dysfunction and energy failure in cardiomyocytes leading to mitochondria-initiated cardiomyocyte death (Ingwall and Weiss, Circ Res 95:135-145, 2014; Ingwall , Cardiovasc Res 81:412-419, 2009; Zhou and Tian , J Clin Invest 128:3716-3726, 2018). In contrast, animal studies suggest GR activation in cardiomyocytes has a cardioprotective role, including in heart failure.

Relationships of Telomere Homeostasis with Oxidative Stress and Cardiac Dysfunction in Human Ischaemic Hearts

Although the roles of telomeres and oxidative stress in ischaemic cardiomyopathy (ICM) are known, mechanisms of telomere homeostasis and their relationship with oxidative stress are incompletely understood. We performed two RNA-seq analyses (mRNA n = 23; ncRNA n = 30) and protein validation on left ventricles of explanted hearts from ICM and control subjects. We observed dysregulation of the shelterin and cohesin complexes, which was related to an increase in the response to cellular oxidative stress. Moreover, we found alterations at mRNA level in the mechanisms of telomeric DNA repair. Specifically, increased RAD51D mRNA levels were correlated with left ventricular diameters. RAD51D protein levels were unaltered, however, and were inversely corelated with the miR-103a-3p upregulation. We also observed the overexpression of lncRNAs (TERRA and GUARDIN) involved in telomere protection in response to stress and alterations in their regulatory molecules. Expression of the TERRA transcription factor ATF7 was correlated with superoxide dismutase 1 expression and left ventricular diameters. The levels of GUARDIN and its transcription factor FOSL2 were correlated with those of catalase. Therefore, we showed specific alterations in the mechanisms of telomeric DNA repair and protection, and these alterations are related to an increase in the response mechanisms to oxidative stress and cardiac dysfunction in ICM.

New genetic variants associated with major adverse cardiovascular events in patients with acute coronary syndromes and treated with clopidogrel and aspirin

Although a few studies have reported the effects of several polymorphisms on major adverse cardiovascular events (MACE) in patients with acute coronary syndromes (ACS) and those undergoing percutaneous coronary intervention (PCI), these genotypes account for only a small fraction of the variation and evidence is insufficient. This study aims to identify new genetic variants associated with MACE end point during the 18-month follow-up period by a two-stage large-scale sequencing data, including high-depth whole exome sequencing of 168 patients in the discovery cohort and high-depth targeted sequencing of 1793 patients in the replication cohort. We discovered eight new genotypes and their genes associated with MACE in patients with ACS, including MYOM2 (rs17064642), WDR24 (rs11640115), NECAB1 (rs74569896), EFR3A (rs4736529), AGAP3 (rs75750968), ZDHHC3 (rs3749187), ECHS1 (rs140410716), and KRTAP10-4 (rs201441480). Notably, the expressions of MYOM2 and ECHS1 are downregulated in both animal models and patients with phenotypes related to MACE. Importantly, we developed the first superior classifier for predicting 18-month MACE and achieved high predictive performance (AUC ranged between 0.92 and 0.94 for three machine-learning methods). Our findings shed light on the pathogenesis of cardiovascular outcomes and may help the clinician to make a decision on the therapeutic intervention for ACS patients.

H3K27ac acetylome signatures reveal the epigenomic reorganization in remodeled non-failing human hearts

BACKGROUND

H3K27ac histone acetylome changes contribute to the phenotypic response in heart diseases, particularly in end-stage heart failure. However, such epigenetic alterations have not been systematically investigated in remodeled non-failing human hearts. Therefore, valuable insight into cardiac dysfunction in early remodeling is lacking. This study aimed to reveal the acetylation changes of chromatin regions in response to myocardial remodeling and their correlations to transcriptional changes of neighboring genes.

RESULTS

We detected chromatin regions with differential acetylation activity (DARs; Padj. < 0.05) between remodeled non-failing patient hearts and healthy donor hearts. The acetylation level of the chromatin region correlated with its RNA polymerase II occupancy level and the mRNA expression level of its adjacent gene per sample. Annotated genes from DARs were enriched in disease-related pathways, including fibrosis and cell metabolism regulation. DARs that change in the same direction have a tendency to cluster together, suggesting the well-reorganized chromatin architecture that facilitates the interactions of regulatory domains in response to myocardial remodeling. We further show the differences between the acetylation level and the mRNA expression level of cell-type-specific markers for cardiomyocytes and 11 non-myocyte cell types. Notably, we identified transcriptome factor (TF) binding motifs that were enriched in DARs and defined TFs that were predicted to bind to these motifs. We further showed 64 genes coding for these TFs that were differentially expressed in remodeled myocardium when compared with controls.

CONCLUSIONS

Our study reveals extensive novel insight on myocardial remodeling at the DNA regulatory level. Differences between the acetylation level and the transcriptional level of cell-type-specific markers suggest additional mechanism(s) between acetylome and transcriptome. By integrating these two layers of epigenetic profiles, we further provide promising TF-encoding genes that could serve as master regulators of myocardial remodeling. Combined, our findings highlight the important role of chromatin regulatory signatures in understanding disease etiology.

Deletion of the Cardiomyocyte Glucocorticoid Receptor Leads to Sexually Dimorphic Changes in Cardiac Gene Expression and Progression to Heart Failure

Background

The contribution of glucocorticoids to sexual dimorphism in the heart is essentially unknown. Therefore, we sought to determine the sexually dimorphic actions of glucocorticoid signaling in cardiac function and gene expression. To accomplish this goal, we conducted studies on mice lacking glucocorticoid receptors (GR) in cardiomyocytes (cardioGRKO mouse model).

Methods and Results

Deletion of cardiomyocyte GR leads to an increase in mortality because of the development of spontaneous cardiac pathology in both male and female mice; however, females are more resistant to GR signaling inactivation in the heart. Male cardioGRKO mice had a median survival age of 6 months. In contrast, females had a median survival age of 10 months. Transthoracic echocardiography data showed phenotypic differences between male and female cardioGRKO hearts. By 3 months of age, male cardioGRKO mice exhibited left ventricular systolic dysfunction. Conversely, no significant functional deficits were observed in female cardioGRKO mice at the same time point. Functional sensitivity of male hearts to the loss of cardiomyocyte GR was reversed following gonadectomy. RNA‐Seq analysis showed that deleting GR in the male hearts leads to a more profound dysregulation in the expression of genes implicated in heart rate regulation (calcium handling). In agreement with these gene expression data, cardiomyocytes isolated from male cardioGRKO hearts displayed altered intracellular calcium responses. In contrast, female GR‐deficient cardiomyocytes presented a response comparable with controls.

Conclusions

These data suggest that GR regulates calcium responses in a sex‐biased manner, leading to sexually distinct responses to stress in male and female mice hearts, which may contribute to sex differences in heart disease, including the development of ventricular arrhythmias that contribute to heart failure and sudden death.

Silybum marianum provides cardioprotection and limits adverse remodeling post-myocardial infarction by mitigating oxidative stress and reactive fibrosis

AIMS

Milk thistle (Silybum marianum; SM) is an herb commonly used for hepatoprotection with antioxidant and antifibrotic properties. We investigated in pigs the cardiac effects of SM intake during the acute phase of myocardial infarction (MI) and remodeling period post-MI.

METHODS

Study-1 tested the effect of SM use on the acute phase of MI. Hence, animals were distributed to a control group or to receive SM prior infarction (1.5 h ischemia). Animals were sacrificed after 2.5 h of reperfusion. Study-2 tested the effect of SM use in the cardiac remodeling phase. Accordingly, animals received for 10 d diet ± SM prior MI and followed the same regime for 3 weeks and then sacrificed. Study-3 tested the effect of SM in a non-infarcted heart; therefore, animals received for 10 d diet ± SM and then sacrificed.

RESULTS

Animals taking SM before MI showed a reduction in cardiac damage (decreased oxidative damage, ROS production and xanthine oxidase levels; preserved mitochondrial function; and increased myocardial salvage; p < 0.05) versus controls. Animals that remained on chronic SM intake post-MI improved left ventricular remodeling. This was associated with the attenuation of the TGFß1/TßRs/SMAD2/3 signaling, lower myofibroblast transdifferentiation and collagen content in the border zone (p < 0.05 vs. all other groups). Cardiac contractility improved in animals taking SM (p < 0.05 vs. post-MI-control). No changes in cardiac function or fibrosis were detected in animals on SM but without MI.

CONCLUSION

Intake of SM protects the heart against the deleterious effects of an MI and favors cardiac healing. These benefits may be attributed to the antioxidant and antifibrotic properties of SM.

Monitoring reperfused myocardial infarction with delayed left ventricular systolic dysfunction in rabbits by longitudinal imaging

Background

An experimental imaging platform for longitudinal monitoring and evaluation of cardiac morphology-function changes has been long desired. We sought to establish such a platform by using a rabbit model of reperfused myocardial infarction (MI) that develops chronic left ventricle systolic dysfunction (LVSD) within 7 weeks.

Methods

Fifty-five New Zeeland white (NZW) rabbits received sham-operated or 60-min left circumflex coronary artery (LCx) ligation followed by reperfusion. Cardiac magnetic resonance imaging (cMRI), transthoracic echocardiography (echo), and blood samples were collected at baseline, in acute (48 hours or 1 week) and chronic (7 weeks) stage subsequent to MI for in vivo assessment of infarct size, cardiac morphology, LV function, and myocardial enzymes. Seven weeks post MI, animals were sacrificed and heart tissues were processed for histopathological staining.

Results

The success rate of surgical operation was 87.27%. The animal mortality rates were 12.7% and 3.6% both in acute and chronic stage separately. Serum levels of the myocardial enzyme cardiac Troponin T (cTnT) were significantly increased in MI rabbits as compared with sham animals after 4 hours of operation (P<0.05). According to cardiac morphology and function changes, 4 groups could be distinguished: sham rabbits (n=12), and MI rabbits with no (MI_NO_LVSD; n=10), moderate (MI_M_LVSD; n=9) and severe (MI_S_LVSD; n=15) LVSD. No significant differences in cardiac function or wall thickening between sham and MI_NO_LVSD rabbits were observed at both stages using both cMRI and echo methods. cMRI data showed that MI_M_LVSD rabbits exhibited a reduction of ejection fraction (EF) and an increase in end-systolic volume (ESV) at the acute phase, while at the chronic stage these parameters did not change further. Moreover, in MI_S_LVSD animals, these observations were more striking at the acute stage followed by a further decline in EF and increase in ESV at the chronic stage. Lateral wall thickening determined by cMRI was significantly decreased in MI_M_LVSD versus MI_NO_LVSD animals at both stages (P<0.05). As for MI_S_LVSD versus MI_M_LVSD rabbits, the thickening of anterior, inferior and lateral walls was significantly more decreased at both stages (P<0.05). Echo confirmed the findings of cMRI. Furthermore, these in vivo outcomes including those from vivid cine cMRI could be supported by exactly matched ex vivo histomorphological evidences.

Conclusions

Our findings indicate that chronic LVSD developed over time after surgery-induced MI in rabbits can be longitudinally evaluated using non-invasive imaging techniques and confirmed by the entire-heart-slice histomorphology. This experimental LVSD platform in rabbits may interest researchers in the field of experimental cardiology and help strengthen drug development and translational research for the management of cardiovascular diseases.

Identifying key genes associated with acute myocardial infarction

BACKGROUND

This study aimed to identify key genes associated with acute myocardial infarction (AMI) by reanalyzing microarray data.

METHODS

Three gene expression profile datasets GSE66360, GSE34198, and GSE48060 were downloaded from GEO database. After data preprocessing, genes without heterogeneity across different platforms were subjected to differential expression analysis between the AMI group and the control group using metaDE package. P < .05 was used as the cutoff for a differentially expressed gene (DEG). The expression data matrices of DEGs were imported in ReactomeFIViz to construct a gene functional interaction (FI) network. Then, DEGs in each module were subjected to pathway enrichment analysis using DAVID. MiRNAs and transcription factors predicted to regulate target DEGs were identified. Quantitative real-time polymerase chain reaction (RT-PCR) was applied to verify the expression of genes.

RESULT

A total of 913 upregulated genes and 1060 downregulated genes were identified in the AMI group. A FI network consists of 21 modules and DEGs in 12 modules were significantly enriched in pathways. The transcription factor-miRNA-gene network contains 2 transcription factors FOXO3 and MYBL2, and 2 miRNAs hsa-miR-21-5p and hsa-miR-30c-5p. RT-PCR validations showed that expression levels of FOXO3 and MYBL2 were significantly increased in AMI, and expression levels of hsa-miR-21-5p and hsa-miR-30c-5p were obviously decreased in AMI.

CONCLUSION

A total of 41 DEGs, such as SOCS3, VAPA, and COL5A2, are speculated to have roles in the pathogenesis of AMI; 2 transcription factors FOXO3 and MYBL2, and 2 miRNAs hsa-miR-21-5p and hsa-miR-30c-5p may be involved in the regulation of the expression of these DEGs.

Analysis of region specific gene expression patterns in the heart and systemic responses after experimental myocardial ischemia

Aims

Ischemic myocardial injury leads to the activation of inflammatory mechanisms and results in ventricular remodeling. Although great efforts have been made to unravel the molecular and cellular processes taking place in the ischemic myocardium, little is known about the effects on the surrounding tissue and other organs. The aim of this study was to determine region specific differences in the myocardium and in distant organs after experimental myocardial infarction by using a bioinformatics approach.

Methods and Results

A porcine closed chest reperfused acute myocardial infarction model and mRNA microarrays have been used to evaluate gene expression changes. Myocardial infarction changed the expression of 8903 genes in myocardial-, 856 in hepatic- and 338 in splenic tissue. Identification of myocardial region specific differences as well as expression profiling of distant organs revealed clear gene-regulation patterns within the first 24 hours after ischemia. Transcription factor binding site analysis suggested a strong role for Kruppel like factor 4 (Klf4) in the regulation of gene expression following myocardial infarction, and was therefore investigated further by immunohistochemistry. Strong nuclear Klf4 expression with clear region specific differences was detectable in porcine and human heart samples after myocardial infarction.

Conclusion

Apart from presenting a post myocardial infarction gene expression database and specific response pathways, the key message of this work is that myocardial ischemia does not end at the injured myocardium. The present results have enlarged the spectrum of organs affected, and suggest that a variety of organ systems are involved in the co-ordination of the organism´s response to myocardial infarction.

UM206, a selective Frizzled antagonist, attenuates adverse remodeling after myocardial infarction in swine

Modulation of Wnt/Frizzled signaling with UM206 reduced infarct expansion and prevented heart failure development in mice, an effect that was accompanied by increased myofibroblast presence in the infarct, suggesting that Wnt/Frizzled signaling has a key role in cardiac remodeling following myocardial infarction (MI). This study investigated the effects of modulation of Wnt/Frizzled signaling with UM206 in a swine model of reperfused MI. For this purpose, seven swine with MI were treated with continuous infusion of UM206 for 5 weeks. Six control swine were treated with vehicle. Another eight swine were sham-operated. Cardiac function was determined by echo in awake swine. Infarct mass was estimated at baseline by heart-specific fatty acid-binding protein ELISA and at follow-up using planimetry. Components of Wnt/Frizzled signaling, myofibroblast presence, and extracellular matrix were measured at follow-up with qPCR and/or histology. Results show that UM206 treatment resulted in a significant decrease in infarct mass compared with baseline (-41±10%), whereas infarct mass remained stable in the Control-MI group (+3±17%). Progressive dilation of the left ventricle occurred in the Control-MI group between 3 and 5 weeks after MI, while adverse remodeling was halted in the UM206-treated group. mRNA expression for Frizzled-4 and the Frizzled co-receptor LRP5 was increased in UM206-treated swine as compared with Control-MI swine. Myofibroblast presence was significantly lower in infarcted tissue of the UM206-treated animals (1.53±0.43% vs 3.38±0.61%) at 5 weeks follow-up. This study demonstrates that UM206 treatment attenuates adverse remodeling in a swine model of reperfused MI, indicating that Wnt/Frizzled signaling is a promising target to improve infarct healing and limit post-MI remodeling.

Cardiac GR and MR: From Development to Pathology

The efficacy of mineralocorticoid receptor (MR) antagonism in the treatment of certain patients with heart failure has highlighted the pivotal role of aldosterone and MR in heart disease. The glucocorticoid (GC) receptor (GR) is also expressed in heart, but the role of cardiac GR had received much less attention until recently. GR and MR are highly homologous in both structure and function, although not in cellular readout. Recent evidence in animal models has uncovered a tonic role for GC action via GR in cardiomyocytes in prevention of heart disease. Here, we review this evidence and the implications for a balance between GR and MR activation in the early life maturation of the heart and its subsequent health and disease.

Impact of neonatal sertraline exposure on the post-myocardial infarction outcomes of adult male mice

Neonatal exposure to a selective serotonin reuptake inhibitor (SSRI) leads to decreased left ventricular volumes and sympathetic activation in adult mice. We hypothesized this neonatal SSRI exposure-induced small left heart syndrome would increase post-myocardial infarction (MI) morbidity and mortality. C57BL/6 mice received saline or sertraline (5 mg/kg intraperitoneally) on postnatal days 1-14. At 5 months, male mice underwent coronary artery ligation and were monitored by radiotelemetry until death or 4 weeks after ligation. After ligation, SSRI-exposed mice had increased heart rates (SSRI, 516 ± 13 bpm; control, 470 ± 15 bpm; P < 0.05). SSRI-exposed mice had significant reductions in left ventricular systolic volumes both before and after coronary ligation (SSRI: baseline = 20 ± 3 μL, post-MI = 37 ± 10 μL; control: baseline = 30 ± 3 μL, post-MI = 65 ± 23 μL). Post-MI echocardiography showed significantly decreased ejection fraction in control mice (baseline = 60% ± 4%, post-MI = 41% ± 2%, P < 0.01) but not the SSRI-exposed mice (baseline = 65% ± 3%, post-MI = 53% ± 7%). Neonatal SSRI exposure did not significantly alter post-MI survival. We conclude that the preexisting SSRI-induced small left heart syndrome may provide protection from post-MI ventricular dilation.

Development of a closed chest model of chronic myocardial infarction in Swine: magnetic resonance imaging and pathological evaluation

Our aim was to develop an easy-to-induce, reproducible, and low mortality clinically relevant closed-chest model of chronic myocardial infarction in swine using intracoronary ethanol and characterize its evolution using MRI and pathology. We injected 3-4 mL of 100% ethanol into the mid-LAD of anesthetized swine. Heart function and infarct size were assessed serially using MRI. Pigs were euthanized on days 7, 30, and 90 (n = 5 at each timepoint). Postoperative MRI revealed compromised contractility and decreased ejection fraction, from 53.8% ± 6.32% to 43.79% ± 7.72% (P = 0.001). These values remained lower than baseline thorough the followup (46.54% ± 11.12%, 44.48% ± 7.77%, and 40.48% ± 6.40%, resp., P < 0.05). Progressive remodeling was seen in all animals. Infarcted myocardium decreased on the first 30 days (from 18.09% ± 7.26% to 9.9% ± 5.68%) and then stabilized (10.2% ± 4.21%). Pathology revealed increasing collagen content and fibrous organization over time, with a rim of preserved endocardial cells. In conclusion, intracoronary ethanol administration in swine consistently results in infarction. The sustained compromise in heart function and myocardial thinning over time indicate that the model may be useful for the preclinical evaluation of and training in therapeutic approaches to heart failure.

Transcriptional profiling of HMGB1-induced myocardial repair identifies a key role for Notch signaling

Exogenous high-mobility group box 1 protein (HMGB1) administration to the mouse heart, during acute myocardial infarction (MI), results in cardiac regeneration via resident c-kit(+) cell (CPC) activation. Aim of the present study was to identify the molecular pathways involved in HMGB1-induced heart repair. Gene expression profiling was performed to identify differentially expressed genes in the infarcted and bordering regions of untreated and HMGB1-treated mouse hearts, 3 days after MI. Functional categorization of the transcripts, accomplished using Ingenuity Pathway Analysis software (IPA), revealed that genes involved in tissue regeneration, that is, cardiogenesis, vasculogenesis and angiogenesis, were present both in the infarcted area and in the peri-infarct zone; HMGB1 treatment further increased the expression of these genes. IPA revealed the involvement of Notch signaling pathways in HMGB1-treated hearts. Importantly, HMGB1 determined a 35 and 58% increase in cardiomyocytes and CPCs expressing Notch intracellular cytoplasmic domain, respectively. Further, Notch inhibition by systemic treatment with the γ-secretase inhibitor DAPT, which blocked the proteolytic activation of Notch receptors, reduced the number of CPCs, their proliferative fraction, and cardiomyogenic differentiation in HMGB1-treated infarcted hearts. The present study gives insight into the molecular processes involved in HMGB1-mediated cardiac regeneration and indicates Notch signaling as a key player.

Chronic carvedilol treatment partially reverses the right ventricular failure transcriptional profile in experimental pulmonary hypertension

Right ventricular failure (RVF) is the most frequent cause of death in patients with pulmonary arterial hypertension (PAH); however, specific therapies targeted to treat RVF have not been developed. Chronic treatment with carvedilol has been shown to reduce established maladaptive right ventricle (RV) hypertrophy and to improve RV function in experimental PAH. However, the mechanisms by which carvedilol improves RVF are unknown. We have previously demonstrated by microarray analysis that RVF is characterized by a distinct gene expression profile when compared with functional, compensatory hypertrophy. We next sought to identify the effects of carvedilol on gene expression on a genome-wide basis. PAH and RVF were induced in male Sprague-Dawley rats by the combination of VEGF-receptor blockade and chronic hypoxia. After RVF was established, rats were treated with carvedilol or vehicle for 4 wk. RNA was isolated from RV tissue and hybridized for microarray analysis. An initial prediction analysis of carvedilol-treated RVs showed that the gene expression profile resembled the RVF prediction set. However, a more extensive analysis revealed a small group of genes differentially expressed after carvedilol treatment. Further analysis categorized these genes in pathways involved in cardiac hypertrophy, mitochondrial dysfunction, and protein ubiquitination. Genes encoding proteins in the cardiac hypertrophy and protein ubiquitination pathways were downregulated in the RV by carvedilol, while genes encoding proteins in the mitochondrial dysfunction pathway were upregulated by carvedilol. These gene expression changes may explain some of the mechanisms that underlie the functional improvement of the RV after carvedilol treatment.

Identification of temporal and region-specific myocardial gene expression patterns in response to infarction in swine

Molecular mechanisms associated with pathophysiological changes in ventricular remodelling due to myocardial infarction (MI) remain poorly understood. We analyzed changes in gene expression by microarray technology in porcine myocardial tissue at 1, 4, and 6 weeks post-MI.MI was induced by coronary artery ligation in 9 female pigs (30-40 kg). Animals were randomly sacrificed at 1, 4, or 6 weeks post-MI (n = 3 per group) and 3 healthy animals were also included as control group. Total RNA from myocardial samples was hybridized to GeneChip® Porcine Genome Arrays. Functional analysis was obtained with the Ingenuity Pathway Analysis (IPA) online tool. Validation of microarray data was performed by quantitative real-time PCR (qRT-PCR).More than 8,000 different probe sets showed altered expression in the remodelling myocardium at 1, 4, or 6 weeks post-MI. Ninety-seven percent of altered transcripts were detected in the infarct core and 255 probe sets were differentially expressed in the remote myocardium. Functional analysis revealed 28 genes de-regulated in the remote myocardial region in at least one of the three temporal analyzed stages, including genes associated with heart failure (HF), systemic sclerosis and coronary artery disease. In the infarct core tissue, eight major time-dependent gene expression patterns were recognized among 4,221 probe sets commonly altered over time. Altered gene expression of ACVR2B, BID, BMP2, BMPR1A, LMNA, NFKBIA, SMAD1, TGFB3, TNFRSF1A, and TP53 were further validated.The clustering of similar expression patterns for gene products with related function revealed molecular footprints, some of them described for the first time, which elucidate changes in biological processes at different stages after MI.