Project description:Mechanical unloading by ventricular assist devices (VAD) leads to significant gene-expression changes often summarized as reverse remodeling. However, little is known on individual transcriptome changes during VAD-support and its relationship to non-failing hearts (NF). In addition no data are available for the transcriptome regulation during non-pulsatile VAD-support. Therefore we analysed the gene-expression patterns of 30 paired samples from VAD-supported (including 8 non-pulsatile VADs) and 8 non-failing control hearts (NF) using the first total human genome-array available. Transmural myocardial samples were collected for RNA-isolation. RNA was isolated by commercial methods and processed according to chip-manufacturer recommendations. cRNA were hybridized on Affymetrix HG-U133 Plus 2.0 arrays, providing coverage of the whole human genome Array. Data was analyzed using Microarray Analysis Suite 5.0 (Affymetrix) and clustered by Expressionist software (Genedata). 352 transcripts were differentially regulated between samples from VAD-implantation and NF, whereas 510 were significantly regulated between VAD-transplantation and NF (paired t-test p<0.001, fold change >=1.6). Remarkably, only a minor fraction of 111 transcripts was regulated in heart failure (HF) and during VAD-support. Unsupervised hierarchical clustering of paired VAD- and NF-samples revealed separation of HF- and NF- samples, however individual differentiation of VAD-implantation and VAD-transplantation was not accomplished. Clustering of pulsatile and non-pulsatile VAD did not lead to robust separation of gene expression patterns. During VAD-support myocardial gene expression changes do not indicate reversal of the HF-phenotype, but reveal a distinct HF-related pattern. Transcriptome analysis of pulsatile and non-pulsatile VAD-supported hearts did not provide evidence for a pump-mode specific transcriptome pattern. Microarrays were used to elucidate the differences between non-failing control hearts and those, suffering from end-stage heart failure pre and post mechanical unloading.

Project description:Heart failure is associated with high morbidity and mortality and its incidence increases worldwide. MicroRNAs (miRNAs) are potential markers and targets for diagnostic and therapeutic applications, respectively. We determined myocardial and circulating miRNA abundance and its changes in patients with stable and end-stage heart failure before and at different time points after mechanical unloading by a left ventricular assist device (LVAD) by small-RNA-sequencing. MiRNA changes in failing heart tissues partially resembled that of fetal myocardium. Consistent with prototypical miRNAM-bM-^@M-^Starget-mRNA interactions, target mRNA levels were negatively correlated to changes in abundance for highly expressed miRNAs in heart failure and fetal hearts. The circulating small RNA profile was dominated by miRNAs, and fragments of tRNAs and small cytoplasmic RNAs. Heart- and muscle-specific circulating miRNAs (myomirs) increased up to 140-fold in advanced heart failure, which coincided with a similar increase in cardiac troponin I protein, the established marker for heart injury. These extracellular changes nearly completely reversed 3 months following initiation of LVAD support. In stable heart failure, circulating miRNAs showed less than 5-fold differences compared to normal, and myomir and cardiac troponin I levels were only captured near the detection limit. These findings provide the underpinning for miRNA-based therapies and emphasize the usefulness of circulating miRNAs as biomarkers for heart injury performing similar to established diagnostic protein biomarkers. Total RNA isolated from human left ventricular myocardium of failing hearts due to dilated or ischemic cardiomyopathy before and after mechanical unloading by a left ventricular assist device, and fetal myocardium compared to non-failing postnatal myocardium was subjected to multiplexed small RNA-sequencing on the Illumina platform. mRNA gene expression data using Illumina HumanHT-12v4 beadarrays for a subset of the myocardial samples is available (GSE52601).

Project description:Full Title: Transition from Compensated Hypertrophy to Systolic Heart Failure in the Spontaneously Hypertensive Rat: Structure, Function, and Transcript Analysis Gene expression changes and left ventricular remodeling associated with the transition to systolic heart failure (HF) were determined in the spontaneously hypertensive rat (SHR). By combining transcriptomics of left ventricles from six SHR with HF with changes in function and structure we aimed to better understand the molecular events underlying the onset of systolic HF compared to six age-matched, SHR with compensated hypertrophy. Left ventricle (LV) ejection fraction was depressed (82Â±4 to 52Â±3 %) in compensated vs. failing animals.Â Systolic blood pressure decreased and LV end-diastolic and systolic volume increased with HF.Â Failing SHR hearts also demonstrated increases in left and right ventricular mass relative to non-failing SHRs.Â Â LV papillary muscle force development and shortening velocity decreased, Î²-adrenergic responsiveness was depressed, myocardial stiffness and myocardial fibrosis increased with HF relative to non-failing animals. Initial micro-array analysis revealed that 1,431 transcripts were differentially expressed with HF compared to non-failing SHR (p<0.05). Of the identified transcripts, lipopolysaccharide binding protein, the most highly expressed transcript with HF, was negatively correlated to myocardial force while elevated expression of the collagen cross-linking enzyme lysyl oxidase correlated positively with muscle stiffness. Besides these individual transcripts, gene set enrichment analysis (GSEA) identified multiple enriched pathways with HF, most prominent of the altered signaling pathways involved TGF-Î² and insulin signaling. GESA analysis additionally identified altered gene sets involving inflammation, oxidative stress, cell degradation and cell death, among others (all p<0.01). In contrast to diastolic HF where few transcripts are reported to be altered, our data indicate multiple genes and pathways involved in a variety of biological processes characterize the onset of systolic HF, consistent with many functional and structural changes present in the failing hypertensive heart. Comprehensive gene expression profiling of heart failure Rat model vs control.

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