Project description:Background: There are critical molecular mechanisms that can be activated to induce myocardial repair and in humans this is most efficient during fetal development. The timing of heart development in relation to birth and the size/electrophysiology of the heart are similar in humans and sheep, providing a model to investigate the repair capacity of the mammalian heart and how this can be applied to adult heart repair. Methods: Myocardial infarction was induced by ligation of the left anterior descending coronary artery in fetal (105d gestation when cardiomyocytes are proliferative) and adolescent sheep (6 months of age when all cardiomyocytes have switched to an adult phenotype). An ovine gene microarray was used to compare gene expression in sham and infarcted (remote, border and infarct areas) cardiac tissue from fetal and adolescent hearts. Results: The gene response to myocardial infarction was less pronounced in fetal compared to adolescent sheep hearts and there were unique gene responses at each age. There were also region-specific changes in gene expression between each age, in the infarct tissue, tissue bordering the infarct, and tissue remote from the infarction. In total, there were 880 genes that responded to MI uniquely in the adolescent samples compared with 170 genes in the fetal response, as well as 742 overlap genes that showed concordant direction of change responses to infarction at both ages. Conclusions: In response to myocardial infarction, there were specific changes in genes within pathways of mitochondrial oxidation, muscle contraction, and haematopoietic cell lineages, suggesting that the control of energy utilisation and immune function are critical for effective heart repair. The more restricted gene response in the fetus may be an important factor in its enhanced capacity for cardiac repair.
Project description:Affymetrix microarray analysis of molecular changes after myocardial infarction. Samples of heart tissue were analyzed after myocardial infarction from WT and reg3beta knock-out mice. Samples from scar tissue and samples adjacent to the scar were analyzed. In the experiment we primarily compared infarction zone of wild-type to infarction zone of knock-out animals, and remote zone of wild-type to remote zone of knock-outs.
Project description:We demonstrate an age-independent loss of type H bone endothelium in heart failure after myocardial infarction in both mice and in humans. Using single-cell RNA sequencing, we delineate the transcriptional heterogeneity of human bone marrow endothelium showing increased expression of inflammatory genes, including IL1B and MYC, in ischemic heart failure. Endothelial-specific overexpression of MYC was sufficient to induce type H bone endothelial cells, whereas inhibition of NLRP3-dependent IL-1 production partially prevents the post-myocardial infarction loss of type H vasculature in mice.
Project description:We demonstrate an age-independent loss of type H bone endothelium in heart failure after myocardial infarction in both mice and in humans. Using single-cell RNA sequencing, we delineate the transcriptional heterogeneity of human bone marrow endothelium showing increased expression of inflammatory genes, including IL1B and MYC, in ischemic heart failure. Endothelial-specific overexpression of MYC was sufficient to induce type H bone endothelial cells, whereas inhibition of NLRP3-dependent IL-1 production partially prevents the post-myocardial infarction loss of type H vasculature in mice.
Project description:Tissue repair after myocardial infarction entails a vigorous angiogenic response that mitigates scarring and worsening of heart function and may represent a therapeutic target. Angiogenesis in the infarct wound is guided by incompletely defined myeloid cell–endothelial cell interactions. Here we identify the myeloid cell-expressed 75‑amino acid microprotein BRICK1 (short name: BRK1) as an indispensable driver of postinfarction angiogenesis. As a subunit of the intracellular actin-regulatory WAVE complex, BRK1 was not previously known to function outside the cell. We show that BRK1 translocates to the extracellular space after myocardial infarction in mice and humans. We find that BRK1 is not actively secreted but released from dying monocytes and macrophages. Cre-loxP-mediated myeloid cell-selective genetic deletion of Brk1 or antibody neutralization of extracellular BRK1 impaired microvessel formation in the infarct border zone and resulted in severe postinfarction heart failure in mice. Treatment with recombinant BRK1, conversely, preserved heart function after myocardial infarction. Mechanistically, BRK1 induced an angiogenic phenotype in human cardiac endothelial cells by signaling via the small GTPase RAP1 and mitogen-activated protein kinases 1 and 3 to promote retinoblastoma protein hyperphosphorylation and E2F transcription factor activation. BRK1 thus emerges as an angiogenic growth factor linking myeloid cell death to ischemic tissue repair and potentially enabling a protein-based therapy for myocardial infarction.
Project description:We tested it in an animal model of myocardial infarction to ensure whether early initiation of dapagliflozin (DAPA), or different orders of combination with sacubitril-valsartan would result in a greater improvement of heart function than sacubitril-valsartan alone in post-myocardial infarction heart failure.
Project description:To test the mechanism by which IGF1 is cardioprotective, we performed single cell RNA sequencing on myeloid cells isolated from the heart 3 days after myocardial infarction of mice with and without IGF1 treatment. Myocardial infarction was induced in C57Bl6/J mice by 45 min occlusion of the left anterior descending artery followed by 3 days of reperfusion. Animals of the IGF1 group (n=3) received 40 ng/g mature recombinant IGF1 subcutaneously as bolus at the beginning of reperfusion. In addition, IGF1 (1 µg/g/d) was administered continuously during reperfusion using micro-osmotic pumps (Alzet, 1003D) that were implanted subcutaneously. Control mice received vehicle (0.1% BSA). After 3 days hearts were digested and CD45+CD11b+ cells were isolated using FACS cell sorting. Each sample contained cells containing 1 control and 1 IGF1 treated mouse, labeled with TotalSeq hashtags. 16000 cells were used as input for the single-cell droplet libraries generation for each sample.
Project description:Background and Aims: It is known that inflammatory processes are activated in heart failure, but the regulation of cytokines and their role in the pathogenesis of the disease are not well understood. To address this issue, we have performed microarray analysis of non-infarcted left ventricular tissue from mice at various time-points after myocardial infarction. Methods: Molecular alterations in myocardial tissue were measured 3, 5, 7 and 14 days after induced infarction by using cDNA microarrays. Sham operated mice served as controls. Altered gene transcriptions were verified by real-time polymerase chain reaction. Attention focused on genes encoding cytokines which had not previously been assigned a role in heart failure development. Results: The highest number of regulated genes was found at day 5 post myocardial infarction, and 22 genes encoding cytokines were identified as being regulated. Several of the identified genes encoding cytokines have not previously been associated with HF, and among those fractalkine showed strongest up-regulation. Keywords: Disease state analysis, time course