Project description:Abstract BACKGROUND: Exosome therapy shows potential for cardiac repair after injury. However, intrinsic challenges such as short half-life and lack of clear targets hinder the clinical feasibility. Here, we report a noninvasive and repeatable method for exosome delivery through inhalation after myocardial infarction (MI), which we called stem cell–derived exosome nebulization therapy (SCENT). METHODS: Stem cell–derived exosomes were characterized for size distribution and surface markers. C57BL/6 mice with MI model received exosome inhalation treatment through a nebulizer for 7 consecutive days. Echocardiographies were performed to monitor cardiac function after SCENT, and histological analysis helped with the investigation of myocardial repair. Single-cell RNA sequencing of the whole heart was performed to explore the mechanism of action by SCENT. Last, the feasibility, efficacy, and general safety of SCENT were demonstrated in a swine model of MI, facilitated by 3-dimensional cardiac magnetic resonance imaging. RESULTS: Recruitment of exosomes to the ischemic heart after SCENT was detected by ex vivo IVIS imaging and fluorescence microscopy. In a mouse model of MI, SCENT ameliorated cardiac repair by improving left ventricular function, reducing fibrotic tissue, and promoting cardiomyocyte proliferation. Mechanistic studies using single-cell RNA sequencing of mouse heart after SCENT revealed a downregulation of Cd36 in endothelial cells (ECs). In an EC-Cd36fl/− conditional knockout mouse model, the inhibition of CD36, a fatty acid transporter in ECs, led to a compensatory increase in glucose utilization in the heart and higher ATP generation, which enhanced cardiac contractility. In pigs, cardiac magnetic resonance imaging showed an enhanced ejection fraction (Δ=11.66±5.12%) and fractional shortening (Δ=5.72±2.29%) at day 28 after MI by SCENT treatment compared with controls, along with reduced infarct size and thickened ventricular wall. CONCLUSIONS: In both rodent and swine models, our data proved the feasibility, efficacy, and general safety of SCENT treatment against acute MI injury, laying the groundwork for clinical investigation. Moreover, the EC-Cd36fl/− mouse model provides the first in vivo evidence showing that conditional EC-CD36 knockout can ameliorate cardiac injury. Our study introduces a noninvasive treatment option for heart disease and identifies new potential therapeutic targets.
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: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:Despite a substantial progress in diagnosis and therapy, acute myocardial infarction (MI) is a major cause of mortality in the general population. A novel insight into the pathophysiology of myocardial infarction obtained by studying gene expression should help to discover novel biomarkers of MI and to suggest novel strategies of therapy. The aim of our study was to establish gene expression patterns in leukocytes from acute myocardial infarction patients. ST-segment elevation myocardial infarction alters expression of several groups of genes. On admission, several genes and pathways that could be directly or indirectly linked with lipid/glucose metabolism, platelet function and atherosclerotic plaque stability were affected (signaling of PPAR, IL-10, IL-6). Analysis at discharge highlighted specific immune response (upregulation of immunoglobulins). Highly significant and substantial upregulation of SOCS3 and FAM20 genes expression in the first 4-6 days of myocardial infarction in all patients is the most robust observation of our work Twenty-eight patients with ST-segment elevation myocardial infarction (STEMI) were included. The blood was collected on the 1st day of myocardial infarction, after 4-6 days, and after 6 months. Control group comprised 14 patients with stable coronary artery disease (CAD), without history of myocardial infarction. Gene expression analysis was performed with Affymetrix GeneChipM-BM-. Human Gene 1.0 ST microarrays and GCS3000 TG system.