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RNA-seq analysis of young swine following cardiac ischemia/reperfusion injury.

ABSTRACT: This study was a part of a larger study assessing the response of young pigs to cardiac ischemia/reperfusion (IR) injury. A mild cardiac injury approach (IR) was used in post-weaned pigs (1-month), to assess regenerative repair in young large mammals after transient ischemic injury. Female and male postnatal day (P)30 pigs were subjected to cardiac ischemia (1-hour) by occlusion of the left anterior descending artery followed by reperfusion (IR), or to sham operation. In pigs subjected to IR, myocardial damage occurred, indicated by increased circulating cardiac troponin I 2-hours post-ischemia. In addition, cardiac ejection fraction (EF) was significantly decreased 2-hours post-ischemia and reduced EF was maintained to the 4-week study end-point. Histology demonstrated evidence of CM cell cycling at 2-months of age in multinucleated CMs in both sham-operated and IR pigs. Following IR, regional scar formation and inflammation in the epicardial region proximal to injury were observed 4-weeks post-IR. Sex differences in cardiac function and collagen deposition were found, highlighting the importance of representing both sexes in cardiac injury studies. Together, our results describe an effective novel cardiac injury model in 1-month old swine, at a time when CM are still cycling. However, pigs subjected to IR show a prolonged decrease in cardiac function, and the formation of a small, regional scar with increased inflammation. Together, these data demonstrate that 1-month old pigs do not regenerate myocardium, but form a scar, after transient IR injury.

ORGANISM(S): Sus scrofa

PROVIDER: GSE137293 | GEO | 2020/04/27

REPOSITORIES: GEO

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Project description:Background The axon guidance cue Slit2 recently has been found to regulate calcium homeostasis and molecular signaling in various stress events in different organs. However, whether Slit2 plays a role in cardiac ischemia-reperfusion (IR) injury has not been reported. Here, we aimed to investigate the role of Slit2 and the underlying mechanisms in cardiac IR injury. Methods Langendorff-perfused isolated hearts from Slit2-overexpressing (Slit2-Tg) mice and their background strain C57BL/6J mice were subjected to 20 min of global ischemia followed by 40 min of reperfusion. Left ventricular function of isolated hearts was monitored. Infarct size of post-IR hearts was determined by staining with 2,3,5-triphenyltetrazolium chloride (TTC) and histological changes of cardiac tissues and cells were determined with hematoxylin-eosin (HE) staining and transmission electron microscopy. Transcriptomic analysis was used to predict the biological processes and signaling pathways affected by Slit2 overexpression in the post-IR myocardium. Pro-Q staining and Western blotting was used to assess the phosphorylation levels of cardiac myofilaments and expression levels of myofilament-associated protein kinase and phosphatases. Results Slit2 overexpression increased post-IR left ventricular developed pressure (LVDP) by 35% and reduced infarct size by 53%, along with decreased myofibrillar disruption, mitochondrial swelling, and mitochondrial cristae dissolution. Slit2 overexpression significantly changed post-IR gene expression profiles. Functional products of these genes include regulation of cation transmembrane transport, cation homeostasis, collagen fibril organization, and regulation of heart rate. And post-IR myocardial KEGG pathways upregulated by Slit2 overexpression include ECM-receptor interaction, PI3K-Akt signaling pathway, and adrenergic signaling. Slit2 overexpression impacted myofilament phosphorylation together with myofilament-associated protein kinase C (PKC) isoforms and protein phosphatases (PPs). IR in C57BL/6J hearts upregulated phosphorylation of cardiac troponin-I (cTnI), which was suppressed by Slit2 overexpression. Myofilament‐associated PKCε, PKCδ, and PP2A were significantly increased post‐IR in C57BL/6J hearts, but in Slit2‐Tg hearts, myofilament‐associated PKCε and PP2A were increased and PKCδ was suppressed. Conclusions Our results demonstrate that Slit2 overexpression protects cardiac function and reduces IR injury, which is associated with Slit2‐induced gene profile shifts. The suppression of MyBP‐C and troponin‐I phosphorylation, and myofilament‐associated PKCδ levels induced by Slit2 overexpression could contribute to the cardioprotection of Slit2 in post-IR myocardium.