A Brief Note On Myocardial Infarction Of The United States

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Specific aims: Myocardial infarction is one of the leading causes of death in the United States. Inflammation plays an important role in ventricular remodeling after myocardial infarction. Inflammatory cells are responsible for removing necrosis myocardial cells and repairing the damaged tissue. The remodeling process requires a well-balanced interplay between pro-inflammatory and anti-inflammatory pathways. Simply targeting for either process had lead to poor clinical results. (van Amerongen et al., 2007; Kaikita et al.,2004; Seropian et al.,2014) Therefore, a better understanding of the function of main player-macrophages in both pathways, will lead to potential therapies. Recently, studies have shown that tissue resident macrophages…show more content…
The neonatal heart responses to injury by expanding yolk sac derived resident macrophages (CCR2-MHC-IIhi and lo), while the adult heart by recruiting CCR2+ monocyte derived macrophages. It is also known that the CCR2- macrophages are reparative but the CCR2+ macrophages are harmful after cardiac injury (Lavine et al., 2014). Additionally, people have found that mice embryo experience three waves of hematopoiesis, primitive(E7), transient definitive stage(E8.25), and definitive(E10.5). During the primitive hematopoiesis, hematopoietic progenitors appear in the extra-embryonic yolk sac(YS) and produce macrophages. From E8.25, multi-lineage erythro-myeloid progenitors (EMPs) and lympho-myeloid progenitors (LMPs) emerge in the YS. EMP can enter the circulation to colonize the fetal live. After E8.5, pre-HSC are generated and colonize the FL at around E10.5, which is the definitive stage and give rise to bone marrow (Hoeffel et al., 2015). Different macrophage precursors are produced in these three waves. To summarize, macrophages’ embryonic precursors include yolk sac macrophages(YS-Macs) at E8.5-9.0, fetal liver monocytes(FL-MOs) from E12.5, and HSC in the bone marrow from E17.5. Fetal monocytes differentiate to
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