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Preservation of Functional Microvascular Bed Is Vital for Long-Term Survival of Cardiac Myocytes Within Large Transmural Post-Myocardial Infarction Scar.

Authors
  • Nofi, Colleen1
  • Bogatyryov, Yevgen1
  • Dedkov, Eduard I2
  • 1 Department of Biomedical Sciences, College of Osteopathic Medicine, New York Institute of Technology, Old Westbury, New York.
  • 2 Department of Biomedical Sciences, Cooper Medical School of Rowan University, Camden, New Jersey. , (Jersey)
Type
Published Article
Journal
Journal of Histochemistry & Cytochemistry
Publisher
SAGE Publications
Publication Date
Feb 01, 2018
Volume
66
Issue
2
Pages
99–120
Identifiers
DOI: 10.1369/0022155417741640
PMID: 29116876
Source
Medline
Keywords
License
Unknown

Abstract

This study was aimed to understand the mechanism of persistent cardiac myocyte (CM) survival in myocardial infarction (MI) scars. A transmural MI was induced in 12-month-old Sprague-Dawley rats by permanent coronary artery ligation. The hearts were collected 3 days, 1, 2, 4, 8, and 12 weeks after MI and evaluated with histology, immunohistochemistry, and quantitative morphometry. Vasculature patency was assessed in 4-, 8-, and 12-week-old scars by infusion of 15-micron microspheres into the left ventricle before euthanasia. The infarcted/scarred area has a small continually retained population of surviving CMs in subendocardial and subepicardial regions. Surprisingly, whereas the transverse area of subepicardial CMs remained relatively preserved or even enlarged over 12 post-MI weeks, subendocardial CMs underwent progressive atrophy. Nevertheless, the fractional volume of viable CMs remained comparable in mature scars 4, 8, and 12 weeks after MI (3.6 ± 0.4%, 3.4 ± 0.5%, and 2.5 ± 0.3%, respectively). Despite the opposite dynamics of changes in size, CMs of both regions displayed sarcomeres and gap junctions. Most importantly, surviving CMs were always accompanied by patent microvessels linked to a venous network composed of Thebesian veins, intramural sinusoids, and subepicardial veins. Our findings reveal that long-term survival of CMs in transmural post-MI scars is sustained by a local microcirculatory bed.

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