Myofibroblasts in reperfused myocardial infarcts express the embryonic form of smooth muscle myosin heavy chain (SMemb)

Nikolaos G. Frangogiannis, Lloyd H. Michael, Mark L. Entman

Research output: Contribution to journalArticle

135 Citations (Scopus)

Abstract

Objective: The purpose of this study is to examine the cellular content of healing myocardial infarcts and study the phenotypic characteristics of fibroblasts during scar formation utilizing a canine model of coronary occlusion and reperfusion. Methods: Ischemia/Reperfusion experiments were performed in dogs undergoing 1 h of coronary occlusion followed by reperfusion intervals ranging from 5 h to 28 days. Fibrotic and control areas were studied using immunohistochemistry. Results: The healing ischemic and reperfused myocardium demonstrated significant proliferative activity peaking after 3 to 7 days of reperfusion, predominantly in myofibroblasts. The numbers of proliferating cells decreased during the maturation phase of the scar (PCNA index: 13.7 ± 2.25% at 5 days vs. 4.8 ± 1.1% at 28 days; P < 0.05, n = 5). During the proliferative phase of healing (3-7 days) α-smooth muscle actin (α-SMAc) expression was markedly increased in the fibrotic areas. α-SMAc predominantly localized in myofibroblasts which were vimentin positive, smooth muscle myosin, calponin and desmin negative. We examined expression of smooth muscle myosin heavy chain isoforms in myofibroblasts infiltrating the healing areas and found a marked induction of the embryonal isoform of myosin heavy chain (SMemb) in α-SMAc positive spindle shaped cells in the border of the scar. Myofibroblasts did not express SM2, a marker for mature smooth muscle cells. In contrast myocardial arterioles were positive for SM2, but did not express SMemb. Conclusions: Healing myocardial infarcts undergo rapid changes in their content of myofibroblasts. During the proliferative phase fibroblasts undergo phenotypic changes leading to expression of contractile proteins such as α-SMAc, and production of SMemb, a marker for dedifferentiated smooth muscle cells. Expression of embryonic isoforms indicates dedifferentiation and allows the myofibroblast pool to serve as a versatile cell population, assuming different phenotypes depending on the physiological needs. (C) 2000 Elsevier Science B.V.

Original languageEnglish (US)
Pages (from-to)89-100
Number of pages12
JournalCardiovascular Research
Volume48
Issue number1
DOIs
StatePublished - Oct 2000
Externally publishedYes

Fingerprint

Smooth Muscle Myosins
Myofibroblasts
Myosin Heavy Chains
Myocardial Infarction
Reperfusion
Cicatrix
Protein Isoforms
Coronary Occlusion
Smooth Muscle Myocytes
Fibroblasts
Contractile Proteins
Myocardial Reperfusion
Desmin
Proliferating Cell Nuclear Antigen
Arterioles
Vimentin
Muscle Cells
Smooth Muscle
Canidae
Actins

Keywords

  • Fibrosis
  • Histo(patho)logy
  • Infarction
  • Reperfusion
  • Smooth muscle

ASJC Scopus subject areas

  • Cardiology and Cardiovascular Medicine

Cite this

Myofibroblasts in reperfused myocardial infarcts express the embryonic form of smooth muscle myosin heavy chain (SMemb). / Frangogiannis, Nikolaos G.; Michael, Lloyd H.; Entman, Mark L.

In: Cardiovascular Research, Vol. 48, No. 1, 10.2000, p. 89-100.

Research output: Contribution to journalArticle

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abstract = "Objective: The purpose of this study is to examine the cellular content of healing myocardial infarcts and study the phenotypic characteristics of fibroblasts during scar formation utilizing a canine model of coronary occlusion and reperfusion. Methods: Ischemia/Reperfusion experiments were performed in dogs undergoing 1 h of coronary occlusion followed by reperfusion intervals ranging from 5 h to 28 days. Fibrotic and control areas were studied using immunohistochemistry. Results: The healing ischemic and reperfused myocardium demonstrated significant proliferative activity peaking after 3 to 7 days of reperfusion, predominantly in myofibroblasts. The numbers of proliferating cells decreased during the maturation phase of the scar (PCNA index: 13.7 ± 2.25{\%} at 5 days vs. 4.8 ± 1.1{\%} at 28 days; P < 0.05, n = 5). During the proliferative phase of healing (3-7 days) α-smooth muscle actin (α-SMAc) expression was markedly increased in the fibrotic areas. α-SMAc predominantly localized in myofibroblasts which were vimentin positive, smooth muscle myosin, calponin and desmin negative. We examined expression of smooth muscle myosin heavy chain isoforms in myofibroblasts infiltrating the healing areas and found a marked induction of the embryonal isoform of myosin heavy chain (SMemb) in α-SMAc positive spindle shaped cells in the border of the scar. Myofibroblasts did not express SM2, a marker for mature smooth muscle cells. In contrast myocardial arterioles were positive for SM2, but did not express SMemb. Conclusions: Healing myocardial infarcts undergo rapid changes in their content of myofibroblasts. During the proliferative phase fibroblasts undergo phenotypic changes leading to expression of contractile proteins such as α-SMAc, and production of SMemb, a marker for dedifferentiated smooth muscle cells. Expression of embryonic isoforms indicates dedifferentiation and allows the myofibroblast pool to serve as a versatile cell population, assuming different phenotypes depending on the physiological needs. (C) 2000 Elsevier Science B.V.",
keywords = "Fibrosis, Histo(patho)logy, Infarction, Reperfusion, Smooth muscle",
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T1 - Myofibroblasts in reperfused myocardial infarcts express the embryonic form of smooth muscle myosin heavy chain (SMemb)

AU - Frangogiannis, Nikolaos G.

AU - Michael, Lloyd H.

AU - Entman, Mark L.

PY - 2000/10

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N2 - Objective: The purpose of this study is to examine the cellular content of healing myocardial infarcts and study the phenotypic characteristics of fibroblasts during scar formation utilizing a canine model of coronary occlusion and reperfusion. Methods: Ischemia/Reperfusion experiments were performed in dogs undergoing 1 h of coronary occlusion followed by reperfusion intervals ranging from 5 h to 28 days. Fibrotic and control areas were studied using immunohistochemistry. Results: The healing ischemic and reperfused myocardium demonstrated significant proliferative activity peaking after 3 to 7 days of reperfusion, predominantly in myofibroblasts. The numbers of proliferating cells decreased during the maturation phase of the scar (PCNA index: 13.7 ± 2.25% at 5 days vs. 4.8 ± 1.1% at 28 days; P < 0.05, n = 5). During the proliferative phase of healing (3-7 days) α-smooth muscle actin (α-SMAc) expression was markedly increased in the fibrotic areas. α-SMAc predominantly localized in myofibroblasts which were vimentin positive, smooth muscle myosin, calponin and desmin negative. We examined expression of smooth muscle myosin heavy chain isoforms in myofibroblasts infiltrating the healing areas and found a marked induction of the embryonal isoform of myosin heavy chain (SMemb) in α-SMAc positive spindle shaped cells in the border of the scar. Myofibroblasts did not express SM2, a marker for mature smooth muscle cells. In contrast myocardial arterioles were positive for SM2, but did not express SMemb. Conclusions: Healing myocardial infarcts undergo rapid changes in their content of myofibroblasts. During the proliferative phase fibroblasts undergo phenotypic changes leading to expression of contractile proteins such as α-SMAc, and production of SMemb, a marker for dedifferentiated smooth muscle cells. Expression of embryonic isoforms indicates dedifferentiation and allows the myofibroblast pool to serve as a versatile cell population, assuming different phenotypes depending on the physiological needs. (C) 2000 Elsevier Science B.V.

AB - Objective: The purpose of this study is to examine the cellular content of healing myocardial infarcts and study the phenotypic characteristics of fibroblasts during scar formation utilizing a canine model of coronary occlusion and reperfusion. Methods: Ischemia/Reperfusion experiments were performed in dogs undergoing 1 h of coronary occlusion followed by reperfusion intervals ranging from 5 h to 28 days. Fibrotic and control areas were studied using immunohistochemistry. Results: The healing ischemic and reperfused myocardium demonstrated significant proliferative activity peaking after 3 to 7 days of reperfusion, predominantly in myofibroblasts. The numbers of proliferating cells decreased during the maturation phase of the scar (PCNA index: 13.7 ± 2.25% at 5 days vs. 4.8 ± 1.1% at 28 days; P < 0.05, n = 5). During the proliferative phase of healing (3-7 days) α-smooth muscle actin (α-SMAc) expression was markedly increased in the fibrotic areas. α-SMAc predominantly localized in myofibroblasts which were vimentin positive, smooth muscle myosin, calponin and desmin negative. We examined expression of smooth muscle myosin heavy chain isoforms in myofibroblasts infiltrating the healing areas and found a marked induction of the embryonal isoform of myosin heavy chain (SMemb) in α-SMAc positive spindle shaped cells in the border of the scar. Myofibroblasts did not express SM2, a marker for mature smooth muscle cells. In contrast myocardial arterioles were positive for SM2, but did not express SMemb. Conclusions: Healing myocardial infarcts undergo rapid changes in their content of myofibroblasts. During the proliferative phase fibroblasts undergo phenotypic changes leading to expression of contractile proteins such as α-SMAc, and production of SMemb, a marker for dedifferentiated smooth muscle cells. Expression of embryonic isoforms indicates dedifferentiation and allows the myofibroblast pool to serve as a versatile cell population, assuming different phenotypes depending on the physiological needs. (C) 2000 Elsevier Science B.V.

KW - Fibrosis

KW - Histo(patho)logy

KW - Infarction

KW - Reperfusion

KW - Smooth muscle

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