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[Myofibroblasts in a myocardial infarct zone]
Abstract:
Electron microscopy and immunomorphological studies were made to explore the scar 2, 3, 4, 5, 7, 9, 11, 30, 45, 60 and 120 days after myocardial infarction in white rats. After 3-5 days there was a poor response to smooth muscle myosin in some of elongate cells of the postinfarction scar. The response was found to be remarkably enhanced after 11 days. Myofibroblasts with an ultrastructure characteristic of activated fibroblasts were found in the scar by using electron microscopy after 3-5 days of the experiment. They also exhibited some properties typical of the smooth cell ultrastructure, containing myofilament bundles with dense bodies along the cytoplasm periphery, as well as the fragments of the basal membrance. In the later periods of the experiment, myofibroblasts were more closely related to smooth muscle cells in ultrastructure. The origin and function of myofibroblasts in the postinfarction scar are discussed.
Insights
Myofibroblasts in rat heart scars after myocardial infarction show developing smooth muscle cell characteristics. Their function and origin in the post-infarction scar tissue are key research areas.
Area of Science:
- Cardiovascular Biology
- Cellular Ultrastructure
- Tissue Repair Mechanisms
Context:
- Myocardial infarction leads to scar formation in the heart.
- Understanding the cellular components of cardiac scars is crucial for therapeutic development.
- Myofibroblasts are key cells in wound healing and scar remodeling.
Purpose:
- To investigate the ultrastructural changes and differentiation of myofibroblasts in post-infarction cardiac scars.
- To determine the temporal relationship between myofibroblast development and smooth muscle cell markers.
- To elucidate the origin and functional role of myofibroblasts in cardiac scar tissue.
Summary:
- Electron microscopy and immunomorphology revealed myofibroblasts in rat cardiac scars 3-5 days post-myocardial infarction.
- These myofibroblasts exhibited features of activated fibroblasts and smooth muscle cells, including myofilament bundles and basal membrane fragments.
- A significant increase in smooth muscle myosin response was observed in scar cells by day 11, indicating myofibroblast maturation.
Impact:
- Provides insights into the cellular dynamics of cardiac scar formation and remodeling.
- Highlights the potential of myofibroblasts as therapeutic targets for improving heart function after infarction.
- Contributes to the understanding of cell differentiation and plasticity in response to injury.