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[Interactions between cardiomyocytes and extracellular matrix in the failing human heart]
Insights
Dilated cardiomyopathy causes significant changes in heart muscle cells (myocytes) and the surrounding extracellular matrix. These alterations create a harmful cycle, worsening heart function and leading to failure.
Area of Science:
- Cardiovascular Biology
- Cellular Pathology
- Biochemistry
Context:
- Dilated cardiomyopathy (DCM) is a leading cause of heart failure.
- Morphological changes in the myocardium are key indicators of disease progression.
- Understanding these changes is crucial for developing targeted therapies.
Purpose:
- To detail the specific morphological alterations in myocytes and the extracellular matrix during DCM.
- To investigate the potential interaction between myocytes and the extracellular matrix in disease pathogenesis.
- To hypothesize a mechanism driving myocardial deterioration in DCM.
Summary:
- Human myocardium in dilated cardiomyopathy exhibits myocyte hypertrophy/atrophy, degenerative changes (nuclear abnormalities, cytoskeletal disorganization), and extracellular matrix expansion (fibrosis).
- The enlarged extracellular space contains increased matrix proteins (fibronectin, laminin, collagens), cellular debris, macrophages, and fibroblasts.
- A proposed hypothesis suggests cellular debris stimulates extracellular matrix cells, leading to myocyte damage and a detrimental cycle of myocardial deterioration.
Impact:
- Provides a detailed morphological basis for understanding DCM.
- Highlights the potential role of myocyte-extracellular matrix interactions in disease progression.
- Offers insights into the vicious cycle contributing to heart failure in DCM.
Abstract:
Numerous morphological changes can be observed in human myocardium failing because of dilated cardiomyopathy. These can be observed by electron microscopy and by immunofluorescence microscopy using monoclonal antibodies. These changes include: 1) the occurrence of hypertrophied and atrophied myocytes as well as cells of normal size, 2) degenerative changes in myocytes; these consist of nuclei of varying size and shape, lack of contractile material, disorganization of the cytoskeleton, and sequestration of cellular particles into the extracellular space and 3) an enlarged extracellular space, that is, fibrosis, which contains increased amounts of the different matrix proteins such as fibronectin and laminin, the various collagens, and chondroitin sulfate, in addition to cellular debris and numerous macrophages and fibroblasts. On the basis of these findings it is hypothetized that there exists an interaction between myocytes and the extracellular matrix. The cells of the latter may be stimulated to higher rates of proteins synthesis by the presence of cellular debris. This process, in turn, may be harmful for the structural integrity of myocytes which consequently sequester more cellular particles. In this manner, a vicious circle may be started that leads to further structural and functional deterioration of the myocardium, finally resulting in failure.