Age related changes of the collagen network of the human heart
Introduction
The interstitial collagen matrix is an important component of the myocardium, which surrounds and supports cardiac myocytes and the coronary microcirculation (Borg and Caufield, 1981, Robinson et al., 1983). The interstitial collagen also maintains the myocytes alignment, the myocyte–capillary relationship, and the heart architecture throughout the cardiac cycle (Borg and Caufield, 1981). Therefore, the form and distribution of the connective tissue of the heart is such that it may play an important role in the elastic properties and viscous properties of the left ventricle. The major types of collagen present in the interstitium of myocardium are I, III and V, with type I predominating. In non-human primate myocardium, for example, the distribution of collagen types is as follows, 85% type I; 11% type III and 3% type V (Weber et al., 1988). In the myocardium, fibers which surround large bundles of myocytes and individual myocytes appear to be a copolymerization of the I and III collagen molecules (Contard et al., 1991).
Collagen is the only protein in the organism showing definite age changes. A relationship with the general process of aging has, therefore, been assumed. Physicochemical changes in the chemical and thermic contraction have been demonstrated in collagen fibers of different ages (Chvapil and Hruza, 1959, Werzár, 1964). Moreover, biochemical changes in the tissues such as a decrease in the content of extractable collagen (Boucek et al., 1958, Kao and MacGavack, 1959, Koberle and Chvapil, 1962, Wirtschaftler and Bentley, 1962) show a relationship with increasing age, and the total collagen content in certain tissues has been found to increase with age (Sobel and Marmorston, 1956, Clausen, 1963, Gomes et al., 1997, Akamatsu et al., 1999).
In order to understand the changes in the human myocardial tissue in disease, a knowledge of their detailed structure in the normal state is required. However, there have been few studies on the aging of collagen in the human heart. The aim of the present investigation was to determine the types of collagen, to measure the collagen content and the collagen fibril diameters of the left ventricle of the human heart and to observe any differences between young and aged.
Section snippets
Materials and methods
Twelve human hearts obtained at necropsy from male individuals aged 20–25 (young group, n=6) and 67–87 (aged group, n=6) with no earlier pathologies were used. From the esternocostal region of the left ventricle, a segment of 2 cm2 was obtained.
Young group
Collagen fibers of the myocardium formed an intricate and highly structured network. In the hearts of the young group, in sections stained with Picrossirius and observed with polarization microscopy, the perimysium presents thick, yellow or red, strongly birefringent collagen fibers, characteristic of collagen type I and also thin, pale fibers of greenish color, typical of collagen type III (Fig. 1A). The endomysium, which lies between cardiac myocites, presented the same composition, but with
Discussion
In our study, we demonstrated that polarized light facilitates quantitative image analysis of collagen. When examined in bright field, collagen appears red and muscle yellow after Picrosirius red staining. This brightfield contrast between collagen and muscle has been used, in conjunction with digital image analysis, to assess myocardial collagen content (Michel et al., 1986). However, it is the combination of Picrosirius red and polarized light microscopy that provides a more powerful method
References (29)
- et al.
Collagen chain mRNAs in isolated heart cells from young and adults rats
J. Mol. Cell. Cardiol.
(1988) - et al.
Transforming growth factor-ß stimulates the expression of fibronectin and collagen and their incorporation into the extracellular matrix
J. Biol. Chem.
(1986) - Akamatsu, F.E., De Souza, R.R., Liberti, E.A., 1999. Fall in the number of intracardiac neurons in aging rats, Mech....
- et al.
The collagen matrix of the heart
Feder. Proc.
(1981) - et al.
Structural basis of ventricular stiffness
Lab. Invest.
(1981) - et al.
The effects of age, sex and race upon the acetic acid fractions of colagen
J. Gerontol.
(1958) Relation of structure to function of the tissues of the wall of blood vessels
Physiol. Rev.
(1954)- et al.
Inducible collagenolytic activity in isolated perfused rat hearts
Am. J. Phatol.
(1988) - et al.
The influence of aging and undernutrition on chemical contractility and relaxation of collagen fibers in rats
Gerontologia (Basel)
(1959) Influence of age on chondroitin sulfates and collagen of human aorta, myocardium and skin
Lab. Invest.
(1963)
Specific alterations in the distribution of extracellular components within rat myocardium during the development of pressure overload
Lab. Invest.
Collagen gene expression and molecular basis of fibrosis in the myocardium
Heart failure
Collagen accumulation in the heart ventricles as a function of growth and aging
Cardiovasc. Res.
Cited by (186)
All the small things: Nanoscale matrix alterations in aging tissues
2024, Current Opinion in Cell BiologyCardiac Fibrosis in heart failure: Focus on non-invasive diagnosis and emerging therapeutic strategies
2023, Molecular Aspects of MedicineGetting physical: Material mechanics is an intrinsic cell cue
2023, Cell Stem CellSenescent cardiac fibroblasts: A key role in cardiac fibrosis
2023, Biochimica et Biophysica Acta - Molecular Basis of DiseaseOn the structural origin of the anisotropy in the myocardium: Multiscale modeling and analysis
2023, Journal of the Mechanical Behavior of Biomedical Materials