Age-related changes in the elastic tissue of the human aorta
Background: Age-related arterial alterations affecting cells, matrix and biomolecules are the main culprit for initiation and progression of cardiovascular disease. The objective of this study is to gain further insights into the complex mechanism of elastic tissue ageing in human aortic blood vessels. Methods: One hundred and nineteen human aortic tissue samples were collected from adult patients (101 males, 18 females; age 40-86 years) undergoing coronary artery bypass grafting. Overall extracellular matrix architecture was examined by multiphoton laser scanning microscopy and histology. Matrix metalloproteinases 2 and 9, corresponding tissue inhibitors 1 and 2 as well as desmosine were determined. mRNA levels of tropoelastin were assessed by quantitative RT-PCR. Results: Age-related destruction of the vascular elastic laminas as well as a loss of interlamina cross-links were observed by laser scanning microscopy. These results were confirmed by histology indicating increasing interlamma gaps. There were no significant differences in matrix turnover or desmosine content. A steady decrease in tropoelastin mRNA by about 50% per 10 years of age increase was observed. Conclusions: Our findings indicate that ageing is accompanied by a destruction of the elastic vascular structure. However, tropoelastin expression analysis suggests that elastogenesis occurs throughout life with constantly decreasing levels.