5.3 Age-Related Changes in the Micromechanical Properties of Ovine Aorta

• Published in: Artery research Vol. 3; no. 4; p. 155
• Main Authors: Akhtar, R., Kridiotis, C., Graham, H. K., Sherratt, M. J., Trafford, A. W., Cruickshank, J. K., Derby, B.
• Format: Journal Article
• Language: English
• Published: Dordrecht Springer Netherlands 01-12-2009; Springer Nature B.V; BMC
• Subjects: Collagen; Coronary vessels; Mechanical properties; Microscopy; Oral Presentation Abstracts; Sheep
• ISSN: 1872-9312; 1876-4401; 1876-4401
• DOI: 10.1016/j.artres.2009.10.161

Scanning Acoustic Microscopy (SAM) images have a spatial resolution at 1 GHz comparable to conventional optical microscopy. Each pixel in the image can be analysed to determine mechanical properties, allowing their precise correlation with microstructural components of tissue. Although loss of elasticity is a common feature of most ageing tissues, their micromechanical properties remain to be determined. In this study, mechanical properties of aortic tissue sections were measured for young (18 months old) and aged (
≥
8 years) sheep using quantitative analysis on SAM images. Acoustic wave speed (AWS), which is related to tissue stiffness, was determined using SAM at ultra-high frequencies (960 MHz to 1.1 GHz). Collagen and elastin content were determined using polarised light microscopy on picrosirius red stained sections (collagen) and fluorescence microscopy on H&E stained sections (elastin).
SAM revealed increased AWS of approximately 20 ms
−1
in the old sheep aorta compared to young sheep aorta. Histological assessment revealed an increase in both collagen content (44.9%
±
5.0 vs. 31.0 %
±
2.6) and elastin content (63.8 % ± 4.0 vs. 51.8%
±
3.6) in the old aorta vs the young (P<0.05, n
=
6). Increased elastin content was coupled with a lack of organisation with fenestrations visible in the aged aorta. These data show that age-related disturbances in the collagen and elastin architecture of elastic arteries impact upon their micromechanical properties and hence contribute to arterial stiffening.