Localised micro-mechanical stiffening in the ageing aorta

Area of Science:

• Biomedical Engineering
• Cardiovascular Research
• Tissue Mechanics

Background:

• Age-related loss of tissue elasticity contributes to human morbidity.
• Arteriosclerosis, or vascular stiffening, is linked to stroke and heart failure.
• Micro-mechanical testing is crucial for understanding arteriosclerosis causes.

Purpose of the Study:

• Quantify age-related changes in macro-mechanical stiffness of sheep aorta.
• Map micro-scale changes in acoustic wave speed (tissue stiffness).
• Characterize collagen and elastic fiber remodeling with age.

Main Methods:

• Utilized a sheep aorta aging model (young vs. old).
• Performed macro-mechanical stiffness testing.
• Employed high-frequency scanning acoustic microscopy for in situ micro-mechanical and micro-structural analysis.

Main Results:

• Increased macro-mechanical stiffness and mean microscopic wave speed with age.
• Age-related stiffness increases localized to collagen-rich regions between elastic lamellae.
• Significant increases in collagen and elastic fiber content observed in older aortas.

Conclusions:

• Localized collagen fibrosis plays a key role in age-related arteriosclerosis.
• High-frequency scanning acoustic microscopy effectively co-localizes micro-mechanical and micro-structural changes.
• Findings provide insights into the mechanisms of vascular aging and stiffening.