Augmented Flow-Induced Outward Remodelling Occurs with Ageing in Mice

Area of Science:

• Vascular biology and aging research
• Cardiovascular pathology and disease mechanisms
• Arterial remodeling processes

Background:

• Arterial outward remodeling is implicated in cardiovascular diseases such as atherosclerosis and aneurysm.
• Aging is a significant risk factor for atherosclerosis and aneurysmal disease.
• Understanding age-related arterial remodeling is crucial for developing effective therapies.

Purpose of the Study:

• To investigate the impact of aging on carotid artery remodeling in response to increased blood flow.
• To compare the extent and characteristics of arterial remodeling between young and old mice.

Main Methods:

• Comparison of right carotid artery remodeling in young (2 months) and old (18-20 months) mice after left carotid artery ligation.
• Analysis of media area, thickness, collagen content, and α-SM-actin content per cell.
• Assessment of matrix metalloproteinase-2 (MMP-2) protein levels.

Main Results:

• Older mice exhibited greater baseline media area, thickness, and collagen content in carotid arteries compared to younger mice.
• Augmented positive arterial remodeling was observed in old mice, characterized by a larger increase in lumen size and reduction in media area and thickness.
• While young mice showed increased MMP-2 during remodeling, old mice did not, suggesting altered matrix degradation pathways.

Conclusions:

• The extent of positive carotid artery remodeling is significantly greater in aged mice compared to young mice.
• Aging leads to a less resilient medial layer with reduced α-SM-actin content per cell, elastin, and collagen, potentially predisposing to atherosclerosis and aneurysm.
• Age-related changes in arterial remodeling pathways, including MMP-2 activity, may contribute to the increased risk of cardiovascular pathologies in older individuals.