Wall remodeling after wall shear rate normalization in rat mesenteric arterial collaterals

Area of Science:

• Vascular biology
• Cardiovascular physiology
• Arterial remodeling

Background:

• Elevated arterial wall shear rates can induce endothelial and smooth muscle cell hyperplasia during arterial expansion.
• Previous research indicates hyperplasia occurs, but the long-term remodeling outcomes are not fully understood.

Purpose of the Study:

• To investigate if arterial remodeling induced by elevated wall shear stress results in vessels with normal intimal and medial cell densities.
• To compare overall wall characteristics of remodeled arteries to control arteries.

Main Methods:

• A rat mesenteric model was utilized to study collateral arteries following arterial occlusion.
• Wall shear rates were elevated, and collateral arteries were analyzed 12 weeks post-occlusion.
• In vivo measurements and morphometric evaluations assessed arterial diameter, luminal area, medial area, cell densities, and medial thickness to radius ratio.

Main Results:

• Collateral arteries showed a significant increase in inner diameter (27-75%) and luminal area (79%).
• Medial area increased by 56%, while medial cell density decreased.
• Intimal cell density remained similar to control arteries, and the medial thickness to radius ratio was comparable.

Conclusions:

• Enlarged collateral arteries exhibit many similarities to control arteries in terms of evaluated wall characteristics.
• Cellular regression in the intima and media appears correlated with a decrease in wall shear force towards normal levels.
• Arterial remodeling under elevated shear stress can lead to vessels resembling normal architecture.