Side-specific mechanical properties of valve endothelial cells

Area of Science:

• Cardiovascular Biology
• Biophysics
• Cell Biology

Background:

• Aortic valve endothelial cells (ECs) experience diverse shear stress levels.
• The biomechanical differences between ECs on the aortic and ventricular sides of the valve are not well understood.

Purpose of the Study:

• To investigate the morphology and mechanical properties of native and cultured aortic valve ECs.
• To examine the autocrine effects of endothelial-derived mediators on EC compliance and actin expression.

Main Methods:

• Scanning ion conductance microscopy (SICM) was used to assess EC morphology and membrane compliance on intact porcine aortic valve cusps.
• Immunofluorescent staining was employed to analyze actin filament density.
• The influence of nitric oxide (NO) donors, endothelin-1, and nitric oxide synthase inhibitors on EC biomechanics was evaluated.

Main Results:

• Aortic side ECs displayed a more elongated shape and were aligned along a single axis compared to ventricular ECs.
• Aortic side ECs were significantly softer than ventricular ECs, a pattern observed in both native and cultured cells.
• Nitric oxide donor affected ventricular EC compliance, while endothelin-1 influenced aortic EC compliance, indicating side-specific responses.
• Ventricular ECs showed higher actin filament density than aortic ECs.

Conclusions:

• Significant side-specific biomechanical differences exist between aortic and ventricular valve ECs.
• These distinct cellular properties may play a crucial role in overall aortic valve function.
• Endothelial-derived mediators differentially regulate the mechanical properties of ECs based on their valve location.