A Method to Quantify Tensile Biaxial Properties of Mouse Aortic Valve Leaflets

Abstract

Understanding aortic valve (AV) mechanics is crucial in elucidating both the mechanisms that drive the manifestation of valvular diseases as well as the development of treatment modalities that target these processes. Genetically modified mouse models have provided mechanistic insight into AV development and disease. However, very little is known about mouse aortic valve leaflet (MAVL) tensile properties due to their microscopic size (~500µm long and 45µm thick) and the lack of proper mechanical testing modalities to assess uniaxial and biaxial tensile properties of the tissue. We developed a method in which the biaxial tensile properties of MAVL tissues can be assessed by adhering the tissues to a silicone rubber membrane utilizing dopamine as an adhesive. Applying equiaxial tensile loads on the tissue-membrane composite and tracking the engineering strains on the surface of the tissue resulted in the characteristic orthotropic response of AV tissues seen in human and porcine tissues. Our data suggests that the circumferential direction is approximately 155 kPa stiffer than the radial direction (n=6, P=0.0006) in MAVL tissues. This method can be implemented in future studies involving longitudinal mechanical stimulation of genetically modified MAVL tissues bridging the gap between cellular and biomolecular mechanisms and valve mechanics in popular mouse models of valve disease.

S2 Heart Sound Detects Aortic Valve Calcification Independent of Hemodynamic Changes in Mice

“…The difference in tensile properties of human and mouse AoV tissues, both healthy and diseased, remains unknown due to the small, microscopic size of mouse AoV leaflets. Recently, we developed a method to quantify equiaxial properties of mouse AoV leaflets ( 60 ), which could lead to a better understanding of the similarities between the mechanical properties of both species and how they influence sound production.…”

Pigmentation Affects Elastic Fiber Patterning and Biomechanical Behavior of the Murine Aortic Valve

“…Despite challenges with assessing small regions of interest for micromechanical testing, this is the first study to compare localized stiffness with corresponding ECM fiber patterning in freshly isolated wholemount murine AoV. Although we previously reported that unequal levels of pigmentation may occur amongst the left, right and coronary leaflets of the AoV (25), in this study all WT and K5-Edn3 leaflets that were used for biomechanical analyses were pigmented and we did not tract their anatomical position within the valve. We recognize this may have introduced some biases in the results and suggest that future studies take into consideration leaflet position to account for potential ontogenetic and histological differences among the three leaflets.…”