Aortic Strain Correlates with Elastin Fragmentation in Fibrillin-1 Hypomorphic Mice.

BACKGROUND

High frequency ultrasound has facilitated in vivo measurements of murine ascending aortas, allowing aortic strains to be gleaned from two-dimensional images. Thoracic aortic aneurysms associated with mutations in fibrillin-1 () display elastin fragmentation, which may impact aortic strain. In this study, we determined the relationship between elastin fragmentation and aortic circumferential strain in wild type and fibrillin-1 hypomorphic ( ) mice.

METHODS AND RESULTS

Luminal diameters of the ascending aorta from wild type and FBN1 hypomorphic ( ) mice were measured in systole and diastole. Expansion of the ascending aorta during systole in male and female wild type mice was 0.21±0.02 mm (16.3%) and 0.21±0.01 mm (17.0%) respectively, while expansion in male and female mice was 0.11±0.04 mm (4.9%) and 0.07±0.02 mm (4.5%) respectively. Reduced circumferential strain was observed in mice compared to wild type littermates. Elastin fragmentation was inversely correlated to circumferential strain (R^2 = 0.628 p = 0.004) and significantly correlated with aortic diameter. (R^2 = 0.397, p = 0.038 in systole and R^2 = 0.515, p =0.013 in diastole).

CONCLUSIONS

mice had increased aortic diameters, reduced circumferential strain, and increased elastin fragmentation. Elastin fragmentation in and their wild type littermates was correlated with reduced circumferential strain.