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Mechanobiology of Disease
Poster Abstracts
45
4-POS
Board 4
Investigation of the Microstructural Organization and Mechanical Properties of Human
Abdominal Aortic Aneurysms
Anju R. Babu
1
, Tina U. Cohnert
2
, Gerhard A. Holzapfel
1,3
.
1
Graz University of Technology, Graz, Styria, Austria,
2
Medical University of Graz, Graz,
Styria, Austria,
3
NTNU, Trondheim, Norway.
Elastin and collagen are the major structural components determining the passive mechanical
properties of aortic walls. Aging and different pathological conditions are linked to active
remodeling of aortic wall constituents and alteration in mechanical properties. Abdominal aortic
aneurysm (AAA) is a local dilation of the aorta associated with changes in arterial wall
constituents and properties. Aortic rupture, the main complication of AAA, is a life-threatening
emergency situation.
The main goal of this study is to determine the mechanical properties of AAA and understand
alteration in aortic wall microstructural contents and morphology. In this study biaxial
mechanical experiments are performed on AAA tissue obtained from patients (n=10) undergoing
surgical repair at Medical University of Graz, Austria. A combination of optical clearing method
and second-harmonic generation (SHG) imaging is used to investigate the collagen organization.
SHG signals obtained are processed by Fourier transform and fitted to maximum likelihood
estimation distribution function to understand the dispersion of collagen fibers. Alteration in
elastin content in the AAA tissue wall is analyzed by immuno-histochemical staining. The
material response and structural organization AAA tissues obtained are compared with healthy
abdominal aortas (AA).
Biaxial experimental results show a nonlinear mechanical response for AA tissues with a well-
organized elastin and collagen architecture. Compared to healthy tissue, AAAs show a stiffer
response with alteration in collagen fiber morphology and organization. Aneurysms are
associated with degradation of elastin and correspond to a decrease in elastin content, as
confirmed from histological analysis. Results from this study show a relationship between the
change in the mechanical properties of AAAs and the remodeling of arterial wall constituents.
Future work aims at determining the alteration in collagen and elastin crosslinks in abdominal
aortic aneurysms.