MECHANICAL PROPERTIES CHANGE IN THE RAT XENOGRAFT MODEL TREATED BY MESENCHYMAL CELLS CULTURED IN AN HYALURONIC ACID-BASED HYDROGEL

This study investigated the efficiency of a cellular therapy with mesenchymal stem cells (MSCs) cultured in an hyaluronic acid-based hydrogel on growth of abdominal aortic aneurysms (AAA) obtained in the rat xenograft model. The experimental model was devoted to create an AAA at D14 after grafting of a decellularized abdominal aorta obtained from guinea pigs before being transplanted into rats. At D21, geometrical measurements as radius and length of AAA were performed on untreated ([Formula: see text]) and treated ([Formula: see text]) arteries. When compared to different cases, it was shown that the proposed cellular treatment significantly reduced the expansion of radius and length of AAA. Furthermore, to explore the mechanical properties change of the arterial wall, an inverse finite element method was performed where AAA is represented by an elliptical geometry with varying thicknesses. To identify the material parameters, the AAA tissue was assumed to behave isochoric and isotropic undergoing large strains and described by the Yeoh’s strain energy function. Although limitations exist in this study such as the time of the experimental protocol, the isotropic behavior law of the AAA wall and the axisymmetric geometry of the artery, the results revealed that arterial wall stiffness change and the maximum effective stress decreased during expansion of AAA when cellular treatment is applied.

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Histology and Biaxial Mechanical Behavior of Abdominal Aortic Aneurysm Tissue Samples

Journal of Biomechanical Engineering ◽

10.1115/1.4035261 ◽

2017 ◽

Vol 139 (3) ◽

Cited By ~ 9

Author(s):

Francesco Q. Pancheri ◽

Robert A. Peattie ◽

Nithin D. Reddy ◽

Touhid Ahamed ◽

Wenjian Lin ◽

...

Keyword(s):

Mechanical Properties ◽

Mechanical Behavior ◽

Circumferential Stress ◽

Aortic Aneurysms ◽

Smoking History ◽

Tissue Samples ◽

Abdominal Aortic ◽

Wall Stiffness ◽

Risk Of Rupture ◽

Biaxial Tests

Abdominal aortic aneurysms (AAAs) represent permanent, localized dilations of the abdominal aorta that can be life-threatening if progressing to rupture. Evaluation of risk of rupture depends on understanding the mechanical behavior of patient AAA walls. In this project, a series of patient AAA wall tissue samples have been evaluated through a combined anamnestic, mechanical, and histopathologic approach. Mechanical properties of the samples have been characterized using a novel, strain-controlled, planar biaxial testing protocol emulating the in vivo deformation of the aorta. Histologically, the tissue ultrastructure was highly disrupted. All samples showed pronounced mechanical stiffening with stretch and were notably anisotropic, with greater stiffness in the circumferential than the axial direction. However, there were significant intrapatient variations in wall stiffness and stress. In biaxial tests in which the longitudinal stretch was held constant at 1.1 as the circumferential stretch was extended to 1.1, the maximum average circumferential stress was 330 ± 70 kPa, while the maximum average axial stress was 190 ± 30 kPa. A constitutive model considering the wall as anisotropic with two preferred directions fit the measured data well. No statistically significant differences in tissue mechanical properties were found based on patient gender, age, maximum bulge diameter, height, weight, body mass index, or smoking history. Although a larger patient cohort is merited to confirm these conclusions, the project provides new insight into the relationships between patient natural history, histopathology, and mechanical behavior that may be useful in the development of accurate methods for rupture risk evaluation.

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Stability of Membrane Elastodynamics with Applications to Cylindrical Aneurysms

Journal of Applied Mathematics ◽

10.1155/2011/906475 ◽

2011 ◽

Vol 2011 ◽

pp. 1-24 ◽

Cited By ~ 2

Author(s):

A. Samuelson ◽

P. Seshaiyer

Keyword(s):

Mathematical Model ◽

Stability Analysis ◽

Arterial Wall ◽

Abdominal Aortic Aneurysms ◽

Medical Problem ◽

Aortic Aneurysms ◽

Numerical Techniques ◽

Abdominal Aortic ◽

Complex Fluid ◽

Fluid Solid Interaction

The enlargement and rupture of intracranial and abdominal aortic aneurysms constitutes a major medical problem. It has been suggested that enlargement and rupture are due to mechanical instabilities of the associated complex fluid-solid interaction in the lesions. In this paper, we examine a coupled fluid-structure mathematical model for a cylindrical geometry representing an idealized aneurysm using both analytical and numerical techniques. A stability analysis for this subclass of aneurysms is presented. It is shown that this subclass of aneurysms is dynamically stable both with and without a viscoelastic contribution to the arterial wall.

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Functional Endoluminal Paving (FELP): Thermoforming, Biodegradation, and Mechanical Properties of a Novel Polymer Graft for Abdominal Aortic Aneurysms

ASME 2010 Summer Bioengineering Conference, Parts A and B ◽

10.1115/sbc2010-19463 ◽

2010 ◽

Cited By ~ 1

Author(s):

John H. Ashton ◽

James A. M. Mertz ◽

Megan J. Alexander ◽

Marvin J. Slepian ◽

Joseph L. Mills ◽

...

Keyword(s):

Mechanical Properties ◽

Stent Graft ◽

Endovascular Repair ◽

Abdominal Aortic Aneurysms ◽

Aortic Aneurysms ◽

Complex Anatomy ◽

Abdominal Aortic ◽

Drug Treatments

The preferred method to treat abdominal aortic aneurysms (AAAs) is endovascular repair with a stent-graft (EVAR). Although EVAR is fairly successful, there are several challenges to address, which include patient ineligibility due to complex anatomy and long-term failure due to migration and endoleak. Drug treatments that reduce or halt AAA growth are also currently under investigation [1].

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Diameter and thickness-related variations in mechanical properties of degraded arterial wall in the rat xenograft model

Journal of Biomechanics ◽

10.1016/j.jbiomech.2016.09.012 ◽

2016 ◽

Vol 49 (14) ◽

pp. 3467-3475 ◽

Cited By ~ 4

Author(s):

Louise Marais ◽

Grégory Franck ◽

Eric Allaire ◽

Mustapha Zidi

Keyword(s):

Mechanical Properties ◽

Arterial Wall ◽

Xenograft Model

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A continuum description of the damage process in the arterial wall of abdominal aortic aneurysms

International Journal for Numerical Methods in Biomedical Engineering ◽

10.1002/cnm.1472 ◽

2011 ◽

Vol 28 (1) ◽

pp. 87-99 ◽

Cited By ~ 22

Author(s):

Giacomo Marini ◽

Andreas Maier ◽

Christian Reeps ◽

Hans-Henning Eckstein ◽

Wolfgang A. Wall ◽

...

Keyword(s):

Arterial Wall ◽

Abdominal Aortic Aneurysms ◽

Aortic Aneurysms ◽

Abdominal Aortic ◽

Damage Process ◽

Continuum Description

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Comparison of the Mechanical Properties of the Intraluminal Thrombus in Abdominal Aortic Aneurysms and Thrombus Mimics

ASME 2008 Summer Bioengineering Conference, Parts A and B ◽

10.1115/sbc2008-193031 ◽

2008 ◽

Author(s):

John H. Ashton ◽

Darren G. Haskett ◽

Jonathan P. Vande Geest

Keyword(s):

Mechanical Properties ◽

Abdominal Aortic Aneurysms ◽

Aortic Aneurysms ◽

Mechanical Modeling ◽

Risk Models ◽

Intraluminal Thrombus ◽

Aneurysmal Wall ◽

Abdominal Aortic ◽

Model Fluid ◽

Flow Through

An intraluminal thrombus (ILT) forms along the inner layer of the aorta in 75% of abdominal aortic aneurysms (AAAs) [1] and can often times cover a large surface area of the AAA wall. Mechanical modeling of the ILT is essential in many AAA studies. For example, inclusion of the ILT in rupture risk models significantly affects the estimated stress acting on the aneurysmal wall [2]. In addition, using ILT mechanical properties to model fluid flow through the ILT is critical to developing an intraluminal drug delivery treatment of AAAs to ensure the drug reaches the aneurysmal wall.

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Local Mechanical Properties of Abdominal Aortic Aneurysms

ASME 2008 Summer Bioengineering Conference, Parts A and B ◽

10.1115/sbc2008-192892 ◽

2008 ◽

Cited By ~ 1

Author(s):

Evelyne van Dam ◽

Marcel Rutten ◽

Frans van de Vosse

Keyword(s):

Mechanical Properties ◽

Stress Analysis ◽

Vessel Wall ◽

Computational Models ◽

Wall Stress ◽

Abdominal Aortic Aneurysms ◽

Aortic Aneurysms ◽

Patient Specific ◽

Rupture Risk ◽

Abdominal Aortic

Rupture risk of abdominal aortic aneurysms (AAA) based on wall stress analysis may be superior to the currently used diameter-based rupture risk prediction [4; 5; 6; 7]. In patient specific computational models for wall stress analysis, the geometry of the aneurysm is obtained from CT or MR images. The wall thickness and mechanical properties are mostly assumed to be homogeneous. The pathological AAA vessel wall may contain collageneous areas, but also calcifications, cholesterol crystals and large amounts of fat cells. No research has yet focused yet on the differences in mechanical properties of the components present within the degrading AAA vessel wall.

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Automatic Identification and Validation of Planar Collagen Organization in the Aorta Wall with Application to Abdominal Aortic Aneurysm

Microscopy and Microanalysis ◽

10.1017/s1431927613013251 ◽

2013 ◽

Vol 19 (6) ◽

pp. 1395-1404 ◽

Cited By ~ 17

Author(s):

Stanislav Polzer ◽

T. Christian Gasser ◽

Caroline Forsell ◽

Hana Druckmüllerova ◽

Michal Tichy ◽

...

Keyword(s):

Arterial Wall ◽

Three Dimensional ◽

Polarized Light ◽

Vascular Diseases ◽

Aortic Aneurysms ◽

Fast Fourier Transformation ◽

Automatic Identification ◽

Collagen Organization ◽

Aorta Wall ◽

Abdominal Aortic

AbstractArterial physiology relies on a delicate three-dimensional (3D) organization of cells and extracellular matrix, which is remarkably altered by vascular diseases like abdominal aortic aneurysms (AAA). The ability to explore the micro-histology of the aorta wall is important in the study of vascular pathologies and in the development of vascular constitutive models, i.e., mathematical descriptions of biomechanical properties of the wall. The present study reports and validates a fast image processing sequence capable of quantifying collagen fiber organization from histological stains. Powering and re-normalizing the histogram of the classical fast Fourier transformation (FFT) is a key step in the proposed analysis sequence. This modification introduces a powering parameterw, which was calibrated to best fit the reference data obtained using classical FFT and polarized light microscopy (PLM) of stained histological slices of AAA wall samples. The values ofw= 3 and 7 give the best correlation (Pearson's correlation coefficient larger than 0.7,R2about 0.7) with the classical FFT approach and PLM measurements. A fast and operator independent method to identify collagen organization in the arterial wall was developed and validated. This overcomes severe limitations of currently applied methods like PLM to identify collagen organization in the arterial wall.

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Three-band decomposition analysis in multiscale FSI models of abdominal aortic aneurysms

International Journal of Modern Physics C ◽

10.1142/s0129183116500170 ◽

2015 ◽

Vol 27 (02) ◽

pp. 1650017 ◽

Cited By ~ 9

Author(s):

Maria G. C. Nestola ◽

Alessio Gizzi ◽

Christian Cherubini ◽

Simonetta Filippi

Keyword(s):

Arterial Wall ◽

A Priori ◽

Decomposition Analysis ◽

Abdominal Aortic Aneurysms ◽

Aortic Aneurysms ◽

Risk Indicators ◽

Axially Symmetric ◽

Abdominal Aortic ◽

Moving Domains ◽

Symmetric Geometry

Computational modeling plays an important role in biology and medicine to assess the effects of hemodynamic alterations in the onset and development of vascular pathologies. Synthetic analytic indices are of primary importance for a reliable and effective a priori identification of the risk. In this scenario, we propose a multiscale fluid-structure interaction (FSI) modeling approach of hemodynamic flows, extending the recently introduced three-band decomposition (TBD) analysis for moving domains. A quantitative comparison is performed with respect to the most common hemodynamic risk indicators in a systematic manner. We demonstrate the reliability of the TBD methodology also for deformable domains by assuming a hyperelastic formulation of the arterial wall and a Newtonian approximation of the blood flow. Numerical simulations are performed for physiologic and pathologic axially symmetric geometry models with particular attention to abdominal aortic aneurysms (AAAs). Risk assessment, limitations and perspectives are finally discussed.

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