The Effects of Arterial Tissue Reorganization on the Geometrical Outputs of Pressure- and Flow-Induced Remodeling: A Theoretical Study

2012 ◽  
Author(s):  
Tarek Shazly ◽  
Alexander Rachev
Keyword(s):  
Mechanical Properties ◽  
Smooth Muscle ◽  
Vascular Tissue ◽  
Arterial Remodeling ◽  
Structural Components ◽  
Constrained Mixture ◽  
Mass Redistribution ◽  
Mass Fractions ◽  
Tissue Reorganization ◽  
Induced Changes

Arterial remodeling in response to sustained alterations in blood pressure and/or flow induces changes in vessel geometry, structure, and composition. In conditions of hypertension and elevated blood flow, remodeling results in increased vessel mass that is distributed in a manner to maintain the local mechanical environment of the vascular cells at a baseline state. A majority of theoretical studies on remodeling have assumed that new mass is formed via a proportional production of load-bearing constituents, namely elastin, collagen, and smooth muscle. Therefore, when the vascular tissue is considered as a constrained mixture of these structural components, their mass fractions do not change as a result of remodeling. However, increased arterial mass is primarily attributed to smooth muscle cell hypertrophy and upregulated collagen production, implying a change in the mass fractions of all constituents and therefore the tissue mechanical properties [1]. Moreover, few papers account for remodeling-induced changes in the configuration and/or orientation of collagen fibers, both of which may also alter tissue mechanical properties. The objective of this study is to build a mathematical model that enables evaluation of the effects of mass redistribution among structural components and changes in collagen fiber configuration on the geometrical outputs of arterial remodeling.

Circumferential Variation of Mechanical Properties of Ascending Aorta (AA): A Comparative Study of Healthy and Dilated AA

2007 ◽  
Author(s):  
Dominique Tremblay ◽  
Raymond Cartier ◽  
Louis Leduc ◽  
Rosaire Mongrain ◽  
Richard Leask
Keyword(s):  
Mechanical Properties ◽  
Smooth Muscle ◽  
Aortic Valve ◽  
Aortic Wall ◽  
Vascular Tissue ◽  
Vascular System ◽  
Cardiovascular Complications ◽  
Ascending Aorta ◽  
Local Properties

The biomechanics within the ascending aorta (AA) characterizes the pressure and flow for the entire vascular system. In the aortic wall, it is the structured medial layer that is responsible for the mechanical properties of the AA. The mechanical properties are determined to a large extent by the composition of elastin, collagen and smooth muscle cells (SMCs). Changes in AA biomechanics that arise with age and/or disease can lead to cardiovascular complications and death. Most studies that have investigated the biomechanics of these diseases have assumed homogeneous and isotropic aortic wall properties. Very little work has been done in vitro to determine the local mechanical properties of human vascular tissue. In order to better understand the biomechanics of the human AA, the local properties of pathologic AA tissue from both tricuspid and bicuspid aortic valve patients have been studied and compared with the properties of healthy aortas.

scholarly journals Extrusion Based 3D Printing of Sustainable Biocomposites from Biocarbon and Poly(trimethylene terephthalate)

Molecules ◽  
2021 ◽  
Vol 26 (14) ◽  
pp. 4164
Author(s):  
Elizabeth Diederichs ◽  
Maisyn Picard ◽  
Boon Peng Chang ◽  
Manjusri Misra ◽  
Amar Mohanty
Keyword(s):  
Mechanical Properties ◽  
3D Printing ◽  
Surface Finish ◽  
Three Dimensional ◽  
Morphological Properties ◽  
Great Promise ◽  
Structural Components ◽  
Computer Aided ◽  
Trimethylene Terephthalate ◽  
Optimal Quantity

Three-dimensional (3D) printing manufactures intricate computer aided designs without time and resource spent for mold creation. The rapid growth of this industry has led to its extensive use in the automotive, biomedical, and electrical industries. In this work, biobased poly(trimethylene terephthalate) (PTT) blends were combined with pyrolyzed biomass to create sustainable and novel printing materials. The Miscanthus biocarbon (BC), generated from pyrolysis at 650 °C, was combined with an optimized PTT blend at 5 and 10 wt % to generate filaments for extrusion 3D printing. Samples were printed and analyzed according to their thermal, mechanical, and morphological properties. Although there were no significant differences seen in the mechanical properties between the two BC composites, the optimal quantity of BC was 5 wt % based upon dimensional stability, ease of printing, and surface finish. These printable materials show great promise for implementation into customizable, non-structural components in the electrical and automotive industries.

scholarly journals Complementary vasoactivity and matrix remodelling in arterial adaptations to altered flow and pressure

2008 ◽  
Vol 6 (32) ◽  
pp. 293-306 ◽  
Author(s):  
A Valentín ◽  
L Cardamone ◽  
S Baek ◽  
J.D Humphrey
Keyword(s):  
Smooth Muscle ◽  
Continuum Theory ◽  
Muscle Contractility ◽  
Smooth Muscle Contractility ◽  
Rates Of Change ◽  
Biomechanical Loading ◽  
Smooth Muscle Proliferation ◽  
And Function ◽  
Diverse Data ◽  
Induced Changes

Arteries exhibit a remarkable ability to adapt to sustained alterations in biomechanical loading, probably via mechanisms that are similarly involved in many arterial pathologies and responses to treatment. Of particular note, diverse data suggest that cell and matrix turnover within vasoaltered states enables arteries to adapt to sustained changes in blood flow and pressure. The goal herein is to show explicitly how altered smooth muscle contractility and matrix growth and remodelling work together to adapt the geometry, structure, stiffness and function of a representative basilar artery. Towards this end, we employ a continuum theory of constrained mixtures to model evolving changes in the wall, which depend on both wall shear stress-induced changes in vasoactive molecules (which alter smooth muscle proliferation and synthesis of matrix) and intramural stress-induced changes in growth factors (which alter cell and matrix turnover). Simulations show, for example, that such considerations help explain the different rates of experimentally observed adaptations to increased versus decreased flows as well as differences in rates of change in response to increased flows or pressures.

Influence of different concentrations of fibrinogen on the properties of a fibrin matrix for vascular tissue engineering

2021 ◽  
Vol 29 (1) ◽  
pp. 21-34
Author(s):  
Vera G. Matveeva ◽  
Mariam Yu. Khanova ◽  
Tatyana V. Glushkova ◽  
Larisa V. Antonova
Keyword(s):  
Mechanical Properties ◽  
Tissue Engineering ◽  
Metabolic Activity ◽  
Vascular Tissue ◽  
Physical And Mechanical Properties ◽  
Vascular Tissue Engineering ◽  
Test Machine ◽  
Fibrin Matrix ◽  
Before And After ◽  
The Difference

Aim. To evaluate the potential utility of fibrin matrices containing 10, 20, and 25 mg/ml of fibrinogen (fibrin-10, fibrin-20, and fibrin-30, respectively) in vascular tissue engineering (VTE). Materials and Methods. Fibrinogen was isolated using the method of ethanol cryoprecipitation and polymerized using a solution of thrombin and CaCl2. The fibrin structure was studied in a scanning electron microscope, and the physical and mechanical properties of the material were tested on a Zwick/Roell test machine. The metabolic activity of endothelial cells (EC) on the fibrin surface was evaluated by the MTT assay, and the viability of fibroblasts in the thickness of fibrin and possibility for migration by in fluorescent and light microscopy. Percent of fibrin shrinkage was determined from the difference in the sample volumes before and after removal of moisture. Results. The fiber diameter did not differ among all fibrin samples, but the pore diameter in fibrin-30 was smaller than those in fibrin-10 and fibrin-20. A possibility for migration of fibroblasts into the depth of the fibrin matrix and preservation of 97-100% viability of cells at a depth 5 mm was confirmed. The metabolic activity of EC on the surface of fibrin-20 and fibrin-30 exceeded that on collagen, fibronectin, and fibrin-10. All fibrin samples shrank in volume to 95.5-99.5%, and the highest shrinkage was seen in fibrin-10. The physical and mechanical properties of fibrin were inferior to those of human A. mammaria by a factor of 10. Conclusion. Fibrin with fibrinogen concentrations of 20 and 30 mg/ml maintains a high metabolic and proliferative activity of EC on the surface and also a high viability of fibroblasts in the matrix. Its availability, ease of preparation, and a number of other favorable properties make fibrin a promising material for VTE. However, the problem of insufficient strength requires further investigations.

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