Scaffolding / Bio-Scaffolds
Seyedeh Sara Kamali; Haniye Abdi Kordlar; Maryam Saadatmand; Shohreh Mashayekhan
Volume 14, Issue 1 , May 2020, , Pages 43-53
Abstract
Successful cell culture in large scale 3D scaffolds in tissue engineering is still challenging and requires full control over physical, chemical and mechanical properties of the applied scaffolds. Recently, using printers for the fabrication of 3D scaffold with a structural arrangement of fibers has ...
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Successful cell culture in large scale 3D scaffolds in tissue engineering is still challenging and requires full control over physical, chemical and mechanical properties of the applied scaffolds. Recently, using printers for the fabrication of 3D scaffold with a structural arrangement of fibers has been extensively developed, because it is possible to define the structure of scaffold geometry before manufacturing. The aim of this study was the investigation of the effective geometrical parameters on the 3D symmetric porous scaffold from the mass and momentum transport phenomena point of view. In this way, the mass and momentum transfer equations were solved using COMSOL Multiphysics software. In 3D scaffolds, the optimum model is the one that can provide a more appropriate environment for the cultured cells leading an increase in the attached cell number. The oxygen concentration reaching the bone cells should be greater than 0.02 mol/m3 in order to prevent cell death. Moreover, the fluid shear stress regime must be such that (between 10-5 to 10-3 Pa) it could not cause cell detachment. After studying the results of the simulation and changing the different parameters such as fiber diameter, fiber distance and the width of the channels, the appropriate structure was obtained regarding maximum shear stress and minimum oxygen concentration, and then the effect of fluid flow rate on maximum shear stress was examined for the appropriate structure. The optimized model with a fiber diameter of 0.25 mm, a fiber distance of 0.25 mm, and a channel width of 0.25 mm was proposed that fluid flow inlet velocity was 5×10-5 m/s.
Fluid-Structure Interaction in Biological Media / FSI
Saeid Siri; Malikeh Nabaei; Nasser Fatouraee
Volume 9, Issue 3 , December 2015, , Pages 229-241
Abstract
Every organ has its own metabolic and functional requirements and needs a variable amount of blood; hence, autoregulation is an important phenomenon. Shear stress induced autoregulation is defined as the innate ability of an organ to keep its hemodynamic conditions stable against changes in heart rate ...
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Every organ has its own metabolic and functional requirements and needs a variable amount of blood; hence, autoregulation is an important phenomenon. Shear stress induced autoregulation is defined as the innate ability of an organ to keep its hemodynamic conditions stable against changes in heart rate and perfusion pressure. For example, when heart rate changes arterial vessels undergo vasodilation or vasoconstriction in order to stabilize the hemodynamic forces and stresses with respect to the flow needed. The current study examines the local mechanisms employed in automatic control. Local regulatory mechanisms function independently of external control mechanisms, such as sympathetic nerves and endocrine hormones. Therefore, they can be considered isolated mechanisms. The application of boundary conditions in numerical modeling is of utmost importance, hence, using arterial tree modeling to achieve appropriate boundary conditions seems necessary. Thus, we have presented a zero-dimensional (lumped parameter) extensive model first. Then, we used this model to achieve boundary conditions for the common carotid artery. As one of the most important hemodynamic parameters, shear stress regulation will then be modeled in an axisymmetric model of this artery.
