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    A model for cell density effect on stress fiber alignment and collective directional migration

    , Article Physical Biology ; Volume 12, Issue 6 , 2015 ; 14783967 (ISSN) Abeddoust, M ; Shamloo, A ; Sharif University of Technology
    2015
    Abstract
    In this study, numerical simulation of collective cell migration is presented in order to mimic the group migration of endothelial cells subjected to the concentration gradients of a biochemical factor. The developed 2D model incorporates basic elements of the cell, including both the cell membrane and the cell cytoskeleton, based on a viscoelastic cell mechanic model. Various cell processes - including cell random walk, cell-cell interactions, cell chemotaxis, and cellular cytoskeleton rearrangements - are considered and analyzed in our developed model. After validating the model by using available experimental data, the model is used to investigate various important parameters during... 

    Modeling of photoplethysmography signal for quantitative analysis of endothelial cells during reactive hyperemia

    , Article 2012 19th Iranian Conference of Biomedical Engineering, ICBME 2012 ; 2012 , Pages 174-178 ; 9781467331302 (ISBN) Shiri, F ; Firoozabadi, B ; Saidi, M. S ; Sharif University of Technology
    2012
    Abstract
    In this study, at first the cardiovascular system is modeled based on the 1D method and then the simulation of the reactive hyperemia experiment has been applied on the model. In this simulation, by applying a cuff at the brachial artery, the flow downstream of the cuff is occluded. Then with releasing the cuff immediately, a large amount of shear stress, about 4 times the basal amount, is applied downstream of the cuff and consequently to the endothelial cells in a very short moment. Considering a reported experimental transfer function between shear stress and vasodilation, the increase of the artery diameter due to the sudden increase of the shear stress is obtained. Finally, the... 

    Biomechanical analysis of actin cytoskeleton function based on a spring network cell model

    , Article Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science ; Volume 231, Issue 7 , 2017 , Pages 1308-1323 ; 09544062 (ISSN) Ghaffari, H ; Saidi, M. S ; Firoozabadi, B ; Sharif University of Technology
    SAGE Publications Ltd  2017
    Abstract
    In this study, a new method for the simulation of the time-dependent behavior of actin cytoskeleton during cell shape change is proposed. For this purpose, a three-dimensional model of endothelial cell consisting of cell membrane, nucleus membrane, and main components of cytoskeleton, namely actin filaments, microtubules, and intermediate filaments is utilized. Actin binding proteins, which play a key role in regulating actin cytoskeleton behavior, are also simulated by using a novel technique. The actin cytoskeleton in this model is more dynamic and adoptable during cell deformation in comparison to previous models. The proposed model is subjected to compressive force between parallel micro... 

    A portable culture chamber for studying the effects of hydrostatic pressure on cellular monolayers

    , Article Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science ; 2018 ; 09544062 (ISSN) Kiyoumarsioskouei, A ; Saidi, M ; Mosadegh, B ; Firoozabadi, B ; Sharif University of Technology
    SAGE Publications Ltd  2018
    Abstract
    Hydrostatic pressure is one of the most fundamental and common mechanical stimuli in the body, playing a critical role in the homeostasis of all organ systems. Kidney function is affected by high blood pressure, namely hypertension, by the increased pressure acting on the glomerular capillary walls. This general effect of hypertension is diagnosed as a chronic disease, but underlying mechanistic causes are still not well understood. This paper reports a portable and adaptive device for studying the effects of hydrostatic pressure on a monolayer of cells. The fabricated device fits within a conventional incubation system and microscope. The effects of various pressures and durations were... 

    A portable culture chamber for studying the effects of hydrostatic pressure on cellular monolayers

    , Article Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science ; Volume 233, Issue 3 , 2019 , Pages 807-816 ; 09544062 (ISSN) Kiyoumarsioskouei, A ; Saidi, M. S ; Mosadegh, B ; Firoozabadi, B ; Sharif University of Technology
    SAGE Publications Ltd  2019
    Abstract
    Hydrostatic pressure is one of the most fundamental and common mechanical stimuli in the body, playing a critical role in the homeostasis of all organ systems. Kidney function is affected by high blood pressure, namely hypertension, by the increased pressure acting on the glomerular capillary walls. This general effect of hypertension is diagnosed as a chronic disease, but underlying mechanistic causes are still not well understood. This paper reports a portable and adaptive device for studying the effects of hydrostatic pressure on a monolayer of cells. The fabricated device fits within a conventional incubation system and microscope. The effects of various pressures and durations were... 

    Induced cell migration based on a bioactive hydrogel sheet combined with a perfused microfluidic system

    , Article Biomedical Materials (Bristol) ; Volume 15, Issue 4 , May , 2020 Jafarkhani, M ; Jafarkhani, M ; Salehi, Z ; Mashayekhan, S ; Kowsari Esfahan, R ; Dolatshahi Pirouz, A ; Bonakdar, S ; Shokrgozar, M. A ; Sharif University of Technology
    Institute of Physics Publishing  2020
    Abstract
    Endothelial cell migration is a crucial step in the process of new blood vessel formation - a necessary process to maintain cell viability inside thick tissue constructs. Here, we report a new method for maintaining cell viability and inducing cell migration using a perfused microfluidic platform based on collagen gel and a gradient hydrogel sheet. Due to the helpful role of the extracellular matrix components in cell viability, we developed a hydrogel sheet from decellularized tissue (DT) of the bovine heart and chitosan (CS). The results showed that hydrogel sheets with an optimum weight ratio of CS/DT = 2 possess a porosity of around 75%, a mechanical strength of 23 kPa, and display cell... 

    Simulation of Dynamic Behavior of Endothelial Cell During Compression Test

    , M.Sc. Thesis Sharif University of Technology Ghaffari, Hamed (Author) ; Saidi, Mohammad Said (Supervisor) ; Firoozabadi, Bahar (Supervisor)
    Abstract
    Investigation of the behavior of living cells in different biological conditions could play a key role in exploring the main reasons of humans' disorders and diseases. In this regard, many researchers are studying different subjects related to the living cells. Although most of these research activities are based on experimental methods, numerical approach could be utilized to investigate some topics which cannot be studied by experimental methods.In this study a three dimensional model of endothelial cell is proposed for the investigation of cell performance during compression test. The model consists of cell membrane, nucleus and main components of cytoskeleton, namely actin filaments,... 

    Simulation of NO Production Process from Endothelial Cells and its Effect on Coronary Artery Flow Field

    , M.Sc. Thesis Sharif University of Technology Shahriari, Amir Hossein (Author) ; Firoozabadi, Bahar (Supervisor)
    Abstract
    Endothelial derived nitric oxide (NO) and its role in regulating the physiological conditions of blood vessels is one of the favorite topics among researchers. The majority of previous studies have focused on nitric oxide transport in blood vessels, less attention has been paid to its vasodilative effects in blood vessels. The main aim of this study is to propose an integrated model to study the effects of endothelial-derived nitric oxide on hemodynamic conditions of blood vessels. Nitric oxide is produced by endothelial cells upon exposure to mechanical forces such as hemodynamic shear stress. The synthesized nitric oxide then diffuses into the neighboring vascular smooth cells, where it... 

    Control of Blood Flow by Endothelial-Secreted Biochemicals NO, Ca2+ and Growth Factor VEGF: Numerical Simulation Using Lattice Boltzmann-Finite Difference Hybrid

    , M.Sc. Thesis Sharif University of Technology Asghanian, Alireza (Author) ; Firoozabadi, Bahar (Supervisor)
    Abstract
    Endothelial cells that cover the inner wall of blood cells and are sensitive to receiving mechanical signals play important role in regulating many vital activities of the human body especially the function of the cardiovascular system. One of the factors affecting the mechanical functions of these cells is the shear stress applied to them. Due to blood velocity increasing or decreasing the endothelial cells shear stress change and leads to some chemical reactions and finally releasing biochemical substances including Nitrogen-Monoxide and Calcium-ion. Nitrogen-Monoxide produced by endothelial cells by affecting the smooth muscle cells in the vessel wall causes dilating of the vessel wall,... 

    A microfluidic device for 2D to 3D and 3D to 3D cell navigation

    , Article Journal of Micromechanics and Microengineering ; Volume 26, Issue 1 , November , 2015 ; 09601317 (ISSN) Shamloo, A ; Amirifar, L ; Sharif University of Technology
    Institute of Physics Publishing  2015
    Abstract
    Microfluidic devices have received wide attention and shown great potential in the field of tissue engineering and regenerative medicine. Investigating cell response to various stimulations is much more accurate and comprehensive with the aid of microfluidic devices. In this study, we introduced a microfluidic device by which the matrix density as a mechanical property and the concentration profile of a biochemical factor as a chemical property could be altered. Our microfluidic device has a cell tank and a cell culture chamber to mimic both 2D to 3D and 3D to 3D migration of three types of cells. Fluid shear stress is negligible on the cells and a stable concentration gradient can be... 

    In situ synthesized TiO2-polyurethane nanocomposite for bypass graft application: In vitro endothelialization and degradation

    , Article Materials Science and Engineering C ; Volume 114 , May , 2020 Kianpour, G ; Bagheri, R ; Pourjavadi, A ; Ghanbari, H ; Sharif University of Technology
    Elsevier Ltd  2020
    Abstract
    The in vitro endothelial response of human umbilical vein endothelial cells was investigated on a poly (caprolactone)-based polyurethane surface vs an in situ TiO2-polyurethane nanocomposite surface, which has been produced as scaffolds for artificial vascular graft. The in situ synthesis of TiO2 nanoparticles in polyurethane provided surface properties that facilitated cellular adhesion, cell sensing, cell probing and especially cell migration. Cells on the nanocomposite surface have elongated morphology and were able to produce more extracellular matrix. All of these advantages led to an increase in the rate of endothelialization of the nanocomposite scaffold surface vs pure polyurethane.... 

    A validated reduced-order dynamic model of nitric oxide regulation in coronary arteries

    , Article Computers in Biology and Medicine ; Volume 139 , 2021 ; 00104825 (ISSN) Moshfegh, H ; Tajeddini, F ; Pakravan, H. A ; Mahzoon, M ; Azadi Yazdi, E ; Bazrafshan Drissi, H ; Sharif University of Technology
    Elsevier Ltd  2021
    Abstract
    Nitric Oxide (NO) provides myocardial oxygen demands of the heart during exercise and cardiac pacing and also prevents cardiovascular diseases such as atherosclerosis and platelet adhesion and aggregation. However, the direct in vivo measurement of NO in coronary arteries is still challenging. To address this matter, a mathematical model of dynamic changes of calcium and NO concentration in the coronary artery was developed for the first time. The model is able to simulate the effect of NO release in coronary arteries and its impact on the hemodynamics of the coronary arterial tree and also to investigate the vasodilation effects of arteries during cardiac pacing. For these purposes, flow... 

    Bilayered heparinized vascular graft fabricated by combining electrospinning and freeze drying methods

    , Article Materials Science and Engineering C ; Volume 94 , 2019 , Pages 1067-1076 ; 09284931 (ISSN) Khayat Norouzi, S ; Shamloo, A ; Sharif University of Technology
    Elsevier Ltd  2019
    Abstract
    Small diameter vascular grafts (<6 mm) are highly demanded for patients suffering from severe occluded arteries to be used as a bypass or substituted conduit. Fabricating a graft with appropriate structural, mechanical and cell growth properties which has simultaneously anti-thrombogenic trait is a challenge nowadays. Here, we proposed a bilayer heparinized vascular graft that can mimic the structural and mechanical characteristics close to those of the native coronary artery by combining electrospinning and freeze drying methods. In this study, the inner layer was made by co-electrospinning of synthetic polymer, poly-caprolactone (PCL) and the natural polymer, gelatin (Gel). Also, heparin... 

    Bilayered heparinized vascular graft fabricated by combining electrospinning and freeze drying methods

    , Article Materials Science and Engineering C ; Volume 94 , 2019 , Pages 1067-1076 ; 09284931 (ISSN) Khayat Norouzi, S ; Shamloo, A ; Sharif University of Technology
    Elsevier Ltd  2019
    Abstract
    Small diameter vascular grafts (<6 mm) are highly demanded for patients suffering from severe occluded arteries to be used as a bypass or substituted conduit. Fabricating a graft with appropriate structural, mechanical and cell growth properties which has simultaneously anti-thrombogenic trait is a challenge nowadays. Here, we proposed a bilayer heparinized vascular graft that can mimic the structural and mechanical characteristics close to those of the native coronary artery by combining electrospinning and freeze drying methods. In this study, the inner layer was made by co-electrospinning of synthetic polymer, poly-caprolactone (PCL) and the natural polymer, gelatin (Gel). Also, heparin... 

    Simulation of a Simple Model of Endothelial Cell Using Dissipative Particle Dynamics Method

    , M.Sc. Thesis Sharif University of Technology Kiyoumarsi Oskouei, Amir (Author) ; Saeedi, Mohammad Saeed (Supervisor) ; Firoozabadi, Bahar (Co-Advisor)
    Abstract
    Endothelium is the interior layer of an artery made up of tremendous number of endothelial cells which are located side by side. Finding the effective parameters that cause the cells to obtain mechanical strength in different morphologies is a major effort in cell engineering studies. In this work a numerical model for endothelial cells is developed. This model has included cell's plasma membrane (the outer membrane of the cell), nucleus and cytoskeleton main components including intermediate and actin filaments as well as microtubules. The model has been validated by simulating the adhesion of the cells to a flat substrate and also atomic force microscopy (AFM) experiments. The two most... 

    Numerical Modeling of Endothelial Cell’s Groups Migration in a Microfluidics Device

    , M.Sc. Thesis Sharif University of Technology Abeddoust, Mohammad (Author) ; Shamloo, Amir (Supervisor)
    Abstract
    Cell migration plays a key role in many biological processes including metastasis, wound healing, inflammatory response, body immune response and formation of new blood vessels. The migration of cells in response to the gradient of concentration gradient is regarded as chemotaxis. In the present study, the group chemotaxis of endothelial cells is simulated in response to gradient concentration of biochemical species using a developed cell migration model. At the first step, the numerical simulation of fluid flow and concentration transport of biochemical species is performed using a developed FVM code. At the second part, a model is developed to mimic the group migration of endothelial... 

    Simulation of the Blood Flow in a Stenotic Left Coronary Bifurcation to Study the Effects on the Endothelial Cells

    , M.Sc. Thesis Sharif University of Technology Jahromi, Reza (Author) ; Saeedi, Mohammad Saeed (Supervisor)
    Abstract
    Morphology and alignment of endothelial cells (ECs) have great influence on plaque formation. These alignments are based on the cyclic strains and wall shear stress (WSS) on the arterial wall. In the present study, cyclic strains and WSS are investigated to predict the secondary plaque locations downstream of the primary stenosis. Therefore, left coronary artery (LCA) with its branches to left anterior descending (LAD) and left circumflex (LCX) are 3D located on a virtual sphere to consider the cardiac motion. Stenoses are placed at the beginning of the bifurcation with varying degrees from 40% to 70% based on diameter reduction. Healthy coronary is also constructed to compare with those of... 

    Multiscale Modeling of Coronary Blood Flow and Effects on Endothelial Cells

    , Ph.D. Dissertation Sharif University of Technology Pakravan, Hossein Ali (Author) ; Saeedi, Mohammad Saeed (Supervisor) ; Firoozabadi, Bahar (Co-Advisor)
    Abstract
    Atherosclerosis in coronary arteries is one of the most important topics due to its high prevalence and the importance of these arteries for supplying blood to the heart. The morphology of endothelial cells (ECs) is an independent index for determining the atheroprone sites. The ECs show a regular elongated and aligned configuration to the blood flow, at the atheroprotected regions; on the other hand, at the atheroprone regions, the cells have a polygonal, randomly oriented morphology. The thesis intended to propose a method for coronary artery simulation, which is able to determine the atheroprone sites regarding the ECs morphology. In addition, the attempts were made to investigate the... 

    Design and Fabrication of a Microfluidic Device to Study the Growth of Breast Cancer Cell

    , M.Sc. Thesis Sharif University of Technology Mohammad Hashemi, Hanieh (Author) ; Vosughi, Manuchehr (Supervisor) ; Shamloo, Amir (Supervisor) ; Naserifar, Naser (Supervisor)
    Abstract
    for decades Cancer has been one of the major causes of death universally. Though extensive efforts in developing new anticancer therapies, they face failures in clinical trials and curing the sick owing to time consuming and expensive preclinical models with poor predictions of drug responses in human. To address this challenge it is crucial to develop preclinical models mimicking the main aspects of a tumor that can provide effective prediction of therapeutic responses. Tumor on chip technology has appeared as a promising approach for providing effective cancer models and reliable preclinical predictions. In this project, collagen was first extracted as the main constituent of the tumor... 

    Thickness as an important parameter in designing vascular grafts

    , Article 2014 21st Iranian Conference on Biomedical Engineering, ICBME 2014 ; Nov , 2014 , p. 40-43 Mohseni, M ; Shamloo, A ; Samani, S. A ; Dodel, M ; Sharif University of Technology
    Abstract
    The main goal of this study is to investigate the role of vascular graft thickness in wall stress gradient in anastomosis region. Atherosclerosis is a common heart disease causes high mortality rates every year. The gold standard treatment of atherosclerosis is replacing with autologous vein extracted from patient's body. Since proper autologous vein is limited, researchers have made efforts to achieve compliance engineered blood vessels. Mechanical stress has great effect on both smooth muscle cells and endothelial cells and it is considered as a stimulus in plaque formation. In this study, we evaluate the role of thickness in wall stress of anastomosis region. For this purpose, two...