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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... 

    Flow mediated dilation with photoplethysmography as a substitute for ultrasonic imaging

    , Article Physiological Measurement ; Volume 36, Issue 7 , 2015 , Pages 1551-1571 ; 09673334 (ISSN) Mashayekhi, G ; Zahedi, E ; Movahedian Attar, H ; Sharifi, F ; Sharif University of Technology
    Institute of Physics Publishing  2015
    Abstract
    Flow mediated dilation (FMD) is a non-invasive method for endothelial function assessment providing an index extracted from ultrasonic B-mode images. Although utilized in the research community, the difficulty of its application and high cost of ultrasonic devices prevent it from being widely used in clinical settings. In this study we show that substituting the ultrasonic device with more easily handled and low cost photoplethysmography and electrocardiography is possible. We introduce new indices based on the photoplethysmogram (PPG) and electrocardiogram (ECG) and show that they are correlated with the ultrasound-based FMD Index. To this end, a conventional ultrasound FMD test was carried... 

    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... 

    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... 

    Autoregressive modeling of the photoplethysmogram AC signal amplitude changes after flow-mediated dilation in healthy and diabetic subjects

    , Article 2012 19th Iranian Conference of Biomedical Engineering, ICBME 2012 ; 2012 , Pages 170-173 ; 9781467331302 (ISBN) Amiri, M ; Zahedi, E ; Behnia, F ; Sharif University of Technology
    2012
    Abstract
    It is proved that the endothelial (artery inner lumen cells) function is associated with cardiovascular risk factors. Among all the common non-invasive methods employed in the research setting for assessing endothelial function, flow-mediated dilation is the most widely used one. This technique measures endothelial function by inducing reactive hyperemia using temporary arterial occlusion and measuring the resultant relative increase in blood vessel diameter via ultrasound. In this paper, the limitations associated with the ultrasound technique are overcome by using the photoplethysmogram (PPG) signal recorded during FMD. The correctness of this approach is investigated by modeling the AC... 

    Non-invasive techniques for assessing the endothelial dysfunction: ultrasound versus photoplethysmography

    , Article IFMBE Proceedings, 3 December 2008 through 6 December 2008 ; Volume 23 , 2009 , Pages 65-68 ; 16800737 (ISSN) ; 9783540928409 (ISBN) Zaheditochai, M ; Jaafar, R ; Zahedi, E ; Sharif University of Technology
    Abstract
    Endothelial dysfunction, which can be noninvasively assessed by flow mediated vasodilation (FMD), predicts an increased rate of adverse cardiovascular events. The endothelial dysfunction is considered as a leading cause of development and progression of the atherosclerotic process. The main aim of this study is to review different non-invasive methods to assess the endothelial dysfunction and to propose enhancements to a new method based on photoplethysmography (PPG). First, non-invasive techniques developed for the evaluation of peripheral endothelial function (including the Doppler ultrasound (US)) will be reviewed. Although noninvasive, US -based techniques present a few disadvantages. To... 

    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... 

    Meaurement of Flow Mediated Dilation Using Photoplethysmography

    , M.Sc. Thesis Sharif University of Technology Goldoozian, Layli Sadat (Author) ; Zahedi, Edmond (Supervisor)
    Abstract
    Endothelial cells cover the inner surface of blood vessels. In response to different physical (such as reactive hyperemia-RH) and pharmacological stimuli, they maintain homeostasis by changing the vascular diameter (by releasing chemical agents like nitric oxide). The endothelium inability to respond to metabolic need (endothelial dysfunction) is an early marker of cardiovascular diseases such as atherosclerosis. Flow mediated dilation (FMD) measurement using ultrasound imaging (FMD-US) has been established as a standard method for assessing the endothelial function. Recently, a less skilled-operator demanding method has been proposed based on the photoplethysmographic (PPG) signal changes... 

    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.... 

    VEGF Isolation from Platelet Lysate

    , M.Sc. Thesis Sharif University of Technology Sanaei, Reza (Author) ; Abdekhodaie, Mohammad Jafar (Supervisor)
    Abstract
    Platelet-rich plasma as a juvenile to the narrow repertoire of orthopedic medicine, has risen hope to attain a generic autologous regenerative formula for different conditions. Vast plethora of GFs, cytokines and chemokines has endowed PRP with excellent regenerative properties, however not all of them would favor different conditions. Vascular endothelial growth factor has been demonstrated to be involved in the progress of Osteoarthritis by amplifying the catabolic processes which deteriorate the extracellular matrix of cartilage. Though cumbersome, the result of eliminating VEGF from platelet lysate would be promising. VEGF isolation from platelet lysate requires selectivity. By employing... 

    Analyzing the Endothelial Function by Means of Photoplethysmogram Signal Modeling

    , M.Sc. Thesis Sharif University of Technology Amiri, Mina (Author) ; Zahedi, Edmond (Supervisor) ; Behnia, Fereidoon (Supervisor)
    Abstract
    The endothelial (the artery inner lumen cells) function is associated with cardiovascular risk factors. Its assessment methods can be classified into the two groups of invasive and noninvasive ones. The most widely used method among the current non-invasive tests employed in research settings is flow-mediated dilation (FMD). This technique measures endothelial function by inducing reactive hyperemia via the temporary arterial occlusion and measuring the resultant relative increase in the blood vessel diameter via ultrasound. The high price and large size of the device, and being operator dependent are the limitation of this method. In this work, we propose using the photoplethysmogram (PPG)... 

    Modeling the Endothelial Function in the Brachial Artery Using Photoplethysmography

    , M.Sc. Thesis Sharif University of Technology Mashayekhi, Ghoncheh (Author) ; Zahedi, Edmond (Supervisor) ; Jahed, Mehran (Supervisor)
    Abstract
    Flow Mediated Dilation (FMD) is a non-invasive method for endothelial function assessment providing an index extracted from ultrasonic B-mode images. Although utilized in the research community, the difficulty of its application and high cost of ultrasonic device prevent it from being widely used in clinical settings. In this study we show that substituting the ultrasonic device with more easily handled and low cost photoplethysmography and electrocardiography is possible. We introduce new indices based on the photoplethysmogram (PPG) and electrocardiogram (ECG) and show that they are correlated with the ultrasound-based FMD index. To this end, conventional ultrasound FMD test was carried... 

    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... 

    Investigation of Molecular Interactions of VEGFR and its Inhibitors by Molecular Dynamics Simulation

    , M.Sc. Thesis Sharif University of Technology Didandeh, Mohsen (Author) ; Bastani, Daruoosh (Supervisor) ; Mashayekhan, Shohreh (Co-Supervisor) ; Karami, Layla (Co-Supervisor)
    Abstract
    One of the chief kinds of receptors in cancer angiogenesis is the tyrosine kinase VEGFR-2. This target receptor is presented in both forms; active and inactive. adenosine triphosphate (ATP) residue is the location of deformational change from inactive to active form. Small molecule inhibitors have been designed for various forms of this receptor. In current study, the interaction of small molecular inhibitors including; Regorafenib, Cabozantinib and Thiosanib with dual VEGFR-2 receptor forms was investigated by molecular dynamics with Gromacs software. Cabozantinib and Regorafenib inhibitors had a lower binding energy in interaction with the inactive state however, Thiosanib inhibitors in... 

    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,... 

    Electrical analog model of arterial compliance during reactive hyperemia

    , Article 2011 1st Middle East Conference on Biomedical Engineering, MECBME 2011, 21 February 2011 through 24 February 2011, Sharjah ; 2011 , Pages 49-53 ; 9781424470006 (ISBN) Goldoozian, L. S ; Zahedi, E ; Sharif University of Technology
    2011
    Abstract
    Flow mediated dilation (FMD) measurement using ultrasound imaging (FMD-US) has been established as a standard method for assessing the endothelial function. Recently, a less skilled-operator demanding method has been proposed based on the photoplethysmogram (PPG) changes during reactive hyperemia. It was shown that the amplitude of the PPG pulse (FMD-PPG) changed in a quite similar manner to that of the artery diameter in the method of the FMD-US i.e. increases following releasing the cuff and then gradually returns to baseline. In this study PPG changes following reactive hyperaemia were modelled using time-varying passive electrical elements (R, L and C). The output of the electric analog...