Full Research Paper
Tissue Engineering
Fateme Shamsi; Mohsen Janmaleki; Nasser Fatouraee
Volume 3, Issue 4 , June 2009, Pages 265-274
Abstract
In this study a mechanism was modeled to control the jet path of nanofibers produced by electrospinning through inducing a magnetic field over the jet path. Firstly, a model was developed for the jet path in which the fibers composed of a series of viscoelastic segments. Considering the mass and momentum ...
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In this study a mechanism was modeled to control the jet path of nanofibers produced by electrospinning through inducing a magnetic field over the jet path. Firstly, a model was developed for the jet path in which the fibers composed of a series of viscoelastic segments. Considering the mass and momentum conservation and maxwellian model of stretching viscoelastic segments using three equations governing the jet dynamics of the jet model in electrospinning, a program was developed in MATLAB with Runge–Kutta method. After ensuring the accuracy of the model, its behavior was evaluated in the presence of a magnetic field. The field induced a uniform force distribution over the jet. As the intensity of the magnetic field increased; the instability and bending radius of the jet reduced. The results of the research showed that utilizing a suitable mechanism for applying magnetic field can provide help in controlling the jet path and alignment of the nanofibers.
Full Research Paper
Biomechanics of Bone / Bone Biomechanics
Mahmoud Azami; Fathollah Moztarzadeh; Mohammad Rabiee
Volume 3, Issue 4 , June 2009, Pages 275-284
Abstract
During past decade, using biomimetic approaches has received much attention by scientists in the field of tissue substitutes preparation. These approaches have been employed for synthesis of bone tissue engineering scaffolds in the case of either materials or synthesis methods. In this study, an apatite ...
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During past decade, using biomimetic approaches has received much attention by scientists in the field of tissue substitutes preparation. These approaches have been employed for synthesis of bone tissue engineering scaffolds in the case of either materials or synthesis methods. In this study, an apatite phase has been synthesized within gelatin hydrogel in biomimetic condition. The obtained composite hydrogel has changed to a porous scaffold with the application of freeze drying technique in order to be used in bone tissue engineering. To characterize the chemical composition and crystal structure of the synthesized precipitate within hydrogel, FTIR, XRD and TEM analysis were used. Surface morphology and porous structure of the scaffold were studied with SEM. SEM analysis was also used to investigate the quality of cultured osteoblast cells activity. Results approved formation of an apatite phase within gelatin hydrogel in biomimetic condition with crystallite size ranging between 7-10 nm. Porosity percentage of the obtained nanocomposite scaffold was about 82% with pores sizes in the range of 100-350μm. Young’s elastic modulus of the scaffold was comparable with that of the spongy bone. The osteoblast cells cultured on the scaffold showed adhesion, immigration and extracellular matrix excretion on the scaffold internal surfaces. Thus, obtained results indicated the potential ability of the prepared biomimetic bone tissue engineering scaffold to be used in bone tissue repair process.
Full Research Paper
Spinal Biomechanics
Mehran Kasra
Volume 3, Issue 4 , June 2009, Pages 285-290
Abstract
The influence of compression on intervertebral disc cells has been examined in a number of previous studies. However, in most of these studies hydrostatic pressure was used at low levels, and few studies reported the effects of high pressures within a large range of frequencies on intervertebral disc ...
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The influence of compression on intervertebral disc cells has been examined in a number of previous studies. However, in most of these studies hydrostatic pressure was used at low levels, and few studies reported the effects of high pressures within a large range of frequencies on intervertebral disc cells response. The aim of the study was to test the hypothesis that frequency dependent hydrostatic pressure stimulates collagen synthesis in the intervertebral disc cells to a certain level. Hydrostatic pressure was applied to the intervertebral disc cells in a monolayer culture using a custom-made piston chamber pressure vessel. Briefly, cells were harvested from the intervertebral discs in the lumbar region of a pig, plated, and grown to confluence in culture flasks; they were then trypsinized and re-attached to 35mm culture dishes. With cyclic, hydrostatic loading, the cells were exposed to varied pressures and frequencies for 20 minutes a day for 3 and 7 days (the controls received no loading). The intracellular collagen was labeled with 3[H]-proline after loading on days 2 and 6. Following treatments on days 3 and 7, both the media and cells were frozen separately. Scintillation counting determined the amount of collagen incorporated in the cells and released into the media; these values were normalized by DNA. In this culture system, the results indicated significant differences (P<0.05) in cell response at different loading conditions. Compared to the control group there was a significant decrease in released collagen at high loading amplitude and low frequency (5MPa, 1Hz) which increased significantly at high loading frequencies (5MPa, 15Hz) indicating anabolic response at high pressures which became catabolic at high frequencies.
Full Research Paper
Biomechanics of Bone / Bone Biomechanics
Masoume Haghbin Nazarpak; Farzane Pourasgari; Mohammad Nabi Sarbolouki
Volume 3, Issue 4 , June 2009, Pages 291-298
Abstract
The scaffolds for bone tissue engineering should consider the functional requirements: porosity, biocompatibility, and biodegradability. In this study, porous Poly (lactic-co-glycolic acid)/Hydroxyapatite composites were prepared with different weight ratios. Porous samples were fabricated by freeze-extraction ...
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The scaffolds for bone tissue engineering should consider the functional requirements: porosity, biocompatibility, and biodegradability. In this study, porous Poly (lactic-co-glycolic acid)/Hydroxyapatite composites were prepared with different weight ratios. Porous samples were fabricated by freeze-extraction method, coated with triblock copolymer and sterilized by UV. Then, human mesenchymal stem cells were cultured on scaffolds. Microstructural studies with SEM suggest the formation of about 50 micrometer size porous structure and interconnected porosity so that cells adhesion within the structure is well in depth in coated samples. DAPI fluorescence microscopy showed cells adhesion to the coated scaffolds and cells diffusion into the pores. Also, direct assay of cell proliferation performed with MTT test showed that, cells grew on the scaffold similar to or more than control samples result. Therefore, these findings suggest that the triblock-coated Poly (lactic-coglycolic acid)/ Hydroxyapatite porous composite scaffolds could provide cells adhesion and proliferation and are appropriate matrices for bone tissue engineering.
Full Research Paper
Tissue Engineering
Mehdi Navidbakhsh; Milade Jafarnejad
Volume 3, Issue 4 , June 2009, Pages 299-306
Abstract
The cancer changes the cytoskeleton of the cells .This change has some effects on the cell mechanobiology and will lead to some changes in the deformability of the cells. The moving ability of the cancer cells would be more than healthy cells. Thus, they can migrate through the tissue in human body. ...
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The cancer changes the cytoskeleton of the cells .This change has some effects on the cell mechanobiology and will lead to some changes in the deformability of the cells. The moving ability of the cancer cells would be more than healthy cells. Thus, they can migrate through the tissue in human body. In this survey, a valid FEM of a cancer cell is presented. Then the effects of various factors such as membrane thickness, elasticity, strain, and frequency response are studied during a process of being converted from normal cells into cancerous malignant cells. Besides, the initial mathematical models are provided. The results clarify that an increase in membrane elasticity, strain, and frequency would lead to increase in the reaction force. However, an increase in the membrane thickness decreases the reaction force.
Full Research Paper
Tissue Engineering
Mohsen Rabbani; Mohammad Tafazzoli Shadpour; Zahra Goli Malekabadi; Mohsen Janmaleki; Mohammad Taghi Khorasani; Mohammad Ali Shokrgozar
Volume 3, Issue 4 , June 2009, Pages 307-314
Abstract
Vital function of the cell is correlated with the mechanical loads that the cell experiences. The cell shape and morphology are also related to its mechanical environments. Different methods have been proposed to obtain cell groups with the same morphology and alignment which considered desirable features ...
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Vital function of the cell is correlated with the mechanical loads that the cell experiences. The cell shape and morphology are also related to its mechanical environments. Different methods have been proposed to obtain cell groups with the same morphology and alignment which considered desirable features in tissue engineering applications. For instance, applying cyclic loading makes cells elongated and aligned as bundles in a specific direction to the tension axis. Applying static stretches also affect the cells morphology, extra-cellular matrix, enzymes secretion and genes expression. The effect of applying in vivo static stretch on cellular alignment was evaluated in this study. Human mesenchymal stem cells (hMSCs) were cultured on the elastic membrane, and then subjected to static stretch. The results demonstrated that applying a 10% static stretch for 24 hours aligns intra-structure actin filaments and applying a 20% static stretch had a significant effect on the arrangement of the oriented fibers.
Full Research Paper
Tissue Engineering
Rana Imani; Parisa Rahnama Moshtaq; Shahriar Hojati Emami; Sasan Jalili; Ali Mohammad Sharifi
Volume 3, Issue 4 , June 2009, Pages 315-324
Abstract
Cell therapy based on cell encapsulation technology holds out the promise of the treatment of many diseases. The technology of cell encapsulation represents a strategy in which cells that secrete therapeutic products are immobilized and immunoprotected within polymeric and biocompatible carriers. Hydrogels ...
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Cell therapy based on cell encapsulation technology holds out the promise of the treatment of many diseases. The technology of cell encapsulation represents a strategy in which cells that secrete therapeutic products are immobilized and immunoprotected within polymeric and biocompatible carriers. Hydrogels - highly hydrated polymer networks- have ideal characteristics for this application because of good biocompatibility and mimicking natural ECM properties. They can homogeneously incorporate and suspend cells, growth factors, and other bioactive compounds. Temperature-sensitive hydrogels, which can form implants in situ in response to temperature change, from ambient to body temperature, have been extensively used in various cell encapsulation, and tissue repair. The objective of this study was preparation, Characterization and selection the optimum composition of agarose-gelatin blend hydrogel, for cell encapsulation application. In order to obtain hydrogel with appropriate properties, rheological, mechanical, and structural characteristics of obtained hydrogels were examined. Furthermore, the stability of samples was characterized by degradation and gelatin release measurements under physiological condition. Cell attachment and cytotoxicity analysis were also performed. Based on the results, hydrogel containing a 1:1 mixture of gelatin and agarose exhibited sol-to-gel transition near body temperature. Samples contain 50% agarose and more, exhibited mechanical integrity under physiological condition. Indentation test of the mechanical properties demonstrated viscoelastic behavior of the blend gelatin-agarose hydrogels under static load; however by increasing the agarose portion, hydrogel behaved more elastically. In vitro biocompatibility experiments showed undetectable cytotoxicity of the hydrogels. Also adding gelatin to agarose modified cell attachment behavior. The results of this study indicate the possibility of the potential use of prepared thermo-responsive agarose/gelatin conjugate with nearly same portion of two components as cell encapsulation carrier.
