Sharif Digital Repository

In general, repair and regeneration of damaged tissues or lost organ is base definition of a technology named tissue engineering. Tissue engineering technology provides innovative path to achieve better medical treatment, including different methods which manipulate natural or synthetic biomaterials mimicking stem cells environmental condition inside the body, in order to facilitate desired cell expansion and differentiation. Recently, application of cell carriers in form of microcarriers which are injectable, biodegradable and biocompatible have attracted significant attention. Due to increasing effectiveness in animal cell culture.
The aim of this work was fabrication of... 

Major bone defects resulted from diseases or hurts that can not heal naturally, requaire bone transplantation. golden standard for transplantation is autologus one but it has some disad-vantages such as economic burden, the lack of graft source, surgery on patient, and so on. so exploring altrnative ways led to exploit stem cells.traditionally bone marrow mesenchymal stem cells (MSCs) used for stem cell-bsaed bone regeneration. bone marrow aspiration to aquaire stem cells is painfull and give a population of cells such as hematopoetic cells that requaire to seperate and can not be handled in first passages. MSCs can be substituted by multipotent adipose tissue-derived stem cells (ADSCs) in... 

Tissue engineering is an interdisciplinary field that incorporates principles of engineering with the life sciences. Tissue engineering consists of three principle; cells, scaffolds for cells expansion and growth factors. These factors together can help tissue engineers to provide appropriate microenvironments for directing special cells behavior.
Fibrous scaffolds have found many applications in tissue engineering due to their nanometer dimensions and high surface to volume ratio. Fibrous scaffolds can impart mechanical strength, structure for cell attachment and act as reservoirs for biomolecule delivery in much a same way as the natural fibrous components of the extracellular... 

In recent years, many studies have conducted research about stem cells due to their prominent features such as proliferation and differentiation. By changing the specific parameters of the cellular micro-environment, it is possible to determine the stem cells fate and thereby use them in medical affairs. For this purpose, various devices and methods have been designeds such as microfluidic devices and scaffolds. The microfluidic devices has been especially focuced in the researchs due to their unique features, like the possibility of testing with small amounts of samples, the creation and control of low cost cellular micro-environment and low practical time. Two-dimensional scaffolds made up... 

Since its successful synthesis as single layer during the past decades, Graphene and its derivatives have been extensively employed by many researchers in various science and engineering fields. The studies to characterize and define graphene behaviour are still in demand to answer the questions around these structures. The unique feathures of graphene such as high strength, good conductivity, large available surface, intoxicity and biocompatibility, has made it a suitable candidate to used in novel structures and materials. In this work, hybrid structures made from graphene and carbon nanotubes are investigated which can be utilized as scaffolds in tissue engineering.After an introduction... 

Graphene nanogrids fabricated by graphene nanoribbons obtained through oxidative unzipping of multi-walled carbon nanotubes, used as two-dimensional selective templates for accelerated differentiation of human mesenchymal stem cells (hMSCs), isolated from umbilical cord blood, into osteogenic lineage. The biocompatible and hydrophilic graphene nanogrids showed high actin cytoskeleton proliferations that coinciding with patterns of the nanogrids. The amounts of proliferations found are slightly better than proliferation on hydrophilic graphene oxide (GO) sheets, and significantly higher than non-uniform proliferations on hydrophobic reduced graphene oxide (rGO) sheets and polydimethylsiloxane... 

The heart diseases and in particular coronary artery disease have been vastly increased in recent years. Bypass operation is the major recognized way of this disease treatment however, one third of patients don’t have the suitable autologous vein for this operation. It should be noted that for this operation a suitable conduit with diameter as narrow as possible is needed. On the other hand, usage of synthetic polymers won’t be suitable for this operation due to the coagulation forming. The only way to overcome this problem is the use of tissue engineering with the aid of scaffold and autologous cells with the natural tissue function, which reconstructed the desire tissue causing no... 

Molecularly imprinted polymers (MIPs) with synthetic recognition sites are capable of detecting and separating chemical species in complex environments. These characteristics are of increasing interest for bioanalytical applications. The chief advantages of MIPs are mechanical and chemical stability, low cost, and ease of preparation. Recently, imprinting technology has been used for fabrication polymer thin films with recognition sites of proteins, plant viruses, and yeasts. Also few investigations applied lithography for synthesis of cell imprinted polymers targeting cell detection and observation of cell morphology.
For the first time, we demonstrate surface imprinting for the... 

In this study, differentiation of rabbit embryonic-derived mesenchymal stem cells to osteogenic cells has been characterized. Bone tissue engineering is based upon the understanding of bone tissue construct and it’s formation in-vivo, and the Preparation of tissue engineered bone constructs to repair large size defects is it’s major goal. We sought to investigate the combined effect of three elemnts of tissue engineering: cells, scaffolds and growth factors. Mesenchymal stem cells are unspecialized cells which due to their unlimited self-renewal capacity and the remarkable ability to differentiate along multiple linage pathways are natural choice for application in tissue repair and... 

Microcarriers (MCs) are an attractive technology with various applications in tissue engineering. In this study, chitosan/gelatin MCs were fabricated with blends of different ratio of chitosan/gelatin, by using a setup containing high voltage electrostatic field and syringe pump. Optimization of blend ratio, voltage and syringe pump flow carried out by the “Design expert” software leads to fabrication of MCs with constant diameter while having various elasticity. Mechanical strength and elasticity of MCs were determined. Human umbilical cord mesenchymal stem cells (hUCMSCs) were cultured on MCs dynamically by using mini-rocher in an incubator. Cells adhesion on MCs were successfully shown by... 

Centrifugal microfluidic systems due to their unique properties, including the ease of sample transfer, high controllability, the need for samples and reagents in a small volume scale, the possibility of embedding a complete laboratory and modeling a variety of processes on a disk, they have great potential to be used in the field of point of care diagnosis. Such devices can perform several different processes simultaneously and continuously by using inertial and pneumatic forces as well as a complex network of microchannels. The purpose of this research is to design and build a centrifugal microfluidic disc for lysing amniotic stem cells, followed by DNA extraction, in order to detect fetal... 

Cancer is one of the leading causes of death worldwide, and despite all the advances in medical science, there isn't any definitive cure for it, yet. Researchers have recently considered the presence of cancer stem cells with the capability of tumorigenesis, invasion, metastasis, self-renewal, etc. as the main cause of inefficiency of cancer treatment. It means current therapies are able to kill the tumor mass, but they are not successful in confront of cancer stem cells and this causes the disease to recur a while after the apparent recovery. To study these specific cells, in this project, first the population of cancer stem-like cells was increased in the cancer cell mass, in other words,... 

The aim of this dissertation is to investigate and determine the optimal composition of hydrogels that can meet the needs of stem cells for the growth and proliferation of mesenchymal stem cells. In this research, firstly, unfunctionalized and functionalized mesoporous silica nanoparticles (with an average diameter of approximately 90 nm), were synthesized. Scanning electron microscopy and zeta potential measurement were utilized to study their morphology and surface charge. Then, graphene oxide nanosheets were synthesized. Field emission electron microscopy, zeta potential measurement and Fourier transform infrared spectrum analysis were used to examine their morphology, surface charge and... 

Nowadays, tissue engineering and stem cells-based therapies have outlined a promising prospect in neural networks regeneration. But it usually requires biocompatible and conductive scaffolds for culturing neural stem cells and directing their differentiation toward the neurons. Graphene due to its unique physical and chemical properties has attracted much interest in tissue engineering. For this purpose, in this study biocompatible graphene oxide foams have been used for neural stem cell culturing. For the first time, graphene oxide foam were fabricated by precipitation of chemically exfoliated graphene oxide sheets in an aqueous suspension onto the PET substrate at ~80 oC under UV...