Sharif Digital Repository

Bone scaffolds are combinations of several materials, for achieving suitable properties and usage for replacing with defected bone. In this study, TCP/Agarose scaffolds are fabricated by two different approaches. The first one is using polymer sponge and gel casting technique and the other one is using foaming agent in order to obtain scaffolds with same porosity. The results show that in spite of same structure and porosity, scaffolds have different mechanical properties due to their different morphologies. Compressive strength of the scaffolds which were fabricated using polymer sponge method is 2.25MPa and elastic modulus is 56.8MPa. After coating with Agarose, compressive strength... 

Mechanical behavior of tissue engineering scaffolds plays a key role in their biological performance; however the effect of microstructural features on mechanical behavior of such scaffolds is still under investigation. The objective of this study was to investigate the influence of pore architecture and relative density on mechanical behavior of rapid prototyped scaffolds. In this regard, scaffolds with different cubic, hexagonal and trigonal unit cells were designed. These unit cells were repeated in different arrangements in 3D space to produce different nodal connectivities. The internal dimension of pores varied from 500 to 600 μm. Plastic models of scaffolds then fabricated by 3D... 

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... 

This project aimed to fabricate the bone scaffolds with applying thermoplastic starch-based nano-biocomposites. The starting materials for this scaffold are as follows: thermoplastic starch, ethylene vinyl alcohol as the polymer matrix and nanoforsterite as the ceramic reinforcing phase. Furthermore, vitamin E was used as antioxidant for preserving starch against thermo-mechanical degradations. Likewise, 3D pore structure was developed using azo-dicarbonamide and water in injection moulding process. With blending thermoplastic starch and ethylene vinyl alcohol, some thermoplastic starch’s properties including degradation rate and water absorption were modified. In addition, having... 

Nerve repair plays a very prominent and significant role among the efforts that have been made to integrate the concepts of tissue engineering in strategies to repair almost all parts of the body. This is partly due to the complexity of the nervous anatomy system and its function as well as the inefficiency of conventional repair methods that are based on a component of biomaterials or cells alone. Studies show that electrical stimulation can enhance the nerve regeneration process; so the use of conducting polymers has attracted much attention for the construction of neural tissue engineering scaffolds. In this study, the electrical properties of neurons and the effects of electrical... 

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... 

The heart stoke which happens due to an obstruction in the coronary artery can result in the presence of a dead part on the heart muscle called Myocardial Infarction (MI). MI can lead to next heart strokes and even the death of the patient. So far, a great number of biomaterials consisting of natural and synthetic polymers and Extra Cellular Matrix (ECM) of human body have been recommended for being used in tissue engineering approaches aiming to rehabilitate the infarcted site. The use of ECM is recommended for mimicking the microenvironment of the body as much as possible which can be very helpful in proliferation of the cultured cells. In this project, we fabricated a composite... 

Chronic wounds are among the serious injuries which have called the attention of scientists to invest in an effort to fabricate temporary skin grafts and wound dressing materials. One of the widely acceptable solutions to this obstacle is to design a bioactive scaffold capable of regenerating tissue as well as delivering active agents to the site specific area. To this end, natural biopolymers are considered as suitable candidates to be employed in regenerative medicine due to their excellent biocompatibility. In addition, nanoparticles possess special properties such as the ability in sequestering the drug release which make them promising candidates in the fabrication of the... 

Once damaged, articular cartilage has very little capacity for spontaneous healing because of the avascular nature of the tissue. Although many repair techniques have been proposed over the past decades, none has successfully regenerated long-lasting tissue to replace damaged cartilage. Tissue engineering have recently demonstrated tremendous approaches for regeneration of cartilage tissue lesions. Tissue engineering is based on three principles: cells, scaffolds for cell adhesion and growth factors. Three-dimensional biodegradable scaffolds play an important role in tissue engineering. In this study, novel cross-linked hybrid chitosan/ECM scaffolds were prepared for articular cartilage... 

Cartilage is an avascular tissue, having limited ability to repair itself. Since the methods for treatment of cartilage defects have been not effective, in recent years, new therapies based on tissue engineering are considered.This paper reports on the development of porous microcarriers composed of acellular matrix of cartilage and natural polymer chitosan. Microcarriers were prepared by electrospray method. Results of mechanical tests, SEM imaging, water uptake behaviour, biodegradation test, and MTT assay demonstrated that the microcarriers composed of 2% (wt) chitosan and 1% (wt) ECM has the best potential for growth and proliferation of primary chondrocyte cells. These results... 

In present work, hydroxyapatite nano-rods are synthesized using a simple sol-gel method with calcium nitrate and potassium dihydrogenphosphate as calcium and phosphorus precursors respectively and ammonia was used for adjusting the pH=9. To obtain rod shape hydroxyapaite powder, multi wall carbon nanotubes were added to the solution, nHA powder was calcinated at 60 and 450 ℃. In second step, chitosan-gelatin/nanoHA solution were prepared by blending chitosan and gelatin in different concentrations with nanoHA powder, then the solution was freeze dried to maintain a composite scaffold. The prepared HA powder and bio-composite scaffold were characterized by X-ray diffraction (XRD), field... 

Following heart coronary artery occlusion, heart stroke (HS) happens which leads to the creation of a dead zone on heart tissue named Myocardial Infarction (MI), the presence of which on a patient’s heart will result in succeeding HSs and the death of the patient. In this study, porous microcarriers capable of being utilized in cardiovascular tissue engineering is fabricated using a mixture of myocardium ectracellular matrix (ECM) and Chitosan (Cs). Results of Elasticity tests, SEM images, swelling behavior, biodegradability test, and cell proliferation assay showed that the scaffold consisting of 3.5% (w/w) Chitosan and 0.66% (w/w) ECM has the best potential in providing cardiovascular... 

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... 

The main goal of this project is to fabricate the scaffolds including Polycaprolactone and Polyvinyle alcohol nanofibers in order to use as artificial skin. For this purpose, electrospinning parameters have been optimized for various injection rates and the scaffolds containing different percent of PCL and PVA have been made. By investigating the cell growth on these scaffolds, the one made up PVA/PCL (30% ) has been introduced as the best scaffold. To improve biological properties of chosen scaffold, a layer of collagen was coated. The angiogenesis capacity has been improved by adding Heparin to PVA nanofibers. Based on assay of heparin release, it was shown that Heparin is released within... 

Cardiovascular disease is responsible for a majority of health problem in developing countries. Heart diseases are the leading cause of death in the United State with approximately 40% of the death occurs by heart failures and coronary artery defects. Myocardial infarction is one of the diseases that occurs by coronay artery blockage. Cardiac tissue engineering (CTE) is an emerging field that holds great promise towards the development of innovative treatment strategies for heart disease. There are two common scaffolds for CTE, electrospun fiber mats and hydrogels. Although fibers are known as 3D environment for cells, they actually act as a 2D surface, because of lack of cell infilteration.... 

The the nervous system as a most comlicated body system , plays an important and vital role for the body systems. damage to the peripheral nervous system result in nervous system disorders which claissified to Neuropraxia, Axonotmesis and Neurotmesis based on damage itensity. tissue engineering considered as one of the repairing nervous damage way, which by creating 3D substrat (scaffold) with proper physical structure, increses possibility of adhesion, growth and proliferation of cells to increase regeneration rate of damaged nerve. in this study, a combination of dual-electrospinning and rolling the spun film used to preparate a nerve guidance conduit (NGC) based on gelatin, PCL and... 

A novel thermo responsive decorated system is designed by coating Fe3O4 magnetic nanoparticles with conjugated Pluronic-ATPEG copolymer incorporated into the PEG-PMDA Hydrogel for drug delivery to the cartilage tissue. Grafted copolymer was synthesized by reaction between carboxylated Pluronic and amino terminated Poly ethylene glycol (ATPEG) and confirmed by FTIR and NMR analysis. The magnetic nanoparticles were modified with the produced copolymer and characterized by TEM, HRTEM, XRD, DLS, and VSM. A typical product has 13 nm magnetic core and 105 nm hydrodynamic diameter with narrow size distribution. DLS results showed that there was an increase in size by increasing temperature from 25℃... 

In this work, wool keratin/polyethylene oxide (PEO) nanofibrous scaffolds were fabricated by electrospinning method. Bacterial cellulose nanofibrils (BCNFs) were embedded in the electrospun keratin/PEO nanofibers. Incorporation of BCNFs into the nanofibers enhances their hydrophilicity, mechanical properties and cell viability, adhesion and proliferation. Water contact angle of the nanofibers decreased from 126˚ to 83˚by addition of 1 wt % BCNFs. A thermogelling hydrogel based on carboxylated pluronic (Pl-COOH) and gum tragacanth (GT) was fabricated and polymer conjugation was confirmed by FTIR and H-NMR spectroscopy. Morphological and viscoelastic properties of GT-grafted Pl-COOH hydrogels... 

Methods that has been used for articular defects are faced with many limitations, so new therapies based on tissue engineering were taken into consideration in recent years. However, tissue engineering also encounters challenges regarding optimal scaffold construction and suitable cell source selection. Mature harvested chondrocytes are limited in number and may lose their chondrogenic potential in several cultures, leading to dedifferentiation. In addition, using stem cells also presents unique challenges associated with them, among which hypertrophic differentiation is the most substantial problem. Choosing the appropriate biomaterial similar to the cartilage structure with sufficient... 

Generally, the concept of producing ‘spare parts’ of the body for replacement of damaged or lost organs lies at the core of the varied biotechnological practices referred as tissue engineering. Tissue engineering is an interdisciplinary field that incorporates principles of engineering with the life sciences. Tissue engineering is based on three principle; cells, scaffolds for cells expansion, attachment as an environment like ECM and growth factors. These things together can help tissue engineers to provide microenvironments which are suitable for special cells. The most important thing in this kind of works is the ability to simulate environment for cells the same as body. According to the...