Sharif Digital Repository

Articular cartilage Function is vital to joint tasks and its motion. The main biomechanical tasks of articular cartilage are a) the distribution of loads occurred in joints; b) providing joints with frictionless surface. The particular mechanical properties of articular cartilage make it possible for the Cartilage tissue to do its duty successfully. The biological factor that causes articular cartilage to damage is still unknown. It is believed that mechanical factors are the main reason for the cartilage destruction in osteoarthritis. Factors like age, heavy exercises and impact can begin tissue destructions and result in change in mechanical properties. To study the process of the... 

In this study, mechanical behavior of soft tissue is investigated considering its hierarchical structure. The elastic and viscoelastic behavior of tissue is investigated using multisclae methods. To this end, the tissue is considered as nonlinear composite material consists of non fibrillar matrix reinforced by the collagen fibers. A physically motivated constitutive model is proposed to predict the tisues constitutents behavior. The numerical homogenization is preforemd with the aid of the ABAQUS software and the UMAT subroutine. The results of the presented study is validated with the available experimental results in the literature. Results show that the increasing the loading rate can... 

In this study, lyophilized advance platelet rich fibrin (A-PRF) was used in combination with collagen membrane for the first time to accelerate bone regeneration as a result of growth factor release. Firstly, collagen was extracted from calf skin and analyzed using SDS-PAGE. FTIR has shown that EDC/NHS were chemically crosslinked collagen to collagen and collagen to chitosan. The morphology of collagen, collagen/chitosan composite membrane with different chitosan content, lyophilized A-PRF attached to membrane were showed using SEM images. The pore sizes were varied from 100 to 300 µm. Response surface methodology (RSM) was used to design experimental condition and to correlate the effect... 

Corneal diseases are one of the most common causes of blindness worldwide. The most common way to treat these diseases is to replace the damaged cornea with the donor cornea by corneal transplant. But limitations such as donor tissue deficiency, the risk of disease transmission and transplant rejection have made treatment of these diseases very difficult. A cornea made by tissue engineering can be used as a suitable alternative because of the limitations mentioned for corneal transplantation with donated tissue. At the same time, similarity of the scaffold to normal corneal tissue, both in terms of matrial and structural properties, is essential for proper repair of this scaffold by cells... 

Platelet Rich Plasma (PRP) is a blood-derived product containing concentrate of platelets, which are a rich source of autologous growth factors. PRP injection has been used clinically as a therapeutic method for cartilage repair. However, clinical efficiency of this method is unpredictable, maybe as a result of burst release of growth factors then fail cell-stimulating potential as most biomolecules are cleaned before they can exert a therapeutic effect. The aim of this project was to prepare a suitable scaffold for PRP delivery to regenerate cartilage injuries. In order to resemble polysaccharide-protein nature of the cartilaginous extracellular matrix, in this study, we developed an... 

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... 

Understanding biological systems requires extensive knowledge of individual parameters, and to study the processes of cell differentiation and cell behavior, a suitable environment must be created with the physiological conditions of the human body. For this purpose, with the knowledge of microfluidics, a microenvironment can be provided to study the behavior of cells on a small scale. The use of bone tissue model microfluidic chips is an alternative and new method in which it is possible to study the behavior of cells to differentiate into bone and to examine the toxicity of drugs, which in itself can help in the effective and successful treatment of these cases show. Therefore, in this...