Papers by Keyword: Cartilage

Abstract: Tissue engineering (TE) is a modern medical approach to reconstruct damage tissue in a shorter period. Scaffold is the main structure for cells adhesion and provides 3D space for cell proliferation and growth. Biomaterials were selected to fabricate a scaffold according to properties and target tissues. In this study, Hydroxyapatite (HA), Silk Fibroin (SF), and Chitosan (CS) were selected to fabricate the scaffold in different combination ratios by freeze drying (FD) technique. According to the physical properties of the fabricated scaffold, cartilage tissue was selected as a study target area for the future medical application. Scaffold characterization was performed to observe the scaffolds properties in each materials ratio. In this study, CS scaffold provided highest abilities which related to cartilage tissue structure. Moreover, the combination of SF in CS provided highest ability for cartilage cell proliferation in vitro. Therefore, CS could be used as a cartilage scaffold for cartilage TE and SF could be added to increased the cells viability of the scaffold.

Abstract: Composite hydrogels on the basis of hydroxyapatite (HAp) and polyvinyl alcohol (PVA) has been proposed as a promising materials for bone and cartilage tissue engineering. HAp/PVA composite hydrogels with phase ratio 50:50wt% and 70:30wt% were obtained via in situ wet chemical precipitation technique in combination with the freeze-thawing approach. The XRD studies of sintered products revealed that HAp/PVA composite hydrogels synthesized from PVA with degree of hydrolysis (DH) 98% and molecular weights (MW) 25 kDa and 78 kDa are more suitable for biomedical purposes due to the formation of stoichiometric HAp. Swelling studies indicated that HAp/PVA 50:50 (78 kDa, 88% and 98%) hydrogels after 24h of immersion swell ~4.25-6.5 times less than identical samples with phase composition of 70:30wt%, which is accounted to different number of intermolecular hydrogen bonds formed. After 16 subsequent freeze-thawing cycles (FTC), HAp/PVA 50:50 (78 kDa, 88% and 98%) hydrogels contain ~1.2 times higher content of crosslinked PVA than HAp/PVA 70:30 (78 kDa, 88% and 98%) hydrogel samples.

Abstract: Knee malalignment is considered one of the key biomechanical factors that influence the progression of knee osteoarthritis. In this context, a three-dimensional Finite Element model of the knee joint is developed and used to investigate the effect of the frontal plane femoro-tibial angle as well as the body weight load on the stress distribution in the knee cartilage and menisci. Therefore, the knee joint model is obtained through CAD software. Bones, articular cartilage and menisci are considered linear, elastic and isotropic materials. Ligaments were modelled using connectors. Consequently, contact pressures and equivalent stress (von-Mises) are calculated in Abaqus software. This model was validated using experimental and numerical results obtained by other authors. Results of this work demonstrated that; compressive stress and contact pressure on the medial compartment of the knee joint were found to be larger compared to those in the lateral compartment when the femoro-tibial angle and the body weight load increased from 0° to 12° varus and 500 N to 1250 N, respectively, suggesting that these two parameters might be risk factors for developing medial compartment knee osteoarthritis.

Abstract: The purpose of this research was to study the synovial fluid diffusion behavior involved in articular cartilage and evaluation of some parameters, which affecting the cartilage degeneration, such as the porosity, surface permeability, fluid concentration and etc. For the analysis, it was to implement the triphasic theory into a mathematical model and a commercial finite element method to solved practical problems in cartilage mechanics. The experimental results of confined compression of articular cartilage were found that the factors affecting to fluid diffusion in cartilage were the surface permeability, the porosity of structure, the change of solute concentration and dynamic loading on articular cartilage.

Abstract: The most advanced options nowadays available in joint arthroplasty rely on the application to diseased joints of human-made bearing surfaces consisting of microstructurally engineered polyethylene and ceramics as substitutes for the damaged joint cartilage and, partly, for bone. However, it is progressively becoming clear that, whatever superior the biomaterial designed for this purpose, owing to the quite severe structural requirements for human joints, including high contact stresses and aggressive environment at the load-bearing surface, it will have a necessarily limited service lifetime. Giving a quite critical but fundamentally true statement, one could say that, so far, no single product has yet been capable to meet all such severe requirements. Moreover, it is not clear if such a perfect biomaterial will ever exist. This is the main reason for pursuing repair (rather than replacement) of damaged cartilage. In this paper, we inquire about the present status and expected progress in healing osteoarthritis (OA) of chronically damaged joints, and surmise that such innovative procedures could sometime, in the near future, replace the current joint arthroplasty procedures, thus avoiding the unavoidably intrusive surgery associated with nowadays total joint replacements. After reviewing the state of art in the new field of joint cartilage healing, we shall stress the potential importance of vibrational spectroscopy both in diagnostics and in accelerating discoveries through the future developments of therapeutic approaches to cartilage diseases.

Abstract: In this work a novel three-dimensional ostechondral substitute is proposed that is made of an inorganic/organic hybrid material, namely collagen/hydroxyapatite. The two components of the substitute have been characterized separately. The inorganic part, a hydroxyapatite scaffold, was fabricated by a polymer sponge templating method using a reactive sub-micron powder synthesized in our laboratory by hydroxide precipitation sol-gel route. The organic part, a collagen scaffold, was fabricated by a freeze-dying technique varying design parameters. Both the parts were analysed by scanning electron microscopy and their mechanical properties assessed by compression tests. The hydroxyapatite scaffold showed a high and highly interconnected porosity and a mechanical strength equal to 0.55 MPa, higher than those reported in literature. The collagen scaffolds were seeded by chondrocytes, processed for histology analysis and tested in compression. The biological tests proved the ability of the scaffolds to be positively populated by chondrocytes and the mechanical analysis showed that the mechanical strength of the scaffolds significantly increased after 3 weeks of culture.

Abstract: In the present study, we have demonstrated that alginate and collagen sponge can act as scaffolds in order to support 3-dimensional structure for the differentiated bone marrow derived mesenchymal stem cells (BMSCs) during chondrogenesis in vitro and in vivo. The chondrogenic induced BMSCs were well distributed and differentiation in scaffolds system before implantation, then they produced sufficient ECM in the implants to form chondroid aggregates in vivo. In our opinion, well-differentiated BMSCs is a crucial feature of cartilage repair and only can be achieved in scaffold matrix. Furthermore, when dealing with cartilage defects, alginate seem to be superior to collagen sponge, and the combinational strategy of pre-induced BMSCs combined with alginate 3D-culture might be useful in improving conventional autologous cells transplantation or free-cells scaffolds.

Abstract: Carbon nanotubes (CNTs) are composed of two-dimensional hexagonal graphite sheets rolled up to form into a seamless hollow tube or cylinder of diameters ranging from 0.7 to 100 nm and length of several micrometres up to several millimetres [1, 2]. CNTs can be synthesised in two configurations, as single-walled nanotubes (SWCNTs) and multi-walled nanotubes (MWCNTs). Whereas SWCNTs are made of one tubular structure, MWCNTs consist of concentrically arranged carbon tubes with a typical spacing of ≈ 0.34 nm between the different layers. Owing to their remarkable structural characteristics (light weight, high aspect ratio, high specific surface area), as well as attractive mechanical (high stiffness and strength), electrical (high conductivity) and chemical (versatile surface chemistry, easily to functionalise) properties [2], there is increasing interest in biomedical applications of CNTs.

Abstract: Hip hemiarthroplasty is a popular method for curing hip joint diseases. Comparing with the total hip replacement (THR), hip hemiarthroplasty has some advantages, such as simpler operation, lower cost and less injury. However, inevitable acetabular cartilage wear, which leads to ultimately conversion to THR, has been reported by many authors. That limits its applications. To solve this problem, more suitable biomaterial should be chosen to make the femoral head. In this research, a kind of carbon femoral head, which was made of graphite coated with low temperature isotropic pyrolytic carbon, was studied in vivo. Nineteen New Zealand adult white rabbits were divided into 3 groups. Every rabbit was taken the replacement operation and time-dependently killed after certain periods. X-ray photographs of the hip joint, macroscopic apperarance and histological morphometry of the neocartilage around the prosthesis, were examined. The results proved that the coating material of the femoral head was biocompatible and the neocartilage tissue around the prothetic head might protect the acetabulum from wear. However, because of the complicated physiological environment, further research is needed.

Abstract: Many biomaterials have been developed to replace articular cartilage. One of these materials, polyvinyl alcohol (PVA) hydrogel is proposed to be used as artificial cartilage in joint replacement. To better understand the differences between human articular cartilage and PVA hydrogel, microstructure analysis and unconfined compression were developed. In microstructure analysis, the surface of articular cartilage was smooth and free from any significant morphological features. Some small holes were found in the surface and cross-section of PVA hydrogel. The porous structure of PVA hydrogel was observed clearly by Environmental scanning electron microscopy (ESEM). In unconfined compression tests, the compression modulus of articular cartilage was higher than that of PVA hydrogel. In the creep tests, the strain value of articular cartilage was lower than that of PVA hydrogel all the time. It is indicated that the microstructure of each material has a great influence on their biphasic property which related to their mechanical behavior.