• Proceedings of the Materials Research Society of Korea Conference
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• 2009.05a
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• pp.47.1-47.1
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• 2009

Nanostructured biomaterials have increased those potential for utilizing in many medical applications. In this study, benefit of nanotechnology for the response with biological targets will be described in terms of size, effective surface area and surface energy (physical aspect). Also, correlations between physical and biological interactions (greater protein adsorption on nano surface roughness) will be discussed for understanding biocompatibility of nanostructured biomaterials including carbon nanotube composites and nanostructured titanium surfaces. In the application parts, various major tissue cells, such as bone, cartilage, vascular and bladder cell responses will be discussed with suggested nanomaterials. Lastly, immune responses with macrophage (adhesion and several major cytokines) on nanostructured biomaterials will be described for evasive immune response.

• Polymer(Korea)
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• v.36 no.6
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• pp.789-794
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• 2012

Poly(lactic-co-glycolic acid) (PLGA) has been most widely used due to its advantages such as good biodegradability, controllable rate of degradation and metabolizable degradation products. We manufactured composite scaffolds of PLGA scaffold penetrated DBP gel (PLGA/DBP gel) by a simple method, solvent casting/salt leaching prep of PLGA scaffolds and subsequent soaking in DBP gel. Chondrocytes were seeded on the PLGA/DBP gel. The mechanical strength of scaffold, histology (H&E, Safranin-O, Alcian-blue) and immunohistochemistry (collagen type I, collagen type II) were performed to elucidate in vitro and in vivo cartilage-specific extracellular matrices. It was better to keep the characteristic of chondrocytes in the PLGA/DBP gel scaffolds than that PLGA scaffolds. This study suggests that PLGA/DBP gel scaffold may serve as a potential cell delivery vehicle and a structural basis for in vivo tissue engineered cartilage.

• Progress in Medical Physics
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• v.20 no.2
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• pp.62-71
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• 2009

Recently, optical coherence tomography (OCT) has demonstrated considerable promise for the noninvasive assessment of biological tissues. However, OCT images difficult to analyze due to speckle noise. In this paper, we tested various image processing techniques for speckle removal of human and rabbit cartilage OCT images. Also, we distinguished the images which get with methods of image segmentation for OCT images, and found the most suitable method for segmenting an image. And, we selected image segmentation suitable for OCT before image reconstruction. OCT was a weak point to system design and image processing. It was a limit owing to measure small a distance and depth size. So, good edge matching algorithms are important for image reconstruction. This paper presents such an algorithm, the chamfer matching algorithm. It is made of background for 3D image reconstruction. The purpose of this paper is to describe good image processing techniques for speckle removal, image segmentation, and the 3D reconstruction of cartilage OCT images.

• Tuberculosis and Respiratory Diseases
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• v.52 no.1
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• pp.54-61
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• 2002

Background: Tracheal stenosis is an urgent but uncommon disease. Therefore, primary care clinicians have limited clinical experience. Animal models of a tracheal stenosis can be used conveniently for the learning, teaching, and developing new diagnostic and therapeutic modalities for tracheal stenosis. Recently, a canine model of a tracheal stenosis was developed using a Nd-YAG laser. To describe the methods and results of developed animal model, we performed this study. Methods : Six Mongrel dogs were generally anesthetized and the anterior 180 degree of tracheal cartilage of the animal was photo-coagulated using a Nd-YAG laser. The animals were bronchoscopically evaluated every week for 4 weeks and a pathologic evaluation was also made. Results : Two weeks after the laser coagulation, the trachea began to stenose and the stenosis progressed through 4 weeks. All animals suffered from shortness of breath, wheezing, and weight loss in the 3 weeks after the laser treatment, and two died of respiratory failure just before the fourth week. The gross pathologic findings showed the loss of cartilage and a dense fibrosis, which resulted in a fibrous stricture of the trachea. Microscopy also showed that the fibrous granulation tissue replaced destroyed cartilage. Conclusion : The canine model can assist in the understanding and development of new diagnostic and therapeutic modalities for tracheal stenosis.

• Archives of Plastic Surgery
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• v.33 no.5
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• pp.616-620
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• 2006

Purpose: The isolated human chondrocytes for cartilage reconstruction and transplantation presents a major problem as these cells would change biologically in vitro. For more effective applications of these cells in the clinical field, it is necessary to get a large amount of cells in a short period without affecting their function and phenotype. Methods: This study reports the effects of placenta extract on chondrocytes in vitro. We initiated this study on the basis of the hypothesis that placenta extract can influence both the proliferation of chondrocytes and their biologic functions(for example, to express cell specific gene or to produce their own extracellular matrix). Chondrocytes in monolayer culture with or without placenta extract were collected and analyzed by MTT assay, ECM assay, and RT-PCR. Results: Placenta extract stimulated the proliferation of chondrocytes in monolayer culture. The phenotype of chondrocytes was well maintained during the expansion in monolayers. Chondrocytes expanded in the presence of placenta extract produced ECM, glycosaminoglycan, abundantly. Compared to chondrocyte expanded in culture medium only, chondrocytes expanded with placenta extract demonstrated higher COL2A1 expression that was biochemically comparable to primary chondrocytes. This study provides an evidence that placenta extract is helpful to expand chondrocytes during tissue cultivation, to maintain their differentiated phenotype and to promote their function. Conclusion: These results suggest that placenta extract during cultivation play an important role in controlling cell behaviors. Furthermore, these results provide a biologic basis for cartilage tissue engineering.

• Asian-Australasian Journal of Animal Sciences
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• v.19 no.2
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• pp.245-251
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• 2006

The aim of this study was to investigate the effects of caponization on the bone characteristics, biomechanical property and histology in Taiwan country chickens fed to market age of 26 wks. Male Taiwan country chickens $D{\times}L_2$ were caponized or sham-operated at 8 wks of age, and selected healthy sham-operated and completely caponized chickens (prominent degenerated comb) were selected at 16 wks old and fed to 26 wks old for the trials. Fifteen intact male chickens (Intact), sham-operated chickens (Sham) and caponized chickens (Capon) were assigned for trial 1, and sixteen Intact and Capon were assigned for trial 2. Results in trial 1 showed that the abdominal fat and relative abdominal fat weights of Capon were significantly heavier than Intact and Sham (p<0.05), while the tibia weight and relative weight were the lightest (p<0.05). The tibia breaking strength, bending moment and stress of Capon were the poorest among groups (p<0.05). The trial 2 produced the similar observation that Capon were significantly lighter than Intact (p<0.05) in the tibia weight, relative tibia weight and their biomechanical properties. On histological determinations, Capon showed a thinner cartilage end and fewer chondrocytes (about 50%) and trabecular, and bigger marrow cavity; while decreased hemopoietic cells number with increased adipocytes than Intact observed by H&E stain and at low magnification. At high magnification, Capon showed a decrease in the chondrocyte size by 33 to 50%, with smaller nucleus located near the cell membrane, and exhibited monocellular form chondrocytes. Capon also showed a less strongly acidic sulfated mucosubstance with weaker dyeing property within cartilage zone, and smaller chondrocytes size by Alcian blue stain.

• Journal of Embryo Transfer
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• v.27 no.3
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• pp.175-181
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• 2012

The synovial tissues are a valuable MSCs source for cartilage tissue engineering because these cells are easily obtainable by the intra-articular biopsy during diagnosis. In this study, we isolated and characterized the canine MSCs derived from synovial fluid of female and male donors. Synovial fluid was flushed with saline solution from pre and post-puberty male (cM1-sMSC and cM2-sMSC) and female (cF1-sMSC and cF2-sMSC) dogs, and cells were isolated and cultured in advanced-DMEM (A-DMEM) supplemented with 10% FBS in a humidified 5% $CO_2$ atmosphere at $38.5^{\circ}C$. The cells were evaluated for the expression of the early transcriptional factors, such as Oct3/4, Nanog and Sox2 by RT-PCR. The cells were induced under conditions conductive for adipogenic, osteogenic, and chondrogenic lineages, then evaluated by specific staining (Oil red O, von Kossa, and Alcian Blue staining, respectively) and analyzed for lineage specific markers by RT-PCR. All cell types were positive for alkaline phosphatase (AP) activity and early transcriptional factors (Oct3/4 and Sox2) were also positively detected. However, Nanog were not positively detected in all cells. Further, these MSCs were observed to differentiate into mesenchymal lineages, such as adipocytes (Oil red O staining), osteocytes (von Kossa staining), and chondrocytes (Alcian Blue staining) by cell specific staining. Lineage-specific genes (osteocyte; osteonectin and Runx2, adipocytes; PRAR-${\gamma}2$, FABP and LEP, and chondrocytes; collagen type-2 and Sox9) were also detected in all cells. In this study, we successfully established synovial fluid derived mesenchymal stem cells from female and male dogs, and determined their basic biological properties and differentiation ability. These results suggested that synovial fluid is a valuable stem cell source for cartilage regeneration therapy, and it is easily accessible from osteoarthritic knee.

• Biomaterials Research
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• v.22 no.4
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• pp.271-278
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• 2018

Background: The chondrogenic differentiation of mesenchymal stem cells (MSCs) is regulated by many factors, including oxygen tensions, growth factors, and cytokines. Evidences have suggested that low oxygen tension seems to be an important regulatory factor in the proliferation and chondrogenic differentiation in various MSCs. Recent studies report that synovium-derived mesenchymal stem cells (SDSCs) are a potential source of stem cells for the repair of articular cartilage defects. But, the effect of low oxygen tension on the proliferation and chondrogenic differentiation in SDSCs has not characterized. In this study, we investigated the effects of hypoxia on proliferation and chondrogenesis in SDSCs. Method: SDSCs were isolated from patients with osteoarthritis at total knee replacement. To determine the effect of oxygen tension on proliferation and colony-forming characteristics of SDSCs, A colony-forming unit (CFU) assay and cell counting-based proliferation assay were performed under normoxic (21% oxygen) or hypoxic (5% oxygen). For in vitro chondrogenic differentiation, SDSCs were concentrated to form pellets and subjected to conditions appropriate for chondrogenic differentiation under normoxia and hypoxia, followed by the analysis for the expression of genes and proteins of chondrogenesis. qRT-PCR, histological assay, and glycosoaminoglycan assays were determined to assess chondrogenesis. Results: Low oxygen condition significantly increased proliferation and colony-forming characteristics of SDSCs compared to that of SDSCs under normoxic culture. Similar pellet size and weight were found for chondrogensis period under hypoxia and normoxia condition. The mRNA expression of types II collagen, aggrecan, and the transcription factor SOX9 was increased under hypoxia condition. Histological sections stained with Safranin-O demonstrated that hypoxic conditions had increased proteoglycan synthesis. Immunohistochemistry for types II collagen demonstrated that hypoxic culture of SDSCs increased type II collagen expression. In addition, GAG deposition was significantly higher in hypoxia compared with normoxia at 21 days of differentiation. Conclusion: These findings show that hypoxia condition has an important role in regulating the synthesis ECM matrix by SDSCs as they undergo chondrogenesis. This has important implications for cartilage tissue engineering applications of SDSCs.

• Journal of the Korean Society for Precision Engineering
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• v.20 no.12
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• pp.198-204
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• 2003

The bone fracture healing is simulated by using one of the complex system rules, named cellular automata method. It is assumed that each cell has property of Bone, Cartilage or Fibrous connective tissue. Nine local rules are adopted to change the property of each cell against the mechanical stimulus, which consists of the strain energy density, and the existence of bone in the surroundings. Two dimensional sheep metatarsal model is considered and the bone fracture healing is simulated. The simulation results agree well with those obtained by using fuzzy logic model and experimental data. The cellular automata method found to be one of the simulation methods to express the bone fracture healing. The cellular automata method is expected to be effective in representing biological phenomenon.

• Proceedings of the PSK Conference
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• 2003.10b
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• pp.237.3-238
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• 2003

Tissue engineering may be adequately defined as the science of persuading the body to regenerate or repair tissue that fail to regenerate or heal spontaneously. In the various techniques of cartilage tissue engineering, the use of 3-dimensional polymeric scaffolds implanted at a tissue defect site is usually involved. These scaffolds provided a framework for cells to attach, proliferate, and form extracellular matrix(ECM). The scaffolds may also serve as carriers for cells and/or growth factors. In the ideal case, scaffold absorb at a predefined rate so that the 3-dimensional space occupied by the initial scaffold is replaced by regenerated host tissue. (omitted)