• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2004.11a
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• pp.362-366
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• 2004

Quantitative evaluation of substrates for cells is essential to understanding cell-material adhesive interaction and it is also necessary for the development of new biomaterials. Many cells on adhesive molecules will form an organization of actin into bundles and production of the large, highly organized structures termed focal adhesions. To better understand adhesion formations between cells and substrata, we have quantified the force required to displace attached cell. we allowed rabbit knee chondrocyte to attach on a substratum of microscope slide glass. Our results demonstrate that a force is required to detach cells is changed according to detachment time variation.

• Tribology and Lubricants
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• v.21 no.5
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• pp.236-240
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• 2005

In order to prepare for the suitable surfaces of implants or medical devices, quantitative evaluation of adhesion between cells and biomaterials is essential. To better understand adhesion formation between cells and biomaterials, we used the cytodetachment technique which measures the adhesive force of a single cell through changing the, culture time and detachment speed. The results showed that the adhesive force could be affected by the culture time of cells on the surface of materials and the detachment speed. Moreover, there was a large discrepancy among the adhesion strength measured by similar techniques conducted on the different cells and substrates. It can be 'concluded that the variation of the force measurement technique can seriously alter the level of the force required to detach a cell on the surface of materials.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2006.05a
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• pp.173-174
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• 2006

Understanding chondrocyte behavior inside complex, three-dimensional environments with controlled patterning of geometrical factors would provide significant insights into the basic biology of tissue regenerations. One of the fundamental limitations in studying such behavior has been the inability to fabricate controlled 3D structures. To overcome this problem, we have developed a three-dimensional microfabrication system. This system allows fabrication of predesigned internal architectures and pore size by stacking up the photopolymerized materials. Photopolymer SL5180 was used as the material for 3D scaffolds. The results demonstrate that controllable and reproducible inner-architecture can be fabricated. Chondrocytes harvested from human nasal septum were cultured in two kinds of 3D scaffolds to observe cell adhesion behavior. Such 3D scaffolds might provide effective key factors to study cell behavior in complex environments and could eventually lead to optimum design of scaffolds in various tissue regenerations such as cartilage, bone, etc. in a near future.

• Proceedings of the KSME Conference
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• 2007.05a
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• pp.1265-1270
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• 2007

Conventional methods for fabricating three-dimensional (3-D) scaffolds have substantial limitations. In this paper, we present 3-D scaffolds that can be made repeatedly with the same dimensions using a microstereolithography system. This system allows the fabrication of a pre-designed internal structure, such as pore size and porosity, by stacking photopolymerized materials. The scaffolds must be manufactured in a material that is biocompatible and biodegradable. In this regard, we synthesized liquid photocurable biodegradable TMC/TMP, followed by acrylation at terminal ends. And also, solidification properties of TMC/TMP polymer are to be obtained through experiments. Cell adhesion to scaffolds significantly affects tissue regeneration. As a typical example, we seeded chondrocytes on two types of 3-D scaffold and compared the adhesion results. Based on these results, the scaffold geometry is one of the most important factors in chondrocyte adhesion. These 3-D scaffolds could be key factors for studying cell behavior in complex environments and eventually lead to the optimum design of scaffolds for the regeneration of various tissues, such as cartilage and bone.

• Polymer(Korea)
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• v.36 no.3
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• pp.357-363
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• 2012

Surface-modified poly(L-lactic acid) (PLLA) films and scaffolds were treated with plasma discharge in oxygen gas and subsequently subjected to $in$ $situ$ grafting of acrylic acid (AA) in order to increase the cell compatibility. The surface of AA-grafted PLLA was converted to hydroxyapatite (HA)-deposited PLLA in stimulated body fluid (SBF). After the samples were immersed in phosphate-buffered saline (PBS), fetal bovine serum (FBS), normal saline, or cell medium, the water contact angles were significantly reduced on the surface of HA-deposited PLLA. Chondrocyte and osteoblast showed a higher attachment and cell proliferation on HA-deposited surfaces and in particular, it was confirmed that chondrocyte was considerably influenced by HA. However, osteoblast showed better cell proliferation on the surfaces immersed in FBS, cell medium or HA-deposited surface. In addition, the cell proliferation in 3D scaffolds was much higher than that on film type, irrespective of chondrocyte and osteoblast. Therefore, such surface-modified PLLAs are expected to be useful as organic-inorganic hybrid scaffolds in the regeneration of cartilage and bone.

• Polymer(Korea)
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• v.30 no.2
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• pp.168-174
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• 2006

To utilize as highly functional scaffolds for tissue engineering by improving hydrophobicity and cell compatibility of the exist polymer scaffolds, the biodegradable poly(L-lactic acid) (PLLA) films and scaffolds having the optimal hydrophilicity were prepared by in situ plasma treatment and grafting of a carboxyl acid-containing monomer, acrylic acid (AA) in the chamber. From the results of surface analyses, surface-modified nonporous PLLA film and dual pore scaffold surfaces showed high hydrophilicity due to the decrease in contact angle and the increase in carboxylic groups as compared with untreated PLLA control. In particular, among various surface modification methods, Ar(argon)+AA+AA sample prepared by Ar plasma and then acrylic acid treatments displayed lower contact angle and more carboxylic groups thar Ar/AA and Ar+TP(thermal polymerization) samples, indicating that Ar+AA+AA sample was optimally treated for improving its hydrophilicity. In the cases of surface modified nonporous PLLA films and dual pore scaffolds, the adhesion and proliferation of chondrocytes increased with increasing their hydrophilicity.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.18 no.3
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• pp.411-427
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• 1996

The purpose of this study was to observe the healing process and the distribution of fibronectin in injured condylar cartilage and bone by using LM and SEM. In order to perform this study, 40 male rat, weighing about 250g were selected. Under general anesthesia with Pentobarbital sodium, condylar cartilage and neck bone were resected. Then, the wound was irrigated with saline and closed with 5-0 chromic catgut and 4-0 silk by layer-to-layer suturing. The experimental rats were sacrificed by perfusion with 3% paraformaldehyde at 1st and 4th week after operation. The condylar process and surrounding tissues were cut, demineralized, dehydrated and embedded in paraffin. The histological observation of the specimens in LM level was performed after H-E stain and Azan stain. For localization of fibronectin, immunostaining was achieved by the avidin-biotin complex method. To study the change on condylar surface, the specimens were dehydrated, dried, gold coated and were observed with a scanning electron microscope(Hitachi S-2300). The results were as follows ; 1. The cartilage group and the bone group were repaired with epiphyseal cartilage layer on the cut surface as the normal control group. 2. The cut surface was repaired more quickly in the cartilage group than in the bone group. 3. Chondrocytes, diferentiated during healing, were stained strongly to anti-fibronectin, and fibronectin was supposed to participatein chondrocyte differentiation and cartilagenous matrix formation. 4. Fibronectin was distributed more in the new bone than in the old bone, and the osteoblasts surrounding it were also stained strongly. Fibronectin was supposed to participate in new bone matrix formation. 5. Fibronectin is supposed to be associated with the differentiation, migration and adhesion of chondrocyte and osteoblast and to participate in endochondral bone formation.

• Development and Reproduction
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• v.15 no.2
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• pp.99-111
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• 2011

The present experiment was performed to evaluate the chondrogenic differentiation potential of human adipose tissue-derived mesenchymal stem cells (ATMSCs) in the chondrogenic induction medium (CIM) with transforming growth factor-${\beta}1$ (TGF-${\beta}1$) and to evaluate the chondrogenic differentiation of ATMSCs seeded in gelatin-chondroitinglucosamine scaffold (GCG-scaffold). ATMSCs and mouse chondrocytes were cultured in the basic medium and CIM without TGF-${\beta}1$ (CIM1) or with TGF-${\beta}1$ (CIM2) for chondrogenic differentiation potential. The chondrogenic differentiation of ATMSCs was evaluated by glycosaminoglycan (GAG) synthesis and histochemical staining. In pellet culture, GAG synthesis of ATMSCs and chondrocyte was increased in culture on 14 days, but higher in CIM1 than basic medium, especially highest in CIM2. Cartilage matrix was observed in ATMSCs cultured in CIM2 on 14 days by Safranin O and trichrome staining. In well plate culture, proliferation of ATMSCs was continuously increased in culture on 10 days and higher in CIM than basic medium. The cell adhesion rate of ATMSCs seeded in flask or scaffolds was continuously increased during culture period, but higher in scaffold than flask. GAG synthesis of ATMSCs seeded in scaffolds showed no change in control group. In the CIM groups, GAG synthesis of ATMSCs was continuously increased than control group during culture period, especially very high in CIM2 and in the GCG-scaffold was slightly higher than the gelatin scaffold (G-scaffold). The present results demonstrated that ATMSCs showed an low chondrogenic differentiation potential, compared to mouse chondrocytes for 14 days of culture. TGF-${\beta}1$ is important factor in chondrogenic differentiation of ATMSCs. Gelatin scaffold was considered to increasing the effective chondrogenic differentiation environment. ATMSCs seeded in GCG-scaffold was more effective in chondrogenesis than in G-scaffold. Conclusively, the present results demonstrated that the treatment of chondroitin and glucosamine in the scaffold was more effective to promote the cartilage matrix formation.

• Polymer(Korea)
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• v.36 no.6
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• pp.768-775
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• 2012

Alginate, obtained from the seaweeds, is a widely used biomaterial for cell transplantation, since its positive effect on viability of capsulized cells and its easier encapsulation capability of living cells. Demineralized bone powder (DBP), derived from the natural bone tissue, is widely applied for clinical trials for its low rate of reaction and antigenicity. A chondrocyte was seeded into an alginate with DBP of different contents, and a microcapsule was produced. The adhesion and proliferation of cells was observed through the MTT analysis, and the PCR was applied to estimate the content of the glycosaminoglycan (sGAG) and collagen, and confirm the specific genetic pattern of the chondrocytes. Also, the alginate microcapsule where the chondrocyte is seeded was extracted after transplantation under the skin of a nude mouse, and was immunochemically stained. The experimental result confirmed that the alginate microcapsule containing 1% of DBP not only showed the highest proliferation of cell but had a positive effect of chondrocytes by the interaction between the alginates and the growth factor in DBP. It can be expected that the microcapsule with application of the alginates and DBP might be an appropriate scaffold for tissue engineering.