• Journal of Veterinary Clinics
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• v.33 no.6
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• pp.332-339
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• 2016

Polycaprolactone (PCL) scaffold have been developed as an alternative to natural donor tissue to repair a large osteochondral defect. The objective of this study is to evaluate efficacy and biocompatibility of bilayer PCL scaffold implanted for osteochondral repair in rabbit. Twenty-two male New Zealand White rabbits were used in this animal experiment. Rabbits were divided into three groups. Experimental surgery was carried out under general anesthesia. Osteochondral defects (5 mm diameter and 5 mm deep) were made in the center of the patellar groove using a 5 mm diameter biopsy punch. In group I (3D plotting) and group II (salt-leaching), the scaffold was implanted using the press-fitted technique into the defect. In control group, after osteochondral defect was created, the defect was left without implant. After four and eight weeks, rabbits were sacrificed and the defects were evaluated by macro -and microscopical methods. There were not found animal death and severe inflammatory evidence during the experimental periods. There were no significant differences between the experimental groups in gross evaluation. However the group I scored significantly higher than group II at 8 weeks in histological evaluation (P < 0.05). The 3-D plotting PCL scaffold was more suitable method for reconstruction of osteochondral defect than a salt-leaching PCL scaffold.

• Journal of Industrial and Engineering Chemistry
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• v.67
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• pp.388-395
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• 2018

Significant efforts have been applied toward fabricating three-dimensional (3D) scaffolds using 3D-bioprinting tissue engineering techniques. Gelatin has been used in 3D-bioprinting to produce designed 3D scaffolds; however, gelatin has a poor printability and is not useful for fabricating desired 3D scaffolds using 3D-bioprinting. In this study, we fabricated pore size controlled 3D gelatin scaffolds with two step 3D-bioprinting approach: a low-temperature ($-10^{\circ}C$) freezing step and a crosslinking process. The scaffold was crosslinked with 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide hydrochloride (EDC) and N-hydroxysuccinimide (NHS). The pore sizes of the produced 3D gelatin scaffolds were approximately 30% smaller than the sizes of the designed pore sizes. The surface morphologies and pore sizes of the 3D gelatin scaffolds were confirmed and measured using scanning electron microscopy (SEM). Human dermal fibroblasts (HDFs) were cultured on a 3D gelatin scaffold to evaluate the effect of the 3D gelatin scaffold pore size on the cell proliferation. After 14 days of culture, HDFs proliferation throughout the 3D gelatin scaffolds prepared with more than $580{\mu}m$ pore size was approximately 14% higher than proliferation throughout the 3D gelatin scaffold prepared with a $435{\mu}m$ pore size. These results suggested that control over the 3D gelatin scaffold pore size is important for tissue engineering scaffolds.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.31 no.3
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• pp.198-206
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• 2009

Purpose: The aims of this study were to assess the in vitro co-culturing pattern of isolated skin-derived precursor cells (SKPs) with a mixed demineralized bone (DMB) and fibrin glue scaffold and to evaluate in vivo osteogenesis after transplantation of autogenous SKPs with a these mixed scaffold in the animal's mandibular defects. Materials and Methods: We isolated SKPs from the ears of adult 4 miniature pigs. The isolated SKPs were co-cultured with a mixed DMB and fibrin glue scaffold in a non-osteogenic medium for 1, 2, and 4 weeks. Histological characteristics of in vitro co-cultured cells and scaffold were evaluated. $1{\times}10^7\;cells/100\;{\mu}l$ of autogenous porcine SKPs were grafted into the mandibular defects with a DMB and fibrin glue scaffold. In the control sites, only a scaffold was grafted, without SKPs. After two animals each were euthanized at 2 and 4 weeks after grafting, the in vivo osteogenesis was evaluated with histolomorphometric and osteocalcin immunohistochemical studies. Results: Homogeneously shaped skin-derived cells were isolated from porcine ear skin after 3 or 4 weeks of primary culture. In vitro osteogenic differentiation of SKPs was observed after co-culturing with a DMB and fibrin glue scaffold in a non-osteogenic medium. Von Kossa-positive bone minerals were also noted in the co-cultured medium at 4 weeks. As the culture time progressed, the number of observable cells increased. Trabecular new bone formation and osteocalcin expression were more pronounced in the SKP-grafted group compared to the control group. Conclusion: These findings suggest that autogenous SKP grafting with a DMB and fibrin glue scaffold can serve as a useful alternative to bone grafting technique.

• Membrane Journal
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• v.24 no.2
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• pp.113-122
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• 2014

Porous poly(L-lactic acid)(PLLA) scaffold membranes were prepared via. phase separation process. Chloroform, dichloromethane and 1,4-dioxane were used as solvent and, ethyl alcohol was used as non-solvent. Morphologies, mechanical properties and mass transfer characteristics of the scaffold membranes were investigated through SEM, stress-strain test and glucose diffusion test. The scaffold membranes obtained from the casting solutions with chloroform and with dichloromethane showed similar morphologies. They showed sponge-like porous structure with the pore size in the range of $3-10{\mu}m$ and, their porosities were in 50-80% range. Using 1,4-dioxane as solvent, nano-fibrous scaffold membranes with porosities over 80% were fabricated. When the polymer content in the solution with 1,4-dioxane was lowered to 4%, highly porous, macroporous and nano-fibrous scaffold membranes were obtained. The size of the macropore was tens of the microns and the porosity was around 90%. These results indicate that the solvent has significant effect on the scaffold membrane structure and, that scaffold membranes with various structures can be fabricated through phase separation method by choosing solvent and by controlling polymer concentration in the casting solution.

• Archives of Craniofacial Surgery
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• v.19 no.3
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• pp.181-189
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• 2018

Background: Autogenous bone grafts have several limitations including donor-site problems and insufficient bone volume. To address these limitations, research on bone regeneration is being conducted actively. In this study, we investigate the effects of a three-dimensionally (3D) printed polycaprolactone (PCL)/tricalcium phosphate (TCP) scaffold on the osteogenic differentiation potential of adipose tissue-derived stem cells (ADSCs) and bone marrow-derived stem cells (BMSCs). Methods: We investigated the extent of osteogenic differentiation on the first and tenth day and fourth week after cell culture. Cytotoxicity of the 3D printed $PCL/{\beta}-TCP$ scaffold was evaluated by 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium assay, prior to osteogenic differentiation analysis. ADSCs and BMSCs were divided into three groups: C, only cultured cells; M, cells cultured in the 3D printed $PCL/{\beta}-TCP$ scaffold; D, cells cultured in the 3D printed $PCL/{\beta}-TCP$ scaffold with a bone differentiation medium. Alkaline phosphatase (ALP) activity assay, von Kossa staining, reverse transcription-polymerase chain reaction (RT-PCR), and Western blotting were performed for comparative analysis. Results: ALP assay and von Kossa staining revealed that group M had higher levels of osteogenic differentiation compared to group C. RT-PCR showed that gene expression was higher in group M than in group C, indicating that, compared to group C, osteogenic differentiation was more extensive in group M. Expression levels of proteins involved in ossification were higher in group M, as per the Western blotting results. Conclusion: Osteogenic differentiation was increased in mesenchymal stromal cells (MSCs) cultured in the 3D printed PCL/TCP scaffold compared to the control group. Osteogenic differentiation activity of MSCs cultured in the 3D printed PCL/TCP scaffold was lower than that of cells cultured on the scaffold in bone differentiation medium. Collectively, these results indicate that the 3D printed PCL/TCP scaffold promoted osteogenic differentiation of MSCs and may be widely used for bone tissue engineering.

• Proceedings of the Korean Society for Bioinformatics Conference
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• 2004.11a
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• pp.191-202
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• 2004

한국화합물은행(KCB)에서 보유중인 12만 개의 화합물을 주요 골격에 따라 분류하고, 4 가지 protease 작용점에 대한 활성도와 골격사이의 관계를 조사하였다. 화합물들은 합성기관의 합성 목적과 주요 고리골격 등을 고려하여 분류되었으며, 이를 이용하여 scaffold 분류를 위한 분류 계통도를 작성하였다. 화합물들은 이 계통도에 따라 7 가지의 race, 168 tribe, 493 parent, 439 child, 325 grandchild 등 1,087개의 scaffold로 분류되었으며, 각 race 및 scaffold 별 골격의 개수는 고르게 분포되었다. 골격별 분류 시스템을 이용하여 4 가지의 protease에 대한 활성도와 골격 간의 상관관계를 조사한 결과, Protease C에 대하여 몇 가지 골격이 활성이 뛰어남을 보였다.

• Steel and Composite Structures
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• v.35 no.3
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• pp.385-404
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• 2020

Since the scaffold is composed of modular members, the total height of multi-story scaffolds does not often meet with the headroom of construction buildings. At this time, other supporting members need to be set up on the top of scaffolds. However, the mechanical behaviors of the combined system of scaffolds and other supporting members have seldom been discussed. This study explores the stability of the combined system of scaffolds and shores. The loading tests conducted in the laboratory show that the critical load of the combined system of two-story scaffolds and wooden shores is about half that of the three-story scaffold system with the same height. In the failure of both the "scaffold system" and the "combined system of scaffolds and shores' after loading, the deformation mainly occurs in the in-plane direction of the scaffold. The outdoor loading test shows that no failure occurs on any members when the combined system fails. Instead, the whole system buckles and then collapses. In addition, the top formwork of the combined system can achieve the effect of lateral support reinforcement with small lateral support forces in the outdoor loading test. This study proposes the preliminary design guidelines for the scaffolding structural design.

• Journal of the Semiconductor & Display Technology
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• v.19 no.1
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• pp.36-41
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• 2020

In this paper, We need to change all print factors when which print scaffold with 400 ㎛ pore using FDM 3d printer. Therefore the print quantity is 10 billion times, So we are difficult to print on workplace. To solve the problem, we used the prediction model based machine learning regression. We preprocessed and learned the securing print condition data, and we produced different kinds of prediction models. We predicted the pore size of scaffolds not securing with new print condition data using prediction models. We have derived the print conditions that satisfy the pore size of 400 ㎛ among the predicted print conditions of pore size. We printed the scaffolds 5 times on the condition. We measured the pore size of the printed scaffold and compared the average pore size with the predicted pore size. We confirmed that error was less than 1%, and we were identify the model with the highest pore size prediction performance of scaffold.

• International Journal of Industrial Entomology and Biomaterials
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• v.23 no.2
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• pp.193-199
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• 2011

Silk protein and agarose are widely known as biocompatible materials in the human body. A three-dimensional (3D) scaffold composed of agarose and low-molecular- weight silk fibroin (LSF) was fabricated and examined in terms of structural characteristics and cellular responses in bone tissue engineering. This study showed that mouse pluripotent precursor cells attached to and proliferated uniformly on and within the LSF-containing 3D scaffold. Interestingly, cell proliferation and attachment was shown to be higher in a 3D scaffold containing 0.02% LSF, as compared to other LSF concentrations. The results of this study suggest that agarose-LSF scaffolds may be useful materials for tissue engineering.

• Journal of Microbiology and Biotechnology
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• v.18 no.5
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• pp.975-982
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• 2008

We investigated whether transplantation of osteogenically differentiated bone marrow-derived mesenchymal stem cells (BMMSCs) and the use of an hydroxyapatite (HAp) scaffold can enhance the in vivo bone formation efficacy of human BMMSCs. Three months after implantation to the subcutaneous dorsum of athymic mice, transplantation of osteogenically differentiated human BMMSCs increased the bone formation area and calcium deposition to 7.1- and 6.2-folds, respectively, of those of transplantation of undifferentiated BMMSCs. The use of the HAp scaffold increased the bone formation area and calcium deposition to 3.7- and 3.5-folds, respectively, of those of a polymer scaffold. Moreover, a combination of transplantation of osteogenically differentiated BMMSCs and HAp scaffold further increased the bone formation area and calcium deposition to 10.6- and 9.3-folds, respectively, of those of transplantation of undifferentiated BMMSCs seeded onto polymer scaffolds. The factorial experimental analysis showed that osteogenic differentiation of BMMSCs prior to transplantation has a stronger positive effect than the HAp scaffold on in vivo bone formation.