Kyoung-Hwa Kim

Seoul National University, Sŏul, Seoul, South Korea

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Publications (27)54.1 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: Peri-implantitis is a chronic inflammatory process with advanced bone loss and impaired healing potential. For peri-implantitis treatment, tissue engineering can be applied to enhance bone regeneration of peri-implant defects. This study aimed to evaluate ex vivo bone morphogenetic protein 2 (BMP2) gene delivery using canine periodontal ligament stem cells (PDLSCs) for regeneration of peri-implantitis defects. Canine PDLSCs were transduced with adenoviral vectors containing BMP2 (BMP2/PDLSCs). After peri-implantitis was induced by ligatures in six beagle dogs, regenerative procedures were performed; hydroxyapatite (HA) particles and collagen gel with autologous canine PDLSCs (PDLSC group) or BMP2/PDLSCs (BMP/PDLSC group) or without cells (control group) were grafted into the defects and covered by an absorbable membrane. Three months later, the animals were sacrificed. In vitro, BMP2/PDLSCs showed similar levels of stem cell properties to PDLSCs, such as colony-forming efficiency and expression of MSC markers STRO-1 and CD 146. BMP2/PDLSCs produced BMP-2 until day 21 at a concentration of 4-8 ng/ml. In vivo, the BMP2/PDLSC group showed significantly more new bone formation and re-osseointegration in peri-implantitis defects compared to the other groups. In conclusion, ex vivo BMP2 gene delivery using PDLSCs enhanced new bone formation and re-osseointegration in peri-implantitis defects.
    Journal of Biomedical Materials Research Part A 03/2014; · 2.83 Impact Factor
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    ABSTRACT: Bone tissue healing is a dynamic, orchestrated process that relies on multiple growth factors and cell types. Platelet-derived growth factor-BB (PDGF-BB) is released from platelets at wound sites and induces cellular migration and proliferation necessary for bone regeneration in the early healing process. Bone morphogenetic protein-2 (BMP-2), the most potent osteogenic differentiation inducer, directs new bone formation at the sites of bone defects. This study evaluated a combinatorial treatment protocol of PDGF-BB and BMP-2 on bone healing in a critical-sized defect model. To mimic the bone tissue healing process, a dual delivery approach was designed to deliver the rhPDGF-BB protein transiently during the early healing phase, whereas BMP-2 was supplied by rat bone marrow stromal cells (BMSCs) transfected with an adenoviral vector containing the BMP2 gene (AdBMP2) for prolonged release throughout the healing process. In in vitro experiments, the dual delivery of rhPDGF-BB and BMP2 significantly enhanced cell proliferation. However, the osteogenic differentiation of BMSCs was significantly suppressed even though the amount of BMP-2 secreted by the AdBMP2-transfected BMSCs was not significantly affected by the rhPDGF-BB treatment. In addition, dual delivery inhibited the mRNA expression of BMP receptor type II and Noggin in BMSCs. In in vivo experiments, critical-sized calvarial defects in rats showed enhanced bone regeneration by dual delivery of autologous AdBMP2-transfected BMSCs and rhPDGF-BB in both the amount of new bone formed and the bone mineral density. These enhancements in bone regeneration were greater than those observed in the group treated with AdBMP2-transfected BMSCs alone. In conclusion, the dual delivery of rhPDGF-BB and AdBMP2-transfected BMSCs improved the quality of the regenerated bone, possibly due to the modulation of PDGF-BB on BMP-2-induced osteogenesis.
    Tissue Engineering Part A 07/2013; · 4.64 Impact Factor
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    ABSTRACT: This study was performed to establish an experimental rabbit model for single-stage maxillary sinus augmentation with simultaneous implant placement. Twelve mature New Zealand white rabbits were used for the experiments. The rabbit maxillary sinuses were divided into 3 groups according to sinus augmentation materials: blood clot (BC), autogenous bone (AB), and bovine-derived hydroxyapatite (BHA). Small titanium implants were simultaneously placed in the animals during the sinus augmentation procedure. The rabbits were sacrificed 4 and 8 weeks after surgery and were observed histologically. Histomorphometric analyses using image analysis software were also performed to evaluate the parameters related to bone regeneration and implant-bone integration. The BC group showed an evident collapse of the sinus membrane and limited new bone formation around the original sinus floor at 4 and 8 weeks. In the AB group, the sinus membrane was well retained above the implant apex, and new bone formation was significant at both examination periods. The BHA group also showed retention of the elevated sinus membrane above the screw apex and evident new bone formation at both points in time. The total area of the mineral component (TMA) in the area of interest and the bone-to-implant contact did not show any significant differences among all the groups. In the AB group, the TMA had significantly decreased from 4 to 8 weeks. Within the limits of this study, the rabbit sinus model showed satisfactory results in the comparison of different grafting conditions in single-stage sinus floor elevation with simultaneous implant placement. We found that the rabbit model was useful for maxillary sinus augmentation with simultaneous implant placement.
    Journal of periodontal & implant science 12/2012; 42(6):204-11.
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    ABSTRACT: Background: This study was performed to evaluate the potential of bone morphogenetic protein-2 (BMP-2) gene transduced bone marrow stem cells (BMSCs) to facilitate osseous healing after rabbit maxillary sinus augmentation in conjunction with implant placement. Methods: Autologous BMSCs derived from New Zealand white rabbits were cultured and transduced with the BMP-2 gene using an adenovirus vector. Transduced BMSCs (BMP-2/BMSCs) were then combined with a deproteinized bovine bone mineral (DBBM) scaffold. There were 27 animals randomly allocated into 3 groups: (1) control group, sinus grafted with DBBM alone; (2) BMSC group, sinus grafted with non-transduced BMSCs and DBBM; (3) BMP-2/BMSC group, sinus grafted with BMP-2/BMSCs and DBBM. During these procedures, a mini-implant was placed in the floor of the sinus. Animals were sacrificed at 2, 4, and 8 weeks after surgery. New bone area and bone to implant contact (BIC) were evaluated histomorphometrically. Results: At 2 and 4 weeks, the BMP-2/BMSC group showed more new bone area and higher BIC than the other 2 groups. Using confocal microscopy, BMP-2/BMSCs were detected up to 4 weeks, which indicates that transduced cells contributed to new bone formation. However, at 8 weeks, there was no difference in new bone area or BIC among all 3 groups. Conclusion: These results suggest that BMP-2 gene delivery using BMSCs may result in earlier and more bone formation in the maxillary sinus. It is possible that this finding may offer more stable bone support to implant and reduce healing times. However, this study also revealed limitations in the stimulatory effect of BMP-2/ BMSCs such as diminished activity over time in later healing stages.
    Journal of Periodontology 08/2012; · 2.40 Impact Factor
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    ABSTRACT: The purpose of this study was to investigate the effects of the immunosuppressants FK506 and cyclosporin A (CsA) on the osteogenic differentiation of rat mesenchymal stem cells (MSCs). The effect of FK506 and CsA on rat MSCs was assessed in vitro. The MTT assay was used to determine the deleterious effect of immunosuppressants on stem cell proliferation at 1, 3, and 7 days. Alkaline phosphatase (ALP) activity was analyzed on days 3, 7, and 14. Alizarin red S staining was done on day 21 to check mineralization nodule formation. Real-time polymerase chain reaction (RT-PCR) was also performed to detect the expressions of bone tissue-specific genes on days 1 and 7. Cell proliferation was promoted more in the FK506 groups than the control or CsA groups on days 3 and 7. The FK506 groups showed increased ALP activity compared to the other groups during the experimental period. The ALP activity of the CsA groups did not differ from the control group in any of the assessments. Mineralization nodule formation was most prominent in the FK506 groups at 21 days. RT-PCR results of the FK506 groups showed that several bone-related genes-osteopontin, osteonectin, and type I collagen (Col-I)-were expressed more than the control in the beginning, but the intensity of expression decreased over time. Runx2 and Dlx5 gene expression were up-regulated on day 7. The effects of 50 nM CsA on osteonectin and Col-I were similar to those of the FK506 groups, but in the 500 nM CsA group, most of the genes were less expressed compared to the control. These results suggest that FK506 enhances the osteoblastic differentiation of rat MSCs. Therefore, FK506 might have a beneficial effect on bone regeneration when immunosuppressants are needed in xenogenic or allogenic stem cell transplantation to treat bone defects.
    Journal of periodontal & implant science 06/2012; 42(3):73-80.
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    ABSTRACT: Atmosphere Pressure Plasma Jet (APPJ) can be a promising tool for non-thermal microorganism removal because the enormous radical production, such as Nitric Oxide (·NO). The effects of metastable energy level of discharge gases on the ·NO generation are studied by using the helium (He) and argon (Ar). Since the energy level of He metastable (He*), 23.1 eV, is higher than the nitrogen molecule (N2) ionization energy level, 14.5 eV, the He* is able to penning ionize the N2. In case of Ar, however, the energy state of metastable is 14.1 eV and it is not enough to cause the penning ionization on the N2. The APPJs with He and Ar are generated by inducing the sinusoidal LF voltage on the APPJ generator. The APPJ generator consists with concentric φ0.2 mm tungsten wire and quartz gas guiding tube with inner diameter of 2 mm and outer diameter of 4 mm. The ground electrode wraps the quartz tube, 2 mm from the end of the tube. The tungsten electrode is covered with Al2O3 ceramic tube to concentrate the plasma discharge at the end of the electrode. The range of applied voltage amplitude, operating frequency, and gas flow rate are 2-3 kV, 20 kHz, and 3 L/min, respectively. The APPJ produced excited species and density of ·NO with discharge gases are measured by using Optical Emission Spectroscopy (OES) and Laser Absorption Spectroscopy (LAS). In order to evaluate the effect of ·NO on oral bacteria removal, Colony Forming Units (CFU) number of P.gingivalis is counted after APPJ irradiation, in vitro. The characteristic times of oral bacteria removal by He and Ar- APPJ irradiation are 1.63 and 12.1 min, respectively. Those values are inversely proposed to the LAS measured ·NO densities. OES measurements show that the He-APPJ generates the He*, N2+, O2-, and ·NO. However, only the Ar* and O2- are generated in Ar-APPJ- Since the O2- is generated by electron attachment, it can be observed in both APPJs. The absence of the N2+in the Ar-APPJ indicates that the no energetic electrons inside APPJ are involved in N2+ production and ·NO is generated by recombination of N2+ and O2-. Thus the penning ionized at the boundary of APPJ by metastable with higher energy level than N2 ionization energy is the key factor to produce the ·NO generation in APPJ.
    Plasma Science (ICOPS), 2012 Abstracts IEEE International Conference on; 01/2012
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    ABSTRACT: Micro-computed tomography (micro-CT) has been widely used in the evaluation of regenerated bone tissue but the reliability of micro-CT has not yet been established. This study evaluated the correlation between histomorphometric analysis and micro-CT analysis in performing new bone formation measurement. Critical-size calvarial defects were created using a 8 mm trephine bur in a total of 24 Sprague-Dawley rats, and collagen gel mixed with autogenous rat bone marrow stromal cells (BMSCs) or autogenous rat BMSCs transduced by adenovirus containing bone morphogenic protein-2 (BMP-2) genes was loaded into the defect site. In the control group, collagen gel alone was loaded into the defect. After 2 and 4 weeks, the animals were euthanized and calvaria containing defects were harvested. Micro-CT analysis and histomorphometric analysis of each sample were accomplished and the statistical evaluation about the correlation between both analyses was performed. New bone formation of the BMP-2 group was greater than that of the other groups at 2 and 4 weeks in both histomorphometric analysis and micro-CT analysis (P=0.026, P=0.034). Histomorphometric analysis of representative sections showed similar results to histomorphometric analysis with a mean value of 3 sections. Measurement of new bone formation was highly correlated between histomorphometric analysis and micro-CT analysis, especially at the low lower threshold level at 2 weeks (adjusted r(2)=0.907, P<0.001). New bone formation of the BMP-2 group analyzed by micro-CT tended to decline sharply with an increasing lower threshold level, and it was statistically significant (P<0.001). Both histomorphometric analysis and micro-CT analysis were valid methods for measurement of the new bone in rat calvarial defects and the ability to detect the new bone in micro-CT analysis was highly influenced by the threshold level in the BMP-2 group at early stage.
    Journal of periodontal & implant science 10/2011; 41(5):218-26.
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    ABSTRACT: The aim of this study was to compare osteoblast behavior on zirconia and titanium under conditions cultured with bone morphogenetic protein-2. MC3T3-E1 cells were cultured on sandblasted zirconia and sandblasted/etched titanium discs. At 24 hours after seeding MC3T3-E1, the demineralized bone matrix (DBM) gel alone and the DBM gel with bone morphogenetic protein-2 (BMP-2) were added to the culture medium. The surface topography was examined by confocal laser scanning microscopy. Cellular proliferation was measured at 1, 4, and 7 days after gel loading. Alkaline phosphatase activity was measured at 7 days after gel loading. The mRNA expression of ALPase, bone sialoprotein, type I collagen, runt-related transcription factor 2 (Runx-2), osteocalcin, and osterix were evaluated by real-time polymerase chain reaction at 4 days and 7 days. At 1, 4, and 7 days after loading the DBM gel alone and the DBM gel with BMP-2, cellular proliferation on the zirconia and titanium discs was similar and that of the groups cultured with the DBM gel alone and the DBM gel with BMP-2 was not significantly different, except for titanium with BMP-2 gel. ALPase activity was higher in the cells cultured with BMP-2 than in the other groups, but there was no difference between the zirconia and titanium. In ALPase, bone sialoprotein, osteocalcin, Runx-2 and osterix gene expression, that of cells on zirconia or titanium with BMP-2 gel was much more highly increased than titanium without gel at day 7. The gene expression level of cells cultured on zirconia with BMP-2 was higher than that on titanium with BMP-2 at day 7. The data in this study demonstrate that the osteoblastic cell attachment and proliferation of zirconia were comparable to those of titanium. With the stimulation of BMP-2, zirconia has a more pronounced effect on the proliferation and differentiation of the osteoblastic cells compared with titanium.
    Journal of periodontal & implant science 10/2011; 41(5):227-33.
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    ABSTRACT: The aim of this study is to compare the gene expression profile in mesenchymal stem cells derived from dental tissues and bone marrow for characterization of dental stem cells. We employed GeneChip analysis to the expression levels of approximately 32,321 kinds of transcripts in 5 samples of bone-marrow-derived mesenchymal stem cells (BMSCs) (n=1), periodontal ligament stem cells (PDLSCs) (n=2), and dental pulp stem cells (DPSCs) (n=2). Each cell was sorted by a FACS Vantage Sorter using immunocytochemical staining of the early mesenchymal stem cell surface marker STRO-1 before the microarray analysis. We identified 379 up-regulated and 133 down-regulated transcripts in BMSCs, 68 up-regulated and 64 down-regulated transcripts in PDLSCs, and 218 up-regulated and 231 down-regulated transcripts in DPSCs. In addition, anatomical structure development and anatomical structure morphogenesis gene ontology (GO) terms were over-represented in all three different mesenchymal stem cells and GO terms related to blood vessels, and neurons were over-represented only in DPSCs. This study demonstrated the genome-wide gene expression patterns of STRO-1(+) mesenchymal stem cells derived from dental tissues and bone marrow. The differences among the expression profiles of BMSCs, PDLSCs, and DPSCs were shown, and 999 candidate genes were found to be definitely up- or down-regulated. In addition, GOstat analyses of regulated gene products provided over-represented GO classes. These data provide a first step for discovering molecules key to the characteristics of dental stem cells.
    Journal of periodontal & implant science 08/2011; 41(4):192-200.
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    ABSTRACT: The aim of this study is to determine whether certain biomaterials have the potential to support cell attachment. After seeding bone marrow stromal cells onto the biomaterials, we investigated their responses to each material in vitro. Rat bone marrow derived stromal cells were used. The biomaterials were deproteinized bovine bone mineral (DBBM), DBBM coated with fibronectin (FN), synthetic hydroxyapatite (HA), HA coated with FN, HA coated with β-tricalcium phosphate (TCP), and pure β-TCP. With confocal laser scanning microscopy, actin filaments and vinculin were observed after 6, 12, and 24 hours of cell seeding. The morphological features of cells on each biomaterial were observed using scanning electron microscopy at day 1 and 7. The cells on HA/FN and HA spread widely and showed better defined actin cytoskeletons than those on the other biomaterials. At the initial phase, FN seemed to have a favorable effect on cell adhesion. In DBBM, very few cells adhered to the surface. Within the limitations of this study, we can conclude that in contrast with DBBM not supporting cell attachment, HA provided a more favorable environment with respect to cell attachment.
    Journal of periodontal & implant science 04/2011; 41(2):67-72.
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    ABSTRACT: The aim of this study was to investigate the immunomodulatory effects of canine periodontal ligament stem cells on allogenic and xenogenic immune cells in vitro. Mixed cell cultures consisting of canine stem cells (periodontal ligament stem cells and bone marrow stem cells) and allogenic canine/xenogenic human peripheral blood mononuclear cells (PBMCs) were established following the addition of phytohemagglutinin. The proliferation of PBMCs was evaluated using the MTS assay. The cell division of PBMCs was analyzed using the CFSE assay. The apoptosis of PBMCs was assessed using the trypan blue uptake method. Periodontal ligament stem cells and bone marrow stem cells inhibited the proliferation of allogenic and xenogenic PBMCs. Both periodontal ligament stem cells and bone marrow stem cells suppressed the cell division of PBMCs despite the existence of a mitogen. No significant differences in the percentages of apoptotic PBMCs were found among the groups. Canine periodontal ligament stem cells have an immunomodulatory effect on allogenic and xenogenic PBMCs. This effect is not a product of apoptosis of PBMCs but is caused by the inhibition of cell division of PBMCs.
    Journal of periodontal & implant science 12/2010; 40(6):265-70.
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    ABSTRACT: The aim of the present study was to investigate bone regeneration following ex vivo bone morphogenetic protein-2 (BMP-2) gene delivery using human gingival fibroblasts (HGFs) in rat calvarial defects. An 8 mm craniotomy defect was created in Sprague-Dawley rats. The animals were divided into four groups: (1) non-grafted group, the defect was left empty; (2) collagen matrix group, the defect was filled with collagen matrix only; (3) HGF group, the defect was filled with non-transduced HGFs on collagen matrix; (4) BMP-2/HGF group, the defect was filled with BMP-2 gene-transduced HGFs on collagen matrix. Animals were sacrificed at 2 and 4 weeks after surgery, and micro-computed tomographic and histologic observations were performed. The BMP-2/HGF group showed promoted osseous healing of calvarial defects, as compared with the other groups. At both 2 and 4 weeks, regenerated bone area was significantly greater in the BMP-2/HGF group than the other three groups. Quite a few number of transplanted HGFs were observed within the regenerated bone tissues. The results of this study suggest that ex vivo BMP-2 gene delivery induces prominent bone regeneration in vivo and HGFs may be useful as target cells for ex vivo gene therapy.
    Journal Of Clinical Periodontology 03/2010; 37(3):305-11. · 3.69 Impact Factor
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    ABSTRACT: A nonwoven ceramic/polymer composite fabric composed of randomly mixed bioactive and fast degradable CaO-SiO(2) gel fibers and biodegradable poly(epsilon-caprolactone) (PCL) fibers is prepared with a simultaneous electrospinning method for potential use as bone grafting materials. A 17% PCL solution is prepared using 1,1,3,3-hexafluoro-2-propanol as the solvent, whereas the CaO-SiO(2) gel solution is prepared via a condensation reaction following the hydrolysis of tetraethyl orthosilicate. PCL and CaO-SiO(2) gel solutions are spun simultaneously with two separate nozzles. As controls, pure PCL and CaO-SiO(2) gel nonwoven fabrics are also made by the same methods. The three nonwoven fabrics were exposed to simulated body fluid for 1 week and resulted in the deposition of a layer of apatite crystals on the surfaces of both the CaO-SiO(2) gel and PCL/CaO-SiO(2) gel composite fabrics, but not on the PCL fabric. A tensile strength test showed that the fracture behavior of the CaO-SiO(2) gel fabric was brittle, that of the PCL fabric was ductile-tough, and that of the PCL/CaO-SiO(2) gel composite fabric was intermediate between that of the CaO-SiO(2) gel and PCL fabrics. Our in vivo tests showed that the CaO-SiO(2) gel and PCL/CaO-SiO(2) gel composite fabrics had good osteoconductivity and fast degradation rates in calvarial defects of New Zealand white rabbits within 4 weeks, in contrast to the pure PCL fabric. Together, these results suggest that the composite fabric composed of PCL and CaO-SiO(2) gel fibers must have a great potential for use in applications such as bone grafting because of its good osteoconductivity and adequate mechanical properties.
    Journal of Biomedical Materials Research Part A 03/2010; 94(2):649-59. · 2.83 Impact Factor
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    ABSTRACT: The present study was undertaken to evaluate the potential of periodontal ligament stem cells (PDLSCs) and bone marrow SCs (BMSCs) on alveolar bone regeneration in a canine peri-implant defect model. Four adult, male beagle dogs were used in this study. Autologous BMSCs from the iliac crests and PDLSCs from extracted teeth were cultured. Three months after extraction, BMSC- and PDLSC-loaded hydroxyapatite/beta-tricalcium phosphate (HA/TCP) (test groups) and cell-free HA/TCP (control group) were implanted in three rectangular, saddle-like peri-implant defects, respectively. The left side of the mandible was initially prepared, and after 8 weeks, the right side was also prepared. The animals were sacrificed after an 8-week healing period. Undecalcified ground sections were prepared. New bone formation and bone-to-implant contact (BIC) were measured histomorphometrically. BMSCs and PDLSCs were fluorescently labeled and traced. Alveolar bone regeneration in surgically created peri-implant saddle-like defects was more effective in test groups than the control group. The BMSC group had the highest new bone formation (34.99% and 40.17% at healing times of 8 and 16 weeks, respectively) followed by the PDLSC group (31.90% and 36.51%) and control group (23.13% and 28.36%), respectively. Test groups exhibited a significantly higher new bone formation than the control group at 8 weeks, but the same was true for only the BMSC group at 16 weeks (P <0.05). Fluorescently labeled cells were identified adjacent to HA/TCP carriers and, partly, near connective tissues and osteoids. This study demonstrated the feasibility of using stem cell-mediated bone regeneration to treat peri-implant defects.
    Journal of Periodontology 11/2009; 80(11):1815-23. · 2.40 Impact Factor
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    ABSTRACT: To analyze the outcomes of a single- and a double-layered collagen membrane on the efficacy of onlay block grafts in terms of bone resorption and augmentation. A total of 36 New Zealand white rabbits were used in this study. Calvarial bone blocks were obtained from one side of the parietal bone and fixed on the contaralateral side. The onlay grafts were covered with either no (C group), one (M1 group), or two (M2 group) layers of a non-cross-linked collagen membrane (BioGide((R))). After 2, 4, and 6 months of healing, rabbits were sacrificed and explanted specimens were prepared for histologic and histomorphometric analysis. At each period, the overall pattern of graft bone resorption and membrane biodegradation were examined histologically, and the sustained external form of grafted bone (%) and the remaining mineralized bone volume (%) were measured histomorphometrically. The M1 and M2 groups exhibited decreased bone resorption compared with the C group at all periods. The M2 group had less graft resorption and a higher bone density of the grafted bone than the M1 group. In the M1 group, the collagen membrane was degraded partially or completely by 4 months and was absent at 6 months. Conversely, for the M2 group, the membrane body was retained up to 6 months. Our results demonstrated that the collagen membrane used here can reduce graft bone resorption. Furthermore, the double-layer technique using non-cross-linked collagen membranes (BioGide((R))) can enhance the efficacy of the onlay block bone graft technique in terms of both bone resorption and augmentation compared with a single-layer collagen membrane.
    Clinical Oral Implants Research 07/2009; 20(10):1124-32. · 3.43 Impact Factor
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    ABSTRACT: The evaluations of the fibers characteristics, bioactivity, pre-osteoblastic cell responses, and osteoconductivity of the non-woven SiO(2)-CaO gel fabric made by electrospinning method was carried out. Silica gels with four different calcium contents were prepared by condensation following hydrolysis of tetraethyl orthosilicate under acidic conditions. The molar ratios of Ca to Si prepared ranged from 0 to 0.15. SiO(2)-CaO gel fabrics were heat-treated at 300 degrees C for 3 h after spinning under an electric field of 2 kV/cm. As the Ca to Si ratio increased, the diameter of electrospun SiO(2)-CaO gel fibers increased because the viscosity of the SiO(2)-CaO gel solution increased. The apatite-forming ability of heat-treated, non-woven SiO(2)-CaO gel fabric was evaluated in simulated body fluid and tended to increase with an increasing Ca to Si molar ratio. However, proliferation and differentiation tended to decrease with an increasing Ca to Si molar ratio. The sample which had the Ca to Si ratio as 0.10 showed good osteoconductivity in vivo in the calvarial defect New Zealand white rabbit model compared to that had the Ca to Si ratio as 0 and empty defect. These results strongly suggest that non-woven SiO(2)-CaO gel fabric made by the electrospinning method has potential for application as a bone grafting material.
    Journal of Biomedical Materials Research Part B Applied Biomaterials 03/2009; 90(2):679-87. · 2.31 Impact Factor
  • The Journal of The Korean Academy of Periodontology. 01/2009; 39.
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    The Journal of The Korean Academy of Periodontology. 01/2009; 39(2).
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    ABSTRACT: Evaluations of the osteoblast-like cell responses and osteoconductivity of a non-woven silica gel fabric were carried out to determine its potential for application as a scaffold material for use in bone tissue engineering. The silica gel solution was prepared by condensation following hydrolysis of tetraethyl orthosilicate under acidic conditions. The solution was spun under a 2kVcm(-1) electric field. The diameters of the as-spun silica gel fibers were in the range of approximately 0.7-6microm. The fabric was then heat-treated at 300 degrees C for 3h. The proliferation of pre-osteoblastic MC3T3-E1 cells evaluated by the MTS assay was lower than on the tissue culture plate (TCP) as many cells leaked through the large voids formed by the randomly placed long, narrow silica gel fibers, which further retarded cell growth. However, the expressions of extracellular signal-regulated kinase and transcriptional factor from the cells were higher when cultured on the non-woven silica gel fabrics than on TCP. The alkaline phosphatase (ALP) activity and differentiation marker expressions assessed by amplication via the reverse transcription-polymerase chain reaction, such as type I collagen, ALP and osteocalcin, were higher for cells cultured on non-woven silica gel fabrics than on TCP. The non-woven silica gel fabric showed good osteoconductivity in the calvarial defect New Zealand white rabbit model. To this end, the non-woven silica gel fabric has good potential as a scaffold material for bone tissue engineering due to its good biological properties.
    Acta biomaterialia 08/2008; 5(1):462-9. · 5.09 Impact Factor
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    ABSTRACT: The aim of the present study was to test the osteogenic effects of BMP-2 (bone morphogenetic protein-2) gene transfer in BMSCs (bone-marrow stromal cells) and rabbit calvarial bone defects. The pBMP-2-cDNA3.1 plasmid was constructed by subcloning hBMP-2 (human BMP-2) cDNA into the plasmid pcDNA3.1. BMSCs were transfected with a pBMP-2-cDNA3.1-Lipofect-amine complex. Transfected cells were observed for localization of the BMP-2 coding plasmid. Also, the level of BMP-2 in the culture medium of transfected cells was measured. The culture medium was collected and we tested whether this medium could induce non-transfected BMSCs to express ALP (alkaline phosphatase) and osteocalcin. The pBMP-2-cDNA3.1 complexes were incorporated into the collagen scaffold and the plasmid-loaded collagen scaffolds were then grafted into rabbit calvarial defects. After 2 weeks, granulation tissue at the grafted site was obtained and mRNA of BMP-2 was examined via RT (reverse transcriptase)--PCR. After 4 and 8 weeks, the animals were killed and the calvarial tissue was excised. After specimen preparation, optical microscopical examination was performed to evaluate bone formation. The results show that transfected cells were able to incorporate the BMP-2 gene into their nuclei. Also, the level of expressed and secreted BMP-2 was significantly higher in transfected cells than in untransfected cells (P<0.01). The retrieved culture medium could induce the expression of ALP and osteocalcin in non-transfected BMSCs. hBMP-2 mRNA was detected at the granulation tissue of experimental animals, but not in control animals after 2 weeks. At both 4 and 8 weeks, experimental groups showed significantly more newly formed bone area than the control group (P<0.01). Therefore pBMP-2-cDNA3.1 gene delivery could induce BMSCs into osteoblastic phenotype cells and enhance bone regeneration in rabbit calvarial bone defects.
    Biotechnology and Applied Biochemistry 01/2008; 49(Pt 1):85-96. · 1.35 Impact Factor

Publication Stats

305 Citations
54.10 Total Impact Points

Institutions

  • 2004–2014
    • Seoul National University
      • • Department of Dentistry
      • • Dental Research Institute
      • • College of Dentistry
      Sŏul, Seoul, South Korea
  • 2012
    • Asan Medical Center
      Sŏul, Seoul, South Korea
  • 2004–2006
    • Ewha Womans University
      • • Department of Pharmacy
      • • College of Pharmacy
      Seoul, Seoul, South Korea