Publications (12)

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    [Show abstract] [Hide abstract] ABSTRACT: Initiated chemical vapor deposition (iCVD) was utilized to generate a 200 nm thick, uniform, functionalized polymer nanolayer comprised of glycidyl methacrylate (GMA) on the surface of titanium implants as a means to improve cellular attachment. Dot-patterned GMA-coated specimens were prepared as well as fully coated specimens. In vitro cellular responses, including cell morphology, protein adsorption, cell proliferation assays, alkaline phosphate activity (ALP) assays, and calcium deposition assays were studied using adipose derived stem cells. The mechanical stability of the thin film was investigated by XPS and FE-SEM analysis of the GMA-coated implant after implantation to an extracted bone from a pig. The GMA-coated specimens displayed increased protein adsorption, higher alkaline phosphatase activities, and higher calcium deposition as compared to control sample with no cytotoxicity. Additionally, no defect was observed in the test of mechanical stability. Notably, dot-patterned GMA-coated samples displayed higher alkaline phosphatase activities than others. Functionalized polymer nanolayer deposition via iCVD is a flexible and robust technique capable of mass production of biocompatible layers. These properties make this technique very suitable for implant applications in a variety of ways.
    Full-text available · Article · Feb 2015 · Journal of Colloid and Interface Science
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    Wan-Kyu Ko · Dong Nyoung Heo · Ho-Jin Moon · [...] · Il Keun Kwon
    [Show abstract] [Hide abstract] ABSTRACT: There have been many medical applications based on gold nanoparticles (GNPs) over the past several centuries. Recently, researchers have focused on bone tissue engineering applications utilizing GNPs. The effect of various sizes of gold nanoparticles on the differentiation of human adipose-derived stem cells (ADSCs) into osteoblasts was investigated. The concentration of gold nanoparticles was fixed at 1 mu M and varying sizes of 15, 30, 50, 75 and 100 nm (spherical GNPs) were used. The lack of cytotoxicity was confirmed by establishing viability of ADSCs using cell counting kit-8 (CCK-8) and live/dead assays. The results showed that each size of GNPs had no significant toxicity on ADSCs during 1 week of incubation. Osteogenic differentiation of ADSCs was confirmed by alkaline phosphatase (ALP) staining, ALP activity, calcium deposition, and real time PCR experiments. It was found, through dark field assays and microscope cell images, that 30 nm and 50 nm GNPs were preferentially up taken into the ADSCs. As expected, all sizes of gold nanoparticles promoted the differentiation of ADSCs toward osteoblasts more than control. Among all sizes, 30 and 50 nm GNPs appeared to have the highest differentiation rates. The data consistently demonstrated that 30 and 50 nm GNPs are the most effective in promoting osteogenic differentiation of ADSCs.
    Full-text available · Article · Jan 2015 · Journal of Colloid and Interface Science
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    Dong Nyoung Heo · Wan-Kyu Ko · Ho-Jin Moon · [...] · Il Keun Kwon
    [Show abstract] [Hide abstract] ABSTRACT: Gold nanoparticles (GNPs) have been previously reported to inhibit osteoclast (OC) formation. However, previous research only confirmed the osteoclastogenesis inhibitory effect under in vitro conditions. The aim of this study was to develop a therapeutic agent for osteoporosis based on the utilization of GNPs and confirm their effect both in vitro and in vivo. We prepared beta-cyclodextrin (CD) conjugated GNPs (CGNPs), which can form inclusion complexes with curcumin (CUR-CGNPs), and used these to investigate their inhibitory effects on receptor activator of nuclear factor- κb ligand (RANKL)-induced osteoclastogenesis in bone marrow-derived macrophages (BMMs). The CUR-CGNPs significantly inhibited the formation of tartrate-resistant acid phosphatase (TRAP)-positive multinuclear cells in BMMs without inducing cytotoxicity. The mRNA expressions of genetic markers of OC differentiation including c-Fos, nuclear factor of activated T cells 1 (NFATc1), TRAP, and osteoclast associated receptor (OSCAR), were significantly decreased in the presence of CUR-CGNPs. Also, the CUR-CGNPs inhibited OC differentiation of BMMs through suppression of the RANKL-induced signaling pathway. Additionally, CUR-CGNPs caused a decrease in RANKL-induced actin ring formation, which is an essential morphological characteristic of OC formation allowing them to carry out bone resorption activity. Furthermore, the in vivo results of an ovariectomy (OVX)-induced osteoporosis model showed that CUR-CGNPs significantly improved bone density and prevented bone loss. Therefore, CUR-CGNPs may prove to be useful as therapeutic agents for preventing and treating osteoporosis.
    Full-text available · Article · Nov 2014 · ACS Nano
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    Wan-Kyu Ko · Jun-Young Cho · Ho-Jin Moon · [...] · Il Keun Kwon
    [Show abstract] [Hide abstract] ABSTRACT: Since the 17th century Spica Prunella has been used as a medicinal herb. Dried and pulverized Spica Prunella samples were extracted and used in these experiments. In this study, the effects of Spica Prunella extract (SPE) on RANKL (receptor activator of nuclear factor κB ligand)-induced osteoclastogenesis were examined. Actin ring formation, a typical marker of osteoclastogenesis, was inhibited by SPE without any toxicity. There was also a marked inhibition in the formation of tartrate-resistant acid phosphatase (TRAP)-positive multinucleated cells in bone marrow-derived monocytes (BMMs). SPE also suppressed phosphorylation of c-Jun N-terminal kinase (JNK) and extracellular signal-regulated kinases (ERK) both of which are signals of the mitogen-activated protein kinases (MAPKs) signaling pathway. Additionally, SPE inhibited IκBα (nuclear factor of kappa light polypeptide gene enhancer in B-cells inhibitor, alpha) signaling pathway, which is an important factor in osteoclastogenesis. These results indicate that SPE might suppress osteoclast differentiation by inhibiting the phosphorylation of JNK and ERK in MAPK and NF-κB signaling pathways which act as messengers in the RANKL-induced osteoclast differentiation pathway. This means that SPE could potentially have great therapeutic usage in treating bone erosive diseases such as rheumatoid arthritis or in preventing metastasis associated with bone loss.
    Full-text available · Article · Dec 2013 · Food science and biotechnology
  • Ho-Jin Moon · Wan-Kyu Ko · Min-Seo Jung · [...] · Il Keun Kwon
    [Show abstract] [Hide abstract] ABSTRACT: Coenzyme Q10 (CoQ10), a powerful antioxidant, is a key component in mitochondrial bioenergy transfer, generating energy in the form of ATP. Many studies suggest that antioxidants act as inhibitors of osteoclastogenesis and we also have previously demonstrated the inhibitory effect of CoQ10 on osteoclast differentiation. Despite the significance of this effect, the molecular mechanism when CoQ10 is present at high concentrations in bone remodeling still remains to be elucidated. In this study, we investigated the inhibitory effect of CoQ10 on osteoclastogenesis and its impact on osteoblastogenesis at concentrations ranging from 10 to 100 μM. We found that nontoxic CoQ10 markedly attenuated the formation of receptor activator of nuclear factor κB ligand (RANKL)-induced tartrate-resistant acid phosphatase (TRAP)-positive multinucleated cells in both bone-marrow-derived monocytes (BMMs) and RAW 264.7 cells. Osteoclastogenesis with CoQ10 was significantly suppressed the gene expression of NFATc1, TRAP, and osteoclast-associated immunoglobulin-like receptor, which are genetic markers of osteoclast differentiation and scavenged intracellular reactive oxygen species, an osteoclast precursor, in a dose-dependent manner. Furthermore, CoQ10 strongly suppressed H2 O2 -induced IκBα, p38 signaling pathways for osteoclastogenesis. In bone formation study, CoQ10 acted to enhance the induction of osteoblastogenic biomarkers including alkaline phosphatase, type 1 collagen, bone sialoprotein, osteoblast-specific transcription factor Osterix, and Runt-related transcription factor 2 and, also promoted matrix mineralization by enhancing bone nodule formation in a dose-dependent manner. Together, CoQ10 acts as an inhibitor of RANKL-induced osteoclast differentiation and an enhancer of bone-forming osteoblast differentiation. These findings highlight the potential therapeutic applications of CoQ10 for the treatment of bone disease.
    Article · Apr 2013 · Journal of Food Science
  • Sung-Moon Bang · Ho-Jin Moon · Yong-Dae Kwon · [...] · Il Keun Kwon
    [Show abstract] [Hide abstract] ABSTRACT: Purpose: We evaluated the activities of both osteoblastic and osteoclastic differentiation on sandblasted/acid etched (SLA), hydrophilic SLA surfaces (modSLA) and pretreatment titanium (PT). Material and methods: The osteoblastic differentiation was evaluated by alkaline phosphatase analysis and Alizarin Red S staining, and the expression of bone-related proteins, alkaline phosphatase (ALP), runt-related transcription factor 2 (Runx2), osteopontin (OPN), and osteocalcin (OCN), was investigated by reverse transcriptase-polymerase chain reaction (RT-PCR). Primary mice monocytes were expanded and differentiated in the presence of macrophage-colony stimulating factor (M-CSF), and osteoclastic differentiation was evaluated by actin ring formation assay and tartrate-resistant acid phosphatase (TRAP) activity assay. Real-time PCR tests were performed to investigate the expression of gene mRNA expression levels in osteoclast cells. Result: Differentiation of osteoblasts in the Alizarin Red S test staining and ALP assay was significantly increased in the modSLA surface. The preceding results were supported by the result of RT-PCR for the expression of Runx2, OPN, and OCN. As for osteoclastic activity, differentiated osteoclasts rarely existed on the SLA and modSLA surface with actin ring. The results of real-time PCR and TRAP activity supported the preceding results. Conclusion: It may be concluded that the modSLA surface promotes osteogenic effect and prevents osteoclastic differentiation. Promotion of osteoblastic proliferation after a short-term cell culture might be responsible for stimulated bone regeneration implying that early loading may be possible. Also, the anti-osteoclastic effect of the modSLA surface may contribute to maintenance of the marginal bone level of dental implants, implying long-term stability would be provided by this surface technology. The modSLA surface may not only make early loading possible but possibly reduce marginal bone loss during the maintenance phase.
    Article · Apr 2013 · Clinical Oral Implants Research
  • Ho-Jin Moon · Eun-Kyung Kim · Yun Sik Nam · [...] · Il Keun Kwon
    [Show abstract] [Hide abstract] ABSTRACT: Safflower seed has been reported to have a protective effect against bone loss diseases. However, the precise molecular mechanisms underlying the inhibitory effect of safflower seed in osteoclast differentiation remain unclear. In this study, we investigated the inhibitory action of safflower seed extract (SSE) on the receptor activator of nuclear factor κB ligand (RANKL)-induced osteoclastogenesis in cultured mouse-derived bone marrow macrophages (BMMs). We found that SSE significantly inhibited the formation of tartrate-resistant acid phosphatase (TRAP)-positive multinucleated cells in BMMs without cytotoxicity. The gene expressions of nuclear factor of activated T-cells (NFATc1) and TRAP, which are genetic markers of osteoclast differentiation, were substantially decreased by SSE in a dose-dependent manner. Also, SSE diminished RANKL-mediated intracellular reactive oxygen species (ROS) generation on osteoclastogenesis in a dose-dependent manner. The SSE thereafter suppressed RANKL-induced p38 mitogen-activated protein kinase and IκBα kinase signalling activities which were activated by ROS generation for osteoclastogenesis. Additionally, SSE was found to decrease RANKL-induced actin ring formation, which is required for bone resorption activity. Taken together, our results suggest that SSE acts as a RANKL-induced osteoclastogenesis inhibitor by suppression of ROS generation. This induces a remarkable suppression of the p38 and IκBα kinase pathways, thereby suppressing the gene expression of NFATc1 in osteoclast precursors. Copyright © 2012 John Wiley & Sons, Ltd.
    Article · Nov 2012 · Phytotherapy Research
  • Ho-Jin Moon · Wan-Kyu Ko · Song Wook Han · [...] · Il Keun Kwon
    [Show abstract] [Hide abstract] ABSTRACT: Coenzyme Q10 (CoQ10), selenium, and curcumin are known to be powerful antioxidants. Osteoclasts are capable of resorbing mineralized bone and excessive bone resorption by osteoclasts causes bone loss-related diseases. During osteoclast differentiation, the reactive oxygen species (ROS) acts as a secondary messenger on signal pathways. In this study, we investigated whether antioxidants can inhibit RANKL-induced osteoclastogenesis through suppression of ROS generation and compared the relative inhibitory activities of CoQ10, sodium selenite, and curcumin on osteoclast differentiation. We found that antioxidants markedly inhibited the formation of tartrate-resistant acid phosphatase (TRAP)-positive multinucleated cells in both bone marrow-derived monocytes (BMMs) and RAW 264.7 cells. Antioxidants scavenged intracellular ROS generation within osteoclast precursors during RANKL-stimulated osteoclastogenesis. These also acted to significantly suppress the gene expression of NFATc1, TRAP, and osteoclast-associated immunoglobulin-like receptor (OSCAR), which are genetic markers of osteoclast differentiation in a dose-dependent manner. These antioxidants also suppressed ROS-induced IκBα signaling pathways for osteoclastogenesis. Specially, curcumin displayed the highest inhibitory effect on osteoclast differentiation when concentrations were held constant. Together, CoQ10, selenite, and curcumin act as inhibitors of RANKL-induced NFATc1 which is a downstream event of NF-κB signal pathway through suppression of ROS generation, thereby suggesting their potential usefulness for the treatment of bone disease associated with excessive bone resorption.
    Article · Feb 2012 · Biochemical and Biophysical Research Communications
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    Dong Nyoung Heo · Dae Hyeok Yang · Ho-Jin Moon · [...] · Il Keun Kwon
    [Show abstract] [Hide abstract] ABSTRACT: We describe in this study whether the gold nanoparticle (AuNP) surface-functionalized with PEG, biotin, paclitaxel (PTX) and rhodamine B linked beta-cyclodextrin (β-CD) (AuNP-5') can be useful as a theranostic agent for cancer therapy without the cytotoxic effect on normal cells. Prior to surface-functionalizing AuNPs, the cytotoxicity of the nanoparticles was evaluated, followed by their cytocompatibility. PTX, an anti-cancer agent, formed inclusion complexations with β-CD conjugated AuNPs, and effectively released from the AuNP-2' surface-functionalized with PEG, beta-cyclodextrin (β-CD) and paclitaxel (PTX) using the intracellular glutathione (GSH) level (10 mm). Two types of AuNP-4 surface-functionalized with PEG and rhodamine B linked β-CD and AuNP-5 surface-functionalized PEG, biotin and rhodamine B linked β-CD were used for evaluating their specific interaction on cancer cells such as HeLa, A549 and MG63. These were also tested against normal NIH3T3 cell, determining that the AuNP-5 was more effectively involved with the cancer cells. Confocal laser scanning microscopy (CLSM), fluorescence-activated cell-sorting (FACS) and cell viability analyses showed that the AuNP-5' plays a significant role in the diagnosis and therapy of the cancer cells, and may be used in theranostic agents.
    Full-text available · Article · Jan 2012 · Biomaterials
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    Ha Na Park · Jung Bok Lee · Ho-Jin Moon · [...] · Il Keun Kwon
    Full-text available · Chapter · Nov 2011
  • Ho-Jin Moon · Young-Pil Yun · Choong-Wan Han · [...] · Il Keun Kwon
    [Show abstract] [Hide abstract] ABSTRACT: The failure of orthopedic and dental implants has been attributed mainly to loosening of the implant from host bone, which may be due to weak bonding of the implant material to bone tissue. Titanium (Ti) is used in the field of orthopedic and dental implants because of its excellent biocompatibility and outstanding mechanical properties. Therefore, in the field of materials science and tissue engineering, there has been extensive research to immobilize bioactive molecules on the surface of implant materials in order to provide the implants with improved adhesion to the host bone tissue. In this study, chemically active functional groups were introduced on the surface of Ti by a grafting reaction with heparin and then the Ti was functionalized by immobilizing alendronate onto the heparin-grafted surface. In the MC3T3-E1 cell osteogenic differentiation study, the alendronate-immobilized Ti substrates significantly enhanced alkaline phosphatase activity (ALP) and calcium content. Additionally, nuclear factor kappa B ligand (RANKL)-induced osteoclast differentiation of RAW264.7 cells was inhibited with the alendronate-immobilized Ti as confirmed by TRAP analysis. Real time PCR analysis showed that mRNA expressions of osteocalcin and osteopontin, which are markers for osteogenesis, were upregulated in MC3T3-E1 cells cultured on alendronate-immobilized Ti. The mRNA expressions of TRAP and Cathepsin K, markers for osteoclastogenesis, in RAW264.7 cells cultured on alendronate-immobilized Ti were down-regulated. Our study suggests that alendronate-immobilized Ti may be a bioactive implant with dual functions to enhance osteoblast differentiation and to inhibit osteoclast differentiation simultaneously.
    Article · Aug 2011 · Biochemical and Biophysical Research Communications
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    [Show abstract] [Hide abstract] ABSTRACT: The aim of this study was to investigate biologic function of bone morphorgenic protein-2 (rhBMP-2) immobilized on the heparin-grafted Ti surface. Ti surfaces were first modified by 3-aminopropyltriethoxysilane (ATPES), followed by grafting of heparin. BMP-2 was then immobilized on the heparin-grafted Ti surfaces. Pristine Ti and functionalized Ti surfaces were characterized by X-ray photoelectron spectroscopy (XPS), measurement of water contact angles, and protein adsorption. The biological activity of MG-63 cells on pristine and functionalized Ti surfaces was investigated by cell proliferation assays, measurement of alkaline phosphate (ALP) activity, and determination of calcium deposition. Anti-inflammatory effects were assessed by RT-PCR to measure the transcript levels of IL-6 and TNF-α. XPS revealed that heparin and BMP-2 were successfully grafted and immobilized on the Ti surfaces, respectively. In addition, Ti surfaces with BMP-2 immobilized were more hydrophilic than pristine Ti. Furthermore, BMP-2 immobilized Ti promoted significantly higher ALP activity and calcium deposition by MG-63 cells than pristine Ti. The inflammatory response was also decreased when cells were grown on heparin-grafted, BMP-2-immobilized Ti surfaces. The results of this study suggest that by grafting heparin and immobilizing BMP-2 on Ti surfaces, inflammation can be inhibited and osteoblast function promoted.
    Full-text available · Article · Sep 2010 · Biomaterials