Deok Won Lee

Osteogenesis induction of periodontal ligament cells onto bone morphogenic protein-2 immobilized PCL fibers

The purpose of this study was to develop bone morphogenic protein-2 (BMP-2) immobilized PCL fibers to induce osteogenic differentiation of periodontal ligament cells (PDLCs). The PCL fiber surface was modified with heparin-dopamine (Hep-DOPA) (Hep-PCL) and further immobilized with BMP-2 (BMP-2/Hep-PCL). PCL fibers and surface-modified PCL fibers (Hep-PCL and BMP-2/Hep-PCL) were characterized by X-ray photoelectron spectroscopy (XPS) and contact angle. Osteogenic differentiation of PDLCs was demonstrated by alkaline phosphatase (ALP) activity, calcium deposition, and gene expression. The results of XPS and contact angle revealed that Hep-DOPA and BMP-2 were successfully immobilized onto the PCL surface and that the BMP-2/Hep-PCL fibers have more hydrophilic surface properties than PCL fibers alone. ALP activity, calcium deposition, and gene expression on BMP-2/Hep-PCL fibers showed significantly induced osteogenic differentiation relative to PCL fibers. Therefore, we suggest that BMP-2/Hep-PCL fibers have the potential to effectively induce osteogenic differentiation of PDLCs.

Local delivery of alendronate eluting chitosan scaffold can effectively increase osteoblast functions and inhibit osteoclast differentiation

The aim of this study was to investigate the effect of alendronate released from chitosan scaffolds on enhancement of osteoblast functions and inhibition of osteoclast differentiation in vitro. The surface and cell morphologies of chitosan scaffolds and alendronate-loaded chitosan scaffolds were characterized by variable pressure field emission scanning electron microscope (VP-FE-SEM). Alendronate was released in a sustained manner. For evaluating osteoblast functions in MG-63 cells, we investigated cell proliferation, alkaline phosphatase (ALP) activity, and calcium deposition. Furthermore, for evaluating inhibition of osteoclast differentiation in RAW 264.7 cells, we investigated tartrate-resistant acid phosphatase (TRAP) activity, TRAP staining, and gene expressions. The in vitro studies revealed that osteoblasts grown on alendronate-loaded chitosan scaffold showed a significant increment in cell proliferation, ALP activity, and calcium deposition as compared to those grown on chitosan scaffolds. In addition, the in vitro study showed that osteoclast differentiation in RAW 264.7 cells cultured on alendronate-loaded chitosan scaffolds was greatly inhibited as compared to those cultured on chitosan scaffolds by the results of TRAP activity, TRAP staining, and gene expressions. Taken together, alendronate-loaded chitosan scaffolds could achieve the dual functions of improvement in osteoblast functions and inhibition of osteoclast differentiation. Thus, alendronate-eluting chitosan substrates are promising materials for enhancing osteoblast functions and inhibiting osteoclast differentiation in orthopedic and dental fields.

Inflammatory pseudotumor in the mandible.

Inflammatory pseudotumor (IPT) is a rare benign nonneoplastic lesion. The exact etiology of IPT remains unclear. Inflammatory pseudotumor in the maxillofacial region is exceptionally rare, and it is often mistaken for a malignancy. The diagnosis is still difficult and is based on the histological examination of the lesions composed of 3 types of inflammatory cells: histiocytes, plasma cells, and lymphocytes. Due to its feature mimicking invasive malignant tumors, we should consider this entity before we carry out radical procedures. In this short report, we will present a case of an aggressive IPT involving the mandible and a review of literatures.

The use of heparin chemistry to improve dental osteogenesis associated with implants

In this study, we designed a hybrid Ti by heparin modifying the Ti surface followed by Growth/differentiation factor-5 (GDF-5) loading. After that, products were characterized by physicochemical analysis. Quantitative analysis of functionalized groups was also confirmed. The release behavior of GDF-5 grafted samples was confirmed for up to 21days. The surface modification process was found to be successful and to effectively immobilize GDF-5 and provide for its sustained release behavior. As an in vitro test, GDF-5 loaded Ti showed significantly enhanced osteogenic differentiation with increased calcium deposition under nontoxic conditions against periodontal ligament stem cells (PDLSc). Furthermore, an in vivo result showed that GDF-5 loaded Ti had a significant influence on new bone formation in a rabbit model. These results clearly confirmed that our strategy may suggest a useful paradigm by inducing osseo-integration as a means to remodeling and healing of bone defects for restorative procedures in dentistry.

Heparin-immobilized hydroxyapatite nanoparticles as a lactoferrin delivery system for improving osteogenic differentiation of adipose-derived stem cells

The aim of this study is to fabricate lactoferrin (LF)-carrying hydroxyapatite nanoparticles (HAp NPs) to enhance osteogenic differentiation of rabbit adipose-derived stem cells (rADSCs). HAp NPs were modified with heparin-dopamine (Hep-DOPA) (Hep-HAp) and further immobilized with LF (LF/Hep-HAp). Heparin immobilization on HAp NPs prevented aggregation of HAp NPs in aqueous solution and prolonged the release of LF from LF/Hep-HAp NPs. In vitro studies of rADSCs have demonstrated that LF-Hep/HAp NPs significantly increase alkaline phosphatase (ALP) activity, calcium deposition, and both mRNA expression of osteocalcin (OCN) and osteopontin (OPN) in comparison with HAp and Hep-HAp NPs. These results suggest that LF/Hep-HAp NPs can effectively induce osteogenic differentiation of rADSCs.

Alendronate-Eluting Biphasic Calcium Phosphate (BCP) Scaffolds Stimulate Osteogenic Differentiation

Biphasic calcium phosphate (BCP) scaffolds have been widely used in orthopedic and dental fields as osteoconductive bone substitutes. However, BCP scaffolds are not satisfactory for the stimulation of osteogenic differentiation and maturation. To enhance osteogenic differentiation, we prepared alendronate- (ALN-) eluting BCP scaffolds. The coating of ALN on BCP scaffolds was confirmed by scanning electron microscopy (FE-SEM), energy-dispersive X-ray spectroscopy (EDS), and attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR). An in vitro release study showed that release of ALN from ALN-eluting BCP scaffolds was sustained for up to 28 days. In vitro results revealed that MG-63 cells grown on ALN-eluting BCP scaffolds exhibited increased ALP activity and calcium deposition and upregulated gene expression of Runx2, ALP, OCN, and OPN compared with the BCP scaffold alone. Therefore, this study suggests that ALN-eluting BCP scaffolds have the potential to effectively stimulate osteogenic differentiation.

The Effects of Functionalized Titanium with Alendronate and Bone Morphogenic Protein-2 for Improving Osteoblast Activity

The aim of this study was to investigate the effect of functionalized titanium (Ti) with alendronate (Aln) and bone morphogenic protein-2 (BMP-2) for enhancement of osteoblast activity in vitro. Aln and/or BMP-2 were sequentially immobilized to the heparinized-Ti (Hep-Ti) surface. The compositions of pristine Ti and Hep-Ti with or without Aln and/or BMP-2 were characterized by scanning electron microscope (SEM) and X-ray photoelectron spectroscopy (XPS). Aln and/or BMP-2 onto Hep-Ti surface were released in a sustained manner. Osteoblast activities on all Ti substrates were investigated by cell proliferation assays, alkaline phosphate (ALP) activity, calcium deposition, gene expressions of osteocalcin and osteopontin. Aln/BMP-2/Hep-Ti significantly enhanced ALP activity, calcium mineral deposition, and gene expressions of osteoblast cells when compared with pristine Ti, Aln/Hep-Ti, and BMP-2/Hep-Ti. From these results, functionalized Ti substrates with alendronate and BMP-2 such as Aln/BMP-2/Hep-Ti are a promising material for the enhanced osteoblast activities in orthopedic and dental fields.

Recombinant human bone morphogenic protein-2 (Rhbmp-2) immobilization onto the surface of apatite-coated titanium significantly promotes osteoblast function and mineralization

Titanium (Ti) has been widely used in the dental field owing to its good biocompatibility, superior mechanical properties, and excellent corrosion resistance. However, Ti lacks the osteoconductivity and osteoinductivity required to promote mineralization. In the present study, the authors investigated whether apatite-coated Ti and rhBMP-2 treated apatite-coated Ti promote more mineralization than pristine Ti. Characterizations of pristine Ti, apatite-coated Ti, or rhBMP-2/apatite-coated Ti were analyzed using scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), and attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR). In addition, the release profile of rhBMP-2 from rhBMP-2/apatite-coated Ti was monitored for 28 days, and the biocompatibility of pristine Ti, apatite-coated Ti, and rhBMP-2/apatite-coated Ti was evaluated by measuring cell proliferation, alkaline phosphatase (ALP) activity, calcium deposition, and real-time PCR using MG-63 cells. SEM, EDS, and ATR-FTIR showed that the apatite on apatite-coated Ti surfaces was similar to that of natural bone. Furthermore, rhBMP-2 appeared to be released steadily over 28 days from rhBMP-2/apatite-coated Ti, and MG-63 cells grown on rhBMP-2/apatite-coated Ti showed significantly higher proliferation activity, ALP activity, and calcium deposition compared to MG-63 cells grown on pristine Ti or apatite-coated Ti. Furthermore, osteocalcin and osteopontin gene expression in MG-63 cells grown on rhBMP-2/apatite-coated Ti was significantly greater than that in MG-63 cells grown on pristine Ti or apatite-coated Ti by real-time PCR. Taken together, rhBMP-2/apatite-coated Ti substrate has enhanced osteoblast function and mineralization. Thus, rhBMP-2/apatite-coated Ti may be a more effective substrate than pristine Ti used in the dental field.

Dexmedetomidine Oral Mucosa Patch for Sedation Suppresses Apoptosis in Hippocampus of Normal Rats

Purpose Dexmedetomidine, an α2-adrenergic agonist, provides sedative and analgesic effects without significant respiratory depression. Dexmedetomidine has been suggested to have an antiapoptotic effect in response to various brain insults. We developed an oral mucosa patch using dexmedetomidine for sedation. The effects of the dexmedetomidine oral mucosa patch on cell proliferation and apoptosis in the hippocampus were evaluated. Methods A hydrogel oral mucosa patch was adhered onto the oral cavity of physiologically normal rats, and was attached for 2 hours, 6 hours, 12 hours, or 24 hours. Plasma dexmedetomidine concentrations were determined by liquid chromatography– electrospray ionization–tandem mass spectrometry–multiple-ion reaction monitoring (LC-ESI-MS/MS-MRM). Cell proliferation in the hippocampus was detected by Ki-67 immunohistochemistry. Caspase-3 immunohistochemistry, terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling staining, and Western blotting for Bax and Bcl-2 were performed to detect hippocampal apoptosis. The levels of brain-derived neurotrophic factor (BDNF) and tyrosine kinase B (TrkB) in the hippocampus were also measured by Western blotting. Results Plasma dexmedetomidine concentration increased according to the attachment time of the dexmedetomidine oral mucosa patch. Hippocampal cell proliferation did not change due to the dexmedetomidine oral mucosa patch, and the dexmedetomidine oral mucosa patch exerted no significant effect on BDNF or TrkB expression. In contrast, the dexmedetomidine oral mucosa patch exerted an antiapoptotic effect depending on the attachment time of the dexmedetomidine oral mucosa patch. Conclusions A dexmedetomidine oral mucosa patch can be used as a convenient tool for sedation, and is of therapeutic value due to its antiapoptotic effects under normal conditions.

A large sialolith on the parenchyma of the submandibular gland: A case report.

A 45-year-old female was referred to the Department of Oral and Maxillofacial Surgery with the complaint of pain in the right submandibular region and a dry mouth, which had started one week previously. A clinical examination revealed a swelling and tenderness in the right submandibular region. Panoramic radiography and computed tomography identified a sialolith in the submandibular gland. Surgery on the sialolith was subsequently completed under general anesthesia extraorally. A brownish stone was present in the parenchyma of the submandibular gland, measuring 14×10 mm.