• Journal of Periodontal and Implant Science
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• v.36 no.3
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• pp.613-625
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• 2006

Periodontal ligament(PDL) cells and human gingival fibroblasts(HGFs) play important roles in development, regeneration, normal function, and pathologic alteration. PDL cells and HGFs have the similarity related with general characteristics of fibroblast such as spindle shaped morphology, the presence of vimentin intermediate filament and the synthesis of interstitial collagens and fibronectin. There were many studies about the differences between PDL cells and HGFs, but they were not about whole gene level. In this study, we tried to explain the differences of gene expression profiles between PDL cells and HGFs, and the differences among three individuals by screening gene expression patterns of PDL cells and HGFs, using cDNA microarray. Although there were some variants among three experiments, a set of genes were consistentely and differentially expressed in one cell type. Among 3,063 genes, 49 genes were more highly expressed in PDL cells and 12 genes were more highly expressed in HGFs. The genes related with cell structure and motility were expressed more highly in PDL cells. These are cofilin 1, proteoglycan 1 secretory granule, collagen type I(${\alpha}$ 1), adducin gamma subunit, collagen type III(${\alpha}$ 1), fibronectin, lumican(keratan sulfate proteoglycan), and ${\alpha}$ -smooth muscle actin. Tissue inhibitor of metalloproteinase known as the enzyme controlling extracellular matrix with matrix metalloproteinase is more highly expressed in PDL cells, osteoprotegerin known as osteoclastogenesis inhibitory factor is more highly expressed in HGFs. We performed northern blot to verify cDNA microarray results on selected genes such as tissue inhibitor of metalloproteinase, fibronectin, osteoprogeterin. The result of northern blot analysis showed that each cell expressed the genes in similar pattern with cDNA microarray result. This result indicates that cDNA microarray is a reliable method in screening of gene expression profiles.

• International Journal of Oral Biology
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• v.38 no.2
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• pp.73-80
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• 2013

Leptin is one of the adipocytokines produced from adipose tissue but its functions in periodontal tissue have not previously been investigated. In our current study, we examined the effects of leptin on the expression of interleukin (IL)-6 and IL-8 in periodontal ligament (PDL) cells and gingival fibroblasts. Leptin receptor expression was evaluated by RT-PCR and the production of cytokines was measured by ELISA. The phosphorylation of Akt and Erk1/2 was assessed by western blotting. mRNA of long and short form leptin receptors were detected in both PDL cells and gingival fibroblasts. Leptin was found to increase the production of IL-6 and IL-8 in both of these cell types, an effect which was not blocked by polymyxin B, an inhibitor of lipopolysaccharide (LPS). Leptin did not alter the production of IL-6 and IL-8 induced by LPS in PDL cells but increased Akt and Erk1/2 phosphorylation in these cells. These results suggest that leptin acts as an inducer of IL-6 and IL-8 in PDL cells and gingival fibroblasts.

• The korean journal of orthodontics
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• v.24 no.2
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• pp.295-301
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• 1994

The movement of teeth during orthodontic treatment requires bone remodeling process in periodontal tissue. To find out the changes occuring in the cell itself, mechanical force was applied to the cultured periodontal ligament cells. Following results were obtained from measuring the changes in cyclic AMP and $PGE_2$, $^3H$-thymidine incorporation amount in time lapse after application of mechanical force. 1. When mechanical force was applied to cultured PDL cells, the amount of cAMP in cells were increased significantly after 15 min. of force application, but were decreased gradually as time lapsed. 2. When mechanical force was applied to cultured PDL cells, the amount of PGE2 were increased at 20,40,60 min. and was significantly increased at 20 min. 3. When mechanical force was applied to cultured PDL cells, the amount of $^3H$-thymidine incorporation was some increased, but was not statistically significant.

• Journal of Periodontal and Implant Science
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• v.26 no.4
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• pp.949-965
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• 1996

The main goal of periodontal therapy is to restore the lost periodontal tissue and establish the attachment appratus. Current acceptable therapeutic techniques are included : removal of diseased soft tissue, demineralization of exposed root surface, using the barrier membrane for preventing the downgrowth of gingival epithelial cell, insertion of graft materials as a scaffolding action, and biological mediators for promoting the cell activity. The latest concept one among them has been studied which based on the knowledge of cellular biology of destructed tissue. Platelet-derived growth factor(PDGF) is one of the polypeptide growth factor which have been reported as a biological mediator to regulate activities of wound healing progress including cell proliferation, migration, and metabolism. The purposes of this study is to evaluate the influences of the PDGF as biological mediator to periodontal ligament and bone marrow cell. Both right and left maxillary first molar were extracted from rat which had treated with 0.4% ${\beta}-Aminopropionitril$ for 5 days, and feeded until designed date to sacrifice under anesthesisa. Periodontal ligament were removed from the extracted socket of the rat, and cultured with Dulbecco's Modified Essential Medium(DMEM) contained with 10% Fetal Bovine Serum, 100U/ml penicillin, $100{\mu}g/ml$ streptomycin, $0.5{\mu}g/ml$ amphotericin-B. Bone marrow cell were culture from bone marrow suspension with which washed out from femur with same medium. The study was performed to evaluate the effect of PDGF to periodontal ligament and bone cell, cell proliferation rate, total protein synthesis, and alkaline phosphatase activity of rat periodontal ligament(PDL) cell and bone stromal(RBS) cell in vitro. The effects of growth factors on both cells were measured at 3, 5th day after cell culture with (control group) or without growth factors(experimental group). The results were as follows: 1. The tendency of cell proliferation under the influence of PDGF showed more rapid proliferation pattern than control at 3 and 5 days after inoculation. 2. The activity of Alkaline phosphatase revealed 14, 80% increased respectively at 3, 5 days culture than control group. Measurements of ALPase levels indicated that PDL cells had significantly higher activity when compared with that of co-culture groups and GF only(P<0.05). And, ALPase activity in 10 days was higher than that of 7 days(P<0.05). 3. The tendency of formation of the mineralized nodule were observed dose-depend pattern of PDL cells. There was statistically significant difference among group l(PDL 100%), 2(PDL 70%:GF 30%), and 3(PDL 50%:GF 50%)(P<0.01). But, there was no difference among group 3, 4(PDL 30%:GF 70%), and 5(GF 100%). 4. Also, the number of nodule was greater in co-culture of PDL 70% and GF 30% than in culture of PDL 70%(P<0.05). From the above results, it is assumed that the PDGF on PDL cells and RMB cell culture. GF stimulates the cell growth, which is not that of PDL cells but GF. And, the activity of ALPase depends on the ratio of PDL cells, and ALPase may relate to the initial phase of nodule formation. Also, it is thought that the calcified nodule formation principally depends on PDL cells, is inhibited by GF, and affected by cell density. In conclusion, platelet-derived growth factor can promote rapid osteogenesis during early stage of periodontal tissue regeneration.

• International Journal of Oral Biology
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• v.32 no.1
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• pp.35-43
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• 2007

Tooth loss in elderly is mainly caused by alveolar bone loss via severe periodontitis. Although the severity of periodontitis is known to be affected by age, the aging process or the genetic changes during the aging of periodontal tissue cells are not well characterized. In this study, we investigated the effect of in vitro aging on the change of gene expression pattern in periodontal fibroblasts. Gingival fibroblasts (GF) and periodontal ligament fibroblasts (PDL) were obtained from two young patients and replicative senescence was induced by sequential subcultivation. When more than 90% cells were positively stained with senescence-associated ${\beta},-galactosidase$, those cells were regarded as aged cells. In aged GF and PDL, the level of phosphorylated retinoblastoma (RB) and $p16^{INK4A}$ protein was significantly decreased and increased, respectively. However, the protein level of p53 and p21, well known senescence-inducing genes, did not increase in aged GF and PDL. Although $p27^{Kip1}$ and $p15^{INK4B}$, another cyclin-dependent kinase inhibitors, were reported to be involved in replicative senescence of human cells, they were decreased in aged GF and PDL. Because senescent cells showed flattened and enlarged cell shape and are known to have increased focal adhesion, we examined the protein level of several integrins. Aged GF and PDL showed increased protein level of integrin ${\alpha}2$, ${\alpha}v$, and ${\beta}1$. When the gene expression profiles of actively proliferating young cells and aged cells were compared by cDNA microarray of 3,063 genes and were confirmed by reverse transcription-polymerase chain reaction, 7 genes and 15 genes were significantly and commonly increased and decreased, respectively, in aged GF and PDL. Among them, included are the genes that were known to be involved in the regulation of cell cycle, gene transcription, or integrin signaling. The change of gene expression pattern in GF and PDL was minimally similar to that of oral keratinocyte. These results suggest that $p16^{INK4A}/RB$ might be involved in replicative senescence of periodontal fibroblasts and the change of gene expression profile during aging process is cell type specific.

• International Journal of Oral Biology
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• v.44 no.4
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• pp.182-190
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• 2019

Periodontitis is an inflammatory disease of the supportive tissues surrounding the teeth, and is characterized by irreversible destruction of the gingiva, periodontal ligament (PDL), and alveolar bone, which results in the loss of teeth. In the present study, we elucidated the correlation between periodontitis and apelin (APLN), an adipokine and a regulatory peptide, respectively, which are involved in inflammation and bone remodeling. The expression of APLN is negatively correlated with periodontitis progression in gingival tissue. In addition, treatment with TNF-α downregulated the expression of APLN in PDL cells and gingival fibroblasts, indicating the protective role played by APLN against periodontitis progression. The overexpression of APLN or treatment with exogenous APLN suppressed the TNF-α-mediated catabolic gene expression of MMP1, IL6, and PTGS2 in PDL cells. Moreover, the inhibition of the APLNA-PJ axis by ML221, an APJ inhibitor, induced catabolic gene expression in PDL cells. Thus, the results of this study provided evidence to support APLN as a regulatory factor of the inflammatory response during periodontitis.

• The korean journal of orthodontics
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• v.16 no.1
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• pp.51-70
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• 1986

Parathyroid hormone (PTH) is known to exert its effects on bone cells through the mediation of adenosine 3', 5'-monophosphate (cAMP). Orthodontic forces have also been shown to alter the cAMP content of paradental cells, particularly the alveolar bone osteoblasts. The objective of this experiment was to determine whether a combined orthodontic treatment-PTH administration regimen would have an additive effect on cAMP content in paradental cells in sites of periodontal ligament (PDL) tension. Seven groups of 4 one year old female cats each were treated for 1,3,6,12,24 h, 7 and 14 d by tipping one maxillary canine. PTH was administered twice daily, 30u/kg. Maxillary horizontal sections were stained immunohistochemically for cAMP and the degree of cellular staining intensity was determined microphotometrically as per cent light transmittance at 600nm. Alveolar bone osteoblasts, progenitor cells, PDL fibroblasts and cementoblasts in tenion sites were measured and the data were analyzed statistically by a mixed model analysis of variance. PTH administration increased the cAMP staining of nonorthodontically treated paradental cells in comparison to cells untreated by force or hormone. Cells in PDL tension sites of PTH-treated cats demonstrated significantly darker cAMP staining than cells in non-orthodontically-treated sites. Osteoblasts demonstrated the greatest response in terms of cAMP elevation, while in PDL fibroblasts orthodontic force did not increase cAMP levels above those measured in non-stretched hormonally-treated cells. These results demonstrate that PTH increases cAMP levels in paradental cells, particullarly in osteoblasts, and that the effects of PTH and orthodontic forces on paradental target cells may approach additivity.

• Journal of Korean Dental Science
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• v.8 no.2
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• pp.57-64
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• 2015

Purpose: This study was conducted to determine cell viability and differentiation capability of human periodontal ligament (PDL) cells and to elucidate the effects of cryopreservation on the activity of human third molar PDL cells by comparing PDL cells with and without cryopreservation. Materials and Methods: Human PDL fibroblasts obtained from immature third molars were cultured and divided into two groups. The experimental group was cryopreserved with a slow freezing rate of $0.5^{\circ}C/min$ from $4^{\circ}C$ to $-35^{\circ}C$ followed by plunging in liquid nitrogen at $-196^{\circ}C$ and cultured after fast thawing. The control group was cultured without cryopreservation. Cell viability, growth capacity and morphology were evaluated in both groups. Bivariate statistics were used to compare 2 groups and linear mixed model analysis was used to investigate the growth trends difference over time. Result: Cell viability and growth capacity were not significantly different between the 2 groups (P>0.05). Cultured cell of both groups showed fibroblast-like in appearance, and there were no significant differences in morphology between 2 groups. The mixed model analysis revealed no significant difference of growth capacity between 2 groups over time (${\beta}=-0.0009$; P=0.138). Conclusion: This study demonstrates that cryopreservation under control does not affect the biological properties of PDL cells, supporting the feasibility of autotransplantation of cryopreserved impacted third molars.

• Journal of Periodontal and Implant Science
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• v.52 no.3
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• pp.242-257
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• 2022

Purpose: This study investigated periodontal ligament (PDL) restoration in osseointegrated implants using stem cells. Methods: Commercial pure titanium and zirconium oxide (zirconia) were coated with beta-tricalcium phosphate (β-TCP) using a long-pulse Nd:YAG laser (1,064 nm). Isolated bone marrow mesenchymal cells (BMMSCs) from rabbit tibia and femur, isolated PDL stem cells (PDLSCs) from the lower right incisor, and co-cultured BMMSCs and PDLSCs were tested for periostin markers using an immunofluorescent assay. Implants with 3D-engineered tissue were implanted into the lower right central incisors after extraction from rabbits. Forty implants (Ti or zirconia) were subdivided according to the duration of implantation (healing period: 45 or 90 days). Each subgroup (20 implants) was subdivided into 4 groups (without cells, PDLSC sheets, BMMSC sheets, and co-culture cell sheets). All groups underwent histological testing involving haematoxylin and eosin staining and immunohistochemistry, stereoscopic analysis to measure the PDL width, and field emission scanning electron microscopy (FESEM). The natural lower central incisors were used as controls. Results: The BMMSCs co-cultured with PDLSCs generated a well-formed PDL tissue that exhibited positive periostin expression. Histological analysis showed that the implantation of coated (Ti and zirconia) dental implants without a cell sheet resulted in a well-osseointegrated implant at both healing intervals, which was confirmed with FESEM analysis and negative periostin expression. The mesenchymal tissue structured from PDLSCs only or co-cultured (BMMSCs and PDLSCs) could form a natural periodontal tissue with no significant difference between Ti and zirconia implants, consequently forming a biohybrid dental implant. Green fluorescence for periostin was clearly detected around the biohybrid implants after 45 and 90 days. FESEM showed the invasion of PDL-like fibres perpendicular to the cementum of the bio-hybrid implants. Conclusions: β-TCP-coated (Ti and zirconia) implants generated periodontal tissue and formed biohybrid implants when mesenchymal-tissue-layered cell sheets were isolated from PDLSCs alone or co-cultured BMMSCs and PDLSCs.

• Journal of Periodontal and Implant Science
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• v.37 no.sup2
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• pp.447-463
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• 2007

Periodontal ligament (PDL) cells have been known as multipotential cells, and as playing an important rolesin periodontal regeneration. The PDL cells are composed of heterogeneous cell populations which have the capacity to differentiate into either cementoblasts or osteoblasts, depending on needs and conditions. Therefore, PDL cells have the capacity to produce mineralized nodules in vitro in mineralization medium which include ascorbic acid, ${\beta}$-glycerophosphate and dexamethasone. In spite of these well-known osteoblast like properties of PDL cells, very little is known about the molecules involved in the formation of the mineralized nodules in the PDL cells. In the present study, we analysed gene-expression profiles during the mineralization process of cultured PDL cells by means of a cDNA microarray consisting of 3063 genes. Nodules of mineralized matrix were strongly stained with alizarin red S on the PDL cells cultured in the media with mineralization supplements. Among 3,063 genes analyzed, 35 were up-regulated more than two-fold at one or more time points in cells that developed matrix mineralization nodules, and 38 were down-regulated to less than half their normal level of expression. In accord with the morphological change we observed, several genes related to calcium-related or mineral metabolism were induced in PDL cells during osteogenesis, such as IGF-II and IGFBP-2. Proteogycan 1, fibulin-5, keratin 5, ,${\beta}$-actin, ${\alpha}$-smooth muscle actin and capping protein, and cytoskeleton and extracellular matrix proteins were up-regulated during mineralization. Several genes encoding proteins related to apoptosis weredifferentially expressed in PDL cells cultured in the medium containing mineralization supplements. Dkk-I and Nip3, which are apoptosis-inducing agents, were up-regulated, and Btf and TAXlBP1, which have an anti-apoptosis activity, were down-regulated during mineralization. Also periostin and S100 calciumbinding protein A4 were down-regulated during mineralization.