Calcitonin induces collagen synthesis and osteoblastic differentiation in human periodontal ligament fibroblasts

BackgroundExtracellular matrix (ECM) secretion and osteogenic differentiation in periodontal ligament fibroblasts (PDLF) facilitate the neogenesis of alveolar bone, which is the cellular basis for alveolar bone repair. Calcitonin (CT) has been reported to play an important role in promoting ECM expression and inducing osteogenic differentiation in osteoblast, but its effects on PDLFs remain obscure.MethodsThe expression of CT, transforming growth factor-beta 1(TGF-β1) and bone morphogenetic protein (BMP) in gingival crevicular fluid (GCF) was measured by ELISA. The effects of CT on collagen synthesis and osteogenic differentiation in hPDLFs were investigated by using the primarily cultured hPDLFs infected with adenovirus carrying the CT gene. Gene expression was measured by quantitative PCR and western blot.ResultsThe expression of CT in gingival crevicular fluid (GCF) of patients with periodontitis was significantly higher than that of healthy subjects. In addition, CT expression correlated with the clinical indexes including probing pocket depth (PPD), clinical attachment level (CAL), and gingival index (GI). The in vitro study demonstrated that overexpression of CT by adenovirus infection increased the expression of TGF-β1, collagen type I and III, and osteoblastic markers including BMP-2/-4, alkaline phosphatase and osteocalcin in human PDLFs. Moreover, CT-enhanced collagen synthesis was abrogated in hPDLFs transfected with TGF-β1 siRNA, and CT-induced osteoblastic differentiation was blocked in hPDLFs by BMPs inhibitor noggin.ConclusionsThese results suggest that CT promotes collagen synthesis and osteogenic differentiation in hPDLFs via the TGF-β1 and BMPs signaling pathways, respectively.     

The role of sirtuin 1 in osteoblastic differentiation in human periodontal ligament cells

Lee Y‐M, Shin S‐I, Shin K‐S, Lee Y‐R, Park B‐H, Kim E‐C. The role of sirtuin 1 in osteoblastic differentiation in human periodontal ligament cells. J Periodont Res 2011; 46: 712–721. © 2011 John Wiley & Sons A/S Background and Objective: Activation of sirtuin 1 (SIRT1) promotes the differentiation of keratinocytes and mesenchymal stem cells, but inhibits the differentiation of muscle and fat cells. However, the involvement of SIRT1 in the differentiation of human periodontal ligament cells into osteoblast‐like cells remains unclear. To identify the role of SIRT1 in human periodontal ligament cells, we measured SIRT1 mRNA and SIRT1 protein levels during the osteoblastic differentiation of human periodontal ligament cells. Additionally, we investigated the effects of overexpressing and underexpressing SIRT1 on the differentiation of human periodontal ligament cells, and the signaling mechanisms involved. Material and Methods: Expression of SIRT1 and osteoblastic differentiation markers was assessed by RT‐PCR, real‐time PCR, Alizarin red staining and western blotting. Results: Marked upregulation of SIRT1 mRNA and SIRT1 protein was observed in cells grown for 3 d in osteogenic induction medium (OM). Activation of SIRT1 using resveratrol and isonicotinamide stimulated osteoblastic differentiation in a dose‐dependent manner, as assessed by the expression of mRNAs encoding alkaline phosphatase, osteopontin, osteocalcin, osterix and Runx2, and induced calcium deposition. In contrast, inhibition of SIRT1 using sirtinol, nicotinamide and gene silencing by RNA interference suppressed mineralization and the expression of osteoblast marker mRNAs. Further mechanistic studies revealed that resveratrol treatment increased the phosphorylation of Akt, adenosine monophosphate kinase (AMPK), Smad 1/5/8 and c‐Jun N‐terminal kinase, but reduced OM‐induced activation of nuclear factor‐κB. Conversely, application of sirtinol suppressed the phosphorylation of Akt, AMPK, Smad 1/5/8, p38, ERK and c‐Jun N‐terminal kinase, and enhanced nuclear factor‐κB activity, in OM‐stimulated cells. Conclusion: These data suggest that SIRT1 is a potent regulator of differentiation of human periodontal ligament cells and may have clinical implications for periodontal bone regeneration.     

雌激素受体β对牙周膜细胞骨向分化能力影响的研究

目的 研究小干扰RNA(small interfering RNA,siRNA)抑制人牙周膜成纤维细胞(human periodontal ligament fibroblast cell,HPLF)中雌激素受体β(estrogen receptor β,ERβ)后,对17β-雌二醇(E2)诱导的成骨能力的影响。方法 设计并合成针对ERβ基因siRNA的寡核苷酸序列,插入载体形成重组载体。重组载体经测序鉴定后,以脂质体法转染至HPLF细胞中,蛋白质印迹法及RT-PCR法检测转染前后ERβ的表达情况。鉴定后用1×10-7mol/L的17β-E2干预经ERβsiRNA转染的HPLF细胞和未经ERβsiRNA转染的HPLF细胞,测定细胞的碱性磷酸酶(alkaline phosphatase,ALP)活性和骨钙素(os-teocalcin,OCN)含量。结果 测序鉴定重组质粒后,蛋白质印迹法及RT-PCR结果 显示ERβsiRNA载体可特异地抑制HPLF细胞中ERβ的表达。经雌激素干预后,HPLF细胞ALP活性和OCN含量高于对照组(P<0.01),但ERβsiRNA载体稳定转染的HPLF细胞ALP活性和OCN含量与对照组相比没有显著性差异。结论 雌激素可能通过ERβ亚基促进人牙周膜成纤维细胞的骨向分化能力。     

辛伐他汀对人牙周膜细胞增殖和分化的影响

目的:研究辛伐他汀对人牙周膜细胞增殖和成骨分化的影响.方法:将第4 代人牙周膜细胞在条件矿化培养液中诱导培养,同时加入不同浓度的辛伐他汀(10-9、10-8、10-7、10-6 mol/L),噻唑蓝(methyl thiazolyl tetrazolium,MTT)法检测细胞增殖情况,4-硝基苯基磷酸二钠盐(4-nitrophenyl phosphate,hexahydrate,PNPP)偶氮法检测碱性磷酸酶(alkaline phosphatase,ALP)活性.结果:辛伐他汀各浓度组均能促进人牙周膜细胞的增殖和分化,其中10-8、10-7、10-6 mol/L组与对照组比较,差异有统计学意义(P<0.05),10-7 mol/L的辛伐他汀组促进细胞增殖和ALP活性的作用最明显.结论:适宜浓度的辛伐他汀可有效促进人牙周膜细胞的增殖和成骨分化.     

Effect of estrogen receptor beta on the osteoblastic differentiation function of human periodontal ligament cells

OBJECTIVE: To investigate the effect of estrogen receptor beta (ERbeta) on osteoblastic differentiation function of human periodontal ligament (hPDL) cells by measuring the alkaline phosphatase (ALP) activity and the production of osteocalcin (OCN) in vitro. DESIGN: We employed a short interfering RNA (siRNA) technique to inhibit ERbeta expression in hPDL cells; the cells were cultured with a saturating concentration of 17beta-estradiol (10(-7)M). ALP activity was analysed by colorimetric assay using ALP kit and the amount of OCN was assessed by osteocalcin ELISA kit. RESULTS: It was shown that estradiol significantly enhanced the ALP activity and the production of OCN in hPDL cells. However, the ALP activity and the production of OCN in hPDL-siERbeta cells were not significantly changed after estradiol treatment. CONCLUSIONS: These results indicate that ERbeta may play important roles in estrogen-induced effects on osteoblastic differentiation function of PDL cells and estrogen influences the bone formation capacity of PDL cells mainly via ERbeta.     

Simvastatin promotes cell metabolism, proliferation, and osteoblastic differentiation in human periodontal ligament cells

BACKGROUND: Simvastatin is one of the cholesterol lowering drugs. Recent studies demonstrated that it has a bone stimulatory effect. Periodontal ligament (PDL) cells are believed to play an important role in periodontal regeneration; that is, they may differentiate into specific cells which make cementum, bone, and attachment apparatus. It would be of interest whether simvastatin has a positive effect on PDL cells. Therefore, effects of simvastatin on cell proliferation and osteoblastic differentiation in PDL cells were analyzed. METHODS: Human PDL cells were cultured in monolayer with simvastatin for 24 and 72 hours and cell metabolism and proliferation were determined. To analyze osteoblastic differentiation, human PDL cells were cultured in organoid culture for 7, 14, and 21 days and alkaline phosphatase (ALP) activity, osteopontin (OPN), bone morphogenetic protein (BMP) -2, osteocalcin (OCN), and calcium contents were measured. They were co-treated by simvastatin and mevalonate. RESULTS: Simvastatin enhanced cell proliferation and metabolism dose-dependently after 24 hours. Simvastatin also stimulated ALP activity of human PDL cells dose-dependently, and maximum effect was obtained at the concentration of 10(8) M. In time dependent analysis, 10(8) M simvastatin stimulated ALP activity and osteopontin content after 7 days and calcium contents after 21 days. BMP-2 and OCN contents were not detected. Moreover this statin-enhanced ALP activity was abolished by mevalonate. CONCLUSION: These results suggest that at low concentration, simvastatin exhibits positive effect on proliferation and osteoblastic differentiation of human PDL cells, and these effects may be caused by the inhibition of the mevalonate pathway.     

Asiaticoside induces osteogenic differentiation of human periodontal ligament cells through the Wnt pathway

1 Background

Asiaticoside is a compound isolated from Herb Centella asiatica, which has been shown to promote osteogenic differentiation of human periodontal ligament (hPDL) cells. This study investigated the molecular mechanism underlying the asiaticoside‐induced osteogenic differentiation of hPDL cells.

2 Methods

hPDL cells were incubated with various concentrations of asiaticoside to test cell viability by MTT assay. The mRNA expression levels were analyzed by using quantitative real‐time polymerase chain reaction (PCR). Osteogenic differentiation was determined by alkaline phosphatase activity assay and alizarin red staining. The subcellular localization of β‐catenin was analyzed by both immunofluorescence and western blot.

3 Results

The results showed that asiaticoside had no effect on the cell viability at any of the tested concentrations. Real‐time PCR revealed that osterix (OSX) and dentin matrix protein1 (DMP1) mRNA were significantly enhanced by asiaticoside treatment. Alkaline phosphatase activity and in vitro mineralization were also significantly induced. Interestingly, asiaticoside dose‐dependently increased WNT3A mRNA expression, but not WNT5A and WNT10B. The activation of Wnt signaling was shown to result in nuclear accumulation of β‐catenin as evaluated by immunofluorescence staining and western blot analysis. Pre‐treatment with recombinant human Dickkopf1 (rhDKK1) inhibited asiaticoside‐induced β‐catenin nuclear translocation and osteoblast marker gene expression. Moreover, rhDKK1 attenuated asiaticoside‐induced DMP1 protein expression.

4 Conclusion

The data demonstrate that asiaticoside induces osteogenic differentiation of hPDL cells by activating the Wnt/β‐catenin signaling pathway. The findings suggest that asiaticoside could be used as a novel therapeutic drug for periodontal tissue regeneration.     

FGF-2 induces proliferation of human periodontal ligament cells and maintains differentiation potentials of STRO-1(+)/CD146(+) periodontal ligament cells

The presence of human STRO-1⁺/CD146⁺ periodontal ligament (PDL) cells has been reported, but obtaining a large amount of these cells is difficult. The purpose of this study was to evaluate the percentages of STRO-1⁺/CD146⁺ cells in PDL cells and determine the effects of FGF-2 on the proliferation and multilineage differentiation potency of these cells. Human PDL (HPDL) cells were individually prepared from 15 extracted teeth. HPDL cells were cultured with or without FGF-2, and the percentages of STRO-1⁺/CD146⁺ cells in each HPDL cell culture was examined using FACSAria?. The STRO-1⁺/CD146⁺ cells were sorted with FACSAria?, and the mRNA expression and differentiation potency of the sorted cells were subsequently examined. The numbers of the STRO-1⁺/CD146⁺ cells in the FGF-2 cultures were significantly higher than those cultured in the absence of FGF-2. The sorted STRO-1⁺/CD146⁺ cells expressed mRNA of PDL markers and differentiated into adipocytes and osteoblast-like cells. The present study shows that FGF-2 augmented the proliferation of the STRO-1⁺/CD146⁺ cells in the HPDL cultures whilst retaining adipogenic and osteogenic differentiation potentials. Thus, it may be useful to culture HPDL cells with FGF-2 for the application of the human STRO-1⁺/CD146⁺ PDL cells in periodontal tissue regeneration.     

Differential responsiveness against mechanical stress between osteoblastic cells and periodontal ligament cells

Using the human osteosarcoma-derived osteoblastic cell line, HOS cells, and the human periodontal ligament-derived fibroblast-like cells (Periodontal ligament cells; PDL cells), we examined the responsiveness against mechanical stress (continuously applied compressive force) in HOS and PDL cellsin vitro. SDS-PAGE revealed that loading of mechanical stress (10 g/cm²) promoted intracellular protein production (approx. 30–35 kDa, 40kDa, 55kDa, 65–70kDa) in HOS cells, which are different sizes from those in PDL cells reported previously. Mechanical stress also enhanced heat shock protein (HSP) production in HOS cells and PDL cells: however, the responsiveness was different between HOS cells and PDL cells. In PDL cells, mechanical stress enhanced HSP 60 production more efficiently, in contrast that HSP 70 production was promoted more efficiently in HOS cells. These data suggest that differential responsiveness against mechanical stress between osteoblasts and PDL cells might have important role during orthodontic tooth movement.

     

Porphyromonas gingivalis LPS inhibits osteoblastic differentiation and promotes pro-inflammatory cytokine production in human periodontal ligament stem cells

ObjectivePorphyromonas gingivalis (P. gingivalis) lipopolysaccharide (LPS) induces pro-inflammatory cytokines, such as interleukin-1 β (IL-1β), IL-6, and IL-8, which induce periodontal tissue destruction. Periodontal ligament stem cells (PDLSCs) play an important role in periodontal tissue regeneration and are expected to have future applications in cellular therapies for periodontitis. However, no studies have examined the effects of P. gingivalis LPS on PDLSCs. The aim of this study was to investigate how P. gingivalis LPS affects the osteoblastic differentiation and pro-inflammatory cytokine production of PDLSCs.DesignPDLSCs were obtained from healthy adult human mandibular third molars. The identification of PDLSCs was confirmed by immunohistochemical evaluations of the mesenchymal stem cell markers STRO-1 and SSEA-4. Cell proliferation and osteoblastic differentiation were investigated by culturing the PDLSCs in a normal or osteogenic medium with P. gingivalis LPS (0, 1, or 10 μg/mL) and then measuring the alkaline phosphatase (ALP) activity and the production of collagen type 1 Alpha 1 (COL1A1), osteocalcin production, and mineralisation. Additionally, we examined the production of IL-1β, IL-6, and IL-8 in the PDLSCs.ResultsP. gingivalis LPS inhibited the ALP activity, COL1A1 and osteocalcin production, and mineralisation in the PDLSCs, which are positive for STRO-1 and SSEA-4. P. gingivalis LPS also promoted cell proliferation and produced IL-1β, IL-6, and IL-8.ConclusionsThis study provides the first findings that P. gingivalis LPS inhibits osteoblastic differentiation and induces pro-inflammatory cytokines in PDLSCs. These findings will help clarify the relationship between periodontitis and periodontal tissue regeneration.     

Recombinant human bone morphogenetic protein-2 stimulates osteoblastic differentiation in cells isolated from human periodontal ligament.

Periodontal ligament cells may play an important role in the successful regeneration of the periodontium. We investigated the effects of recombinant human bone morphogenetic protein-2 (rhBMP-2), one of the most potent growth factors that stimulates osteoblast differentiation and bone formation, on cell growth and osteoblastic differentiation in human periodontal ligament cells (HPLC) isolated from four adult patients. rhBMP-2 induced no significant changes in cell growth in any of the HPLCs. rhBMP-2 at concentrations over 50 ng/mL significantly stimulated alkaline phosphatase (ALPase) activity and parathyroid hormone (PTH)-dependent 3', 5'-cyclic adenosine monophosphate accumulation, which are early markers of osteoblast differentiation, in the HPLCs. rhBMP-2 (500 ng/mL) also slightly enhanced the level of PTH/PTH-related peptide receptor mRNA expression in these cells. While interleukin-1 beta enhanced ALPase activity stimulated with rhBMP-2, tumor necrosis factor-alpha inhibited the rhBMP-2-stimulated activity. Interleukin-6 induced no significant changes in ALPase activity stimulated with rhBMP-2. Although HPLCs, whether treated with rhBMP-2 or not, could not produce measurable amounts of osteocalcin, which is a marker of more mature osteoblasts, 1,25-dihydroxyvitamin D3 [1,25(OH)2D3] induced osteocalcin mRNA expression and protein synthesis in these cells. rhBMP-2 inhibited 1,25(OH)2D3-induced osteocalcin synthesis in HPLCs at both the mRNA and protein levels. These results suggest that rhBMP-2 provides an anabolic effect on periodontal regeneration by stimulation of osteoblastic differentiation in human periodontal ligament cells, and that this stimulatory effect is differentially modulated by inflammatory cytokines during the course of periodontal regeneration.     

牙龈卟啉菌和大肠杆菌内毒素对人牙周膜细胞分泌IL-6、TNF-α的影响

目的：研究龈卟啉菌、大肠杆菌内毒素对人牙周膜细胞（PDLC）分泌IL-6、TNF-α的影响。方法：采用细胞培养技术和ELISA方法，检测培养上清中IL-6、TNF-α水平。结果：在孵育6h后，即可在培养上清中检测到IL-6和TNF-α。IL-6在12h、TNF-α在24h内呈时间依赖性方式升高。结论：PDLC在内毒素作用下局部分泌IL-6、TNF-α，参与了牙周炎的发生、发展过程。     

Force-induced IL-8 from periodontal ligament cells requires IL-1beta

During orthodontic tooth movement, mechanical stresses induce inflammatory reactions in the periodontal ligament (PDL). We hypothesized that chemokines released from PDL cells under mechanical stress regulate osteoclastogenesis, and investigated the profiles and mechanisms of chemokine expression by human PDL cells in response to mechanical stress. In vitro, shear stress and pressure force rapidly increased the gene and protein expressions of IL-8/CXCL8 by PDL cells. Consistently, amounts of IL-8 in the gingival crevicular fluid of healthy individuals increased within 2 to 4 days of orthodontic force application. The PDL cells constitutively expressed low levels of IL-1beta, which were not further increased by mechanical stress. Interestingly, neutralization of IL-1beta abolished IL-8 induction by mechanical stresses, indicating that IL-1beta is essential for IL-8 induction, presumably though autocrine or paracrine mechanisms. Finally, experiments with signal-specific inhibitors indicated that MAP kinase activation is essential for IL-8 induction.     

影响牙周膜干细胞成骨分化能力的因素

牙周膜干细胞(PDLSC)是维持牙周组织动态平衡和缺损修复的关键细胞,被认为是牙周组织工程的关键种子细胞之一.近年来的研究证明其有较强的的增殖和分化能力,然而在不同因素影响下其功能差异也较大.认识并研究这些影响因素不仅有助于深入了解和发掘PDLSC的生物学功能,而且对于今后基于PDLSC的牙周修复与再生治疗具有指导意义.该文就影响PDLSC成骨分化的多种因素作一叙述,展望其在牙周缺损修复治疗中的应用前景.     

槲皮素对LPS刺激的人牙周膜细胞表达IL-6的影响

目的研究槲皮素对接受大肠杆菌脂多糖(lipopolysaccharide,LPS)刺激的人牙周膜细胞(human periodontal ligament cells,h PLDCs)表达IL-6(interleukin-6)的影响,探讨槲皮素(quercetin,Que)的抗炎作用。方法使用酶消化组织块法培养人牙周膜细胞并鉴定,根据ELISA(enzyme-linked immunosorbent assay,酶联免疫吸附实验)法测定不同时间点以及不同浓度下槲皮素对人牙周膜细胞抑制LPS诱导细胞表达IL-6的作用。结果 LPS刺激24 h左右时人牙周膜细胞分泌IL-6达到峰值,而槲皮素处理后的细胞再加入LPS刺激所产生的IL-6与单纯的LPS组相对比明显降低,有统计学意义。经不同浓度槲皮素处理细胞后加入LPS刺激所产生的IL-6无统计学差异。结论槲皮素可以抑制LPS诱导的人牙周膜细胞表达IL-6,提示槲皮素可能通过某些途径调节影响IL-6的合成和分泌,因而在炎症的早期发挥其减轻炎症反应的作用。     

白细胞介素-6对人牙周膜细胞MMP-3 mRNA及蛋白表达的影响

目的 观察白细胞介素—6(IL—6)对人牙周膜细胞MMP—3蛋白及mRNA表达的影响，探讨IL—6介导MMPs对牙周组织ECM代谢影响的机制。方法 在体外培养条件下，观察不同浓度IL—6作用前后是否对人牙周膜细胞MMP—3表达的情况产生影响。采用原位杂交、免疫组化技术对HPDLC比表达MMP—3的情况进行检测。结果 当IL—6的浓度为10U／ml及100U／ml时，可显著促进人牙周膜细胞MMP—3 mRNA及蛋白的表达，且具有明显的浓度依赖效应。结论 IL—6的刺激作用，可使HPLCD比表达MMP—3阳性信号增强，表明IL—6介导MMP—3参与调节牙周膜细胞外基质代谢。     

Exendin-4 relieves the inhibitory effects of high glucose on the proliferation and osteoblastic differentiation of periodontal ligament stem cells

BackgroundWith the impaired regenerative potential in patients with diabetes mellitus (DM), Periodontal ligament stem cells (PDLSCs) are regarded as an attractive source of stem cells for periodontal cytotherapy. Recent studies have shown that Exendin-4 (Ex-4) exerts cell-protective effects and bone remodeling ability on many types of cells. The aim of this study was to investigate whether Ex-4 alleviates the inhibition of high glucose on the proliferation and osteogenic differentiation of PDLSCs.MethodsPDLSCs were incubated in medium supplemented with 5.5 mM d-glucose (NG), 30 mM d-glucose (HG), NG plus Ex-4, and HG plus different concentration (1, 10, 20, 100 nM) of Ex-4 respectively. Cell proliferation was detected by CCK-8 assay and cell cycle analysis. Osteogenesis was assessed by Alizarin Red S staining and evaluation of the mRNA expression of Runx2, ALP and Osx at day 7, 14 and 21. Intracellular level of reactive oxygen species (ROS) was detected using 5-(and-6)-chloromethyl-2′,7′-dichlorodihydro-fluorescein diacetate (CMH2DCF-DA).ResultsThe proliferation ability, mineralized nodules forming capacity and the mRNA expression of Runx2, ALP and Osx of PDLSCs in HG group were decreased, the ROS level was increased compared to NG group. With the treatment of Ex-4, the HG-inhibited proliferation ability and osteogenic differentiation ability of PDLSCs were significantly reversed, the HG-increased ROS level could be down-regulated. Moreover, Ex-4 enhanced the osteogenic differentiation of normal PDLSCs.ConclusionsEx-4 alleviates the inhibitory effect of HG on the proliferation and osteoblastic differentiation of PDLSCs, and has a significant enhance in the osteoblastic differentiation of normal PDLSCs, giving new insights into the possible therapeutic method of diabetic periodontitis.     

In vivo differentiation of progenitor cells of the periodontal ligament

The present study was designed to test the hypothesis that during regeneration of cementum, the progenitor cells from periodontal ligament must come in contact with root dentin in order to differentiate into cementoblasts. After reflecting mucoperiosteal flaps, fenestration wounds were made in the buccal cortical plates of mandibular canines in 6 beagle dogs. The exposed root surfaces were curretted to remove all cementum. The exposed root surface on one side was demineralized with citric acid while the contralateral wound had saline treatment. The exposed root surfaces were then dried and pieces of Nuclepore membrane (pore size 0.1 mu) were attached to part of the exposed root surface to prevent contact of progenitor cells with root dentin. The fenestration wounds were then covered with Millipore filter to facilitate the population of wounds by progenitor cells from the periodontal ligament. Histologic analysis was performed after 3 months of healing. In specimens where the Nuclepore membrane had remained attached to root dentin, no new cementum was seen over the membrane. At the borders of the wounds and in specimens where the Nuclepore membrane had detached from root dentin, new connective tissue attachment was consistently seen. Also, root resorption was very rarely observed in both the acid-treated and control specimens. The present findings suggest that contact with root dentin may be necessary for progenitor cell differentiation into formative cells like cementoblasts.