Adhesion Of Periodontal Ligament Cells Research Articles

Cover Image

The cover image is based on the Research Article Effects of DDR1 on migration and adhesion of periodontal ligament cells and the underlying mechanism by Xiaoyan Wang et al., https://doi.org/10.1111/jre.12986.

Effects of DDR1 on migration and adhesion of periodontal ligament cells and the underlying mechanism.

As one of the widely expressed cell surface receptors binding to collagen, the most abundant component of the extracellular matrix (ECM), knowledge of the expression, functions, and mechanisms underlying the role of discoidin domain receptor 1 (DDR1) in human periodontal ligament cells (hPDLCs) is incomplete. This study determined the expression of DDR1 in hPDLCs and the effect of DDR1 upon migration and adhesion to hPDLCs, as well as the related regulatory mechanisms. The expression of DDR1 and the DDR1 isoforms in hPDLCs from six donors were tested. The migratory ability (horizontal and vertical) and adhesive capacity of hPDLCs with or without specific knockdown of DDR1 were evaluated. After treatment with MEK-ERK1/2 inhibitors (PD98059 and U0126) with or without RNAi, the migratory and adhesive capacity of hPDLCs were re-tested. Western blotting was performed to verify p-MEK1/2 and p-ERK1/2, the key factors of the MEK-ERK1/2 signaling pathways. DDR1 was detected in hPDLCs in the mRNA and protein level; DDR1b was the dominant isoform. Knockdown of DDR1 almost halved the migratory capacity and significantly downregulated the adhesive capacity of hPDLCs. The use of MEK-ERK1/2 inhibitors caused declined migratory and adhesive capacity of hPDLCs as well. After DDR1 was knocked down, the expression of p-MEK and p-ERK protein declined significantly while total MEK and ERK showed no obvious change, which means the ratio of p-MEK/MEK and p-ERK/ERK was markedly reduced. DDR1 plays an important role in the migration and adhesion of hPDLCs and might be regulated via the MEK-ERK1/2signaling pathway.

Emulsion electrospun PLA/calcium alginate nanofibers for periodontal tissue engineering.

Objective The regeneration of periodontal bone tissue is a major obstacle in tissue engineering. We have recently designed a compound nanofiber scaffold for the tissue repair of periodontal bone, which was composed of poly(lactic acid) (PLA) and calcium alginate (CA). The obtained improvements in both physical properties and biological effects on periodontal tissue were systematically evaluated and discussed. Method Neat PLA and PLA/CA nanofiber scaffolds were prepared by electrospinning technology. Scanning electron microscopy was applied for the observation of surface morphology. Their mechanical properties were evaluated in terms of elongation at break and elastic modulus. Hydrophilic/hydrophobic nature of the nanofibers was investigated by a stereomicroscope, and their vitro degradation was tested as well. Cell proliferation and adhesion were detected in order to evaluate the biocompatibility of nanofiber scaffolds. Expression of cell mineralization gene and formation of mineralization knots were examined so as to assess scaffolds’ capability of regenerating bone tissues. The expression of Toll-like receptor 4 (TLR4), IL-6, IL-8, and IL-1β was utilized to decide the possibility of tissue inflammation caused by the nanofibers with the assistance of reverse transcription-polymerase chain reaction (RT-PCR) assay. Results The obtained nanofibers possessed uniform surface morphology. The elongation at break and elastic modulus of PLA/CA nanofiber scaffolds were higher than those of neat PLA. CA could enhance the hydrophilicity of PLA fibers; in the meantime, it promoted cell adhesion of periodontal ligament cells (PDLCs) and bone marrow stromal cells (BMSCs). Addition of CA had raised the expression level of cell mineralization gene and the formation of mineralization knots (BMSCs). On the other hand, both neat PLA fibers and PLA/CA fibers could induce higher expression level of inflammatory mediators and TLR4 of human periodontal ligament cells (hPDLCs). Conclusions The introduction of CA enhanced the mechanical properties of neat PLA nanofibers and increased its hydrophilicity. Neat PLA nanofibers and PLA/CA scaffold could both facilitate BMSCs proliferation, while the addition of CA promoted BMSCs osteogenic differentiation. The improved (or enhanced) expression of inflammatory mediators caused by nanofibers might be regulated via TLR4 pathway.

Adhesion of human periodontal ligament cells by three-dimensional culture to the sterilized root surface of extracted human teeth.

Residual periodontal ligament (PDL) and cement mass on the roots of extracted teeth are factors that considerably affect tooth transplantation. Therefore, when normal extracted teeth are used for autologous transplantation, it is necessary to regenerate the PDL of the root surface. Here we describe a method to examine human PDL cell adhesion on sterilized root surfaces. Sample teeth were extracted during orthodontic treatment. PDL cells were obtained from healthy periodontal tissue explants from teeth extracted for orthodontic reasons. We developed a method for adhering PDL cells to sterile root surfaces using three-dimensional culture for 3 weeks. We evaluated the adhesion of human PDL cells to the sterilized root surfaces biochemically and histologically. The adherent PDL cells presented new projections on the sterile root surfaces. Therefore, PDL cells can adhere to sterile root surfaces.

Adhesion and proliferation of human periodontal ligament cells on poly(2-methoxyethyl acrylate).

Human periodontal ligament (PDL) cells obtained from extracted teeth are a potential cell source for tissue engineering. We previously reported that poly(2-methoxyethyl acrylate) (PMEA) is highly biocompatible with human blood cells. In this study, we investigated the adhesion, morphology, and proliferation of PDL cells on PMEA and other types of polymers to design an appropriate scaffold for tissue engineering. PDL cells adhered and proliferated on all investigated polymer surfaces except for poly(2-hydroxyethyl methacrylate) and poly[(2-methacryloyloxyethyl phosphorylcholine)-co-(n-butyl methacrylate)]. The initial adhesion of the PDL cells on PMEA was comparable with that on polyethylene terephthalate (PET). In addition, the PDL cells on PMEA spread well and exhibited proliferation behavior similar to that observed on PET. In contrast, platelets hardly adhered to PMEA. PMEA is therefore expected to be an excellent scaffold for tissue engineering and for culturing tissue-derived cells in a blood-rich environment.

Periodontal ligament fibroblast response to root perforations restored with different materials – a laboratory study

To compare the effect of several materials on the attachment of periodontal ligament (PDL) fibroblasts to experimentally perforated root surfaces. Root specimens (size 5 × 5 mm) were obtained from extracted human molar teeth and perforations with a 1 mm diameter were created. One group was kept as a control and the rest were repaired with the following materials: Amalgam, Dyract, IRM, Super Bond C&B and Mineral trioxide aggregate (MTA). PDL fibroblasts were placed at a density of 8 × 10(4) cells on the root specimens, incubated on tissue culture inserts (48 h) and then transferred to 48 well-plates. MTT assays were performed at 48 and 96 h for PDL fibroblast survival. Cell attachment was observed using confocal microscopy on days 2 and 5. Total RNAs from the root specimens were isolated on day 5 and type I collagen (COL I) and Runt-related transcription factor 2 (Runx2) mRNA expressions were checked using Quantitative-Polymerase Chain Reaction (QPCR). For the MTT assay and QPCR, one-way analysis of variance (anova) and Tukey HSD multiple comparison tests were used to compare the groups. Mineral trioxide aggregate resulted in a significantly higher cell density (P < 0.001). Dyract, IRM and Super Bond C&B groups had a lower cell density when compared with the control and MTA groups at 48 h (P < 0.001). Confocal microscopy revealed that, among the experimental groups, the MTA group had the largest viable cell population over the restoration site when compared with the other materials; however, reduced cell attachment was noted in all groups when compared with the control. Increased Runx2 mRNA expressions were noted in MTA (P < 0.001) and IRM (P < 0.01) groups when compared with control and other tested materials. COL I transcripts were increased in IRM (P < 0.01), D, C&B and MTA (P < 0.001) when compared with the control. Mineral trioxide aggregate provided a more favorable environment for PDL cell adhesion and growth.

Effects of TGF-β1, PDGF-BB, and IGF-1 on the Rate of Proliferation and Adhesion of a Periodontal Ligament Cell Lineage In Vitro.

Considering the role of growth factors in periodontal regeneration, the aim of this study was to evaluate the influence of platelet-derived growth factor (PDGF)-BB, insulin-like growth factor (IGF)-1, and transforming growth factor-beta 1(TGF-β1), alone or in combination, on the rate of proliferation and adhesion of periodontal ligament (PDL) cells in vitro. After establishment and characterization of a primary culture of PDL cells, 72 culture dishes were plated with 103 cells distributed among four test groups and a control group. Test groups had PDGF-BB, TGF-β1, IGF-1, or a combination of all three added to the culture medium, whereas the control group received no growth factor. The samples were counted in triplicate 1, 3, 5, and 7 days after seeding. For the adhesion assay, 14 patients provided 30 root fragments distributed among 10 groups: scaling and root planing (SRP), SRP + growth factors, SRP + citric acid plus tetracycline (CA+T), and SRP + (CA+T) + growth factors. The data were evaluated statistically by analysis of variance complemented by Tukey, Dunnett, and Student-Newman-Keuels methods. Maximum rates of proliferation were observed at day 3 for all groups. TGF-β1 induced a 344.17% ± 58.80% increased proliferation rate over control (P <0.05), followed by the combination (277.5% ± 29.38%), PDGF-BB (238.79% ± 5.79%), and IGF-1 (233.16% ± 19.19%). Groups treated by (CA+T) showed increased numbers of cells attached to root fragments, especially SRP + (CA+T) + combination (13.25 ± 1.79), with significant differences (P <0.05) from groups treated only by SRP. This combination of growth factors stimulated a mitogenic response and favored the adhesion of PDL cells in vitro, suggesting its possible role in periodontal regeneration.

Mechanical stimuli enhances the expression of RGD-CAP/βig-h3 in the periodontal ligament

RGD-CAP, a member of the fasciclin family, is expressed in the periodontal ligament (PDL). Since the PDL is continually subjected to mechanical forces from such orofacial functions as mastication, biting, speech and swallowing, the mechanical stimuli is thought to be associated with the expression of RGD-CAP. Furthermore, the adhesive functions of RGD-CAP may contribute to the maintenance or regeneration of PDL architecture. The objective of this study was to examine whether mechanical stimuli modulate the expression of RGD-CAP in the human PDL, and to examine the effects of recombinant RGD-CAP on the adhesion of PDL cells. During experimental tooth movement, the expression of RGD-CAP was significantly enhanced in the PDL. In vitro experiments with cultured PDL cells showed that the expression of RGD-CAP mRNA was significantly enhanced by mechanical tensile force of 15.4 kPa for 48 h. The induction of RGD-CAP mRNA, meanwhile, was completely inhibited by cycloheximide which is an inhibitor of protein synthesis. Furthermore, neutralising antibody against TGF-β also suppressed the mechanical induction of RGD-CAP. The adhesion of cultured PDL cells onto plates coated with recombinant RGD-CAP increased significantly compared with the controls. These findings suggest that RGD-CAP, induced by TGF-β expressed in response to mechanical stimuli, plays an important role in modulating the homeostasis of PDL.

Effect of cigarette smoking on human PDL fibroblasts attachment to periodontally involved root surfaces in vitro.

Cigarette smoking is one of the most significant risk factors in the development and further advancement of inflammatory periodontal disease. However, no study has been performed to investigate the effect of smoking on the attachment of human periodontal ligament fibroblasts to either periodontally diseased or healthy roots. The present study was conducted to evaluate the attachment of fibroblasts derived from healthy human periodontal ligament (PDL) to periodontally diseased root surfaces of smokers. The subjects included 14 smokers and seven nonsmokers with at least a single periodontally involved anterior tooth planned for extraction. In addition, seven impacted third molars, which had been removed from nonsmoking adolescents, were used as a healthy control. The smoking status of each patient was determined by classifying the volunteers into four groups according to their level of cigarette consumption at the initial examination (seven patients each). Nonsmoking subjects who had never smoked cigarettes and had healthy periodontium were called healthy control (G1). In subjects with periodontal diseases, nonsmoking subjects who had never regularly smoked cigarettes (< 2 cigarettes/week) were called positive control (G2), smokers consuming <or=19 cigarettes/day were placed in group G3, and smokers consuming >or=20 cigarettes/day were located in group G4. To exclude the effects of all local irritants except for the adsorbed tobacco products, all teeth were subjected to thorough scaling and root planing 1 week before extraction. After 1 week of meticulous home care and continued smoking experience, teeth were extracted and the periodontally involved test areas were prepared for PDL culturing. PDL cells were cultured on root segments for 24 h. Samples were prepared for SEM viewing, photographing and counting at x750 in a standard area. The results of this study indicated that smokers' data (G3, G4) revealed a significant reduction of attached PDL cells when compared to that of nonsmokers' healthy and positive controls (G1, G2). No significant difference in the mean number of attached cells was found between data derived from smokers' groups (G3 vs. G4). The attached cells in all groups varied in shape; they were flatter in the control groups, while they were round in smokers' groups, with no dose-dependent effect. The present results suggest that cigarette smoking compromises PDL cell adhesion to root planed surfaces, which might affect periodontal regeneration following therapy.

Repopulation of Dentin Surfaces by Periodontal Ligament Cells and Endothelial Cells

The regeneration of connective tissue attachment is a major goal of clinical periodontics. Recent investigations on biochemically mediated periodontal regeneration have attempted to define the various biological response modifiers which may provide a mechanism for periodontal regeneration. Fibronectin and endothelial cell growth factor have been shown to selectively enhance periodontal ligament (PDL) cell adhesion, migration, and proliferation. In addition, dentin preconditioned with tetracycline HCl (TTC) or citric acid (CA) supports PDL cell adhesion, presumably by exposing collagen fibers. We have now extended these studies to include basic fibroblast growth factor (b-FGF) as a potential meditor of periodontal regeneration. Using AFSCM (assays for specific cell migration), b-FGF in concentrations as low as 10 ng per dentin block significantly stimulated PDL cell chemotaxis, while the antibody against b-FGF inhibited both the chemotactic and proliferative characteristics of the mitogen. We also found that 5 ng and above of b-FGF per dentin block significantly stimulated human endothelial cell migration and proliferation. Using 125I-b-FGF, we demonstrated that the factor binds to native dentin. This binding was increased when the dentin blocks were preconditioned by TTC or CA and reduced when the dentin was subsequently treated with collagenase. 125I-b-FGF also bound with moderate affinity to a type I collagen affinity column whereas the binding to a hydroxylapatite affinity column was negligible. The combination of FN and b-FGF was a marginally more potent chemo-attractant than b-FGF alone for PDL cells.(ABSTRACT TRUNCATED AT 250 WORDS)