Periodontal Ligament Cells Research Articles

Roles of B-cell lymphoma 6 in orthodontic tooth movement of rat molars.

B-cell lymphoma 6 (Bcl6) inhibits osteoclast differentiation in vitro; however, its role in orthodontic tooth movement (OTM) remains unclear. This study aimed to investigate the role of Bcl6 in OTM of rat molars. OTM was performed on the maxillary first molars of male rats using nickel-titanium coil springs (25 gf) for 14 days with or without local injection of FX1 (50mg/kg), a Bcl6 inhibitor (n = 10 per group). Micro-computed tomography (CT) images were used to analyse OTM distance and bone morphometric parameters. Immunohistochemistry (IHC) determined Bcl6 expression and tartrate-resistant acid phosphatase staining (TRAP) staining assessed osteoclast differentiation. TRAP staining, and reverse transcription-quantitative polymerase chain reaction determined the effect of FX1 (1 μM) on in vitro rat osteoclast differentiation. The effect of FX1 on cell proliferation and Smad4 expression in periodontal ligament (PDL) cells was determined. Administration of FX1 significantly increased OTM distance and decreased the bone/tissue volume compared with vehicle treatment. IHC staining showed that the vehicle-OTM group had higher expression of Bcl6 than the FX1-OTM group. The number of osteoclasts on the compression side was significantly higher in the FX1-OTM group than that in the vehicle-OTM group. FX1 enhanced osteoclast differentiation and expression of Nfatc1, Dc-stamp, and Ctsk mRNA in osteoclasts in vitro. FX1 significantly promotes PDL cell proliferation in vivo and in vitro. We evaluated only 14 days of OTM. Bcl6 may play an important role in OTM via modulation of osteoclast differentiation and PDL cell proliferation.

Extracellular Vesicles From Dental Pulp Cells Promote Osteogenic Differentiation in Periodontal Ligament Cells.

Periodontal osseous defects are mainly caused by periodontitis, which seriously affects the quality of patient life. Dental pulp cells (DpCs)-derived extracellular vesicles (EVs) can effectively promote tissue regeneration. Homeobox A9 (HOXA9) mRNA is abundant in EVs derived from DSCs, which may be related to promoting alveolar bone regeneration, but the specific mechanism is unclear. We aimed to elucidate the mechanism through which HOXA9 from DPCs-derived EVs can impact the osteogenic differentiation of periodontal ligament cells (PDLCs). DPCs-derived EVs were isolated and characterized by transmission electron microscopy (TEM), nanoparticle tracking analysis (NTA), and western blot. Lipopolysaccharide (LPS) was employed to induce the inflammatory environment. Cell viability was assessed by CCK8 assay. Calcium deposition was determined by Alizarin red staining. H3K27ac enrichment in the FLI1 enhancer region and the interaction between C/EBPα, HOXA9, and FLI1 were analyzed by ChIP assay. The interaction between HOXA9 and FLI1 enhancer in 293T cells was analyzed by dual luciferase reporter gene assay. DPCs-derived EVs promoted PDLC osteogenesis under LPS treatment and increased HOXA9 expression in PDLCs. HOXA9 knockdown in DPCs reversed the promoting effect of DPCs-derived EVs on PDLC osteogenic differentiation. HOXA9 from DPCs-derived EVs promoted H3K27ac enrichment in the FLI1 enhancer region by facilitating HOXA9 competitively binding FLI1 enhancer region with C/EBPα. Moreover, HOXA9 from DPCs-derived EVs promoted PDLC osteogenesis by activating the PI3K/AKT pathway through upregulating FLI1. HOXA9 from DPCs-derived EVs promoted PDLC osteogenic differentiation by activating the PI3K/AKT pathway through promoting H3K27ac enrichment in the FLI1 enhancer region and upregulating FLI1. Our study identified a previously unknown mechanism that HOXA9/FLI1 signaling axis participates in the processes of EVs derived from DPCs to treat bone tissue injury. Our research presents a theoretical basis for using EVs derived from DPCs to treat bone tissue injury.

An in vitro Evaluation of Periodontal Ligament Cell Viability in Honey as a Transport Medium for an Avulsed Tooth

Abstract Background Dental avulsion is the most severe form of injury to a tooth, and its prognosis is majorly affected by the type of the storage medium prior to re-implantation. Honey is a readily available household substance with anti-inflammatory properties. However, there is paucity of data regarding its use as a transport medium for avulsed teeth. Therefore, this study aims to evaluate the viability of periodontal Ligament (PDL) cells stored in honey and other recommended transport media. Materials and Methods An in vitro study involving the culture of PDL cells, harvested from premolars freshly extracted for orthodontic reasons. The cells were exposed to Dulbecco’s Minimum Essential Medium (DMEM), honey, and Hanks Balanced Salt Solution (HBSS) at room temperature, and their viability was tested with the tetrazolium salt-based colorimetric (MTT) assay after 30 min, 2 h, and 24 h. The Optical Density (OD) of the cells were assessed with a spectrophotometer. The Mean Optical Density (MOD) of the cells stored in DMEM was compared with those of cells in other media at each interval with the independent t-test at P < 0.05 Results The MOD of cells stored in DMEM, honey, and HBSS over the 24-h period ranged between 0.32 ± 0.04 −0.31 ± 0.05; 0.30 ± 0.07−0.28 ± 0.07, and 0.23 ± 0.0−0.21 ± 0.01, respectively. The mean difference between the OD of cells stored in honey and those in DMEM at the end of the study period was 0.03 (t = 1.37; P = 0.18). Conclusion There was no difference in the viability of PDL cells stored in honey and DMEM over the study period.

Impact of mechanotransduction on gene expression changes in periodontal ligament during orthodontic tooth movement.

The periodontal ligament (PDL) is a structure between the alveolar bone and cementum, essential for tooth stability and composed of diverse cell types. Mohawk homeobox (Mkx) is a master transcription factor that regulates tendon and ligament homeostasis. However, the specific cell populations expressing Mkx and its role in mechanotransduction during orthodontic tooth movement (OTM) remain unclear. We conducted single-cell RNA sequencing on wild-type rat PDL at 0day, 1week, and 2weeks of post-OTM using coil springs to elucidate Mkx's function and the changes in cell populations under continuous mechanical stimulation. In addition, RT-qPCR was performed to assess the relationship between tenogenic gene expression and Mkx expression in human PDL cells. The rat PDL was identified to consist of 14 clusters, with Mkx and Scleraxis (Scx) expressed in distinct cell populations. Collagen and ECM production increased throughout the OTM period, while the sterile inflammatory response was initially heightened and later diminished, indicating that bone remodeling occurs later in the inflammatory response. Overexpression of MKX in human PDL cells enhanced COL1A1 and DECORIN expression. Mechanical stimulation of the PDL appears to trigger an aseptic inflammatory response that disrupts PDL homeostasis and promotes bone remodeling. Mkx may exert a protective effect on the PDL during mechanical stimulation.

Effect of c-Myb overexpression on osteoblastic-, odontoblastic-, and cementoblastic differentiation of primary human periodontal ligament cells.

The periodontal ligament (PDL) is a connective tissue, and PDL cells have a potential to differentiate into cementoblasts, osteoblasts, and gingival fibroblasts. This study investigated whether transcription factor c-Myb could induce differentiation of PDL cells for periodontal regeneration. PDL cells were isolated from extracted teeth and cultured. c-Myb was transfected to PDL cells using replication-deficient adenoviral vector. Differentiation of the PDL cells was analyzed by immunoblot, alkaline phosphatase activity, Alizarin red stain, and immunofluorescence analysis. Cell viability on titanium surfaces was analyzed by crystal violet stain and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. PDL cells cultured in osteogenic medium showed increased production of osteogenic and cementogenic molecules. Moreover, c-Myb-transfected cells showed increased production of dentinogenic molecules, in addition to the osteogenic and cementogenic molecules, even in normal culture condition. c-Myb-transfected cells also exhibited increased autophagy and type I collagen production under nutrient deprivation. When grown on a titanium surface, c-Myb-transfected cells showed increased production of osteogenesis-, dentinogenesis-, and cementogenesis-related molecules and cell viability. Thus, these results suggest that c-Myb might play an essential role during periodontal regeneration by improving the differentiation of PDL cells, and c-Myb can be utilized for enhancing the attachment of PDL cells to dental implant surfaces.

Hesperidin Improves Wound Healing and Mineralization of Periodontal Ligament Cells in Elevated Glucose Conditions.

Elevated glucose can have a detrimental effect on the function and healing process of periodontal cells in inflammatory conditions. Hesperidin (HPN), a bioflavonoid found abundantly in citrus fruits, has numerous biological benefits, including regenerative and anti-inflammatory properties. The current in-vitro study aimed to assess the impact of HPN on the proliferation, wound healing, and functionality of periodontal cells in optimal and elevated glucose conditions. Human periodontal ligament cells (HPDLCs) were cultured in optimal glucose (1g/L) (OG) and high glucose (4.5 g/L) (HG) conditions. XTT, wound healing, ALP, and calcium release assays were conducted with or without HPN in the culture media. The statistical analysis revealed that adding different concentrations of HPN (2, 4, 10, or 100 μM) had no significant effect on the viability of HPDLCs under both OG (p=0.436) and HG conditions (p=0.162) compared to the control. However, in the HG condition, the addition of 100 μM HPN resulted in a statistically significant increase in wound closure (p=0.003). Furthermore, in the HG condition, the addition of 100 μM HPN significantly increased ALP activity in the OS- media (p=0.001) and significantly increased calcium release within the OS+ media (p=0.016). The findings of this study suggest that HPN provides beneficial effects, facilitating repair and mineralization in HPDLCs under HG conditions.

Are metal-based antibacterial gels a potential alternative for disinfection in contemporary endodontics?

This study aimed to assess the effectiveness of a novel antimicrobial gel, containing copper and silver nanoparticles, for use in root canal disinfection. Copper and silver-based gels were created in-house, using a support network of biocompatible polymers, including polyvinyl alcohol (PVA), polyvinyl pyrrolidone (PVP), and polyethylene glycol (PEG). Six experimental groups were created, three containing silver ions and three copper ions, where the PVA, PVP and PEG ratios were also adjusted in each group to test the gel's physical state. One control contained no metal nanoparticles. The gels surface characteristics, roughness, mechanical properties, and flowability, were characterised using a combination of atomic force microscopy, scanning electron microscopy, transmission electron microscopy and Rheometery. Further biological testing measured the gels cytotoxicity levels, using human periodontal ligament cells, and the anti-microbial effects against E. Faecalis and a multi-species bacteria biofilm. Each gel demonstrated high levels of viscosity, which was lowered in gels containing a reduced PVA concentration. The overall antimicrobial properties of the gels increased in those with a higher dissolution, lower porosity, and reduced surface roughness. Copper nanoparticles were shown to be significantly more effective against E. Faecalis, compared with silver. Gels containing higher PVA levels, and silver nanoparticles, had greater toxicity levels against human cells, however, testing was not possible for most experimental groups as the gels dissolved before measurements took place. The antimicrobial properties of all gel formulations were significantly less effective than sodium hypochlorite (after 1 h), but a similar outcome was detected in comparison with calcium hydroxide (after 7 days). Developing an antimicrobial gel is highly dependent upon numerous compositional factors, where development is still at the early stages. The use of copper nanoparticles appeared to be more appropriate for use in canal disinfection, compared with silver that also had higher levels of human cell toxicity. The ratios selected for the biocompatible polymers had a critical impact on the physical state, antimicrobial, and toxicity levels. At present, antimicrobial gels are not as effective as sodium hypochlorite.

Zerumbone modulates the expression of inflammatory mediators and antioxidant enzymes in TNF-α-stimulated human periodontal ligament cells

Objectives Periodontal disease is a chronic inflammatory disease caused by periodontopathogenic bacteria, and its progression leads to periodontal tissue destruction and tooth loss. Zerumbone is a bioactive substance found in ginger (Zingiber zerumbet) and is known to have bioactive effects such as anticancer effects, but there have been no attempts to use it for periodontitis treatment. In addition, there have been no reports examining its effects on periodontal tissue component cells. In this experiment, we aimed to determine whether zerumbone affects the production of inflammatory mediators induced by tumor necrosis factor (TNF)-α in human periodontal ligament cells (HPDLCs), including its effects on signaling pathways. Methods HPDLCs were stimulated by TNF-α (10 ng/ml) with or without zerumbone (6.25, 12.5, or 25 µM). Cytokine production in supernatant was determined using ELISA. Activation of signal transduction pathways and intracellular protein expression were investigated using the western blot analysis. Results Zerumbone significantly suppressed TNF-α-induced production of CC chemokine ligand 2 (CCL2), CCL20, CXC chemokine ligand 10 (CXCL10), and interleukin-6 (IL-6) in HPDLCs. In addition, zerumbone decreased intercellular adhesion molecule-1 (ICAM-1) and cyclooxygenase-2 (COX-2) expression in TNF-α-stimulated HPDLCs. Furthermore, zerumbone suppressed activation of nuclear factor (NF)-κB and signal transducer and activator of transcription 3 (STAT3) pathways in TNF-α-treated HPDLCs. Finally, zerumbone enhanced the production of heme oxygenase-1 (HO-1), an antioxidant enzyme, in HPDLCs. Conclusion These results suggest that zerumbone suppressed the production of several inflammatory mediators by inhibiting the NF-κB and STAT3 pathways in HPDLCs.

Curcumin as a Modulator of Osteogenic Potential in Lipopolysaccharide-Treated Human Periodontal Ligament Cells: An In Vitro Study.

Background Periodontal diseases cause alveolar bone destruction driven by anaerobic bacteria. Their virulence factors disrupt the osteogenic potential of human periodontal ligament stem cells (hPDLCs). Curcumin, a polyphenol with anti-inflammatory and osteogenic properties, holds promise for periodontal regeneration Aim This study evaluated the effects of curcumin on the osteogenic potential of hPDLCs under LPS-induced inflammatory conditions by assessing the expression of osteogenic markers, bone morphogenetic protein-2 (BMP-2), and osteopontin (OPN). Materials and methods hPDLCs were isolated from premolars and cultured in the presence of LPS (10 µg/mL) to simulate inflammation. Cells were treated with curcumin at 2.5 µM and 5 µM, with and without LPS exposure. Gene expression of BMP-2 and OPN was quantified using qRT-PCR after 21 days of culture. Results LPS significantly suppressed BMP-2 and OPN expression (p < 0.05). Curcumin treatment restored BMP-2 and OPN expression in a dose-dependent manner, with 5 µM curcumin demonstrating the most substantial effects, nearly restoring OPN levels to control values. Conclusion Curcumin mitigates LPS-induced inflammation and enhances hPDLCs' osteogenic differentiation, demonstrating its potential as a therapeutic adjunct for periodontal tissue regeneration.

Endo 180 participates in collagen remodeling of the periodontal ligament during orthodontic tooth movement

BackgroundOrthodontic tooth movement (OTM) relies on the remodeling of periodontal tissues, including the periodontal ligament (PDL) and alveolar bone. Collagen remodeling plays a crucial role during this process, allowing for the necessary changes in the PDL’s structure and function. Endo180, an urokinase plasminogen activator receptor-associated protein, is a transmembrane receptor regulated collagen remodeling. This study aims to investigate whether and how Endo180 participates in collagen remodeling within the PDL during OTM.Materials and methodsA mechanical force-induced OTM rat model was established using a closed coiled spring to mesially move the right maxillary first molar. The distance of OTM was examined by micro-computed tomography (micro-CT). The collagen remodeling within the PDL was assessed using atomic force microscope (AFM), Hematoxylin-Eosin (HE) staining and Masson staining. Protein expressions of Endo180, collagen I (COL I) and collagen III (COL III) were analyzed via immunofluorescence staining. Additionally, the mRNA expressions of Endo180, COL I, and COL III in force-induced PDL cells were examined by RT-qPCR in vitro. To further illustrate the role of Endo180 in regulating COL I and COL III expressions, Endo180 siRNA (siEndo) was applied to force-stimulated PDL cells.ResultsForce application increased OTM distance and disrupted collagen fiber organization, with a greater decrease in collagen elastic modulus on the mesial side than on the distal side of the PDL. After 7 days of force application, Endo180 and COL III expressions significantly increased in PDL tissues, while COL I expression decreased in PDL tissues. Compressive force loading in vitro upregulated the mRNA expressions of Endo180 and COL III, but downregulated COL I mRNA expression. Notably, Endo180 knockdown using siRNA suppressed force-induced COL III expression while restoring the downregulated COL I expression under compressive force stimuli.ConclusionForce-induced Endo180 expression modulates collagen remodeling in PDL during OTM by upregulating COL III and downregulating COL I. This collagen reorganization facilitates efficient tooth movement, highlighting Endo180 as a potential therapeutic target to optimize orthodontic treatment outcomes.

Cementum attachment protein-derived peptide induces cementum formation.

A pentapeptide AVIFM (CAP-p5) derived from the carboxy-terminus end of cementum attachment protein was examined for its role on proliferation, differentiation, and mineralization of human periodontal ligament cells (HPLC), and for its potential to induce cementum deposition invivo. CAP-p5 capability to induce hydroxyapatite crystal formation on demineralized dentin blocks was characterized by scanning electron microscopy, μRAMAN, and high-resolution transmission electron microscopy. The results revealed that CAP-p5 promoted cell proliferation and cell differentiation and increases alkaline phosphatase activity of HPLC and mineralization at an optimal concentration of 10 μg/mL. It induced the expression of cementum molecular markers BSP, CAP, CEMP1, and ALP at the protein level. In a cell-free system, human demineralized dentin blocks coated with CAP-p5 induced the deposition of a homogeneous and continuous mineralized layer, intimately integrated with the underlying dentin indicating new cementum formation. Physicochemical characterization of this mineral layer showed that it is composed of hydroxyapatite crystals. Demineralized dentin blocks coated with CAP-p5 implanted subcutaneously in BALB/cAnNCrl were analyzed histologically; the results disclosed that CAP-p5 could induce the deposition of a cementum layer intimately integrated with the subjacent dentin with cementocytes embedded into the cementum matrix. Immunostaining showed the expression of cementum molecular markers; v.gr. BSP, CAP, CEMP1 and ALP, validating the molecular identity of the newly deposited cementum. We conclude that CAP-p5 is a new biomolecule with the potential of therapeutic application to contribute to the regeneration of cementum and periodontal structures lost in periodontal disease.

The Application of Resolvin D1-Loaded Gelatin Methacrylate in a Rat Periodontitis Model.

Objective: To evaluate the drug release, cytocompatibility with periodontal ligament cells (PDLCs), and therapeutic efficacy of GelMA hydrogel loaded with resolvin D1 (RvD1) in treating rat periodontal inflammation and alveolar bone damage. Methods: An RvD1 complexed with GelMA was prepared, and its release kinetics and compatibility with PDLCs were assessed. Rats with induced periodontitis were treated weekly with topical applications of vehicle, GelMA, RvD1, or RvD1 complexed with GelMA for four weeks. Periodontal inflammation and tissue regeneration were evaluated using quantitative PCR (qPCR) and histochemical staining, while alveolar bone repair and regeneration were analyzed through micro-CT. Results: The RvD1 complexed with GelMA effectively released RvD1 and enhanced the proliferation and viability of PDLCs. Compared to RvD1 alone, treatment with RvD1 complexed with GelMA significantly reduced inflammatory cell infiltration, TNF-α and RANKL expression, and osteoclast formation in periodontal tissues. Additionally, it promoted the expression of specific anti-inflammatory and regenerative markers. Micro-CT analysis confirmed significant new bone formation in the RvD1 complexed with GelMA-treated group. Conclusions: RvD1 complexed with GelMA provides sustained drug release and biocompatibility, effectively resolves periodontal inflammation, and promotes tissue regeneration in periodontitis.

Investigation of Impact of Oxidative Stress on Human Periodontal Ligament Cells Exposed to Static Compression.

Oxidative stress (OS) is a common feature of many inflammatory diseases, oral pathologies, and aging processes. The impact of OS on periodontal ligament cells (PDLCs) in relation to oral pathologies, including periodontal diseases, has been investigated in different studies. However, its impact on orthodontic tooth movement (OTM) remains poorly understood. This study used an in vitro model with human PDLCs previously exposed to H2O2 to investigate the effects of OS under a static compressive force which simulated the conditions of OTM. Human PDLCs were treated with varying concentrations of H2O2 to identify sub-lethal doses that affected viability minimally. To mimic compromised conditions resembling OTM under OS, the cells were pretreated with the selected H2O2 concentrations for 24 h. Using an in vitro loading model, a static compressive force (2 g/cm2) was applied for an additional 24 h. The cell viability, proliferation, and cytotoxicity were evaluated using live/dead and resazurin assays. Apoptosis induction was assessed based on caspase-3/7 activity. The gene expression related to bone remodeling (RUNX2, TNFRSF11B/OPG, BGLAP), inflammation (IL6, CXCL8/IL8, PTGS2/COX2), apoptosis (CASP3, CASP8), and autophagy (MAP1LC3A/LC3, BECN1) was analyzed using RT-qPCR. This study suggests an altering effect of previous OS exposure on static-compression-related mechanosensing. Further research is needed to fully elucidate these mechanisms.

Inflammation alters the expression and activity of the mechanosensitive ion channels in periodontal ligament cells.

Periodontal ligament cells (PDLCs) possess mechanotransduction capability, vital in orthodontic tooth movement (OTM) and maintaining periodontal homeostasis. The study aims to elucidate the expression profiles of mechanosensitive ion channel (MIC) families in PDLCs and how the inflammatory mediator alters their expression and function, advancing the understanding of the biological process of OTM. Human PDLCs were cultured and exposed to TNF-α. RNA sequencing was conducted to explore the mRNA transcriptome of both normal and TNF-α-treated PDLCs. Differentially expressed MICs were identified and analyzed. The functional expressions of TRPA1 and TRPM8 were further validated by RT-qPCR, Western blot, and calcium influx assays. All 10 identified MIC families or subfamilies were expressed in PDLCs, with the TRP family being the most abundant. KCNK2, PIEZO1, TMEM87A, and PKD2 were the most expressed ion channels in PDLCs. TNF-α altered the expression of the MIC families, resulting in increased expression of PIEZO, K2P, TRP, TMEM63, and TMEM87 families and decreased expression of ENaC/ASIC, TMC/TMHS/TMIE, TMEM150, TMEM120, and L/T/N-Type calcium channel families. Furthermore, 17 DEMICs were identified (false discovery rate < 0.05), with the top five (fold change ≥ 2), including upregulated TRPA1 and TRPM8. The functional expressions of TRPA1 and TRPM8 were verified, suggesting that TNF-α significantly increased their expression and sensitized their activities. The study provides comprehensive expression profiles of the MICs in PDLCs and reveals how inflammation alters the expression and activities of the MICs. Treatments targeting these MICs may offer promising strategies for improving OTM and preventing complications in inflammatory environments, ultimately leading to more effective and safer orthodontic practices.

Comparative Evaluation of the Impact of Chloride and Fluoride Based Electrolytes on PDL Cells Before and After Electrochemical Dissolution

ABSTRACT Objective: Most methods for retrieving fractured instruments have consequences that may affect treatment outcomes. A better outcome can be achieved with electrochemical dissolution without mechanical injury. Materials and Methods: Several electrochemical dissolution solutions are being used including artificial saliva, Tyrode’s solution, and sodium fluoride (NaF). These electrolytes were prepared and their respective electrochemical characterization was done before conducting the assay. The present in vitro study compares the possible cytotoxic effect and viability of periodontal ligament cells in artificial saliva, Tyrode’s solution, and NaF using an MTT assay. Results: The comparative analyses of the cell viability and toxicity effects of the electrolytes considered are reported. It was observed that the Artificial saliva (before dissolution: 84.10±11.32; after dissolution: 69.1±11.32) and Tyrode’s solution (before dissolution: 77.30±4.11; after dissolution: 61.3±4.11) showed higher cell viability percentages and comparatively reduced toxicity levels before and after dissolution compared to NaF (before dissolution: 36.01±5.27; after dissolution: 11.01±5.27). Statistical analysis of the results observed before and after dissolution provided a significant difference (P&lt;0.05). Conclusions: The artificial saliva and the Tyrode’s solution may be considered as a potential electrochemical dissolution solution during the surgery to achieve a better outcome.

Effect of Mechanical Force Stress on the Inflammatory Response in Human Periodontal Ligament Cells.

Human periodontal ligament (hPDL) is continuously exposed to mechanical forces that can induce inflammatory responses in resident stem cells (hPDLSCs). Here, we review the impact of mechanical force on hPDLSCs, focusing on the activation of inflammatory cytokines and related signalling pathways, which subsequently influence periodontal tissue remodelling. The effects of various mechanical forces, including compressive, shear, and tensile forces, on hPDLSCs are discussed. The review highlights the role of pro-inflammatory cytokines such as IL-1β, IL-6, and TNF-α in mediating inflammatory responses, as well as the counteracting effects of anti-inflammatory cytokines like IL-4 and IL-10. Additionally, we underscore the involvement of toll-like receptors (TLRs), particularly TLR4, in transducing mechanical stress signals and modulating cytokine production. This review demonstrates that hPDLSCs respond to different mechanical forces with specific gene expression changes that direct inflammatory and bone remodelling signals, leading to increased osteoblast and osteoclast activity. Moreover, hPDLSCs, together with contiguous hPDL cells, respond to various mechanical forces by regulating the immune function of several immune cells. This complex relationship between the mechanical force stress, inflammation, and the cellular response in hPDLSCs warrants further research to develop therapeutic strategies for periodontal and related diseases.

Investigating the Role of Primary Cilia and Bone Morphogenetic Protein Signaling in Periodontal Ligament Response to Orthodontic Strain In Vivo and In Vitro: A Pilot Study.

Periodontal ligament (PDL) cells are crucial for mechanosensation and mechanotransduction within the PDL, yet the role of primary cilia in orthodontic force transmission has not been examined. While bone morphogenetic protein (BMP) signaling significantly influences ciliary function, its effect on cellular responses to mechanical stress has not been investigated. This study aims to investigate whether primary cilia and BMP signaling are involved in the periodontal ligament's response to orthodontic tooth movement and the resultant mechanical strain. To visualize primary cilia, human PDL cells were cultured on glass-bottom dishes for five days, with a subset fixed daily, followed by immunostaining with anti-acetylated α-tubulin and Alexa Fluor 568 and imaging using a fluorescence microscope under 405 nm and 561 nm laser excitation. Human PDL cells were grown on Bioflex® culture plates and subsequently exposed to static tensile strains of 2.5%, 5%, 10%, 20%, on a FX-6000T™ Tension System for 24 h. RT-qPCR was performed to evaluate changes in expression of primary cilia via Ift88 expression, mechanotransduction via Cox2 expression, and BMP signaling-related genes. Histological specimens from orthodontically loaded and control human premolars were investigated for primary cilia and BMP signaling using immunohistochemistry and confocal microscopy. Primary cilia were observed in PDL cells from day one, with their incidence and length increasing over time alongside cell density. BMP signaling components, including upregulated genes such as Bmp7 (10.99-14.97 fold), Alk2 (3.19-5.45 fold), and Bmpr2 (1.64-8.40 fold), consistently responded to strain, while Cox2 and Ift88 showed differential regulation depending on strain intensity. In vivo, orthodontic movement activated BMP signaling and increased primary cilium incidence in the PDL. These findings indicate the potential role of primary cilia and BMP signaling in the mechanosensitivity of PDL cells under orthodontic forces. Further studies are required to understand the complex mechanotransduction mechanisms and role of these components in cellular adaptation during orthodontic tooth movement.

Wnt/β-catenin Promotes Cementum Apposition in Periodontal Regeneration

Regeneration of periodontal tissue, particularly the cementum–periodontal ligament (PDL)–bone complex, has long been challenging because the differentiation kinetics of cells and the molecular pathways contributing to the regeneration process are largely unknown. We aimed to evaluate the cell behavior and molecular pathways that contribute to periodontal tissue regeneration in vivo. We analyzed the process of periodontal tissue regeneration through subrenal capsule transplantation of immediately extracted molars in mice. We showed that the regenerated periodontal tissue in the subrenal capsule was morphologically comparable to the intact periodontal tissue, with increased cellular cementum thickness in the apical region. Cell tracing analysis revealed that the cells comprising the regenerated periodontal tissue were derived from transplanted teeth and were indispensable for periodontal tissue regeneration, whereas recipient mouse-derived cells partly contributed to angiogenesis. Bioinformatics analysis based on the gene expression profile in the transplanted teeth indicated that Wnt/β-catenin signaling is involved in periodontal tissue regeneration, which was further confirmed through β-catenin immunohistochemistry. Moreover, the constitutive activation of β-catenin in the cells of transplanted teeth was found to promote accelerated cellular cementum apposition, while the conditional knockout of β-catenin in the cells of transplanted teeth suppressed cellular cementum apposition. Notably, the manipulation of Wnt/β-catenin signaling did not interfere with the bone–PDL–cementum complex, while endogenous osteoclast activity was affected in bone. Our results demonstrated the essential roles of endogenous PDL cells in periodontal tissue regeneration and that Wnt/β-catenin signaling is involved in this process, particularly cellular cementum apposition. Hence, controlling this pathway could promote cementum regeneration, which is a critical process for the regeneration of the cementum–PDL–bone complex. This study provides novel insights into cell behavior and signaling pathways that will advance practical periodontal tissue regeneration.

Investigating the Cytotoxic Effects of Artemisia absinthium Extract on Oral Carcinoma Cell Line

Background: Artemisia absinthium (A. absinthium), commonly known as absinthe, is a perennial plant with distinctive broad ovate pointed leaves of a silvery-gray color, reaching a height of 1.5 m. The utilization of this herb as a source of natural compounds and as the primary ingredient in the alcoholic beverage absinthe has recently seen a resurgence following a period of prohibition. This study investigates the biological effects of A. absinthium extract on healthy human periodontal ligament stem cells (hPDLSCs) and the human tongue squamous carcinoma cell line (HSC-3). Methods: A. absinthium element characterization was performed using High-Performance Liquid Chromatography (HPLC) and the Folin method. Alizarin assays evaluated the osteogenic capacity of human periodontal ligament cells (hPDLSCs) while CCK-8 and MTT determined the cytotoxicity of the extract against HSC-3 and hPDLSCs. Results: High artemisinin levels were detected, revealing a concentration of 89 μM (25 μg/mL). The total phenolic concentration of the extract was 1.07 mM +/− 0.11. The in vitro cytotoxicity assays revealed the biocompatible profile of the Artemisia extract in hPDLSCs without exhibiting any osteogenic potential. After 24 h of incubation with HSC-3, Artemisia extract (10 µM) decreased cancer cell viability by 99% and artemisinin by 64%, and increased the expression of Caspase 3 and 9 almost six and two times, respectively. Conclusions: In summary, our preliminary findings suggest that A. absinthium extract exhibits a toxic effect against carcinoma cell lines without affecting healthy human periodontal ligament stem cells.

Beneficial effects of non-invasive physical plasma on human periodontal ligament cells in vitro.

Periodontitis is a chronic inflammatory disease of the periodontium that can lead to the loss of affected teeth if left untreated. It is induced by a multifactorial process centered on microbial pathogens such as Fusobacterium nucleatum (F.n.). Non-invasive physical plasma (NIPP), a highly reactive gas, has become a focus of research, not only for its hemostatic, proliferation-enhancing and apoptotic properties, but also for its antimicrobial potential. The objective of this study was to examine the impact of NIPP on human periodontal ligament (PDL) cells that had been induced into a state of periodontal infection in vitro. Initially, the solitary effect of NIPP was evaluated by measuring temperature and pH and analyzing reactive oxygen species (ROS). Additionally, DAPI and phalloidin staining were employed to investigate possible cytotoxic effects. The cells were pre-incubated with F.n. and treated with NIPP after 24 hours. Interleukin (IL)-6 and IL-8 were analyzed at mRNA and protein levels, respectively, by real-time PCR and ELISA. NIPP alone had no significant effect on PDL cells. However, the F.n.-induced upregulation of IL-6 and IL-8 was counteracted by NIPP. Thus, the utilization of NIPP may be regarded as a promising therapeutic strategy for the treatment of periodontal diseases.