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Background: Diabetes, occasionally diagnosed in orthodontic patients, can impede orthodontic tooth movement (OTM) by accumulating advanced glycation end products (AGEs) in the periodontium. This accumulation impairs the osteogenic differentiation of periodontal ligament stem cells (PDLSCs) due to alterations in the force-loaded microenvironment, yet the underlying mechanisms remain elusive., Methods: Bioinformatics analysis of GSE112122 identified alterations in the mechanical regulation of histone methylation enzyme Lysine Demethylase 6B (KDM6B). OTM models were established in healthy and Nicotinamide/ Streptozotocin-induced type II diabetic rats. The impact of AGEs on mechanically induced osteogenesis and its correlation with KDM6B were evaluated by assessing the therapeutic effects of periodontal ligament injections of the AGEs/RAGE inhibitor FPS-ZM1. To investigate transcriptomic changes, we extracted human PDLSCs, which were subjected to RNA sequencing following the overexpression of KDM6B. Experimental validation further identified potential self-reinforcing loops and their associated antioxidative mechanisms., Results: Mechanical forces upregulated KDM6B expression and function in PDLSCs, modulating extensive downstream osteogenesis-related transcriptional changes. Experiments with AGEs-treated and FPS-ZM1-treated samples demonstrated that AGEs impaired osteogenesis by compromising KDM6B mechanical responsiveness. A positive feedback loop between KDM6B and Wnt pathways was identified, inhibited by AGEs. This loop regulated superoxide dismutase 2 (SOD2), facilitating antioxidative stress and preventing stem cell ageing., Conclusions: This study elucidates a novel mechanism by which AGEs influence the osteogenic process and antioxidative capacity of PDLSCs through the KDM6B/Wnt self-reinforcing loop under orthodontic force. Targeting the AGE/RAGE pathway or enhancing KDM6B may enhance orthodontic treatments for diabetic patients., Competing Interests: Declarations Ethical approval This study involves a human research project titled “Mechanism of Orthodontic Force-Induced Osteogenic Differentiation of PDLSCs Affected by the Diabetic Microenvironment via KDM6B”. It has been reviewed and approved by the Ethics Committee of the Hospital of Stomatology, Shandong University. The ethics approval number is NO. 20231115, and the approval date is November 30, 2023. Additionally, this research includes an animal experiment ethics project entitled “Mechanism of Orthodontic Force-Induced Osteogenic Differentiation of PDLSCs Influenced by the Diabetic Microenvironment through KDM6B”. It has received approval from the Ethics Committee of the Hospital of Stomatology, Shandong University, with the ethics approval number NO. 20231116 granted on November 30, 2023. Consent to participate The acquisition of human PDLSCs involved in this study was obtained with informed consent from the patients, and written informed consent was obtained from the patients or their guardians for participation and the use of samples. Consent to publish The authors affirm that human research participants provided informed consent for the publication of the images related to PDLSCs. Conflict of interests The authors declare no potential conflicts of interest concerning the research, authorship, or publication of this article., (© 2024. The Author(s).)

Background: Oxyresveratrol is the main constituent of mulberries and has many bioactive properties beneficial to human health. The purpose of this study was to assess the anti-inflammatory effects of oxyresveratrol on in vitro periodontitis model., Methods: Human periodontal ligament cells were treated with oxyresveratrol (0, 10, and 20 µg/mL) for 72 h. Cell viability and flow cytometry assays were performed. To investigate anti-inflammatory effect of oxyresveratrol on periodontal inflammation, nitric oxide production under lipopolysaccharide stimulation was assessed. Next, expression of biomarkers associated periodontal inflammation was evaluated. Scratch wound assay was performed to evaluate cell migration/proliferation potential of oxyresveratrol under lipopolysaccharide stimulation., Results: Periodontal ligament cell toxicity was not observed in oxyresveratrol treatment. Oxyresveratrol treatment significantly inhibited nitric oxide production and reduced MMP-2, MMP-9, TNF-α, IL-6, and IL-8 expressions after lipopolysaccharide stimulation. Regarding cell migration/proliferation, open wound area in oxyresveratrol (33.28 ± 6.80%) was the lowest (p < 0.05)., Conclusions: Within the limits of this study, oxyresveratrol inhibited lipopolysaccharide-induced inflammation in periodontal ligament cells and promoted periodontal ligament cell migration/proliferation. These findings suggest that oxyresveratrol could be valuable for the management of periodontal diseases., Competing Interests: Declarations Ethics approval and consent to participate Not applicable. Consent for publication Not applicable. Competing interests The authors declare no competing interests., (© 2024. The Author(s).)

Background: We aimed to investigate the effect and underlying mechanism of titanium (Ti) implant on the polarization of macrophages and subsequent effects on the osteogenic differentiation of periodontal ligament stem cells (PDLSCs) and angiogenesis of human umbilical vein endothelial cells (HUVECs) affected by macrophages., Methods: Firstly, the regulatory effect of Ti implant on macrophage polarization was investigated. Levels of M1 polarization markers and M2 polarization markers in macrophages were evaluated by immunofluorescence staining method and qPCR analysis. The osteogenic differentiation capacity of PDLSCs cultured with supernatants of macrophages of each group was evaluated by the Alizarin Red S (ARS) staining method and qPCR. Angiogenesis related genes were also evaluated in HUVECs cultured in supernatants of macrophages. To explore whether RNA m 5 C modification can modulate the effects of Ti implant on macrophage regulation of osteogenic differentiation and angiogenesis, we analyzed the main genes related to m 5 C in macrophages using RNA m 5 C dot blotting and qPCR methods. The interaction between NSUN2 and IRF4 was verified by m 5 C-RIP, RIP, and double-luciferase gene report experiments., Results: Macrophages were activated as M1 macrophages under the interference of LPS, and macrophages attached to Ti implants were more easily activated as M2 macrophages under the action of LPS. Macrophages activated by Ti implant enhanced osteogenic differentiation of PDLSCs and angiogenesis of HUVECs. NSUN2 level was up-regulated in macrophages treated with LPS and was down-regulated by Ti implant. Over-expression of NSUN2 attenuated the effect of Ti implant on M1 polarization promotion of macrophages and enhanced the M2 polarization promotion of macrophages. Up-regulation of NSUN2 weakened the effects of Ti implant on promotion the capacity of macrophages on osteogenic differentiation of PDLSCs and angiogenesis of HUVECs. The KEGG analysis suggested that IRF4 was enriched in several inflammatory signaling pathways. Moreover, NSUN2 methylates IRF4 to affect the capacity of macrophages on osteogenic differentiation of PDLSCs and angiogenesis of HUVECs., Conclusions: Taken together, macrophages of M1 type can be stimulated by Ti implants in vitro, promoting osteogenic differentiation of PDLSCs and angiogenesis in HUVECs through NSUN2-mediated methylation of IRF4., Competing Interests: Declarations Ethics approval and consent to participate Not applicable. Consent for publication Not applicable. Competing interests The authors declare no competing interests., (© 2024. The Author(s).)

Background: Mechano-growth factor (MGF), which is a growth factor produced specifically in response to mechanical stimuli, with potential of tissue repair and regeneration. Our previous research has shown that MGF plays a crucial role in repair of damaged periodontal ligaments by promoting differentiation of periodontal ligament stem cells (PDLSCs). However, the molecular mechanism is not fully understood. This study aimed to investigated the regulatory effect of MGF on differentiation of PDLSCs and its molecular mechanism., Methods: Initially, we investigated how MGF impacts cell growth and differentiation, and the relationship with the activation of Fyn-p-YAP Y357 and LATS1-p-YAP S127 . Then, inhibitors were used to interfere Fyn phosphorylation to verify the role of Fyn-p-YAP Y357 signal after MGF stimulation; moreover, siRNA was used to downregulate YAP expression to clarify the function of YAP in PDLSCs proliferation and differentiation. Finally, after C3 was used to inhibit the RhoA expression, we explored the role of RhoA in the Fyn-p-YAP Y357 signaling pathway in PDLSCs proliferation and differentiation., Results: Our study revealed that MGF plays a regulatory role in promoting PDLSCs proliferation and fibrogenic differentiation by inducing Fyn-YAP Y357 phosphorylation but not LATS1-YAP S127 phosphorylation. Moreover, the results indicated that Fyn could not activate YAP directly but rather activated YAP through RhoA in response to MGF stimulation., Conclusion: The research findings indicated that the Fyn-RhoA-p-YAP Y357 pathway is significant in facilitating the proliferation and fibrogenic differentiation of PDLSCs by MGF. Providing new ideas for the study of MGF in promoting periodontal regenerative repair., Competing Interests: Declaration of competing interest The authors declare no conflicts of interest., (Copyright © 2024 Elsevier Inc. All rights reserved.)

This study aimed to investigate the cytotoxicity and apoptotic activity of different endodontic sealers: Sealapex, Apexit Plus, AH Plus, MTA-Fillapex and TotalFill BC Sealer in the culture of human periodontal ligament fibroblast (HPDLF) cells. The sealers were mixed, set for 24 h, and then covered with culture medium to obtain extracts, which were diluted to 1:0, 1:1, 1:2, 1:4, and 1:8. Simultaneously, HPDLF cells (1 × 10 4 ) were seeded in 96-well plates and incubated for 24 h at 37 °C 5% CO 2 conditions. The cells were then exposed to 100 µL of diluted extract medium. Cytotoxicity was evaluated using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay to check cell viability, while apoptosis was assessed by TUNEL assay. Statistical analyses were performed using Kruskal-Wallis and Dunn post hoc tests with Mann Whitney U. In MTT and TUNEL assay cells were treated with sealers both 24 and 72 h. All materials showed higher toxicity at 72 h compared to 24 h. AH Plus exhibited the highest cytotoxicity, followed by MTA-Fillapex, Apexit Plus, Sealapex, while TotalFill BC Sealer had the lowest cytotoxicity. Consuquently, it was considered that TotalFill BC Sealer had the lowest cytotoxic potency when compared to other sealers, so it can be considered biocompatible., (© 2024. The Author(s).)

Periodontitis and severe trauma are major causes of damage to the periodontal ligament (PDL). Repairing the native conditions of the PDL is essential for the stability of the tissue and its interfaces. Bioprinting periodontal ligament stem cells (PDLSCs) is an interesting approach to guide the regeneration of PDL and interfacial integration. Herein, a collagen-based bioink mimicking the native extracellular matrix conditions and carrying PDLSCs was tested to guide the periodontal ligament organization. The bioink was tested at two different concentrations (10 and 15 mg/mL) and characterized by swelling and degradation, microstructural organization, and rheological properties. The biological properties were assessed after loading PDLSCs into bioinks for bioprinting. The characterization was performed through cell viability, alizarin red assay, and expression for ALP , COL1A1 , RUNX2 , and OCN . The in vivo biocompatibility of the PDLSC-laden bioinks was verified using subcutaneous implantation in mice. Later, the ability of the bioprinted PDLSC-laden bioinks on dental root fragments to form PDL was also investigated in vivo in mice for 4 and 10 weeks. The bioinks demonstrated typical shear-thinning behavior, a porous microstructure, and stable swelling and degradation characteristics. Both concentrations were printable and provided suitable conditions for a high cell survival, proliferation, and differentiation. PDLSC-laden bioinks demonstrated biocompatibility in vivo , and the bioprinted scaffolds on the root surface evidenced PDLSC alignment, organization, and PDLSC migration to the root surface. The versatility of collagen-based bioinks provides native ECM conditions for PDLSC proliferation, alignment, organization, and differentiation, with translational applications in bioprinting scaffolds for PDL regeneration.

Purpose: This study examines the effects and mechanisms of catalpol (CAT) on the proliferation and osteogenic differentiation of cultured human periodontal ligament stem cells (hPDLSCs) in vitro and assesses the impact of CAT on periodontal remodeling in vivo using an orthodontic tooth movement (OTM) model in rats., Methods: hPDLSCs were cultured in a laboratory setting, and their proliferation and osteogenic differentiation were assessed using the Cell-counting Kit-8 (CCK-8), Alizarin Red Staining (ARS), quantitative calcium assay, alkaline phosphatase (ALP) staining and activity assay, and immunofluorescence assay. Additionally, the expression of collagen type 1 (COL-1), ALP, and runt-related transcription factor-2 (RUNX-2) was evaluated through qRT-PCR and Western blot analysis. To verify the function of the estrogen receptor-α (ER-α)-mediated phosphatidylinositol-3-kinase-protein kinase B (PI3K/AKT) pathway in this mechanism, LY294002 (a PI3K signaling pathway inhibitor) and the ER-α specific inhibitor methyl-piperidine-pyrazole (MPP) were used. The osteogenic markers ER-α, AKT, and p-AKT (phosphoprotein kinase B) were identified through Western blot analysis. Eighteen male Sprague-Dawley rats were assigned to two groups randomly: a CAT group receiving CAT and a control group receiving an equivalent volume of saline. Micro-computed tomography (micro-CT) analysis was employed to evaluate tooth movement and changes in alveolar bone structure. Morphological changes in the periodontal tissues between the roots were investigated using hematoxylin and eosin (HE) staining and tartaric-resistant acid phosphatase (TRAP) staining. The expression of COL-1, RUNX-2, and nuclear factor-κB (NF-κB) ligand (RANKL) was assessed through immunohistochemical staining (IHC) to evaluate periodontal tissue remodeling. Tests were analyzed using GraphPad Prism 8 software. Differences among more than two groups were analyzed by one-way or two-way analysis of variance (ANOVA) followed by the Tukey's test. Values of p  < 0.05 were regarded as statistically significant., Results: In vitro experiments demonstrated that 10 μM CAT significantly promoted the proliferation, ALP activity, and calcium nodule formation of hPDLSCs, with a notable increase in the expression of COL-1, ALP, RUNX-2, ER-α, and p-AKT. The PI3K/AKT pathway was inhibited by LY294002, and further analysis using MPP suggested that ER-α mediated this effect. In vivo, experiments indicated that CAT enhanced the expression of COL-1 and RUNX-2 on the tension side of rat tooth roots, reduced the number of osteoclasts on the compression side, inhibited RANKL expression, and suppressed OTM., Conclusion: CAT can promote hPDLSCs proliferation and osteogenic differentiation in vitro through the ER-α/PI3K/AKT pathway and enhance periodontal tissue remodeling in vivo using OTM models. These findings suggest the potential for the clinical application of catalpol in preventing relapse following OTM., Competing Interests: The authors report no conflicts of interest in this work., (© 2024 Hu et al.)

Nonresolving inflammation causes irreversible damage to periodontal ligament stem cells (PDLSCs) and impedes alveolar bone restoration. The impaired tissue regeneration ability of stem cells is associated with abnormal mitochondrial metabolism. However, the impact of specific metabolic alterations on the differentiation process of PDLSCs remains to be understood. In this study, we found that inflammation altered the metabolic flux of the tricarboxylic acid cycle and induced the accumulation of fumarate through metabolic testing and metabolic flux analysis. Transcriptome sequencing revealed the potential of fumarate in modulating epigenetics. Specifically, histone methylation typically suppresses the expression of genes related to osteogenesis. Fumarate was found to impede the osteogenic differentiation of PDLSCs that exhibited high levels of H3K9me3. Various techniques, including assay for transposase-accessible chromatin with high-throughput sequencing, chromatin immunoprecipitation sequencing, and RNA sequencing, were used to identify the target genes regulated by H3K9me3. Mechanistically, accumulated fumarate inhibited lysine-specific demethylase 4B (KDM4B) activity and increased H3K9 methylation, thus silencing asporin gene transcription. Preventing fumarate from binding to the histone demethylase KDM4B with α-ketoglutarate effectively restored the impaired osteogenic capacity of PDLSCs and improved alveolar bone recovery. Collectively, our research has revealed the significant impact of accumulated fumarate on the regulation of osteogenesis in stem cells, suggesting that inhibiting fumarate production could be a viable therapeutic approach for treating periodontal diseases., Competing Interests: Declaration of Conflicting InterestsThe authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Periodontitis, a common oral disease characterized by the progressive infiltration of bacteria, is a leading cause of adult tooth loss. Periodontal stem cells (PDLSCs) possess good self‑renewal and multi‑potential differentiation abilities to maintain the integrity of periodontal support structure and repair defects. The present study aimed to analyze the roles of Wnt7B and frizzled4 (FZD4) in the osteogenic differentiation and macrophage polarization during periodontitis using an in vitro cell model. First, Wnt7B expression in the periodontitis‑affected gingival tissue of patients and lipopolysaccharide (LPS)‑stimulated PDLSCs was assessed using the GSE23586 dataset and western blot analysis, respectively. In Wnt7B‑overexpressing PDLSCs exposed to LPS, the capacity of osteogenic differentiation was evaluated by detecting alkaline phosphatase activity, the level of Alizarin Red S staining and the expression of genes related to osteogenic differentiation. Subsequently, conditioned medium from PDLSCs overexpressing Wnt7B was used for M0 macrophage culture. The expression of CD86 and INOS was examined using immunofluorescence staining and western blot analysis. In addition, reverse transcription‑quantitative PCR was employed to examine the expression of TNF‑α, IL‑6 and IL‑1β in macrophages. The binding between Wnt7B and FZD4 was estimated using co‑immunoprecipitation. In addition, FZD4 was silenced to perform the rescue experiments to elucidate the regulatory mechanism between Wnt7B and FZD4. The results demonstrated a decreased expression of Wnt7B in periodontitis‑affected gingival tissue and in LPS‑exposed PDLSCs. Wnt7B overexpression promoted the osteogenic differentiation of LPS‑exposed PDLSCs and suppressed the M1 polarization of macrophages. Additionally, Wnt7B bound to FZD4 and upregulated FZD4 expression. FZD4 silencing reversed the effects of Wnt7B overexpression on the osteogenic differentiation in LPS‑exposed PDLSCs and the M1 polarization of macrophages. In summary, Wnt7B plays an anti‑periodontitis role by binding FZD4 to strengthen the osteogenic differentiation of LPS‑stimulated PDLSCs and suppress the M1 polarization of macrophages.

Periodontal ligament mesenchymal stem cells (PDLSCs) are a promising cell resource for stem cell-based regenerative medicine in dentistry, but they inevitably acquire a senescent phenotype after prolonged in vitro expansion. The key regulators of PDLSCs during replicative senescence remain unclear. Here, we sought to elucidate the role of metabolomic changes in determining the cellular senescence of PDLSCs. PDLSCs were cultured to passages 4, 10, and 20. The senescent phenotypes of PDLSCs were detected, and metabolomics analysis was performed. We found that PDLSCs manifested senescence phenotype during passaging. Metabolomics analysis showed that the metabolism of replicative senescence in PDLSCs varied significantly. The AMP-activated protein kinase (AMPK) signaling pathway was closely related to adenosine monophosphate (AMP) levels. The AMP:ATP ratio increased in senescent PDLSCs; however, the levels of p-AMPK, FOXO1 and FOXO3a decreased with senescence. We treated PDLSCs with an activator of the AMPK pathway (AICAR) and observed that the phosphorylated AMPK level at P20 PDLSCs was partially restored. These data delineate that the metabolic process of PDLSCs is active in the early stage of senescence and attenuated in the later stages of senescence; however, the sensitivity of AMPK phosphorylation sites is impaired, causing senescent PDLSCs to fail to respond to changes in energy metabolism.

Background: Several studies have reported the protective effects of mesenchymal stem cell-derived exosomes (MSC-Exos) in reducing inflammation and decreasing conjunctival goblet cell (CGC) loss in dry eye disease. However, whether MSC-Exos provide anti-inflammatory profiles in macrophages, thus contributing to CGC protection, has remained elusive., Methods: Macrophages were incubated with PKH26-labeled periodontal ligament mesenchymal stem cell-derived exosomes (PDLSC-Exos) for 12 h, and uptake of PDLSC-Exos by macrophages was observed by a confocal fluorescence microscope. The mRNA expression of TNF-α, IL-10, and Arg1 was detected by quantitative real-time polymerase chain reaction (qRT-PCR). The protein expression of TNF-α and IL-10 were quantified using western blotting. Then, CGCs were exposed to different macrophage supernatants and qRT-PCR was used to detect the Muc5ac mRNA expression of CGCs in response to or absence of cholinergic stimulation. ELISA was used to determine the Muc5ac secretion of CGCs in response to cholinergic stimulation., Results: The uptake of PDLSC-Exos by M1 macrophages facilitates M2 macrophage polarization with the elevated expressions of IL-10 and Arg1. In macrophage supernatant-treated CGCs systems, PDLSC-Exo-treated M1 macrophage supernatant significantly enhanced the Muc5ac expression of CGCs in response to, or in the absence of, cholinergic stimulation, while the addition of PDLSC-Exos to the control macrophage supernatant did not generate a change in Muc5ac expression. Conversely, the addition of PDLSC-Exos to the diluted control macrophage supernatant induced a significant increase in Muc5ac expression., Conclusion: PDLSC-Exos could protect CGCs against M1 macrophage-mediated inflammation, and the protective effects of PDLSC-Exos are partly attributable to their effects on M1 macrophages.

Approximately half of the adult population is suffering from periodontal disease, and conventional periodontal treatment strategies can only slow the progression of the disease. As a kind of tissue engineering, periodontal regeneration brings hope for the treatment of periodontal disease. Low-intensity pulsed ultrasound (LIPUS) is a form of ultrasound with a frequency of 1-3 MHz and a much lower intensity (< 1W/cm 2 ) than traditional ultrasound energy and output. LIPUS has been adopted for a variety of therapeutic purposes due to its bioeffects such as thermal, mechanical, and cavitation effects, which induce intracellular biochemical effects and lead to tissue repair and regeneration ultimately. In this systematic review, we summarize the basic research of LIPUS in the treatment of periodontal disease in periodontal disease animal models and the influence of LIPUS on the biological behavior (including promoting osteogenic differentiation of stem cells and inhibiting inflammatory response) and potential mechanism of periodontal ligament stem cells (PDLSCs), hoping to provide new ideas for the treatment of periodontal disease. We believe that LIPUS can be used as an auxiliary strategy in the treatment of periodontal disease and play an exciting and positive role in periodontal regeneration., Competing Interests: Declarations Ethical Approval Not applicable. Consent to Participate Not applicable. Consent for Publication Not applicable. Competing Interests The authors declare that they have no competing interest., (© 2024. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

The present study aims to investigate the role of interferon regulatory factor 4 (IRF4) in osteogenic differentiation of periodontal ligament stem cells (PDLSCs) and analyze the underlying signaling of these processes. In this study, IRF4 is upregulated in periodontitis periodontal ligament tissues, as compared to healthy periodontal ligament tissues. IRF4 knockdown increases cell proliferation, decreases levels of tumor necrosis factor-alpha, interleukin-6, and interleukin-8, enhances osteogenic activity, and increases the expression of RUNX family transcription factor 2, Collagen I, and Osteocalcin in PDLSCs. The opposite results are observed in IRF4 overexpressed PDLSCs. Additionally, GSEA shows that IRF4 activates the interleukin-18 (IL-18) signaling pathway. The expressions of IL-18, B-cell translocation gene 2, interleukin-1beta, and caspase-3 are decreased by IRF4 knockdown, while increased by IRF4 overexpression. IL-18 overexpression eliminates the promoting effect of IRF4 knockdown on osteogenic differentiation of PDLSCs. In conclusion, IRF4 suppresses osteogenic differentiation of PDLSCs by activating the IL-18 signaling pathway., (© 2024 Wiley‐VCH GmbH.)

Periodontal ligament stem cells (PDLSCs) have broad applications in tissue engineering and regeneration. However, the function of PDLSCs changes in different microenvironments. This study aimed to explore the effects of different developmental stages on the biological characteristics of PDLSCs. Here, PDLSCs were successfully cultured from the periodontal tissues of various groups, including a group with immature roots, a young group with mature roots, and an aging group with mature roots. By comparing the results of the three experimental groups, we found that the donors with immature roots exhibited the best proliferative ability and osteogenic differentiation, whereas the aging group demonstrated the worst proliferation. The trend for adipogenic differentiation was the opposite to that for osteogenic differentiation. The cell sheet and in vivo experiments revealed that in the immature root group, the cells produced more extracellular matrix and new bone and better absorbed the implant materials. These results indicate that PDLSCs perform various functions at different stages of development. In clinical applications of PDLSCs for periodontal regeneration, donors with incompletely developed roots have stronger biological characteristics.

Periodontitis, a globally prevalent chronic inflammatory disease is characterized by the progressive degradation of tooth-supporting structures, particularly the periodontal ligament (PDL), which can eventually result in tooth loss. Despite the various clinical interventions available, most focus on symptomatic relief and lack substantial evidence of supporting the functional regeneration of the PDL. Dental stem cells (DSCs), with their homology and mesenchymal stem cell (MSC) properties, have gained significant attention as a potential avenue for PDL regeneration. Consequently, multiple therapeutic strategies have been developed to enhance the efficacy of DSC-based treatments and improve clinical outcomes. This review examines the mechanisms by which DSCs and their derivatives promote PDL regeneration, and explores the diverse applications of exogenous implantation and endogenous regenerative technology (ERT) aimed at amplifying the regenerative capacity of endogenous DSCs. Additionally, the persistent challenges and controversies surrounding DSC therapies are discussed, alongside an evaluation of the limitations in current research on the underlying mechanisms and innovative applications of DSCs in PDL regeneration with the aim of providing new insights for future development. Periodontitis, a chronic inflammatory disease, represents a major global public health concern, affecting a significant proportion of the population and standing as the leading cause tooth loss in adults. The functional periodontal ligament (PDL) plays an indispensable role in maintaining periodontal health, as its structural and biological integrity is crucial for the long-term prognosis of periodontal tissues. It is widely recognized as the cornerstone of periodontal regeneration Despite the availability of various treatments, ranging from nonsurgical interventions to guided tissue regeneration (GTR) techniques, these methods have shown limited success in achieving meaningful PDL regeneration. As a result, the inability to fully restore PDL function underscores the urgent need for innovative therapeutic strategies at reconstructing this essential structure. Stem cell therapy, known for its regenerative and immunomodulatory potential, offers a promising approach for periodontal tissue repair. Their application marks a significant paradigm shift in the treatment of periodontal diseases, opening new avenues for functional PDL regeneration. However, much of the current research has primarily focused on the regeneration of alveolar bone and gingiva, as these hard and soft tissues can be more easily evaluated through visual assessment. The complexity of PDL structure, coupled with the intricate interactions among cellular and molecular components, presents significant scientific and clinical hurdles in translating DSC research into practical therapeutic applications. This review provides a thorough exploration of DSC dynamics in periodontal regeneration, detailing their origins, properties, and derived products, while also examining their potential mechanisms and applications in PDL regeneration. It offers an in-depth analysis of the current research, landscape, acknowledging both the progress made and the challenges that remain in bridging the gap between laboratory findings and clinical implementation. Finally, the need for continued investigation into the intricate mechanisms governing DSC behavior and the optimization of their use in regenerative therapies for periodontal diseases is also emphasized., (© 2024. The Author(s).)

Background: The present study aimed to investigate the effects of infrared diode laser irradiation on the proliferation and differentiation capacity of periodontal ligament stem cells (hPDLSCs), which are optimal cell sources for periodontal regeneration., Methods: hPDLSCs were isolated and characterized by flow cytometric analysis of mesenchymal stem cell markers, and their trilineage differentiation capacity was tested. hPDLSCs were then cultured and irradiated with infrared diode laser (970 nm) at a power of 200 mW and a fluence of 4 J/cm 2 for 3 s. MTT assay was performed to assess cellular proliferation. Cell cycle analysis was performed, and the impact of infrared diode laser irradiation on the stemness and osteogenic differentiation potential of hPDLSCs was evaluated via RT‒PCR., Results: Infrared diode laser application enhanced the stemness, viability, proliferation, and differentiation of PDLSCs. Stem cell markers (OCT4, SOX2, and NANOG) were significantly upregulated in hPDLSCs exposed to laser irradiation. There was significant overexpression of RUNX2, ALP, OPN, and OCN on day 14 after laser application., Conclusions: These findings provide valuable insights into the specific applications of infrared diode lasers to effectively regenerate periodontal tissues. The results can aid in the development of precise clinical protocols aimed at enhancing osseointegration and promoting tissue regeneration. Ultimately, the combination of infrared diode laser with hPDLSCs is promising for stimulating periodontal regeneration., (© 2024. The Author(s).)

Background and Objective: Periodontitis is an inflammatory disease typically characterized by the destruction of periodontal tissues and complicated etiology. DNA methyltransferase 3A (DNMT3A) has been implicated in possessing pro-inflammatory properties. This study sought to explore the role of DNMT3A in periodontitis and its relevant mechanism., Methodology: Lipopolysaccharide (LPS) was used to induce inflammation in human periodontal ligament stem cells (hPDLSCs). DNMT3A and KLF5 expressions were detected using RT-qPCR and western blot. The levels of inflammatory cytokines and inflammation-related proteins were detected using ELISA and western blot. NF-κB p65 expression was detected using immunofluorescence (IF) assay, while osteogenic differentiation was assessed using ALP assay and ARS staining. Western blot was used to measure the protein contents associated with osteogenic differentiation. DNMT3A activity was detected using luciferase report assay and chromatin immunoprecipitation (ChIP) was used to verify the interaction between KLF5 and DNMT3A., Results: DNMT3A expression increased in LPS-induced hPDLSCs. Silencing DNMT3A suppressed the LPS-induced inflammation in hPDLSCs, while promoting osteogenic differentiation. It was also found that transcriptional factor KLF5 could bind to DNMT3A promoters and regulate DNMT3A expression. Rescue experiments showed that KLF5 interference partially counteracted the inhibitory impacts of DNMT3A deficiency on inflammation and the promotive effects on osteogenic differentiation in LPS-induced hPDLSCs., Conclusion: DNMT3A, when transcriptionally downregulated by KLF5, could alleviate LPS-challenged inflammatory responses and facilitate osteogenic differentiation in hPDLSCs.

The periodontal ligament (PDL) is crucial for maintaining the integrity and functionality of tooth-supporting structures. Mechanical forces applied to the tooth during orthodontic tooth movement generate pore pressure gradients, leading to interstitial fluid movement within the PDL. The generated fluid shear stress (FSS) stimulates the remodeling of PDL and alveolar bone. Herein, we present the construction of a parallel fluid-flow apparatus to determine the effect of FSS on PDL cells. The chamber was designed and optimized using computer-aided and computational fluid dynamics software. The chamber was formed by PDMS using a negative molding technique. hPDLCs from two donors were seeded on microscopic slides and exposed to FSS of 6 dyn/cm 2 for 1 h. The effect of FSS on gene and protein expression was determined using RT-qPCR and Western blot. FSS upregulated genes responsible for mechanosensing (FOS), tissue formation ( RUNX2 , VEGFA ), and inflammation ( PTGS2/COX2 , CXCL8/IL8 , IL6) in both donors, with donor 2 showing higher gene upregulation. Protein expression of PTGS2/COX2 was higher in donor 2 but not in donor 1. RUNX2 protein was not expressed in either donor after FSS. In summary, FSS is crucial in regulating gene expression linked to PDL remodeling and inflammation, with donor variability potentially affecting outcomes.

Excessive oxidative response, unbalanced immunomodulation, and impaired mesenchymal stem cell function in periodontitis in diabetes makes it a great challenge to achieve integrated periodontal tissue regeneration. Here, a polyphenol-mediated redox-active algin/gelatin hydrogel encapsulating a conductive poly(3,4-ethylenedioxythiopene)-assembled polydopamine-mediated silk microfiber network and a hydrogen sulfide sustained-release system utilizing bovine serum albumin nanoparticles is developed. This hydrogel is found to reverse the hyperglycemic inflammatory microenvironment and enhance functional tissue regeneration in diabetic periodontitis. Polydopamine confers the hydrogel with anti-oxidative and anti-inflammatory activity. The slow, sustained release of hydrogen sulfide from the bovine serum albumin nanoparticles recruits mesenchymal stem cells and promotes subsequent angiogenesis and osteogenesis. Moreover, poly(3,4-ethylenedioxythiopene)-assembled polydopamine-mediated silk microfiber confers the hydrogel with good conductivity, which enables it to transmit endogenous bioelectricity, promote cell arrangement, and increase the inflow of calcium ion. In addition, the synergistic effects of hydrogen sulfide gaseous-bioelectric coupling promotes bone formation by amplifying autophagy in periodontal ligament stem cells and modulating macrophage polarization via lipid metabolism regulation. This study provides innovative insights into the synergistic effects of conductivity, reactive oxygen species scavenging, and hydrogen sulfide on the periodontium in a hyperglycemic inflammatory microenvironment, offering a strategy for the design of gaseous-bioelectric biomaterials to promote functional tissue regeneration in immune-related diseases., (© 2024. The Author(s).)

This study assessed the impact of low-level laser irradiation on the viability and proliferation of human periodontal ligament stem cells (hPDLSCs) cultivated on polylactic acid (PLA) scaffolds. hPDLSCs were obtained, characterized, and grown on the surface of PLA films produced via the solvent casting technique. The study involved two groups: the control group, which was not exposed to radiation, and the laser group, which was irradiated with a diode laser (InGaAIP) with a power of 30 mW, a wavelength of 660 nm, and a single dose of 1 J/cm² emitted continuously. Cell viability was assessed 24 and 48 hours after irradiation using the Alamar blue and Live/Dead assays. Flow cytometry was used to assess cell cycle events, and scanning electron microscopy (SEM) was used to evaluate the interaction between cells and the biomaterial. The results revealed a statistically significant increase in cell metabolic activity in the laser group compared with the control group at 24 hours (p <0.05) and 48 hours (p <0.001), as indicated by the Alamar blue assay. The Live/Dead assay also revealed a greater density of viable cells in the laser group. The cell cycle analysis revealed a significant increase in the number of cells in the proliferative phase (G2/M) in the laser group compared with the control group (p <0.001). The SEM images demonstrated that the irradiated group had a greater concentration of cells while still maintaining their cell shape and projections. This study demonstrated that photobiomodulation can increase the viability and proliferation of periodontal stem cells cultured on PLA scaffolds, suggesting the potential of this protocol for future studies on periodontal tissue engineering., (© 2024. The Author(s), under exclusive licence to Springer-Verlag London Ltd., part of Springer Nature.)

The potential of stem cells, for example upper periodontal ligament stem cells from the maxilla (u-PDLSC) and from the mandible (l-PDLSC), adipose-derived mesenchymal stem cells (AD-MSC), and bone marrow-derived mesenchymal stem cells (BM-MSC), with respect to periodontal remodeling and orthodontic treatment is of great importance. In this work, we focus on the comprehensive adaptability of different stem cell types to mechanical forces with the aim to better understanding cell behavior and to refine a new mechanistic approach to investigate periodontal remodeling. We comprehensively analyze stem cells and observe distinct morphological and proliferation changes under compression in dependence on stem cell type. The cell signaling of extracellular signal-regulated kinase (ERK) and protein kinase B, also called AKT, and their respective phosphorylation shows diverse responses to compression. Additionally, vascular endothelial growth factor and hepatocyte growth factor secretion were reduced under mechanical stress in all cell types, with cell-specific variations. Osteoprotegerin secretion was reduced under compression, particularly in u-PDLSC. At least, diverse soluble receptors of NF-kB-ligand secretion patterns among cell types under pressure were observed, providing crucial insights into bone metabolism. These findings offer a deeper understanding of the behavior of mesenchymal stem cells under mechanical stimuli, highlighting their roles in bone remodeling, wound healing, and tissue regeneration in orthodontic and regenerative medicine contexts. Our results underscore the potential of u-PDLSC, l-PDLSC, and AD-MSC in periodontal regeneration, with AD-MSC showing notable resilience under compression, indicating its promising role for further investigation for orthodontic research. While these findings are encouraging, further research is essential to fully comprehend the mechanism of stem cell-based periodontal therapies., (© The Author(s) 2024. Published by Oxford University Press.)

This study aimed to illustrate the biological behavior and changes in cell function during the progression of apical periodontitis in deciduous teeth and to explore the underlying molecular mechanism. Deciduous teeth periodontal ligament stem cells (DePDLSCs) were derived and their identity was confirmed. The viability, inflammation, and osteogenic ability of cells were tested by exposing them to various concentrations of lipopolysaccharide (LPS) (0-100 μg/mL) using the cell counting kit-8 (CCK-8) assay, reverse transcription polymerase chain reaction (real-time PCR), alkaline phosphatase (ALP) staining, and ALP activity assay. In addition, osteogenic-induced cells with and without 10 μg/mL LPS were harvested for high-throughput sequencing. Based on sequencing data, proinflammatory factors and ALP expression were measured after interference with the PI3K-AKT signaling pathway activator, 740Y-P. LPS biphasically affected the proliferation and osteogenesis of DePDLSCs. Low concentrations of LPS showed stimulatory effects, whereas inhibitory effects were observed at high concentrations. Sequencing analysis showed that the PI3K-AKT signaling pathway was significantly downregulated when DePDLSCs were treated with 10 μg/mL LPS. The LPS-induced inflammation and osteogenesis inhibition of DePDLSCs were partially rescued by 740Y-P treatment. In conclusion, LPS affected DePDLSCs proliferation and osteogenesis in a biphasic manner. Moderate activation of PI3K-AKT signaling pathway was beneficial for osteogenic differentiation and anti-inflammatory effect in DePDLSCs. This research may provide etiological probes for apical periodontitis and its treatment.

This paper elucidated the effects and mechanisms of aldehyde dehydrogenase 2 (ALDH2) on periodontitis. Rat model of periodontitis and periodontal ligament stem cell (PDLSC) model of periodontitis were constructed. PDLSC were transfected by ALDH2 overexpression vectors, and then treated by ML385 (Nrf2 inhibitor), ferrostatin-1 (ferroptosis inhibitor) and FIN56 (ferroptosis inducer), respectively. ALDH2, nuclear factor erythroid 2-related factor 2 (Nrf2) and glutathione peroxidase 4 (GPX4) proteins was evaluated by immunohistochemistry and Western blot. Ferroptosis-related factors, including Fe 2+ and glutathione (GSH), were assessed by commercial kits. Pro-inflammatory factors (interleukin-6 [IL-6] and tumor necrosis factor-α [TNF-α]) and osteogenic differentiation-related proteins (osteocalcin [OCN] and runt-related transcription factor 2 [RUNX2]) were scrutinized by commercial kits and Western blot. In both periodontal tissues of periodontitis rats and PDLSC model of periodontitis, down-regulated ALDH2, Nrf2, GPX4 and GSH, but elevated Fe 2+ level was discovered. ALDH2 overexpression in PDLSC resulted in an increase in Nrf2 expression. In PDLSC model of periodontitis, ALDH2 increased GPX4 and GSH levels, decreased Fe 2+ , IL-6 and TNF-α levels, and elevated OCN and RUNX2 expression. However, these effects of ALDH2 were counteracted by ML385. Additionally, the suppression of ALDH2 on IL-6 and TNF-α levels and promotion of it on OCN and RUNX2 expression in PDLSC model of periodontitis was further intensified by ferrostatin-1, but reversed by FIN56. ALDH2 may alleviate inflammation and facilitate osteogenic differentiation of PDLSC in periodontitis by hindering ferroptosis via activating Nrf2, suggesting it to be a promising candidate for treating periodontitis., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

To better understand the link between periodontitis and metabolic diseases, our in vitro study aimed to assess the influence of the adipokine apelin and/or the periodontal pathogen Fusobacterium nucleatum on periodontal cells. Periodontal ligament (PDL) cells were exposed to F. nucleatum in the presence and absence of apelin. Scratch assays were used to analyze the in vitro wound healing and velocity of cell migration. To investigate if F. nucleatum and/or apelin have a regulatory effect on cell proliferation and apoptosis, proliferation and viability assays were performed as well as an analysis of caspase 9 expression. Both the in vitro wound closure and the cell migration rate were significantly reduced by F. nucleatum. Simultaneous incubation with apelin counteracted the adverse effects of F. nucleatum . The proliferation assay demonstrated that neither apelin nor F. nucleatum significantly affected PDL cell proliferation. Furthermore, neither apelin nor F. nucleatum was cytotoxic or affected apoptosis after 48 h. Apelin could play a modulatory role in the pathogenesis of periodontitis, as it was able to compensate for the inhibitory effects of the periodontal pathogen F. nucleatum on PDL cell migration in vitro.

The high-glucose conditions caused by diabetes mellitus (DM) exert several effects on cells, including inflammation. miR-146a, a kind of miRNA, is involved in inflammation and may be regulated mutually with reactive oxygen species (ROS), which are produced under high-glucose conditions. In the present study, we used human periodontal ligament cells (hPDLCs) to determine the effects of the high-glucose conditions of miR-146a and their involvement in the regulation of oxidative stress and inflammatory cytokines using Western blotting, PCR, ELISA and other methods. When hPDLCs were subjected to high glucose (24 mM), cell proliferation was not affected; inflammatory cytokine expression, ROS induction, interleukin-1 receptor-associated kinase 1 (IRAK1) and TNF receptor-associated factor 6 (TRAF6) expression increased, but miR-146a expression decreased. Inhibition of ROS induction with the antioxidant N-acetyl-L-cysteine restored miR-146a expression and decreased inflammatory cytokine expression compared to those under high-glucose conditions. In addition, overexpression of miR-146a significantly suppressed the expression of the inflammatory cytokines IRAK1 and TRAF6, regardless of the glucose condition. Our findings suggest that oxidative stress and miR-146a expression are mutually regulated in hPDLCs under high-glucose conditions.

Mesenchymal stromal cells (MSCs) are multipotent, progenitor cells that reside in tissues across the human body, including the periodontal ligament (PDL) and gingiva. They are a promising therapeutic tool for various degenerative and inflammatory diseases. However, different heterogeneity levels caused by tissue-to-tissue and donor-to-donor variability, and even intercellular differences within a given MSCs population, restrict their therapeutic potential. There are considerable efforts to decipher these heterogeneity levels using different "omics" approaches, including single-cell transcriptomics. Previous studies applied this approach to compare MSCs isolated from various tissues of different individuals, but distinguishing between donor-to-donor and tissue-to-tissue variability is still challenging. In this study, MSCs were isolated from the PDL and gingiva of 5 periodontally healthy individuals and cultured in vitro. A total of 3,844 transcriptomes were generated using single-cell mRNA sequencing. Clustering across the 2 different tissues per donor identified PDL- and gingiva-specific and tissue-spanning MSCs subpopulations with unique upregulated gene sets. Gene/pathway enrichment and protein-protein interaction (PPI) network analysis revealed differences restricted to several cellular processes between tissue-specific subpopulations, indicating a limited tissue-of-origin variability in MSCs. Gene expression, pathway enrichment, and PPI network analysis across all donors' PDL- or gingiva-specific subpopulations showed significant but limited donor-to-donor differences. In conclusion, this study demonstrates tissue- and donor-specific variabilities in the transcriptome level of PDL- and gingiva-derived MSCs, which seem restricted to specific cellular processes. Identifying tissue-specific and tissue-spanning subpopulations highlights the intercellular differences in dental tissue-derived MSCs. It could be reasonable to control MSCs at a single-cell level to ensure their properties before transplantation., Competing Interests: Declaration of Conflicting InterestsThe authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Human periodontal ligament cells (hPDLCs) contain multipotent postnatal stem cells that can differentiate into PDL fibroblasts, osteoblasts, and cementoblasts. Interaction between the extracellular environment and stem cells is an important factor for differentiation into other progenitor cells. To identify cell surface molecules that induce PDL fibroblastic differentiation, we developed a series of monoclonal antibodies against membrane/ECM molecules. One of these antibodies, an anti-PDL25 antibody, recognizes approximately a 100 kDa protein, and this antigenic molecule accumulates in the periodontal ligament region of tooth roots. By mass spectrometric analysis, we found that the antigenic molecule recognized by the anti-PDL25 antibody is fibroblast activation protein α (FAPα). The expression level of FAPα/PDL25 increased in TGF-β1-induced PDL fibroblasts, and this protein was localized in the cell boundaries and elongated processes of the fibroblastic cells. Ectopic expression of FAPα induced fibroblastic differentiation. In contrast, expression of representative markers for PDL differentiation was decreased by knock down and antibody blocking of FAPα/PDL25. Inhibition of dipeptidyl peptidase activity by a potent FAPα inhibitor dramatically inhibited PDL fibroblastic marker expression but did not affect in cell proliferation and migration., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)

Aims: N6-Methyladenosine (m 6 A) has been confirmed to play a dynamic role in osteoporosis and bone metabolism. However, whether m 6 A is involved in the osteogenic differentiation of human periodontal ligament cells (hPDLCs) remains unclear. The present study aimed to verify the role of methyltransferase-like 3 (METTL3)-mediated m 6 A modification in the osteogenic differentiation of hPDLCs., Methods: The METTL3, Runx2, Osx, and YAP mRNA expression was determined by qPCR. METTL3, RUNX2, OSX, YTHDF1, YAP, IGF2BP1, and eIF3a protein expression was measured by Western blotting and immunofluorescence assays. The levels of m 6 A modification were evaluated by methylated RNA immunoprecipitation (MeRIP) and dot blot analyses. MeRIP-seq and RNA-seq were used to screen potential candidate genes. Nucleic acid and protein interactions were detected by immunoprecipitation. Alizarin red staining was used to evaluate the osteogenic differentiation of hPDLCs. Gene transcription and promoter activities were assessed by luciferase reporter assays (n ≥ 3)., Results: The expression of METTL3 and m 6 A modifications increased synchronously with the osteogenic differentiation of hPDLCs (p = .0016). YAP was a candidate gene identified by MeRIP-seq and RNA-seq, and its mRNA and protein expression levels were simultaneously increased. METTL3 increased the m 6 A methylated IGF2BP1-mediated stability of YAP mRNA (p = .0037), which in turn promoted osteogenic differentiation (p = .0147). Furthermore, METTL3 increased the translation efficiency of YAP by recruiting YTHDF1 and eIF3a to the translation initiation complex (p = .0154), thereby promoting the osteogenic differentiation of hPDLCs (p = .0012)., Conclusion: Our study revealed that METTL3-initiated m 6 A mRNA methylation promotes osteogenic differentiation of hPDLCs by increasing IGF2BP1-mediated YAP mRNA stability and recruiting YTHDF1 and eIF3a to the translation initiation complex to increase YAP mRNA translation. Our findings reveal the mechanism of METTL3-mediated m 6 A modification during hPDLC osteogenesis, providing a potential therapeutic target for periodontitis and alveolar bone defects., (© 2024 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

Introduction and Aims: Specific circular RNAs (circRNAs) have been proven to play crucial roles in osteogenesis in vitro and in vivo. This study aims to identify a certain circRNA involved in the osteogenic differentiation of periodontal ligament stem cells (PDLSCs) and explore its regulatory role., Methods: The expression of 5 candidate circRNAs (circ&#95;0026344, circ&#95;ACAP2, circ&#95;0003764, circ&#95;0008259, and circ&#95;0060731) was detected by real-time quantitative reverse-transcription polymerase chain reaction (qRT-PCR) after PDLSCs were cultured in the osteogenic induction medium or medium supplemented with tumour necrosis factor-α (TNF-α, 10 ng/mL) for 3 and 7 days. The circRNA significantly decreased in both 3 and 7 days of osteogenic induction in PDLSCs and markedly increased in TNF-α-induced PDLSCs for 3 and 7 days screened. Identified circRNA was knocked down or overexpressed, and the effect on the osteogenic differentiation of PDLSCs was investigated by qRT-PCR, western blot, alkaline phosphatase (ALP) staining, and alizarin red S (ARS) staining. Cell counting kit-8 (CCK-8) assay and 5-ethynyl-2'-deoxyuridine (EdU) assay were applied to detect the effect of the circRNA on the proliferation of PDLSCs., Results: qRT-PCR results showed that the expression of circ&#95;0003764 was significantly decreased when PDLSCs were cultured in the osteogenic induction medium for 3 or 7 days, whereas it was dramatically increased in TNF-α-induced PDLSCs. Knockdown of circ&#95;0003764 promoted the expression of the osteogenesis-related genes (RUNX2, ALP, OCN) and proteins (RUNX2, OCN), enhanced the ALP activity, and elevated the mineralization by PDLSCs, as shown by ARS staining. However, with the overexpression of circ&#95;0003764, the osteogenic differentiation capacity of PDLSCs was significantly reduced. The CCK-8 and EdU results indicated that circ&#95;0003764 could inhibit the proliferation of PDLSCs., Conclusion: Circ&#95;0003764 is involved in the osteogenesis process and inhibits the osteogenic differentiation and proliferation of PDLSCs., Clinical Relevance: This study indicates that circ&#95;0003764 can serve as a diagnostic and therapeutic target in bone regeneration-related diseases treated by PDLSCs-based tissue engineering., Competing Interests: Conflict of interest None disclosed., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)

Background and Objectives: The alveolar bone remodelling promoted by reasonable mechanical force triggers orthodontic tooth movement (OTM). The generation of osteoclasts is essential in this process. However, the mechanism of mechanical force mediating osteoclast differentiation remains elusive. Small nucleolar RNA host gene 5 (SNHG5), which was reported to mediate the osteogenic differentiation of bone marrow mesenchymal stem cells in our previous study, was downregulated in human periodontal ligament cells (hPDLCs) under mechanical force. At the same time, the RANKL/OPG ratio increased. Based on this, we probed into the role of SNHG5 in osteoclast formation during OTM and the relevant mechanism., Materials and Methods: SNHG5 and the RANKL/OPG ratio under different compressive forces were detected by western blotting (WB) and qRT-PCR. Impact of overexpression or knockdown of SNHG5 on osteoclast differentiation was detected by qRT-PCR, WB and transwell experiments. The combination of SNHG5 and C/EBPβ was verified by RNA immunoprecipitation and RNA pull-down assays. The expression of SNHG5 and osteoclast markers in gingiva were analysed by qRT-PCR and the paraffin sections of periodontal tissues were used for histological analysis., Results: Compressive force downregulated SNHG5 and upregulated the RANKL/OPG ratio in hPDLCs. Overexpression of SNHG5 inhibited RANKL's expression and osteoclast differentiation. SNHG5 combined with C/EBPβ, a regulator of osteoclast. The expression of SNHG5 in periodontal tissue decreased during OTM., Conclusion: SNHG5 inhibited osteoclast differentiation during OTM, achieved by affecting RANKL secretion, which may provide a new idea to interfere with bone resorption during orthodontic treatment., (© 2024 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

Periodontitis is featured as the periodontium's pathologic destruction caused by the host's overwhelmed inflammation. Omentin-1 has been reported to be aberrantly downregulated in patients with periodontitis, but the specific regulation of Omentin-1 during the pathogenesis of periodontitis remains unclear. In this study, human periodontal ligament stem cells (hPDLSCs) were stimulated by lipopolysaccharide (LPS) from Porphyromonas gingivalis to establish an in vitro inflammatory periodontitis model. hPDLSCs were treated with recombinant human Omentin-1 (250, 500 and 750 ng/mL) for 3 h before LPS stimulation. Results revealed that Omentin-1 significantly inhibited LPS-induced inflammation in hPDLSCs through reducing the production of proinflammatory cytokines (tumor necrosis factor-α (TNF-α), interleukin (IL)-1β and IL-6) and downregulating the expression of Cox2 and iNOS. Meanwhile, Omentin-1 significantly enhanced alkaline phosphatase (ALP) activity and Alizarin red-stained area, accompanied by increasing expression osteogenic markers BMP2, OCN and Runx2, confirming that Omentin-1 restores osteogenic differentiation in LPS-induced hPDLSCs. In addition, the conditioned medium (CM) from LPS-induced hPDLSCs was harvested to culture macrophages, which resulted in macrophage polarization towards M1, while CM from Omentin-1-treated hPDLSCs reduced M1 macrophages polarization and elevated M2 polarization. Furthermore, Omentin-1 also inhibited LPS-triggered endoplasmic reticulum (ER) stress in hPDLSCs, and additional treatment of the ER stress activator tunicamycin (TM) partially reversed the functions of Omentin-1 on inflammation, osteogenic differentiation and macrophages polarization. In summary, Omentin-1 exerted a protective role against periodontitis through inhibiting inflammation and enhancing osteogenic differentiation of hPDLSCs, providing a novelty treatment option for periodontitis., Competing Interests: Conflict of interest The authors declare no potential conflicts of interest to disclose., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Novel methods and technologies that improve mesenchymal stem cells (MSCs) proliferation and differentiation properties are required to increase their clinical efficacy. Photobiomodulation (PBM) and low-intensity pulsed ultrasound (LIPUS) are two strategies that can be used to enhance the regenerative properties of dental MSCs. This study evaluated the cytocompatibility and osteo/odontogenic differentiation of dental pulp, periodontal ligament, and gingival MSCs after stimulation by either PBM or LIPUS and their combined effect. MTT assay, cell migration assay, osteo/odontogenic differentiation by AR staining and ALP activity, and expression of osteo/odontogenic markers (OPG, OC, RUNX2, DSPP, DMP1) by RT-qPCR were evaluated. Statistical analysis was performed using ANOVA, followed by Tukey's post hoc test, with a p-value of less than 0.05 considered significant. The results showed that combined stimulation by PBM and LIPUS resulted in significantly the highest viability of MSCs, the fastest migration, the most dense AR staining, the most increased ALP activity, and the most elevated levels of osteogenic and odontogenic markers. The synergetic stimulation of PBM and LIPUS can be utilized in cell-based regenerative approaches to promote the properties of dental MSCs., (© 2024. The Author(s).)

Aims: The study aimed to investigate the role of miR-146a-5p in osteogenesis of hPDLSCs irradiated with low-energy red LEDs., Methods: After irradiation with 5 J/cm 2 red LED, miR-146a-5p expression was detected by real-time quantitative polymerase chain reaction (RT-qPCR), and osteogenic markers expression was determined by RT-qPCR and Western blotting. Alkaline phosphatase (ALP) activity was assessed by ALP staining, and mineralization was assessed by Alizarin Red staining, respectively. Lentiviral vectors were designed to regulate miR-146a-5p expression. Dual-luciferase reporter assay was performed to confirm the targeted relationship between miR-146a-5p and MAPK1. Short hairpin RNA (shRNA) was used to regulate MAPK1 expression., Results: RT-qPCR and western blotting revealed that 5 J/cm 2 irradiation elevated the levels of the osteogenic markers osterix (OSX) and bone sialoprotein (BSP) in hPDLSCs. miR-146a-5p is downregulated in hPDLSCs under the low-energy red LED light irradiation. miR-146a-5p underexpression markedly promoted the osteogenic potential of hPDLSCs. miR-146a-5p targeted MAPK1. 5 J/cm 2 red LED irradiation rescued the inhibitory effects of upregulated miR-146a-5p on osteogenic differentiation, and the positive influence of red LED irradiation could be reversed by downregulated MAPK1., Conclusion: These findings confirm that miR-146a-5p is involved in the effect of LED irradiation on the osteogenic differentiation of hPDLSCs by targeting MAPK1. Red LED irradiation may be a potential clinical adjunct therapy for periodontal regeneration., (© 2024 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

Secretory leukocyte protease inhibitor (SLPI) functions as a protease inhibitor that modulates excessive proteolysis in the body, exhibits broad-spectrum antimicrobial activity, regulates inflammatory responses, and plays an important role in the innate immunity. The purpose of the study was to artificially synthesize a SLPI, an antimicrobial peptide, and investigate its effect on antimicrobial activity against Porphyromonas gingivalis and interleukin-6 (IL-6) production. SLPI protein with a molecular weight of approximately 13 kDa was artificially synthesized using a cell-free protein synthesis (CFPS) system and investigated by western blotting and enzyme-linked immunosorbent assay (ELISA). Disulfide bond isomerase in the protein synthesis mixture increased the amount of SLPI synthesized. The synthesized SLPI (sSLPI) protein was purified and its antimicrobial activity was investigated based on the growth of Porphyromonas gingivalis and bacterial adhesion to oral epithelial cells. The effect of sSLPI on IL-6 production in human periodontal ligament fibroblasts (HPLFs) was examined by ELISA. Our results showed that sSLPI significantly inhibited the growth of Porphyromonas gingivalis and bacterial adhesion to oral epithelial cells and further inhibited IL-6 production by HPLFs. These results suggested that SLPI artificially synthesized using the CFPS system may play a role in the prevention of periodontal diseases through its antimicrobial and anti-inflammatory effects., (© 2024. The Author(s), under exclusive licence to The Society of The Nippon Dental University.)

Macrophage pyroptosis is of key importance to host defence against pathogen infections and may participate in the progression and recovery of periodontitis. However, the role of pyroptotic macrophages in regulating periodontal ligament stem cells (PDLSCs), the main cell source for periodontium renewal, remains unclear. First, we found that macrophage pyroptosis were enriched in gingiva tissues from periodontitis patients compared with those of healthy people through immunofluorescence. Then the effects of pyroptotic macrophages on the PDLSC osteogenic differentiation were investigated in a conditioned medium (CM)-based coculture system in vitro. CM derived from pyroptotic macrophages inhibited the osteogenic differentiation-related gene and protein levels, ALP activity and mineralized nodule formation of PDLSCs. The osteogenic inhibition of CM was alleviated when pyroptosis was inhibited by VX765. Further, untargeted metabolomics showed that glutamate limitation may be the underlying mechanism. However, exogenous glutamate supplementation aggravated the CM-inhibited osteogenic differentiation of PDLSCs. Moreover, CM increased extracellular glutamate and decreased intracellular glutamate levels of PDLSCs, and enhanced the gene and protein expression levels of system x c - (a cystine/glutamate antiporter). After adding cystine to CM-based incubation, the compromised osteogenic potency of PDLSCs was rescued. Our data suggest that macrophage pyroptosis is related to the inflammatory lesions of periodontitis. Either pharmacological inhibition of macrophage pyroptosis or nutritional supplements to PDLSCs, can rescue the compromised osteogenic potency caused by pyroptotic macrophages., (© 2024 The Authors. Cell Proliferation published by Beijing Institute for Stem Cell and Regenerative Medicine and John Wiley & Sons Ltd.)

Oral cavity stem cells (OCSCs) have been the focus of intense scientific efforts due to their accessibility and stem cell properties. The present work aims to compare the different characteristics of 6 types of dental stem cells derived from the oral cavity: dental pulp stem cells (DPSC), stem cells from human exfoliated deciduous teeth (SHED), periodontal ligament stem cells (PDLSC), stem cells from the apical papilla (SCAP), bone marrow mesenchymal stem cells (BMSC), and gingival mesenchymal stem cells (GMSC). Using immunofluorescence and real-time polymerase chain reaction techniques, we analysed the cells for stem cell, differentiation, adhesion, and extracellular matrix markers; the ability to proliferate in vitro; and multilineage differentiation potential. Markers such as vimentin, CD44, alkaline phosphatase, CD146, CD271, CD49f, Oct 3/4, Sox 9, FGF7, nestin, and BMP4 showed significant differences in expression levels, highlighting the heterogeneity and unique characteristics of each cell type. At the same time, we confirmed that all cell types successfully differentiated into osteogenic, chondrogenic, or adipose lineages, with different readiness. In conclusion, our study reveals the distinct properties and potential applications of various dental-derived stem cells. These findings contribute to a deeper understanding of OCSCs and their significance in future clinical applications., Competing Interests: Conflict of interest None disclosed., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)

Various mechanical loadings, including mechanical stress, orthodontics forces, and masticatory force, affect the functions of periodontal ligament cells. Regulation of periodontal tissue destruction, formation, and differentiation functions are crucial processes for periodontal regeneration therapy. Numerous studies have reported that different types of mechanical loading play a role in maintaining periodontal tissue matrix homeostasis, and osteogenic differentiation of the periodontal ligament cells. This scoping review aims to evaluate the studies regarding the effects of various mechanical loadings on the secretion of extracellular matrix (ECM) components, regulation of the balance between formation and destruction of periodontal tissue matrix, osteogenic differentiation, and multiple differentiation functions of the periodontal ligament. An electronic search for this review has been conducted on two databases; MEDLINE via PubMed and SCOPUS. Study selection criteria included original research written in English that reported the effects of different mechanical loadings on matrix homeostasis and differentiation potential of periodontal ligament cells. The final 204 articles were mainly included in the present scoping review. Mechanical forces of the appropriate magnitude, duration, and pattern have a positive influence on the secretion of ECM components such as collagen, as well as regulate the secretion of matrix metalloproteinases and tissue inhibitors of matrix metalloproteinases. Additionally, these forces regulate a balance between osteoblastic and osteoclast differentiation. Conversely, incorrect mechanical loadings can lead to abnormal formation and destruction of both soft and hard tissue. This review provides additional insight into how mechanical loadings impact ECM homeostasis and multiple differentiation functions of periodontal ligament cells (PDLCs), thus making it valuable for regenerative periodontal treatment. In combination with advancing technologies, the utilization of ECM components, application of different aspects of mechanical force, and differentiation potential of PDLCs could bring potential benefits to future periodontal regeneration therapy., (© 2024 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

Background: The transplantation of periodontal ligament stem cells (PDLSCs) has been shown to enhance periodontal regeneration in animal models and clinical trials. However, it is not known whether PDLSCs are antibacterial and whether this affects oral microbiota and periodontal regeneration., Methods: We isolated human PDLSCs from periodontal ligament of extracted teeth. Rats' periodontal fenestration defects were prepared, and treated with PDLSC injections (Cell group), using saline injections (Saline group) as the control. The oral microbiota was explored by 16 S rDNA sequencing and compared with that before surgery (PRE group). The antibacterial property of PDLSCs and its underlying mechanism were tested in vitro., Results: Microbiome analyses reveal a decreased biodiversity, a changed community structure, and downregulated community functions of the oral microbiome in the Saline group. PDLSCs injections enhance periodontal regeneration, reverse the decrease in diversity, and increase the abundance of non-pathogenic bacterial Bifidobacterium sp. and Lactobacillus sp., making the oral microbiome similar to that of the PRE group. In vitro, PDLSCs inhibit the growth of Staphylococcus aureus, Escherichia coli, and Fusobacterium nucleatum. The main mechanism of action is postulated to involve production of the cationic antimicrobial peptide LL-37., Conclusions: Our findings reveal that PDLSC injections enhance periodontal regeneration and regulate the oral microbiome to foster an oral cavity microenvironment conducive to symbiotic microbiota associated with health., (© 2024. The Author(s).)

Although fine dust is linked to numerous health issues, including cardiovascular, neurological, respiratory, and cancerous diseases, research on its effects on oral health remains limited. In this study, we investigated the protective effects of mature hemp stem extract-induced exosomes (MSEIEs) on periodontal cells exposed to fine dust. Using various methods, including microRNA profiling, PCR, flow cytometry, immunocytochemistry, ELISA, and Alizarin O staining, we found that MSE treatment upregulated key microRNAs, such as hsa-miR-122-5p, hsa-miR-1301-3p, and hsa-let-7e-5p, associated with vital biological functions. MSEIEs exhibited three primary protective functions: suppressing inflammatory genes while activating anti-inflammatory ones, promoting the differentiation of periodontal ligament stem cells (PDLSCs) into osteoblasts and other cells, and regulating LL-37 and MCP-1 expression. These findings suggest that MSEIEs have potential as functional biomaterials for applications in pharmaceuticals, cosmetics, and food industries.

Introduction: Human periodontal ligament-derived mesenchymal stromal cells (hPDL-MSCs) possess a strong ability to modulate the immune response, executed via cytokine-boosted paracrine and direct cell-to-cell contact mechanisms. This reciprocal interaction between immune cells and hPDL-MSCs is influenced by 1,25-dihydroxyvitamin-D 3 (1,25(OH) 2 D 3 ). In this study, the participation of different immunomodulatory mechanisms on the hPDL-MSCs-based effects of 1,25(OH) 2 D 3 on CD4 + T lymphocytes will be elucidated using different co-culture models with various cytokine milieus., Material and Methods: hPDL-MSCs and CD4 + T lymphocytes were co-cultured indirectly and directly with inserts (paracrine interaction only) or directly without inserts (paracrine and direct cell-to-cell contact interaction). They were stimulated with TNF-α or IL-1β in the absence/presence of 1,25(OH) 2 D 3 . After five days of co-cultivation, the CD4 + T lymphocyte proliferation, viability, and cytokine secretion were analyzed. Additionally, the gene expression of soluble and membrane-bound immunomediators was determined in hPDL-MSCs., Results: In the indirect and direct co-culture model with inserts, 1,25(OH) 2 D 3 decreased CD4 + T lymphocyte proliferation and viability. The direct co-culture model without inserts caused the opposite effect. 1,25(OH) 2 D 3 mainly decreased the CD4 + T lymphocyte-associated secretion of cytokines via hPDL-MSCs. The degree of these inhibitions varied between the different co-culture setups. 1,25(OH) 2 D 3 predominantly decreased the expression of the soluble and membrane-bound immunomediators in hPDL-MSCs to a different extent, depending on the co-culture models. The degree of all these effects depended on the absence and presence of exogenous TNF-α and IL-1β., Conclusion: These data assume that 1,25(OH) 2 D 3 differently affects CD4 + T lymphocytes via the paracrine and direct cell-to-cell contact mechanisms of hPDL-MSCs, showing anti- or pro-inflammatory effects depending on the co-culture model type. The local cytokine microenvironment seems to be involved in fine-tuning these effects. Future studies should consider this double-edged observation by executing different co-culture models in parallel., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2024 Behm, Miłek, Schwarz, Rausch-Fan, Moritz and Andrukhov.)

Periodontal ligament cells (PDLCs) and macrophages in bone marrow cells have been widely used to investigate novel therapeutic agents to treat periodontitis. Here, we present a protocol for collecting primary mouse PDLCs and bone marrow cells. We detail steps for culturing and differentiation for both cell types and review data analysis for in vitro experiments using primary PDLCs and bone marrow cells. This protocol can be used to explore the impact of novel therapeutic agents using in vitro experiments. For complete details on the use and execution of this protocol, please refer to Sirisereephap et al. 1 ., Competing Interests: Declaration of interests The authors declare no competing interests., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)

Background: Periodontal ligament cells (PDLCs) are a major component of the periodontal ligament and have an important role in the regeneration of periodontal tissue and maintenance of homeostasis. High glucose can affect the activity and function of PDLCs in a variety of ways; therefore, it is particularly important to find ways to alleviate the effects of high glucose on PDLCs. Annexin A2 (ANXA2) is a calcium- and phospholipid-binding protein involved in a variety of cellular functions and processes, including cellular cytokinesis, cytophagy, migration, and proliferation., Aim: The aim of this study was to exploring whether ANXA2 attenuates the deleterious effects of high glucose on PDLCs and promotes osteogenic differentiation capacity., Methods and Results: Osteogenic differentiation potential, cellular senescence, oxidative stress, and cellular autophagy were detected. Culturing PDLCs with medium containing different glucose concentrations (CTRL, 8 mM, 10 mM, 25 mM, and 40 mM) revealed that high glucose decreased the protein expression of ANXA2 ( p  < 0.0001). In addition, high glucose decreased the osteogenic differentiation potential of PDLCs as evidenced by decreased calcium deposition ( p  = 0.0003), lowered ALP activity ( p  = 0.0010), and a decline in the expression of osteogenesis-related genes ( p  = 0.0008). Moreover, β-Galactosidase staining and expression of p16, p21 and p53 genes showed that it increased cellular senescence in PDLCs ( p  < 0.0001). Meanwhile high glucose increased oxidative stress in PDLCs as shown by ROS ( p  < 0.0001). However, these damages caused by high glucose were inhibited after the addition of 1 µM recombinant ANXA2 (rANXA2), and we found that rANXA2 enhanced autophagy in PDLCs under high glucose conditions., Conclusions and Discussion: Therefore, our present study demonstrates that alterations in ANXA2 under high glucose conditions may be a factor in the decreased osteogenic differentiation potential of PDLCs. Meanwhile, ANXA2 is associated with autophagy, oxidative stress, and cellular senescence under high glucose conditions., Competing Interests: The authors declare there are no competing interests., (©2024 Huang et al.)

The present study aimed to compare the effect of photobiomodulation with different energy densities on the angiogenic differentiation of human periodontal ligament stem cells (hPDLSCs) and stem cells from human exfoliated deciduous teeth (SHED). Photobiomodulation therapy with a 660 nm diode laser (2.4 J/cm 2 and 3.9 J/cm 2 ) on two consecutive days post-culture was applied to two types of stem cells (hPDLSCs and SHED). The Quantitative Real-time Polymerase Chain Reaction (RT-qPCR) test was undertaken to investigate Vascular Endothelial Growth Factor-A (VEGF-A) and Angiopoietin I (ANG-I) genes on days 1, 3, 5, 7, and 10 after the first session of laser application. The 4',6-diamidino-2-phenylindole (DAPI) staining and Methyl Thiazolyl Tetrazolium (MTT) test were conducted on days 1, 3, and 5 after the first session of laser application, to assess the cell viability. The Two-way ANOVA with Tukey post hoc test was used to analyze the outcomes of the MTT and RT-qPCR tests. The results of the MTT and DAPI convergently illustrated that the groups receiving photobiomodulation with 2.4 J/cm 2 had higher cell viability compared to 3.9 J/cm 2 . All experimental groups showed an upregulation of VEGF-A and ANG-I gene expression from day 1 to 5, followed by a downregulation from day 5 to 10. The groups with cultured hPDLSCs and SHED receiving photobiomodulation using 2.4 J/cm 2 had the most amounts of VEGF-A and ANG-I gene expression on day 5, respectively. In conclusion, the 660 nm mediated photobiomodulation therapy of cultured SHED and hPDLSCs with 2.4 J/cm 2 energy density may be associated with higher angiogenic differentiation (the expression of VEGF-A and ANG-I) as well as higher cell viability compared to the photobiomodulation therapy with 3.9 J/cm 2 ., (© 2024. The Author(s).)

Background: Periodontitis is a dental disease characterized by inflammation of periodontal tissues and loss of the periodontal ligaments and alveolar bone. Exosomes are a class of extracellular vesicles that are involved in a variety of diseases by releasing active substances. In this study, we aimed to investigate the effect and mechanism of exosomes from M2 polarized macrophages (M2-exos) on osteogenic differentiation in human periodontal ligament stem cells (hPDLSCs)., Methods: M2-exos were isolated from IL-4-induced RAW264.7 cells (M2 macrophages) and then treated on hPDLSCs. Osteogenic differentiation was assessed by alkaline phosphatase (ALP) staining, alizarin red S (ARS) staining, measurement of osteogenic differentiation-related genes and proteins, and inflammation was evaluated by measuring the levels of inflammatory factors. The mechanism of M2-exo was confirmed through qPCR, western blot, ALP and ARS staining., Results: Results suggested that M2-exo improved osteogenic differentiation and inhibited inflammation in LPS-induced hPDLSCs. CXCL12 expression was elevated in M2 macrophages, but decreased in LPS-induced hPDLSCs. Moreover, the effect of M2-exo on osteogenic differentiation and inflammation in LPS-induced hPDLSCs was reversed by CXCL12 knockdown., Conclusion: We demonstrated that M2-exo facilitated osteogenic differentiation and suppressed inflammation in LPS-induced hPDLSCs through promotion of CXCL12 expression. These results suggested the potential of M2-exo in the treatment of periodontitis, which may provide a new theoretical basis for M2-exo treatment of periodontitis., (© 2024. The Author(s).)

Signal regulatory protein alpha (SIRPα) is mainly expressed by cells of myeloid origin. This membrane glycoprotein is shown to be involved in regulation of different inflammatory conditions, such as colitis and arthritis. However, SIRPα has not been investigated in relationship to periodontitis, an inflammatory condition affecting the tooth supporting tissues. We aim to investigate if resident cells in the periodontium express SIRPα and whether a possible expression is affected by inflammatory conditions. Primary human keratinocytes, fibroblasts, periodontal ligament cells, and osteoblasts were cultured with or without the pro-inflammatory cytokines tumor necrosis factor alpha (TNF-α) or interleukin-1-beta (IL-1β). All different periodontal cell types showed a basal mRNA expression of SIRPα. Pro-inflammatory cytokines induced a 2-3-fold significant increase in SIRPα expression in both cultured human gingival fibroblasts and osteoblasts but neither in keratinocytes nor in periodontal ligament cells. Tissue sections from human gingival tissue biopsies were histochemically stained for SIRPα. Epithelial keratinocytes and gingival fibroblasts stained positive in sections from periodontally healthy as well as in sections from periodontitis. In periodontitis sections, infiltrating leukocytes stained positive for SIRPα. We highlight our finding that oral keratinocytes, gingival fibroblasts, and periodontal ligament cells do express SIRPα, as this has not been presented before. The fact that inflammatory stimulation of gingival fibroblasts increased the expression of SIRPα, while an increased expression by gingival fibroblasts in periodontitis tissue in situ could not be detected, is indeed contradictory.

Background: Periodontal ligament stem cells (PDLSCs) are important seed cells in tissue engineering and clinical applications. They are the priority receptor cells for sensing various mechanical stresses. Yes-associated protein (YAP) is a recognized mechanically sensitive transcription factor. However, the role of YAP in regulating the fate of PDLSCs under tension stress (TS) and its underlying mechanism is still unclear., Methods: The effects of TS on the morphology and fate of PDLSCs were investigated using fluorescence staining, transmission electron microscopy, flow cytometry and quantitative real-time polymerase chain reaction (qRT-PCR). Then qRT-PCR, western blotting, immunofluorescence staining and gene knockdown experiments were performed to investigate the expression and distribution of YAP and its correlation with PDLSCs proliferation. The effects of cytoskeleton dynamics on YAP nuclear translocation were subsequently explored by adding cytoskeleton inhibitors. The effect of cytoskeleton dynamics on the expression of the LINC complex was proved through qRT-PCR and western blotting. After destroying the LINC complex by adenovirus, the effects of the LINC complex on YAP nuclear translocation and PDLSCs proliferation were investigated. Mitochondria-related detections were then performed to explore the role of mitochondria in YAP nuclear translocation. Finally, the in vitro results were verified by constructing orthodontic tooth movement models in Sprague-Dawley rats., Results: TS enhanced the polymerization and stretching of F-actin, which upregulated the expression of the LINC complex. This further strengthened the pull on the nuclear envelope, enlarged the nuclear pore, and facilitated YAP's nuclear entry, thus enhancing the expression of proliferation-related genes. In this process, mitochondria were transported to the periphery of the nucleus along the reconstructed microtubules. They generated ATP to aid YAP's nuclear translocation and drove F-actin polymerization to a certain degree. When the LINC complex was destroyed, the nuclear translocation of YAP was inhibited, which limited PDLSCs proliferation, impeded periodontal tissue remodeling, and hindered tooth movement., Conclusions: Our study confirmed that appropriate TS could promote PDLSCs proliferation and periodontal tissue remodeling through the mechanically driven F-actin/LINC complex/YAP axis, which could provide theoretical guidance for seed cell expansion and for promoting healthy and effective tooth movement in clinical practice., (© 2024. The Author(s).)

Human dental tissue mesenchymal stem cells (DT-MSCs) constitute an attractive alternative to bone marrow-derived mesenchymal stem cells (BM-MSCs) for potential clinical applications because of their accessibility and anti-inflammatory capacity. We previously demonstrated that DT-MSCs from dental pulp (DP-MSCs), periodontal ligaments (PDL-MSCs), and gingival tissue (G-MSCs) show immunosuppressive effects similar to those of BM, but to date, the DT-MSC-mediated immunoregulation of T lymphocytes through the purinergic pathway remains unknown. In the present study, we compared DP-MSCs, PDL-MSCs, and G-MSCs in terms of CD26, CD39, and CD73 expression; their ability to generate adenosine (ADO) from ATP and AMP; and whether the concentrations of ADO that they generate induce an immunomodulatory effect on T lymphocytes. BM-MSCs were included as the gold standard. Our results show that DT-MSCs present similar characteristics among the different sources analyzed in terms of the properties evaluated; however, interestingly, they express more CD39 than BM-MSCs; therefore, they generate more ADO from ATP. In contrast to those produced by BM-MSCs, the concentrations of ADO produced by DT-MSCs from ATP inhibited the proliferation of CD3 + T cells and promoted the generation of CD4 + CD25 + FoxP3 + CD39 + CD73 + Tregs and Th17 + CD39 + lymphocytes. Our data suggest that DT-MSCs utilize the adenosinergic pathway as an immunomodulatory mechanism and that this mechanism is more efficient than that of BM-MSCs.

This study aimed to compare the effects of photobiomodulation therapy (PBMT) with 660 and 980 nm diode lasers on differentiation of periodontal ligament mesenchymal stem cells (PDLMSCs). In this in vitro, experimental study, PDLMSCs were obtained from the Iranian Genetic Bank and cultured in osteogenic medium. They were then subjected to irradiation of 660 and 980 nm diode lasers, and their viability was assessed after one, two, and three irradiation cycles using the methyl thiazolyl tetrazolium (MTT) assay. The cells also underwent DAPI staining, cell apoptosis assay by using the Annexin V/PI, Alizarin Red staining, and real-time polymerase chain reaction (PCR) for assessment of the expression of osteogenic genes. Data were analyzed by two-way ANOVA. The two laser groups had no significant difference in cell apoptosis according to the results of DAPI staining. Both laser groups showed higher cell viability in the MTT assay at 4 and 6 days compared with the control group. Annexin V/PI results showed higher cell viability in both laser groups at 4 days compared with the control group. Rate of early and late apoptosis was lower in both laser groups than the control group at 4 days. Necrosis had a lower frequency in 980 nm laser group than the control group on day 6. Alizarin Red staining showed higher cell differentiation in both laser groups after 3 irradiation cycles than the control group. The highest expression of osteopontin (OPN), osteocalcin (OCN), and Runt-related transcription factor 2 (RUNX2) was noted in 660 nm laser group with 3 irradiation cycles at 14 days, compared with the control group. PBMT with 660 and 980 nm diode lasers decreased apoptosis and significantly increased PDLMSC differentiation after 3 irradiation cycles., (© 2024. The Author(s).)

The recent development of nanobiomaterials has shed some light on the field of periodontal tissue regeneration. Laponite (LAP), an artificially synthesized two-dimensional (2D) disk-shaped nanosilicate, has garnered substantial attention in regenerative biomedical applications owing to its distinctive structure, exceptional biocompatibility and bioactivity. This study endeavors to comprehensively evaluate the influence of LAP on periodontal regeneration. The effects of LAP on periodontal ligament cells (PDLCs) on osteogenesis, cementogenesis and angiogenesis were systematically assessed, and the potential mechanism was explored through RNA sequencing. The results indicated that LAP improved osteogenic and cementogenic differentiation of PDLCs, the regulatory effects of LAP on PDLCs were closely correlated with activation of PI3K-AKT signaling pathway. Moreover, LAP enhanced angiogenesis indirectly via manipulating paracrine of PDLCs. Then, LAP was implanted into rat periodontal defect to confirm its regenerative potential. Both micro-CT and histological analysis indicated that LAP could facilitate periodontal tissue regeneration in vivo. These findings provide insights into the bioactivity and underlying mechanism of LAP on PDLCs, highlighting it might be a potential therapeutic option in periodontal therapy., (© 2024. The Author(s).)

Periodontal regeneration is a challenge, and tissue engineering based on periodontal ligament stem cells (PDLSCs) has been shown to be a promising alternative to this process. However, the need for scaffolds has limited the therapeutic use of PDLSCs. In this context, scaffold-free tissue engineering using the cell sheet (CS) technique has been developed as an alternative approach to improve tissue regeneration. Previously, we showed that Protease-activated receptor-1 (PAR1) can regulate PDLSCs. Herein, we evaluate whether PAR1 influences osteogenesis in CSs produced from PDLSCs, without the use of scaffolds. PDLSCs were isolated and immunophenotyped. Then, CSs were obtained by supplementing the culture medium with ascorbic acid (50 µg/mL), and PAR1 was activated through its agonist peptide (100 nM). Scaffold-free 3D CSs were successfully produced from PDLSCs, and they showed higher proliferation potential than isolated PDLSCs. Also, PAR1 activation decreased senescence and improved osteogenic differentiation of CSs by increasing mineralized nodule deposition and alkaline phosphatase concentration; PAR1 also modulated osteogenic markers at the gene and protein levels. We further demonstrated that this effect was regulated by Wnt, TGF-βI, MEK, p38 MAPK, and FGF/VEGF signaling pathways in PDLSCs (p < 0.05%). Overall, PAR1 activation increased osteogenic activity in CSs, emerging as a promising scaffold-free therapeutic approach for periodontal regeneration.