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Periodontal tissue is a distinctive tissue structure composed three-dimensionally of cementum, periodontal ligament (PDL) and alveolar bone. Severe periodontal diseases cause fundamental problems for oral function and general health, and conventional dental treatments are insufficient for healing to healthy periodontal tissue. Cell sheet technology has been used in many tissue regenerations, including periodontal tissue, to transplant appropriate stem/progenitor cells for tissue regeneration of a target site as a uniform tissue. However, it is still difficult to construct a three-dimensional structure of complex tissue composed of multiple types of cells, and the transplantation of a single cell sheet cannot sufficiently regenerate a large-scale tissue injury. Here, we fabricated a three-dimensional complex cell sheet composed of a bone-ligament structure by layering PDL cells and osteoblast-like cells on a temperature responsive culture dish. Following ectopic and orthotopic transplantation, only the complex cell sheet group was demonstrated to anatomically regenerate the bone-ligament structure along with the functional connection of PDL-like fibers to the tooth root and alveolar bone. This study represents successful three-dimensional tissue regeneration of a large-scale tissue injury using a bioengineered tissue designed to simulate the anatomical structure.

Objectives Mechanical force plays an important role in modulating stem cell fate and behaviours. However, how periodontal ligament stem cells (PDLSCs) perceive mechanical stimulus and transfer it into biological signals, and thereby promote alveolar bone remodelling, is unclear. Materials and Methods An animal model of force‐induced tooth movement and a compressive force in vitro was used. After force application, tooth movement distance, mesenchymal stem cell and osteoclast number, and proinflammatory cytokine expression were detected in periodontal tissues. Then, rat primary PDLSCs with or without force loading were isolated, and their stem cell characteristics including clonogenicity, proliferation, multipotent differentiation and immunoregulatory properties were evaluated. Under compressive force in vitro, the effects of the ERK signalling pathway on PDLSC characteristics were evaluated by Western blotting. Results Mechanical force in vivo induced PDLSC proliferation, which was accompanied with inflammatory cytokine accumulation, osteoclast differentiation and TRPV4 activation; the force‐stimulated PDLSCs showed greater clonogenicity and proliferation, reduced differentiation ability, improved induction of macrophage migration, osteoclast differentiation and proinflammatory factor expression. The biological changes induced by mechanical force could be partially suppressed by TRPV4 inhibition. Mechanistically, force‐induced activation of TRPV4 in PDLSCs regulated osteoclast differentiation by affecting the RANKL/OPG system via ERK signalling. Conclusions Taken together, we show here that TRPV4 activation in PDLSCs under mechanical force contributes to changing their stem cell characteristics and modulates bone remodelling during tooth movement. Mechanical force in vivo induced periodontal ligament stem cell proliferation, which was accompanied with inflammatory cytokine accumulation, osteoclast differentiation and TRPV4 activation. The activation of TRPV4 in PDLSCs under mechanical force contributes to the changes in their stem cell characteristics including clonogenicity, proliferation, multipotent differentiation, and immunoregulation and modulates bone remodelling during tooth movement.

Periodontitis is a chronic disease that begins with a period of inflammation of the supporting tissues of the teeth table and then progresses, destroying the tissues until loss of the teeth occurs. The restoration of the damaged dental support apparatus is an extremely complex process due to the regeneration of the cementum, the periodontal ligament, and the alveolar bone. Conventional treatment relies on synthetic materials that fill defects and replace lost dental tissue, but these approaches are not substitutes for a real regeneration of tissue. To address this, there are several approaches to tissue engineering for regenerative dentistry, among them, the use of stem cells. Mesenchymal stem cells (MSC) can be obtained from various sources of adult tissues, such as bone marrow, adipose tissue, skin, and tissues of the orofacial area. MSC of dental origin, such as those found in the bone marrow, have immunosuppressive and immunotolerant properties, multipotency, high proliferation rates, and the capacity for tissue repair. However, they are poorly used as sources of tissue for therapeutic purposes. Their accessibility makes them an attractive source of mesenchymal stem cells, so this review describes the field of dental stem cell research and proposes a potential mechanism involved in periodontal tissue regeneration induced by dental MSC.

Periodontal disease is one of the most common infectious diseases in adults and is characterized by the destruction of tooth-supporting tissues. Mesenchymal stem cells (MSCs) comprise the mesoderm-originating stem cell population, which has been studied and used for cell therapy. However, because of the lower rate of cell survival after MSC transplantation in various disease models, paracrine functions of MSCs have been receiving increased attention as a regenerative mechanism. The aim of this study was to investigate the regenerative potential of transplanted conditioned medium (CM) obtained from cultured periodontal ligament stem cells (PDLSCs), the adult stem cell population in tooth-supporting tissues, using a rat periodontal defect model. Cell-free CM was collected from PDLSCs and fibroblasts, using ultrafiltration and transplanted into surgically created periodontal defects. Protein content of CM was examined by antibody arrays. Formation of new periodontal tissues was analyzed using microcomputed tomography and histological sections. PDLSC-CM transplantation enhanced periodontal tissue regeneration in a concentration-dependent manner, whereas fibroblast-CM did not show any regenerative function. Proteomic analysis revealed that extracellular matrix proteins, enzymes, angiogenic factors, growth factors and cytokines were contained in PDLSC-CM. Furthermore, PDLSC-CM transplantation resulted in the decreased mRNA level of tumor necrosis factor-α (TNF-α) in healing periodontal tissues. In addition, we found that PDLSC-CM suppressed the mRNA level of TNF-α in the monocyte/macrophage cell line, RAW cells, stimulated with IFN-γ. Our findings suggested that PDLSC-CM enhanced periodontal regeneration by suppressing the inflammatory response through TNF-α production, and transplantation of PDLSC-CM could be a novel approach for periodontal regenerative therapy.

Regenerating periodontal ligament (PDL) tissue is a vital challenge in dentistry that aims to restore periodontal function and aesthetics. This study explores a tissue engineering strategy that combines polycaprolactone (PCL)/collagen/cellulose acetate electrospun scaffolds with collagen hydrogels to deliver curcumin-loaded ZIF-8 nanoparticles fand periodontal ligament stem cells (PDLSCs). Scaffolds were fabricated via electrospinningand collagen hydrogels incorporated PDLSCs and curcumin-loaded ZIF-8 nanoparticles (CURZIF-8) were developed using cross-linking. In vitro assays evaluated biocompatibility, anti-inflammatory, and antioxidative properties. In vivo efficacy was assessed in a rat PDL injury model using histological and ELISA analyses examining tissue regeneration and inflammatory cytokine modulation. In vitro studies demonstrated that the scaffolds effectively supported PDLSC viability and migration. CURZIF-8 hydrogels enhanced anti-inflammatory and antioxidative activities. In vivo study showed that the combined scaffold-hydrogel system significantly promoted PDL regeneration. Tissue levels of bFGF, HGF, and TGF-β that are crucial for tissue repair, angiogenesis, and cell proliferation were evaluated. Whereas, pro-inflammatory cytokines TNF-α and IL-6=were downregulated. Histological analysis confirmed the formation of organized PDL structures and improved bone-cementum integration that arekey indicators of successful periodontal regeneration. The developed scaffold-hydrogel system facilitates PDL regeneration by modulating inflammation and promoting pro-healing factor expression. This approach shows promise for advancing periodontal tissue engineering and warrants further investigation in clinical settings.

The periodontal ligament (PDL) plays a crucial role in transmitting and dispersing occlusal force, acting as mechanoreceptor for muscle activity during chewing, as well as mediating orthodontic tooth movement. It transforms mechanical stimuli into biological signals, influencing alveolar bone remodeling. Recent research has delved deeper into the biological and mechanical aspects of PDL, emphasizing the importance of understanding its structure and mechanical properties comprehensively. This review focuses on the latest findings concerning both macro- and micro- structural aspects of the PDL, highlighting its mechanical characteristics and factors that influence them. Moreover, it explores the mechanotransduction mechanisms of PDL cells under mechanical forces. Structure-mechanics-mechanotransduction interplay in PDL has been integrated ultimately. By providing an up-to-date overview of our understanding on PDL at various scales, this study lays the foundation for further exploration into PDL-related biomechanics and mechanobiology.

Alveolar bone loss is a main manifestation of periodontitis. Human periodontal ligament stem cells (PDLSCs) are considered as optimal seed cells for alveolar bone regeneration due to its mesenchymal stem cell like properties. Osteogenic potential is the premise for PDLSCs to repair alveolar bone loss. However, the mechanism regulating osteogenic differentiation of PDLSCs remain elusive. In this study, we identified Neuron-derived orphan receptor 1 (NOR1), was particularly expressed in PDL tissue in vivo and gradually increased during osteogenic differentiation of PDLSCs in vitro. Knockdown of NOR1 in hPDLSCs inhibited their osteogenic potential while NOR1 overexpression reversed this effect. In order to elucidate the downstream regulatory network of NOR1, RNA-sequencing was used. We found that downregulated genes were mainly enriched in TGF-β, Hippo, Wnt signaling pathway. Further, by western blot analysis, we verified that the expression level of phosphorylated-SMAD2/3 and phosphorylated-SMAD4 were all decreased after NOR1 knockdown. Additionally, ChIP-qPCR and dual luciferase reporter assay indicated that NOR1 could bind to the promoter of TGFBR1 and regulate its activity. Moreover, overexpression of TGFBR1 in PDLSCs could rescue the damaged osteogenic potential after NOR1 knockdown. Taken together, our results demonstrated that NOR1 could activate TGF-β/SMAD signaling pathway and positively regulates the commitment of osteoblast lineages of PDLSCs by targeting TGFBR1 directly.

The goal of periodontal regenerative therapy is to predictably restore the tooth’s supporting periodontal tissues and form a new connective tissue attachment of periodontal ligament (PDL) fibers and new alveolar bone. Periostin is a matricellular protein so named for its expression primarily in the periosteum and PDL of adult mice. Its biological functions have been widely studied in areas such as cardiovascular physiology and oncology. Despite being initially identified in the dental tissues and bone, investigations of Periostin functions in PDL and alveolar-bone-related physiopathology are less abundant. Recently, several studies have suggested that Periostin may be an important regulator of periodontal tissue formation. By promoting collagen fibrillogenesis and the migration of fibroblasts and osteoblasts, Periostin might play a pivotal part in regeneration of the PDL and alveolar bone following periodontal surgery. The aim of this article is to provide an extensive review of the implications of Periostin in periodontal tissue biology and its potential use in periodontal tissue regeneration.

To date, 5 different human dental stem/progenitor cells have been isolated and characterized: dental pulp stem cells (DPSCs), stem cells from exfoliated deciduous teeth (SHED), periodontal ligament stem cells (PDLSCs), stem cells from apical papilla (SCAP), and dental follicle progenitor cells (DFPCs). These postnatal populations have mesenchymal-stem-cell-like (MSC) qualities, including the capacity for self-renewal and multilineage differentiation potential. MSCs derived from bone marrow (BMMSCs) are capable of giving rise to various lineages of cells, such as osteogenic, chondrogenic, adipogenic, myogenic, and neurogenic cells. The dental-tissue-derived stem cells are isolated from specialized tissue with potent capacities to differentiate into odontogenic cells. However, they also have the ability to give rise to other cell lineages similar to, but different in potency from, that of BMMSCs. This article will review the isolation and characterization of the properties of different dental MSC-like populations in comparison with those of other MSCs, such as BMMSCs. Important issues in stem cell biology, such as stem cell niche, homing, and immunoregulation, will also be discussed.

Objective This review comprehensively examined the emerging role of exosomes derived from periodontal ligament stem cells (PDLSC-Exos) in regenerative medicine and dentistry, with a particular focus on their therapeutic potential in periodontitis—a prevalent inflammatory disease characterized by the progressive destruction of periodontal tissues. Methods An initial search on Scopus, Web of Science, and PubMed using terms associated with exosomes (i.e., exosomes, exosomal, extracellular vesicles, and EVs) and periodontal ligament stem cells without any limitation of publication year and field of study was performed on October 31st, 2024. Results PDLSC-Exos demonstrated significant therapeutic efficacy in both bone and periodontal regeneration as well as various medical conditions through the enhancement of cellular proliferation, osteoblast differentiation, and the modulation of inflammatory responses. These exosomes function by regulating miRNA and activating essential signaling pathways, thereby facilitating periodontal/bone regeneration, angiogenesis, and tissue repair in disorders such as periodontitis, OTM, and skeletal bony defects. Furthermore, they exhibited anti-inflammatory properties, leading to improved outcomes under inflammatory conditions such as periodontitis, IBD, and MS. Moreover, PDLSC-Exos played a role in anti-microbial and anti-cancer interventions, demonstrating their diverse applicability. Conclusion The cell-free nature of these therapeutic agents makes PDLSC-Exos a versatile and promising tool for regenerative medicine and immune system regulation. The cell-free nature of these therapeutic agents positions PDLSC-Exos as a promising and adaptable instrument for regenerative medicine and immune system modulation. Clinical relevance PDLSC-Exos offer a promising acellular therapy for periodontal regeneration, overcoming limitations of cell-based approaches by enhancing tissue repair, modulating inflammation, and improving clinical translation in regenerative medicine and dentistry.