Therapeutic potential of periodontal ligament stem cells

Inflammatory periodontal disease known as periodontitis is one of the most common conditions that affect human teeth and often leads to tooth loss.Due to the complexity of the periodontium,which is composed of several tissues,its regeneration and subsequent return to a homeostatic state is challenging with the therapies currently available.Cellular therapy is increasingly becoming an alternative in regenerative medicine/dentistry,especially therapies using mesenchymal stem cells,as they can be isolated from a myriad of tissues.Periodontal ligament stem cells(PDLSCs)are probably the most adequate to be used as a cell source with the aim of regenerating the periodontium.Biological insights have also highlighted PDLSCs as promising immunomodulator agents.In this review,we explore the state of knowledge regarding the properties of PDLSCs,as well as their therapeutic potential,describing current and future clinical applications based on tissue engineering techniques.

Low-power laser irradiation promotes the proliferation and osteogenic differentiation of human periodontal ligament cells via cyclic adenosine monophosphate

Retaining or improving periodontal ligament （PDL） function is crucial for restoring periodontal defects. The aim of this study was to evaluate the physiological effects of low-power laser irradiation （LPLI） on the proliferation and osteogenic differentiation of human PDL （hPDL） cells. Cultured hPDL cel Is were irradiated （660 nm） daily with doses of O, 1, 2 or 4 J .cm-2. Cell proliferation was evaluated by the 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide （MTT） assay, and the effect of LPLI on osteogenic differentiation was assessed by Alizarin Red S staining and alkaline phosphatase （ALP） activity. Additionally, osteogenic marker gene expression was confirmed by real-time reverse transcription-polymerase chain reaction （RT-PCR）. Our data showed that LPLI at a dose of 2 J.cm-2 significantly promoted hPDL cell proliferation at days 3 and 5. In addition, LPLI at energy doses of 2 and 4 J.cm-2 showed potential osteogenic capacity, as it stimulated ALP activity, calcium deposition, and osteogenic gene expression. We also showed that cyclic adenosine monophosphate （cAMP） is a critical regulator of the LPLI-mediated effects on hPDL cells. This study shows that LPLI can promote the proliferation and osteogenic differentiation of hPDL cells. These results suggest the potential use of LPLI in clinical applications for periodontal tissue regeneration.

Exosomes Derived from Human Umbilical Cord Mesenchymal Stem Cells Enhance the Osteoblastic Differentiation of Periodontal Ligament Stem Cells Under High Glucose Conditions Through the PI3K/AKT Signaling Pathway

Objective High glucose(HG)can influence the osteogenic differentiation ability of periodontal ligament stem cells(PDLSCs).Human umbilical cord mesenchymal stem cell-derived exosomes(hUCMSC-exo)have broad application prospects in tissue healing.The current study aimed to explore whether hUCMSC-exo could promote the osteogenic differentiation of hPDLSCs under HG conditions and the underlying mechanism.Methods We used a 30 mmol/L glucose concentration to simulate HG conditions.CCK-8 assay was performed to evaluate the effect of hUCMSC-exo on the proliferation of hPDLSCs.Alkaline phosphatase(ALP)staining,ALP activity,and qRT-PCR were performed to evaluate the pro-osteogenic effect of hUCMSC-exo on hPDLSCs.Western blot analysis was conducted to evaluate the underlying mechanism.Results The results of the CCK-8 assay,ALP staining,ALP activity,and qRT-PCR assay showed that hUCMSC-exo significantly promoted cell proliferation and osteogenic differentiation in a dosedependent manner.The Western blot results revealed that hUCMSC-exo significantly increased the levels of p-PI3K and p-AKT in cells,and the effect was inhibited by LY294002(PI3K inhibitor)or MK2206(AKT inhibitor),respectively.Moreover,the increases in osteogenic indicators induced by hUCMSC-exo were significantly suppressed by LY294002 and MK2206.Conclusion hUCMSC-exo promote the osteogenic differentiation of hPDLSCs under HG conditions through the PI3K/AKT signaling pathway.

Mass acquisition of human periodontal ligament stem cells

The periodontal ligament(PDL)is an essential fibrous tissue for tooth retention in the alveolar bone socket.PDL tissue further functions to cushion occlusal force,maintain alveolar bone height,allow orthodontic tooth movement,and connect tooth roots with bone.Severe periodontitis,deep caries,and trauma cause irreversible damage to this tissue,eventually leading to tooth loss through the destruction of tooth retention.Many patients suffer from these diseases worldwide,and its prevalence increases with age.To address this issue,regenerative medicine for damaged PDL tissue as well as the surrounding tissues has been extensively investigated regarding the potential and effectiveness of stem cells,scaffolds,and cytokines as well as their combined applications.In particular,PDL stem cells(PDLSCs)have been well studied.In this review,I discuss comprehensive studies on PDLSCs performed in vivo and contemporary reports focusing on the acquisition of large numbers of PDLSCs for therapeutic applications because of the very small number of PDLSCs available in vivo.

Effects of Aging on the Proliferation and Differentiation Capacity of Human Periodontal Ligament Stem Cells

periodontal ligament stem cells; aging; proliferation; osteogenic differentiation Objective The aim of this study is to investigate the proliferation, differentiation and apoptosis of periodontal ligament stem cells （PDLSC） derived from different aged donors, and to evaluate the effects of aging on the biological characteristics of PDLSC. Methods Periodontal ligament tissues were obtained from 24 surgically extracted human premolars during orthodontics therapy. The specimens were divided into three groups according to the donor’s age. Group A： 18-20 years, group B： 30-35 years, group C： 45-50 years. PDLSC were isolated and cultured using a tissue-block-based enzymolytic method by limiting dilution assay. The colony forming efficiency of PDLSC for three experimental groups was determined. Senescence-Associated β-Galactosidase （SA-β-G） expression in the three groups was examined using β-galactosidase staining working solution. Cell cycle and apoptosis of the PDLSC were examined by the flow cytometry. Alkaline phosphatase （ALP） activity was evaluated by ALP staining. The expression of osteoplastic differentiation related genes Runt-related transcription factor-2 （Runx-2）, Collagen Type 1 （col-1）, and ALP of PDLSC were examined by quantitative real-time RT-PCR. Results The colony forming efficiency of PDLSC in Group A, B and C was 36.67%, 22.67% and 9.33%, respectively, which decreased with donors’ age （P〈0.05）. SA-β-G expression of the senescent PDLSC in group A, B and C were 4.14%, 16.39%, 50.38%, respectively （P〈0.05）. Cells in G2/S phase was 38.73%, 29.88%, 18.25% （P〈0.05）, and the apoptosis rate was 1.57%, 4.56%, 5.84% （P〈0.05）, in group A, B and C respectively. The ALP staining in the three groups decreased with the increase of donors’ ages, and the expression of Runx-2, col-1 and ALP decreased gradually from group A to group C （all P〈0.05）, which indicated the osteogenic differentiation capacity of PDLSC decreased while donor aging. Conclusion Human PDLSC could be successfully isolated from periodontal ligament tissues of different aged donors. However, the proliferation and osteogenic differentiation capacity of PDLSC decreased while donor aging.

Human periodontal ligament stem cells repair mental nerve injury

Human periodontal ligament stem cells are easily accessible and can differentiate into Schwann cells. We hypothesized that human periodontal ligament stem cells can be used as an alternative source for the autologous Schwann cells in promoting the regeneration of injured peripheral nerve. To validate this hypothesis, human periodontal ligament stem cells （1 × 106） were injected into the crush-injured left mental nerve in rats. Simultaneously, autologous Schwann cells （1 × 106） and PBS were also injected as controls. Real-time reverse transcriptase polymerase chain reaction showed that at 5 days after injection, mRNA expression of low affinity nerve growth factor receptor was sig-nificantaly increased in the left trigeminal ganglion of rats with mental nerve injury. Sensory tests, histomorphometric evaluation and retrograde labeling demonstrated that at 2 and 4 weeks after in-jection, sensory function was significantly improved, the numbers of retrograde labeled sensory neurons and myelinated axons were significantly increased, and human periodontal ligament stem cells and autologous Schwann cells exhibited similar therapeutic effects. These findings suggest that transplantation of human periodontal ligament stem cells show a potential value in repair of mental nerve injury.

Effects of Apatite Nanocrystals on Proliferation, Subcellular Structure, Protein Synthesis Activity of Human Periodontal Ligament Cells

To determine the cellular events occurring in the presence of yttrtum/ hyclroxyapatite（Y / HA ） or HA nanocrystals, human periodontal ligament （HPDL） cells were isolated and maintained in culture. The specificity of the cells was evidenced by their proliferation, subcellular structure, and deposition of extracellular matrix components. The presence of nanocrystals was significantly related to an increase in the proliferation. Moreover, the presence of Y/HA nanocrystals was significantly related to an increase in the proliferation with HA nanocrystals. Transmission electron microscopy （TEM） demonstrated the phagocytotic process of HPDL cells toward Y/ HA or HA nanocrystuls . The presence of Y/ HA or HA nanocrystuls was significantly related to an increase in the protein synthesis activity of HPDL cells.

Influence of baicalin on the expression of receptor activator of nuclear factor-κB ligand and osteoprotegerin in human periodontal ligament cells

Objective To study the effect of baicalin on the expression of receptor activator of nuclear factor-κB ligand(RANKL)and osteoprotegerin(OPG)in cultured human periodontal ligament(HPDL)cells.Methods Small interfering RNA(siRNA)eukaryotic expression vector targeted transforming growth factor βⅡ receptor(TGF-β RⅡ)was constructed and transfected into T cells.HPDL cells with T cells transfected with siRNA or not were placed in the culture medium that had been added with lipopolysaccharide(LPS)and baicalin.The obtained solution was divided into six groups according to the components(group Ⅰ:HPDL cells+LPS+T cells transfected with siRNA1+baicalin;group Ⅱ:HPDL cells+LPS+T cells transfected with siRNA1;group Ⅲ:HPDL cells+LPS+T cells+baicalin;group Ⅳ:HPDL cells+LPS+T cells;group Ⅴ:HPDL cells+baicalin;group Ⅵ:HPDL cells)and was cultured for 48 hours.RT-PCR was used to observe the effect of baicalin on the expression of OPG-RANKL in HPDL cells.Results The ratio of RANKL/OPG in group Ⅰ was lower than that in group Ⅱ(P<0.01)and higher than that in group Ⅲ(P<0.01);The ratio of RANKL/OPG in group Ⅲ was lower than that in group Ⅳ(P<0.01);the ratio of RANKL/OPG in group Ⅳ was higher than that in group Ⅵ(P<0.01);the ratio of RANKL/OPG in group Ⅴ was lower than that in group Ⅵ(P<0.05).Conclusion ① Baicalin could decrease the ratio of RANKL/OPG in HPDL cells.② The TGF-β signaling transduction plays an important role in the effect of baicalin on the RANKL/OPG ratio in HPDL cells.③ Baicalin acts not only through TGF-β to regulate RANKL/OPG in HPDL cells,but also through other pathways.

The Effects of Dense/Nanometer Hydroxyapatite on Proliferation and Osteogenetic Differentiation of Periodontal Ligament Cells

The objective of this study is to investigate possible effects of nanometer powder of hydroxyapatite on proliferation of periodontal ligament cells. With sol-gel method, the nanometer hydroxyapatite powder were fabricated. The primary periodontal ligcament cells were caltured on dense particle hydroxyapatite and nanometer particle hydroxyapatite. The effects on proliferation of periodontal ligament cell were examined in vitro with MTT （ methyl thiazolil tetracolium） test. The intercellalar effects were observed with scanning electron microscopy and energy dispersive X-ray analyzer. In addition, the influence of two materials on osteogenetic differentiation was determined with measurement of ALP （ alkaline phosphatase ） activity. It is concluded that nanometer hydroxyapatite can promote proliferation and osteogenetic differeraiation of periodontal ligament cells and it may become absorbable agent in osseous restoration.

Cell Attachment of Periodontal Ligament Cells on Commercially Pure Titanium at the Early Stage

Summary: In order to study the character of periodontal ligament cells (PDLCs) attaching on commercially pure titanium (cpTi) by morphology and metrology on the early stage (24 h), 1×105/ml PDLCs in 2 ml culture medium were seeded on cpTi discs fixed in 24-well culture plates. Morphology of cell attachment was observed by contrast phase microscope, scanning electron microscope (SEM) and fluroscence microscopy. Cell adhesion was analyzed by MTT at 0.5, 1, 2, 4 h respectively. PDLCs could attach and spread on cpTi discs. SEM showed that PDLCs had pseudopod-like protuberance. PDLCs showed different attaching phases and reached saturation in cell number at 2 h. It was concluded that PDLCs had good biocompatibility with cpTi, and showed a regular and dynamic pattern in the process of attaching to cpTi.

A novel porcine acellular dermal matrix scaffold used in periodontal regeneration

Regeneration of periodontal tissue is the most promising method for restoring periodontal structures.To find a suitable bioactive three- dimensional scaffold promoting cell proliferation and differentiation is critical in periodontal tissue engineering.The objective of this study was to evaluate the biocompatibility of a novel porcine acellular dermal matrix as periodontal tissue scaffolds both in vitro and in vivo.The scaffolds in this study were purified porcine acellular dermal matrix(PADM) and hydroxyapatite-treated PADM(HA-PADM). The biodegradation patterns of the scaffolds were evaluated in vitro.The biocompatibility of the scaffolds in vivo was assessed by implanting them into the sacrospinal muscle of 20 New Zealand white rabbits.The hPDL cells were cultured with PADM or HA-PADM scaffolds for 3,7,14,21 and 28 days.Cell viability assay,scanning electron microscopy(SEM),hematoxylin and eosin(H&E) staining, immunohistochemistry and confocal microscopy were used to evaluate the biocompatibility of the scaffolds.In vitro,both PADM and HA-PADM scaffolds displayed appropriate biodegradation pattern,and also,demonstrated favorable tissue compatibility without tissue necrosis,fibrosis and other abnormal response.The absorbance readings of the WST-1 assay were increased with the time course, suggesting the cell proliferation in the scaffolds.The hPDL cells attaching,spreading and morphology on the surface of the scaffold were visualized by SEM,H&E staining,immnuohjstochemistry and confocal microscopy,demonstrated that hPDL cells were able to grow into the HA-PADM scaffolds and the amount of cells were growing up in the course of time.This study proved that HA-PADM scaffold had good biocompatibility in animals in vivo and appropriate biodegrading characteristics in vitro.The hPDL cells were able to proliferate and migrate into the scaffold.These observations may suggest that HA-PADM scaffold is a potential cell carrier for periodontal tissue regeneration.

Overview of the main biological mechanisms linked to changes in periodontal ligament stem cells and the inflammatory microenvironment

Periodontitis is a complex chronic inflammatory disease.The invasion of pathogens induces the inflammatory microenvironment in periodontitis.Cell behavior changes in response to changes in the microenvironment,which in turn alters the local inflammatory microenvironment of the periodontium through factors secreted by cells.It has been confirmed that periodontal ligament stem cells(PDLSCs)are vital in the development of periodontal disease.Moreover,PDLSCs are the most effective cell type to be used for periodontium regeneration.This review focuses on changes in PDLSCs,their basic biological behavior,osteogenic differentiation,and drug effects caused by the inflammatory microenvironment,to provide a better understanding of the influence of these factors on periodontal tissue homeostasis.In addition,we discuss the underlying mechanism in detail behind the reciprocal responses of PDLSCs that affect the microenvironment.

The Use of Zein and Shuanghuangbu for Periodontal Tissue Engineering

Aim Tissue engineering is a promising area with a broad range of applications in the fields of regenerative medicine and human health. The emergence of periodontal tissue engineering for clinical treatment of periodontal disease has opened a new therapeutic avenue. The choice of scaffold is crucial. This study was conducted to prepare zein scaffold and explore the suitability of zein and Shuanghuangbu for periodontal tissue engineering.Methodology A zein scaffold was made using the solvent casting/particulate leaching method with sodium chloride （NaC1） particles as the porogen. The physical properties of the zein scaffold were evaluated by observing its shape and determining its pore structure and porosity. Cytotoxicity testing of the scaffold was carried out via in vitro cell culture experiments, including a liquid extraction experi- ment and the direct contact assay. Also, the Chinese medicine Shuanghuangbu, as a growth factor, was diluted by scaffold extract into different concentrations. This Shuanghuangbu-scaffold extract was then added to periodontal ligament cells （PDLCs） in order to determineits effect on cell proliferation. Results The zein scaffold displayed a sponge-like structure with a high porosity and sufficient thickness. The porosity and pore size of the zein scaffold can be controlled by changing the porogen particles dosage and size. The porosity was up to 64.1%-78.0%. The pores were well-distributed, interconnected, and porous. The toxicity of the zein scaffold was graded as 0-1. Furthermore, PDLCs displayed full stretching and vigorous growth under scanning electronic microscope （SEM）. Shuanghuangbu-scaffold extract could reinforce proliferation activity of PDLCs compared to the control group, especially at 100 μg.mL^-1 （P〈0.01）. Conclusion A zein scaffold with high porosity, open pore wall structure, and good biocompatibility is conducive to the growth of PDLCs. Zein could be used as scaffold to repair periodontal tissue defects. Also, Shuanghuangbuscaffold extract can enhance the proliferation activity of PDLCs. Altogether, these findings provide the basis for in vivo testing on animals.

Proteomic profiling of various human dental stem cells-a systematic review

BACKGROUND The proteomic signature or profile best describes the functional component of a cell during its routine metabolic and survival activities.Additional complexity in differentiation and maturation is observed in stem/progenitor cells.The role of functional proteins at the cellular level has long been attributed to anatomical niches,and stem cells do not deflect from this attribution.Human dental stem cells(hDSCs),on the whole,are a combination of mesenchymal and epithelial coordinates observed throughout craniofacial bones to pulp.AIM To specify the proteomic profile and compare each type of hDSC with other mesenchymal stem cells(MSCs)of various niches.Furthermore,we analyzed the characteristics of the microenvironment and preconditioning changes associated with the proteomic profile of hDSCs and their influence on committed lineage differentiation.METHODS Literature searches were performed in PubMed,EMBASE,Scopus,and Web of Science databases,from January 1990 to December 2018.An extra inquiry of the grey literature was completed on Google Scholar,ProQuest,and OpenGrey.Relevant MeSH terms(PubMed)and keywords related to dental stem cells were used independently and in combination.RESULTS The initial search resulted in 134 articles.Of the 134 full-texts assessed,96 articles were excluded and 38 articles that met the eligibility criteria were reviewed.The overall assessment of hDSCs and other MSCs suggests that differences in the proteomic profile can be due to stem cellular complexity acquired from varied tissue sources during embryonic development.However,our comparison of the proteomic profile suffered inconsistencies due to the heterogeneity of various hDSCs.We believe that the existence of a heterogeneous population of stem cells at a given niche determines the modalities of regeneration or tissue repair.Added prominences to the differences present between various hDSCs have been reasoned out.CONCLUSION Systematic review on proteomic studies of various hDSCs are promising as an eye-opener for revisiting the proteomic profile and in-depth analysis to elucidate more refined mechanisms of hDSC functionalities.

Comparative analysis of different feeder layers with 3T3 fibroblasts for culturing rabbits limbal stem cells

AIM： To explore the possibility of human umbilical cord mesenchymal stem cells（h UCMSCs）, human umbilical vein endothelial cells（h UVECs）, human dental pulp stem cells（h DPSCs） and human periodontal ligament stem cells（h PDLSCs） serving as feeder cells in co-culture systems for the cultivation of limbal stem cells.METHODS： Different feeder layers were cultured in Dulbecco＇s modified Eagle＇s medium（DMEM）/F12 and were treated with mitomycin C. Rabbits limbal stem cells（LSCs） were co-cultured on h UCMSCs, h UVECs, h DPSCs, h PDLSCs and NIH-3T3, and then comparative analysis were made between each group to see their respective colony-forming efficiency（CFE） assay and immunofluorescence（IPO13,CK3/12）.RESULTS： The efficiency of the four type cells in supporting the LSCs morphology and its cellular differentiation was similar to that of NIH-3T3 fibroblasts as demonstrated by the immunostaining properties analysis, with each group exhibiting a similar strong expression pattern of IPO13, but lacking CK3 and CK12 expression in terms of immunostaining. But h UCMSCs, h DPSCs and h PDLSCs feeder layers were superior in promoting colony formation potential of cells when compared to h UVECs and feedercell-free culture.CONCLUSION： hUCMSCs, hDPSCs and hPDLSCs can be a suitable alternative to conventional mouse NIH-3T3 feeder cells, so that risk of zoonotic infection can be diminished.

Application of dental stem cells in three-dimensional tissue regeneration

Dental stem cells can differentiate into different types of cells.Dental pulp stem cells,stem cells from human exfoliated deciduous teeth,periodontal ligament stem cells,stem cells from apical papilla,and dental follicle progenitor cells are five different types of dental stem cells that have been identified during different stages of tooth development.The availability of dental stem cells from discarded or removed teeth makes them promising candidates for tissue engineering.In recent years,three-dimensional(3D)tissue scaffolds have been used to reconstruct and restore different anatomical defects.With rapid advances in 3D tissue engineering,dental stem cells have been used in the regeneration of 3D engineered tissue.This review presents an overview of different types of dental stem cells used in 3D tissue regeneration,which are currently the most common type of stem cells used to treat human tissue conditions.

Research progress of strontium in promoting periodontal tissue regeneration

Periodontal disease is a chronic infectious disease of the oral cavity.Its main clinical features are periodontal pocket formation and alveolar bone resorption.Scholars'research hotspot is to achieve periodontal tissue regeneration in patients.Studies have found that strontium has certain potential in promoting periodontal tissue regeneration.In recent years,scholars have been conducting research on strontium and periodontal tissue regeneration,with a view to opening a new path for periodontal disease treatment.This article reviews the research status of strontium and periodontal tissue regeneration.The review results show that strontium can induce the proliferation and differentiation of PDLSCs and promote the regeneration of lost bone tissue;it can inhibit osteoclast activity and induce osteoclast apoptosis through a variety of signaling pathways,thereby inhibiting bone resorption;Promote bone formation;Strontium also has the function of promoting early angiogenesis and suppressing immune inflammatory response.Because the current research on strontium and periodontal tissue regeneration is only focused on in vivo and in vitro experiments,there is no relevant clinical trial to apply strontium to periodontal tissue regeneration.Therefore,if strontium is used to promote periodontal tissue regeneration to achieve the treatment of periodontal disease,further research is needed.

Effects of Shuanghuangbu on the total protein content and ultrastructure in cultured human periodontal ligament cells

Background Successful periodontal regeneration depends on the migration, proliferation and differentiation of periodontal ligament cells in periodontal defects. The total protein content and the ultrastructure demonstrate the metabolizability and activity of periodontal ligament cells. This study was conducted to observe the effects of Shuanghuangbu, a mixture of medicin al herbs, on the total protein content and the ultrastructure of human periodontal ligament cells. Methods Periodontal ligament cells were grown to confluence and then cultured in Dulbecco’s modified eagle medium (DMEM) supplemented with Shuanghuangbu over the concentration range of 0 to 1000 μg/ml. The total protein content in cultured cells was determined by using Coommasie brilliant blue technique. Periodontal ligament cells were incubated in 0 and 100 μg/ml Shuanghuangbu decoction for 5 days, then observed through transmission electron microscope.Results The total protein content of human periodontal ligament cells increased in each experiment group added 10-1000 μg/ml Shuanghuangbu respectively, and the effect of 100 μg/ml was excellent. Under the transmission electron microscope, there were more rough endoplasmic reticulums and mitochodrias in the experiment group than those in the control group. Conclusion Shuanghuangbu stimulates the protein synthesis of human periodontal ligament cells and improves human periodontal ligament cells’ metabolizability and activity.

Effects of Ginsenoside Rg-1 on the Proliferation and Osteogenic Differentiation of Human Periodontal Ligament Stem Cells

Objective： TO evaluate the effects of ginsenoside Rg-1 on the proliferation and osteogenic differentiation of human periodontal ligament stem cells （hPDLSCs） and to explore the possible application on the alveolar bone regeneration. Methods： To determine the optimum concentration, the effects of ginsenoside Rg-1 ranging from 10 to 100 μmol/L were evaluated by 3-（4,5）-dimethylthiahiazo（-z-yl）-3,5-di-phenytetrazoliumromide, alkaline phosphatase activity and calcium deposition. Expressions of runt-related transcription factor 2, collagen alpha-2（I） chain, osteopontin, osteocalcin protein were examined using real-time polymerase chain reaction. Results： Compared with the control group, a certain concentration （10 μmol/L） of the Rg-1 solution significantly enhanced the proliferation and osteogenic differentiation of hPDLSCs （P〈0.05）. However, concentrations that exceeds 100 μmol/L led to cytotoxicity whereas concentrations below 10 nmol/L showed no significant effect as compared with the control. Conclusion： Ginsenoside Rg-1 can enhance the proliferation and osteogenic differentiation of hPDLSCs at an optimal concentration of 10 μmol/L.

Vitamin C induces periodontal ligament progenitor cell differentiation via activation of ERK pathway mediated by PELP1

The differentiation of periodontal ligament(PDL)progenitor cells is important for maintaining the homeostasis of PDL tissue and alveolar bone.Vitamin C(VC),a water-soluble nutrient that cannot be biosynthesized by humans,is vital for mesenchymal stem cells differentiation and plays an important role in bone remodeling.Therefore,the objective of this study was to determine the function and mechanism of VC in PDL progenitor cells osteogenic differentiation at the molecular level.We demonstrated that VC could induce the osteogenic differentiation and maturation of PDL progenitor cell without other osteogenic agents.During the process,VC preferentially activated ERK1/2 but did not affect JNK or p38.Co-treatment with ERK inhibitor effectively decreased the Vitamin C-induced expression of Runx2.ERK inhibitor also abrogated Vitamin C-induced the minimized nodules formation.PELP1,a nuclear receptor co-regulator,was up-regulated under VC treatment.PELP1 knockdown inhibited ERK phosphorylation.The overexpression of PELP1 had a positive relationship with Runx2 expression.Taken together,we could make a conclude that VC induces the osteogenic differentiation of PDL progenitor cells via PELP1-ERK axis.Our fi nding implies that VC may have a potential in the regeneration medicine and application to periodontitis treatment.