Research progress on ankylosis of primary molars / 口腔疾病防治

@#Ankylosis of primary molars is a kind of eruption abnormality of the teeth, where the periodontal membrane disappears, owing to a bony union between bone and root. Studies have shown that the common proportion of ankylosed primary molars is 1.3%~8.9% with an equal occurrence. In the primary dentition, the mandibular first primary molar is the most commonly affected tooth, while in the middle mixed dentition stage of development, the second primary molar is more affected. Its etiology may be related to genetics, signaling pathways of mineralization metabolism of local alveolar bone or cementum, cytokines secreted by epithelial rest cells of Malassez, and enhanced inflammatory reactions during physiological absorption of roots. Ankylosis of primary molars can be diagnosed by clinical symptoms and imaging and is classified as mild, moderate and severe according to the degree of infraocclusion. As it may cause a series of complications, such as occlusal disturbances, delayed exfoliation and incomplete alveolar process development, multidisciplinary treatment, including in the departments of pediatric dentistry, orthodontics, periodontics and prosthodontics, should be adopted, and long-term treatment is determined based on the patient's age, severity of infraocclusion, and presence of permanent teeth. This review summarizes the etiology, diagnosis, complications and treatment of ankylosed primary molars to provide a reference for the clinical diagnosis and treatment of decidual molar fixation.

Effects of Foxp3 gene silencing on the expression of inflammatory cytokines and the proliferation and migration of human periodontal ligament fibroblasts in an inflammatory environment / 华西口腔医学杂志

OBJECTIVES@#This study aimed to clarify the effects of Foxp3 silencing on the expression of inflammatory cytokines in human periodontal ligament cells (hPDLFs) in an inflammatory environment and on cell proliferation and invasiveness, as well as to explore the role of Foxp3 gene in the development of periodontitis.@*METHODS@#An small interfering RNA (siRNA) construct specific for Foxp3 was transfected into hPDLFs. Foxp3 silencing efficiency was verified by reverse transcription-polymerase chain reaction (RT-PCR) and Western blotting, and the siRNA with the optimum silencing effect of Foxp3 gene was screened. Using lipopolysaccharide to simulate an inflammatory environment in vitro, CCK-8 detected the effect of silencing Foxp3 on hPDLFs proliferation under inflammatory conditions. Wound-healing experiments and transwell assays were conducted to detect the effect of silencing Foxp3 on hPDLF migration under inflammatory conditions. The expression of the inflammatory cytokines interleukin (IL)-6 and IL-8 was detected by RT-PCR and Western blotting under inflammatory conditions.@*RESULTS@#After siRNA transfection, RT-PCR and Western blotting analyses showed that the expression of Foxp3 mRNA in the Foxp3-si3 group decreased significantly (t=21.03, P<0.000 1), and the protein expression of Foxp3 also decreased significantly (t=12.8, P<0.001). In the inflammatory environment, Foxp3 gene silencing had no significant effect on hPDLFs proliferation (P>0.05), and Foxp3 gene silencing promoted hPDLFs migration (P<0.05). Moreover, the expression of IL-6 and IL-8 increased (P<0.05).@*CONCLUSIONS@#In an inflammatory environment, Foxp3 gene silencing promoted hPDLFs migration but had no significant effect on hPDLFs proliferation. The expression of inflammatory factors expressed in hPDLFs increased after Foxp3 gene silencing, indicating that Foxp3 gene inhibited inflammation in periodontitis.

Hippo-YAP signaling pathway regulates autophagy of human periodontal ligament cells under cyclic tensile stress / 华西口腔医学杂志

OBJECTIVES@#This work aimed to investigate the molecular mechanism of cyclic tensile stress (CTS) stimulating autophagy in human periodontal ligament cells (hPDLCs).@*METHODS@#hPDLCs were isolated and cultured from normal periodontal tissues. hPDLCs were loaded with tensile stress by force four-point bending extender to simulate the autophagy of hPDLCs induced by orthodontic force du-ring orthodontic tooth movement. XMU-MP-1 was used to inhibit the Hippo signaling pathway to explore the role of the Hippo-YAP signaling pathway in activating hPDLC autophagy by tensile stress. The expression levels of autophagy-related genes (Beclin-1, LC3, and p62) in hPDLCs were detected by real-time quantitative polymerase chain reaction. Western blot was used to detect the expression levels of autophagy-related proteins (Beclin-1, LC3-Ⅱ/LC3-Ⅰ, and p62) and Hippo-YAP pathway proteins (active-YAP and p-YAP) in hPDLCs. Immunofluorescence was used to locate autophagy-related proteins (LC3-Ⅱand p62) and Hippo-YAP pathway proteins (active-YAP) of hPDLCs.@*RESULTS@#CTS-activated autophagy in hPDLCs and expression of autophagy-related proteins initially increased and then decreased; it began to increase at 30 min, peaked at 3 h, and decreased (P<0.05). CTS increased the expression of active-YAP protein and decreased the expression of p-YAP protein (P<0.05). When XMU-MP-1 inhibited the Hippo-YAP signaling pathway (P<0.05), active-YAP protein was promoted to enter the nucleus and autophagy expression was enhanced (P<0.05).@*CONCLUSIONS@#The Hippo-YAP signaling pathway is involved in the regulation of autophagy activation in hPDLCs under CTS.

Effect of naringenin on the anti-inflammatory, vascularization, and osteogenesis differentiation of human periodontal ligament stem cells via the stromal cell-derived factor 1/C-X-C motif chemokine receptor 4 signaling axis stimulated by lipopolysaccharide / 华西口腔医学杂志

OBJECTIVES@#This study aimed to investigate how naringenin (Nar) affected the anti-inflammatory, vascula-rization, and osteogenesis differentiation of human periodontal ligament stem cells (hPDLSCs) stimulated by lipopolysaccharide (LPS) and to preliminarily explore the underlying mechanism.@*METHODS@#Cell-counting kit-8 (CCK8), cell scratch test, and Transwell assay were used to investigate the proliferation and migratory capabilities of hPDLSCs. Alkaline phosphatase (ALP) staining, alizarin red staining, lumen-formation assay, enzyme-linked immunosorbent assay, quantitative timed polymerase chain reaction, and Western blot were used to measure the expression of osteopontin (OPN), Runt-related transcription factor 2 (RUNX2), vascular endothlial growth factor (VEGF), basic fibroblast growth factor (bFGF), von Willebrand factor (vWF), tumor necrosis factor-α (TNF-α), and interleukin (IL)-6.@*RESULTS@#We observed that 10 μmol/L Nar could attenuate the inflammatory response of hPDLSCs stimulated by 10 μg/mL LPS and promoted their proliferation, migration, and vascularization differentiation. Furthermore, 0.1 μmol/L Nar could effectively restore the osteogenic differentiation of inflammatory hPDLSCs. The effects of Nar's anti-inflammatory and promotion of osteogenic differentiation significantly decreased and inflammatory vascularization differentiation increased after adding AMD3100 (a specific CXCR4 inhibitor).@*CONCLUSIONS@#Nar demonstrated the ability to promote the anti-inflammatory, vascularization, and osteogenic effects of hPDLSCs stimulated by LPS, and the ability was associated with the stromal cell-derived factor/C-X-C motif chemokine receptor 4 signaling axis.

Effects of low-level laser on the expression of interleukin-6, tumor necrosis factor‑α, osteoprotegerin, and receptor activator of nuclear factor-κB ligand in human periodontal ligament cells / 华西口腔医学杂志

OBJECTIVES@#This study aims to determine the effects of low-level laser (LLL) on the expression of interleukin-6 (IL-6), tumor necrosis factor (TNF)-α, osteoprotegerin (OPG), and receptor activator of nuclear factor-κB ligand (RANKL) in human periodontal ligament cells (HPDLCs) stimulated by high glucose; and identify the molecular mechanism of LLL therapy in the regulation of periodontal inflammation and bone remodeling during orthodontic treatment in diabetic patients.@*METHODS@#HPDLCs were cultured in vitro to simulate orthodontic after loading and irradiated with LLL therapy. The cultured cells were randomly divided into four groups: low glucose Dulbecco's modification of Eagle's medium (DMEM)+stress stimulation (group A), high glucose DMEM+stress stimulation (group B), hypoglycemic DMEM+LLL therapy+stress stimulation (group C), and hyperglycemic DMEM+LLL therapy+stress stimulation (group D). Groups C and D were further divided into C1 and D1 (energy density: 3.75 J/cm2) and C2 and D2 (energy density: 5.625 J/cm2). Cells in groups A, B, C, and D were irradiated by LLL before irradiation. At 0, 12, 24, 48, and 72 h, the supernatants of the cell cultures were extracted at regular intervals, and the protein expression levels of IL-6, TNF-α, OPG, and RANKL were detected by enzyme-linked immunosorbent assay.@*RESULTS@#1) The levels of IL-6 and TNF-α secreted by HPDLCs increased gradually with time under static pressure stimulation. After 12 h, the levels of IL-6 and TNF-α secreted by HPDLCs in group A were significantly higher than those in groups B, C1, and C2 (P<0.05), which in group B were significantly higher than those in groups D1, and D2 (P<0.01). 2) The OPG protein concentration showed an upward trend before 24 h and a downward trend thereafter. The RANKL protein concentration increased, whereas the OPG/RANKL ratio decreased with time. Significant differen-ces in OPG, RANKL, and OPG/RANKL ratio were found among group A and groups B, C1, C2 as well as group B and groups D1, D2 (P<0.05).@*CONCLUSIONS@#1) In the high glucose+stress stimulation environment, the concentrations of IL-6 and TNF-α secreted by HPDLCs increased with time, the expression of OPG decreased, the expression of RANKL increased, and the ratio of OPG/RANKL decreased. As such, high glucose environment can promote bone resorption. After LLL therapy, the levels of IL-6 and TNF-α decreased, indicating that LLL therapy could antagonize the increase in the levels of inflammatory factors induced by high glucose environment and upregulate the expression of OPG in human HPDLCs, downregulation of RANKL expression in HPDLCs resulted in the upregulation of the ratio of OPG/RANKL and reversed the imbalance of bone metabolism induced by high glucose levels. 2) The decrease in inflammatory factors and the regulation of bone metabolism in HPDLCs were enhanced with increasing laser energy density within 3.75-5.625 J/cm2. Hence, the ability of LLL therapy to modulate bone remodeling increases with increasing dose.

Red light-emitting diode light mediated by the KEAP1-NRF2/HO-1 pathway induces osteogenic differentiation and attenuates the oxidative stress damage of human periodontal ligament stem cells induced by high glucose / 口腔疾病防治

Objective@# To explore the effects of red LED light mediated by the Kelch-like ECH-associated protein 1-nuclear factor erythroid 2-related factor 2/heme oxygenase-1 (KEAP1-NRF2/HO-1) pathway on osteogenic differentiation and oxidative stress damage of human periodontal ligament stem cells (hPDLSCs) induced by high glucose, which provides a basis for the application of red light-emitting diode (LED) light in cell antioxidative damage.@*Methods@#hPDLSCs were identified by flow cytometric analysis, alkaline phosphatase (ALP) staining and Alizarin red-S staining; hPDLSCs were pretreated in a high glucose environment for 48 hours and irradiated with 1, 3, or 5 J/cm2 red LED light. A CCK-8 assay was performed to choose the radiant exposure that had the strongest effect on promoting the cell proliferation rate for subsequent experiments. hPDLSCs were divided into a control group, a high glucose group and a high glucose+light exposure group. ALP staining, ALP activity, Alizarin red-S staining and quantitative calcified nodules were used to detect the osteogenic differentiation of hPDLSCs; qRT-PCR and Western blot were used to detect the gene and protein expression levels of ALP, runt-related transcription factor 2 (RUNX2) and osterix (OSX); the relative mRNA expression levels of antioxidant enzyme-related genes superoxide dismutase 2 (SOD2) and catalase (CAT) in hPDLSCs were detected by qRT-PCR; reactive oxygen species (ROS) levels were detected by fluorescence microscopy and flow cytometry; the tumor necrosis factor-α (TNF-α) and interleukin-1β (IL-1β) levels in cell supernatants were detected by ELISA; the NRF2-specific inhibitor ML385 was used to inhibit the NRF2 pathway; ALP staining and ALP activity were used to detect the markers of early osteogenic differentiation; qRT-PCR was used to detect the gene expression of ALP, RUNX2 and OSX; and the protein expression levels of KEAP1, NRF2 and HO-1 were detected by Western blot.@*Results @# Identified, and irradiant exposure of 5 J/cm2 was chosen for subsequent experiments. Red LED light irradiation (5 J/cm2) improved the osteogenic differentiation of hPDLSCs induced by high glucose (P<0.05), increased the mRNA and protein levels of ALP, RUNX2 and OSX (P<0.05), upregulated the mRNA expression levels of SOD2 and CAT (P<0.05), reduced the levels of ROS (P<0.05), and reduced TNF-α and IL-1β levels in the cell supernatants (P<0.05). When ML385 was added to inhibit the NRF2 pathway, the ALP activity of cells was decreased (P<0.05); the gene expression levels of ALP, RUNX2 and OSX were downregulated (P<0.05); the protein level of KEAP1 was upregulated (P<0.05); and the protein levels of NRF2 and HO-1 were downregulated (P<0.05)@*Conclusion@#Red LED light may promote the proliferation and osteoblastic differentiation of hPDLSCs induced by high glucose through the KEAP1-NRF2/HO-1 pathway and reduce the oxidative stress damage to hPDLSCs induced by high glucose.

Astaxanthin inhibits inflammation of human periodontal ligament cells induced by lipopolysaccharide / 中南大学学报(医学版)

OBJECTIVES@#Human periodontal ligament cells (hPDLCs) are important source of periodontal tissue reconstruction. Under chronic inflammation, the multi-directional differentiation potential and chemotaxis in hPDLCs are decreased. Therefore, inhibiting inflammatory microenvironment and improving the functional characteristics of stem cells can better promote periodontal tissue reconstruction. This study was to investigate the effect of astaxanthin (AST) on lipopolysaccharide (LPS)-induced inflammation in hPDLCs and the underlying mechanisms.@*METHODS@#hPDLCs were isolated and cultured in vitro, and vimentin and keratin immunocytochemical staining were used to identify hPDLCs. CCK-8 assay was used to measure the effects of AST (1, 5, 10, 20, 50, 100, and 200 μmol/L) on proliferation of hPDLCs. Quantitative RT-PCR (RT-qPCR) and ELISA were used to measure the mRNA and protein expression of inflammatory factors (IL-6, IL-1β, and TNF-α) in the control (Con) group, the LPS group, and the LPS+AST (5, 10, 20, and 50 μmol/L) group. Western blotting was used to detect the protein expression of IKBα, phosphorylated IKBα (p-IKBα), and p65 in the Con group, the LPS group, the AST (20 μmol/L) group, and the LPS+AST (20 μmol/L) group. After 10 μmol/L PDTC treatment, the mRNA and protein expressions of IL-6, IL-1β, and TNF-α were detected by RT-qPCR and ELISA.@*RESULTS@#Cell morphology and immunocytochemical staining showed that the cells were in line with the characteristics of hPDLCs. Treatment with AST could promote the proliferation of hPDLCs, which reached the peak at 20 μmol/L. The mRNA and protein expressions of IL-6, IL-1β, and TNF-α in the LPS group were higher than those in the Con group (all @*CONCLUSIONS@#AST promotes the proliferation of hPDLCs, which is related to suppression of LPS-induced the secretion of inflammatory factors via inhibiting the activation of NF-κB signaling pathway.

Effects of conditioned medium of human periodontal ligament stem cells on proliferation and osteogenic differentiation of inflammatory tissue-derived human periodontal ligament stem cells / 中国组织工程研究

BACKGROUND: The conditioned medium rich in bioactive substances can maintain the stability of proliferation and biological characteristics of stem cells. Whether the conditioned medium of human periodontal stem cells derived from healthy tissues can affect the proliferation and osteogenesis of human periodontal stem cells derived from inflammatory tissue is significant for periodontal tissue regeneration and reconstruction. OBJECTIVE: To investigate the effect of human periodontal stem cells-conditioned medium derived from healthy tissue on proliferation and osteogenic differentiation of human periodontal stem cells derived from inflammatory tissue. METHODS: HPDLSCs from normal periodontal ligaments of healthy adults were isolated, purified and cultured in vitro. Human periodontal stem cells-conditioned medium was obtained by collecting the supernatants from the serum free medium which was used for the third generation cells grown up to 80% of the bottom of the bottle after 24 hours cultivation. Human periodontal stem cells derived from inflammatory tissue were obtained from pericementum of periodontitis patients, and cultured by using limiting dilution assay. Human periodontal stem cells derived from inflammatory tissue were separately cultured under conditioned medium treatment group (conditioned medium containing 50% human periodontal ligament stem cells + 50% conventional medium) and control group (conventional medium). Protein expression levels of vimentin, Pan Cytokeratin, and stromal cell antigen STRO-1 were identified by immunofluorescence staining. The proliferative activity of cells was analyzed by MTT assay and flow cytometry. After osteogenesis in vitro, alkaline phosphatase activity and the expression levels of three osteogenesis related genes (Runx2, OPN, and OCN) were detected using alkaline phosphatase kit and RT-PCR, respectively in both groups. RESULTS AND CONCLUSION: (1) Both groups of cells were in accordance with the morphological characteristics of adult stem cells, showing long fusiform or polygonal shapes. There was no significant difference in cell morphology between the two groups under inverted phase contrast microscope. (2) The immunofluorescence staining showed that cells in both groups were positive for the specific antibodies of vimentin and STRO-1, but negative for the specific antibody of Pan Cytokeratin. (3) The results of MTT assay showed that after 3, 5 and 7 days, the proliferative activity of conditioned medium treatment group was higher than that of control group (P < 0.01). (4) Cell cycle analysis showed that compared with the control group, the number of cells in G2/M phase and S phase in conditioned medium treatment group increased significantly (P < 0.05). (5) At 5 and 7 days of osteogenic induction in vitro, alkaline phosphatase activity of conditioned medium treatment group was higher than that of control group (P < 0.05). (6) After 21 days of osteogenic induction, the expression levels of osteogenic related genes Runx2, OPN, and OCN in conditioned medium treatment group were significantly higher than those in control group (P < 0.01, P < 0.05). (7) In conclusion, human periodontal stem cells-conditioned medium derived from healthy tissues can enhance the proliferation and osteogenic differentiation of human periodontal stem cells derived from inflammatory tissue.

Long non-coding RNA potassium voltage-gated channel subfamily Q member 1 overlapping transcript 1 regulates the proliferation and osteogenic differentiation of human periodontal ligament stem cells by targeting miR-24-3p / 华西口腔医学杂志

OBJECTIVES@#This study aims to explore the effect and molecular mechanism of long non-coding RNA (lncRNA) potassium voltage-gated channel subfamily Q member 1 overlapping transcript 1 (KCNQ1OT1) on proliferation and osteogenic differentiation in human periodontal ligament stem cells (hPDLSCs).@*METHODS@#The hPDLSCs of normal periodontal tissues were isolated and cultured. The mineralized solution induced the osteoblast differentiation of hPDLSCs. The down-regulation of lncRNA KCNQ1OT1, the overexpression of anti-miR-24-3p on the proliferation and the levels of osteocalcin (OCN), osteopontin (OPN) and alkaline phosphatase (ALP) of hPDLSCs were investigated. Real-time quantitative polymerase chain reaction (RT-qPCR) was used to detect the levels of lncRNA KCNQ1OT1, miR-24-3p, OCN, OPN, and ALP. Methyl thiazolyl tetrazolium (MTT) method was used to detect cell viability and activity. Cell proliferation was evaluated by MTT. Western blot was used to detect protein expression. The targeted relationship between lncRNA KCNQ1OT1 and miR-24-3p was detected by double-luciferase experiment.@*RESULTS@#The expression level of lncRNA KCNQ1OT1 increased, and that of miR-24-3p decreased during the osteogenesis of hPDLSCs (@*CONCLUSIONS@#Down-regulation of lncRNA KCNQ1OT1 inhibited the proliferation and osteogenic differentiation of hPDLSCs by targeting the up-regulated expression of miR-24-3p.

Protective effect of low-level laser irradiation on lipopolysaccharide-mediated inflammatory injury of human periodontal ligament fibroblasts / 华西口腔医学杂志

OBJECTIVES@#To study the effect and mechanism of low-level laser irradiation (LLLI) on lipopolysaccharide (LPS)-induced inflammatory injury of human periodontal ligament fibroblasts (hPDLFs).@*METHODS@#hPDLFs were inoculated into well plates and randomly divided into the normal group, LPS group, and LPS+LLLI group. The cells in the normal group were cultured in conventional medium. The hPDLFs in the LPS and LPS+LLLI groups were cultured in RPMI1640 medium containing 1 mg·L@*RESULTS@#Compared with the normal group, the LPS group showed increased apoptosis rate of hPDLFs and intracellular free Ca@*CONCLUSIONS@#LLLI has a protective effect on the inflammatory injury of hPDLFs induced by LPS, and the effect is most obvious when the irradiation intensity is 4 J·cm

Periostin inhibits hypoxia-induced oxidative stress and apoptosis in human periodontal ligament fibroblasts p38 MAPK signaling pathway / 南方医科大学学报

OBJECTIVE@#To investigate the effect of periostin on hypoxia-induced oxidative stress and apoptosis in human periodontal ligament fibroblasts and the molecular mechanism involved.@*METHODS@# cultured human periodontal ligament fibroblasts were placed in an anaerobic gas-producing bag for hypoxia treatment for 48 h followed by treatment with periostin at low (25 ng/mL), moderate (50 ng/mL) or high (100 ng/mL) doses. MTT assay was used to measure the cell viability, and the cell apoptosis rate was determined using flow cytometry. The contents of IL-1β, IL-6 and TNF-α in the cells were determined with ELISA, and ROS levels were measured using a fluorescent plate reader. The intracellular SOD activity was detected using ELISA. The expressions of HIF-1α, P21, cyclin D1, Bax, cleaved caspase-3, Bcl-2, P38MAPK and p-p38 MAPK proteins in the cells were detected with Western blotting.@*RESULTS@#Hypoxia treatment significantly reduced the cell viability ( < 0.05), increased P21, Bax, and cleaved caspase-3 protein levels ( < 0.05), promoted cell apoptosis ( < 0.05), and decreased cyclin D1 and Bcl-2 protein levels ( < 0.05) in the cells. Compared with the hypoxic group, the cells treated with periostin at different concentrations showed significantly increased cell viability ( < 0.05) with significantly lowered apoptotic rates ( < 0.05) and decreased expression levels of Bax and cleaved caspase-3 ( < 0.05) but significantly increased expression levels of cyclin D1 and Bcl-2 ( < 0.05). Hypoxic exposure of the cells resulted in significantly increased expression levels of HIF-1α and p-p38 MAPK ( < 0.05) and increased levels of IL-1β, IL-6, TNF-α and ROS ( < 0.05) but decreased SOD activity ( < 0.05). Periostin treatment at different concentrations significantly lowered the expression levels of HIF-1α and p-p38 MAPK ( < 0.05) and the levels of IL-1β, IL-6, TNF-α and ROS ( < 0.05) and significantly increased SOD activity in the hypoxic cells ( < 0.05).@*CONCLUSIONS@#Periostin promotes the proliferation, inhibits apoptosis, enhances cellular antioxidant capacity, and reduces inflammatory damage in human periodontal ligament fibroblasts exposed to hypoxia possibly by inhibiting the activation of the p38 MAPK signaling pathway.

Mechanisms of the mechanically activated ion channel Piezo1 protein in mediating osteogenic differentiation of periodontal ligament stem cells via the Notch signaling pathway / 华西口腔医学杂志

OBJECTIVE@#To explore the mechanism of Piezo1 protein in mediating the osteogenic differentiation of human periodontal ligament stem cells (hPDLSCs) via the Notch signaling pathway.@*METHODS@#In this study, young permanent teeth extracted from impacted teeth of 8-14-year-
old children from January 1, 2016 to January 1, 2018 in the Department of Orthodontic, Beijing Children's Hospital were selected as cell sources. hPDLSCs were extracted by enzymatic digestion. Immunohistochemical staining was used to detect the expression of keratin and vimentin, and flow cytometry was used to identify the markers (CD146 and STRO-1) of hPDLSCs. The construction and screening of Piezo1 siRNA gene interference vector and Piezo1 gene overexpression plasmid were completed. Flexcell 4000T mechanical distraction stress instrument was used to construct hPDLSC cell model in vitro. According to the preliminary results, the experiment was divided into five groups: siRNA interference group, overexpression group, blank control group, stretch stress group, and negative control group. Real time quantitative polymerase chain reaction (RT-qPCR) was used to detect the expression of Piezo1, Notch1, alkaline phosphatase (ALP), Runt-related transcription factor 2 (Runx2), osteocalcin (OCN), and bone sialoprotein (BSP). Western blot was used to detect the expression of ALP and Runx2. Fluo-3 AM probe was used to detect intracellular calcium content.@*RESULTS@#Vimentin staining of hPDLSCs was positive, and keratin staining was negative. Flow cytometry was used to detect the expression of STRO-1 and CD146, markers of hPDLSC. Empty viral vectors, siRNA-Piezo1 interference sequence, and Piezo1 overexpression vector sequence could be transfected into hPDLSC by lentivirus, and the transfection efficiency was high (approximately 90%). The reverse transcription-polymerase chain reaction (RT-PCR) results showed that there were significant differences in Piezo1 gene levels among the siRNA interference group, overexpression group, blank control group, stretch stress group, and negative control group (F=9.573, P<0.05). The level of Piezo1 in the overexpression group was significantly higher than that in the siRNA interference group (q=3.893, P<0.05). The level of Piezo1 in the stretch stress group was significantly higher than that in the blank control group (q=2.006, P<0.05). The expression of Notch1 and osteogenic genes ALP, Runx2, OCN, and BSP had the same trend. Western blot results showed that there were significant differences in the expression of ALP in the siRNA interference group, overexpression group, blank control group, stretch stress group, and negative control group (F=11.207, P<0.001). The expression level of ALP in the overexpression group was significantly higher than that in the siRNA interference group (q=2.991, P<0.05). The expression of ALP in the stretch stress group was significantly higher than that in the blank control group (q=3.007, P<0.05). The expression of Runx2 protein showed the same trend. The intracellular calcium fluorescence intensity of the overexpression group was significantly higher than that of the siRNA interference group, and the intracellular calcium fluorescence intensity of the stretch stress group was significantly higher than that of the siRNA interference group.@*CONCLUSIONS@#Mechanical stretch stress can promote the expression of Piezo1 protein. Ca2+ is the second messenger, activates the Notch1 signaling pathway and the expression of ALP, Runx2, OCN, and BSP; and promotes the osteogenic differentiation of hPDLSC. The siRNA-Piezo1 interfering plasmid can block this process. On the contrary, the overexpression plasmid of Piezo1 can promote the osteogenic differentiation of PDLSCs.

Effects of casein kinase 2 interacting protein-1 on the osteogenic differentiation ability of human periodontal ligament stem cells / 口腔疾病防治

Objective @#To investigate the effects of casein kinase 2 interacting protein-1 (CKIP-1) on the osteogenic differentiation ability of human periodontal ligament stem cells (hPDLSCs).@*Methods @#The hPDLSCs were obtained by primary culture with periodontal ligament tissues that were collected from normal humans. Then, a lentiviral vector containing a CKIP-1-specific siRNA sequence was constructed, and the transcriptional level of CKIP-1 in hPDLSCs was downregulated after vector infection. The P4 cells were divided into four groups: the control group, negative control group (infected with a control vector), CKIP-siRNA group (infected by a CKIP-1 siRNA lentivirus) and CKIP-1 group (infected by a CKIP-1 overexpression virus). All of the cells were cultured under osteogenic induction for 21 days. Then, alizarin red staining and quantitative determination were performed to detect the osteogenic differentiation ability of the hPDLSCs. In addition, qPCR was used to detect the transcriptional level of osteogenesis-related regulatory factors, such as Runt-related transcription factor 2 (Runx2), alkaline phosphatase (ALP), osteocalcin (OCN), and receptor activator of nuclear factor kappa-B ligand (RANKL), and the osteogenesis-related regulatory factors of the bone morphogenetic protein (BMP) signaling pathway.@*Results@#There were no differences in the indexes between the negative control group and the control group (P > 0.05). Compared with the negative control group, the CKIP-siRNA group demonstrated more mineralized nodules (P < 0.05), significantly increased calcium salt deposition (P < 0.05), and increased mRNA levels of osteogenesis-related regulatory factors, such as Runx2 , ALP, OCN, and RANKL, and the osteogenesis-related regulatory factors of BMP signaling pathway (P < 0.05). @*Conclusion@#Downregulation of CKIP-1 could promote the osteogenic differentiation of hPDLSCs, which is related to the transcription level of osteogenic-related regulatory factors.

Calcitonin promotes collagen synthesis and osteogenesis in human periodontal ligament stem cells / 第二军医大学学报

Objective: To investigate the effect of calcitonin (CT) on promoting collagen synthesis and osteogenesis of human periodontal ligament stem cells (hPDLSCs). Methods: Fifty adult participants were divided into chronic periodontitis (CP) group (n=25) and control group (n=25). In the CP group, the anterior maxilla with probing depth ≥5 mm and the sites with imaging evidence of bone loss were selected. The gingival crevicular fluid (GCF) samples were collected from 6 maxillary sites in each patient. In the control group, multiple sites without inflammation (10 to 12 per subject) were sampled to ensure that a sufficient amount of GCF was collected. The expression of CT, transforming growth factor β1 (TGF-β1) and bone morphogenetic protein (BMP) 2/4/7 in GCF was detected by enzyme linked immunosorbent assay (ELISA), and the correlation between CT expression and clinical parameters such as periodontal pocket probing depth (PD), clinical attachment loss (CAL) and gingival index (GI), and the above-mentioned indicators was investigated with Spearman correlation analysis. hPDLSCs were infected with the adenoviruses carrying CT gene (Ad.CT) and the expression of mRNA and protein of TGF-β1, BMP2/4/7, alkaline phosphatase (ALP), osteocalcin (OCN) and collagen type I/III (Col I/III) were detected by quantitative real-time PCR and Western blotting. Results: The expression level of CT in GCF of the CP group was significantly higher than that of the control group ([32.62±1.46] ng/mL vs [17.70 ± 0.76] ng/mL, P<0.01). The expression of CT was positively correlated with clinical parameters such as PD, CAL and GI (P<0.01, P<0.05). The expression levels of BMP2/4/7 and TGF-β1 in GCF of the CP group were significantly higher than those of the control group (BMP2: [138.67 ± 4.04] ng/mL vs [103.96 ± 2.78] ng/mL, BMP4: [155.53 ± 3.55] ng/mL vs [133.15 ± 2.92] ng/mL; BMP7: [106.59 ± 2.85] ng/mL vs [90.22±1.56] ng/mL; TGF-β1: [105.92 ± 3.40] ng/mL vs [89.85 ± 2.42] ng/mL; all P<0.01). The expression of BMP2/4/7 and TGF-β1 was negatively correlated with CT expression (P<0.01, P<0.05). The overexpression of CT significantly increased the expression of TGF-β1, Col I/III and osteoblast markers BMP2/4, ALP and OCN in GCF (all P<0.01). Compared with the cells co-infected with Ad.CT and Ad.Null, the cells co-infected with Ad.CT and small interfering RNA specifically blocking TGF-β1 (Ad.TGF-β1 siRNA) had significantly lower collagen expression (Col I: 0.16 ± 0.02 vs 0.22 ± 0.03; Col III: 0.11±0.01 vs 0.15 ± 0.02; both P<0.01). Compared with Ad.CT infected cells, the protein expression levels of ALP and OCN were significantly decreased in Ad.CT and noggin co-treated cells (ALP: 0.19 ± 0.02 vs 0.25 ± 0.03; OCN: 0.13 ± 0.01 vs 0.19 ± 0.02; both P<0.01). Conclusion: CT can promote collagen synthesis and osteogenesis in hPDLSCs through TGF-β1 and BMP signaling transduction pathways.

Effects of EZH2 inhibitor DZNeP on osteogenic differentiation of periodontal ligament stem cells / 国际生物医学工程杂志

Objective To observe the osteogenic differentiation of human periodontal ligament stem cells (hPDLSCs) and to investigate the epigenetic regulation of EZH2 inhibitor DZNeP on osteogenic differentiation of hPDLSCs. Methods The hPDLSCs were isolated and cultured, and their proliferation under different concentrations of DZNeP (0, 1, 2, 5 and 10 μmol/L) was detected by MTT. The effects of DZNeP on osteogenic differentiation of hPDLSCs were observed by alkaline phosphatase (ALP) staining and alizarin red staining. The effect of DZNeP on the trimethylation of histone H3K27 in hPDLSCs was detected by immunofluorescence staining. Results Compared with the control group, the proliferation of hPDLSCs after 1, 2, 5 and 10 μmol/L DZNeP treatment for 48 h was significantly decreased, respectively (all P<0.05), and it was concentration-dependent. The result of ALP staining and alizarin red staining showed that DZNeP could promote the expression of early osteogenic markers ALP and the formation of advanced calcified nodules of hPDLSCs. The immunofluorescence staining result showed that the trimethylation fluorescence intensity of histone H3K27 was significantly decreased in the DZNeP group compared with the control group. Conclusions As an EZH2 inhibitor, DZNeP can inhibit the proliferation of hPDLSCs and promote the differentiation of hPDLSCs into osteoblasts in vitro, suggesting that DZNeP can be used as a potential small molecule drug for the treatment of periodontitis.

Effect of endoplasmic reticulum stress on the osteogenic differentiation of periodontal ligament cells under continuous static pressure / 口腔疾病防治

Objective@#To study the effect of continuous static pressure on the endoplasmic reticulum of human periodontal ligament cells (hPDLCs) and the mechanism of osteogenic differentiation.@*Methods@#hPDLCs cultured in vitro were subjected to 1 g/cm 2 of continuous compressive pressure (CCP) by custom-made, round, glass panes for 0, 2, 4, and 6 h, respectively. Alkaline phosphatase staining was used to detect osteogenic differentiation, and real-time quantitative PCR was used to detect the expression of protein kinase receptor-like ER kinase (PERK), eukaryotic translation initiation factor 2α (eIF2α), and transcription activation factor 4 (ATF-4). The 0 h loading group was the control group.@*Results@#After CCP treatment, the alkaline phosphatase staining of hPDLCs was blue-violet and significantly stronger than that of cells in the control group. The expression levels of PERK and ATF4 in the hPDLCs after CCP treatment were higher than those of cells in the control group (P < 0.05) and increased over time (P < 0.05). The expression of eIF2α was lower in the experimental groups than in the control group (P < 0.05) and decreased over time (P < 0.05).@*Conclusion @#Mechanical stimulation can activate ERS in hPDLCs, leading to enhanced PERK-eIF2α-ATF4 signaling and inducing osteogenic differentiation.

Early morphology observation of human periodontal fibroblast cell line in the presence of human salivary exosomes

@#Human salivary exosomes have been identified as a highly informative nanovesicle with clinical-relevant information for variation of diagnostic purposes. As a continued effort from previous studies on human salivary exosomes effect at gene expression level, this study is carried out to observe the morphology of human periodontal fibroblast (HPdLF) treated with exosomes cells under the same period of changes in genotypic level occurred. In vitro, HPdLF cells were cultured for 24 hours with 10 µg/ml of human salivary exosomes. The morphology of HPdLF cells was examined under inverted light microscopy and scanning electron microscopy (SEM) for both control samples and samples treated with human salivary exosomes, while the cell count was performed via trypan blue staining. There was no significant difference in the morphology under the inverted light microscopy and the cell number of HPdLF cells for both treated and untreated cells with exosomes. However, for SEM, the treated HPdLF with salivary exosomes showed slight observable changes on the filopodia, lamellipodia, cytoplasmic vesicles and the cytoskeleton of the cells. Even within a short period (24 hours) of culturing time for cells with human salivary exosomes, the samples showed minimal changes which positively suggested a simultaneous event of exchanging materials from human salivary exosomes to cells had occurred, hence, potentially proving that human salivary exosomes can enhance cell proliferation

Effects of overexpression of Notch intracellular domain on proliferation and osteogenic differentiation of human periodontal ligament stem cells / 中华口腔医学杂志

Objective@#To investigate the effect of overexpression of Notch intracellular domain (NICD) on proliferation and osteogenic differentiation of human periodontal ligament stem cells (hPDLSC).@*Methods@#The third generation hPDLSC with stable overexpressing of NICD were assigned as experimental group, normal hPDLSC were as negative control group and hPDLSC transfected with empty vector were as blank control group. The effect of overexpressing NICD on proliferation ability of hPDLSC was detected by using cell counting kit-8 (CCK-8). Alizarin Red staining and real-time quantitative PCR (qPCR) were used to detect the effects of NICD on cementum attachment proteins (CAP), osteocalcin (OCN), Runt-related transcription factor 2 (RUNX2) and Notch signal pathway receptor Notch1. The effect of overexpressing NICD on hPDLSC osteogenic protein RUNX2 and flag marker protein (used to label NICD) were detected by using Western blotting.@*Results@#CCK-8 results showed that there were no significant differences in A values amongst the three groups for 1-2 days (P>0.05). The number of cells in the experimental group was significantly increase than that of the two control groups from the third to seventh days (A values were 0.203±0.016, 0.364±0.014, 0.449±0.020, 0.549±0.020 and 0.570±0.020, respectively) (P<0.05). Alizarin red staining showed that compared with the blank control group and negative control group, the mineralized nodules in the experimental group had smaller formation range and lighter color, and the differences were statistically significant (P<0.05). The expressions of CAP gene (0.751±0.058, 0.887±0.025), osteocalcin gene (0.592±0.051, 0.670±0.045) and RUNX2 gene (0.319±0.038, 0.684±0.055) at 14 and 21 days in the experimental group were significantly lower than those in the negative control group respectively (P<0.05). However, the expression levels of Notch1 gene at 14 and 21 days (2.507±0.047, 4.041±0.219) were significantly higher than those of negative and blank control groups (P<0.05). The results of Western blotting showed that the expressions of flag marker protein (0.167±0.007, 0.204±0.010) at 14 and 21 days in the experimental group were significantly higher than those in the negative and blank control groups (P<0.05). However, the expressions of RUNX2 protein (0.075±0.006, 0.074±0.013) at 14 and 21 days were significantly lower than that in the negative control group (0.092±0.003, 0.118±0.008) and blank control group (0.174±0.006, 0.212±0.008) (P<0.05).@*Conclusions@#Overexpression of NICD can promote the proliferation capacity of hPDLSC and inhibit its osteogenic differentiation.

Comparative study with the effect of stromal cell derived factor-1 on osteogenic differentiation of human healthy and inflammatory periodontal ligament stem cells / 华西口腔医学杂志

OBJECTIVE@#This study aims to compare the osteogenic differentiation capability of stem cells derived from human inflammatory periodontal ligament tissues (iPDLSCs) with those of stem cells derived from healthy periodontal ligament tissues (hPDLSCs). Both types of tissues were induced by stromal cell derived factor (SDF-1) in vitro.@*METHODS@#iPDLSCs and hPDLSCs were primarily cultured by tissue digestion method and purified by limited dilution cloning. The cells were passaged and identified by stem cell surface marker expression through flow cytometry. Then, we used thiazolyl blue tetrazolium bromide to detect and compare the proliferation capabilities of the iPDLSCs and hPDLSCs. Express of bone volumes were detected by alizarin red staining after SDF-1 was added to the cells. Using alkaline phosphatase, we evaluated the osteogenic differentiation capability of the cells induced by SDF-1. The expression levels of the osteogenesis-related genes of the cells induced by SDF-1 were determined by reverse transcription-polymerase chain reaction.@*RESULTS@#After purification, both iPDLSCs and hPDLSCs expressed stem cell markers. hPDLCSs had a higher proliferation capability than iPDLSCs. Osteogenesis-related genes had higher expression levels in the cells induced by SDF-1 than in those without induction (P<0.05). SDF-1 at 50 and 200 ng·mL⁻¹ concentration greatly affected the differen-tiation capabilities of iPDLSCs and hPDLSCs respectively.@*CONCLUSIONS@#iPDLSCs and hPDLSCs had osteogenic differentia-tion capability. The level of osteogenic differentiation in normal and inflamed periodontal ligament stem cells increases after SDF-1 induction.

Influence of 3,3'-diindolylmethane on expression of inflammatory cytokines in periodontal ligament cells induced by lipopolysaccharide / 上海交通大学学报（医学版）

Objective: To investigate the effect of 3,3'-diindolylmethane (DIM) on the expression of inflammatory cytokines in human periodontal ligament cells (hPDLCs) induced by lipopolysaccharide (LPS) and to study the related mechanism. Methods: hPDLCs were isolated and cultured, and CCK-8 method was used to detect the effect of DIM on the proliferation of hPDLCs. hPDLCs were randomly divided into 4 groups: blank group (without LPS and DIM), LPS group (10 μg/mL LPS), 10 μg/mL LPS+6.25 μg/mL DIM, 10 μg/mL LPS+12.50 μg/mL DIM. The cells of all groups were cultured for 12 h. The protein levels of TNF-α, IL-1β and IL-6 in supernatant were detected by enzyme linked immunosorbent assay. The change of mitogenactivated protein kinase (MAPK) and nuclear factor κB (NF-κB) signaling pathways were detected by Western blotting. Results: The cell viability was not affected when the DIM concentration was less than 50 μmol/L (P>0.05). DIM at 6.25 and 12.50 μg/mL reduced the LPS-induced expression of TNF-α, IL-1β and IL-6 at protein levels (P<0.05). DIM inhibited the activation of the NF-κB signaling pathway. Conclusion: DIM can reduce the LPS-induced inflammatory cytokine expression in hPDLCs via restraining the activation of the NF-κB signaling pathway.