Static magnetic field-induced IL-6 secretion in periodontal ligament stem cells accelerates orthodontic tooth movement.

Static magnetic field (SMF) promoting bone tissue remodeling is a potential non-invasive therapy technique to accelerate orthodontic tooth movement (OTM). The periodontal ligament stem cells (PDLSCs), which are mechanosensitive cells, are essential for force-induced bone remodeling and OTM. However, whether and how the PDLSCs influence the process of inflammatory bone remodeling under mechanical force stimuli in the presence of SMFs remains unclear. In this study, we found that local SMF stimulation significantly enhanced the OTM distance and induced osteoclastogenesis on the compression side of a rat model of OTM. Further experiments with macrophages cultured with supernatants from force-loaded PDLSCs exposed to an SMF showed enhanced osteoclast formation. RNA-seq analysis showed that interleukin-6 (IL-6) was elevated in force-loaded PDLSCs exposed to SMFs. IL-6 expression was also elevated on the pressure side of a rat OTM model with an SMF. The OTM distance induced by an SMF was significantly decreased after injection of the IL-6 inhibitor tocilizumab. These results imply that SMF promotes osteoclastogenesis by inducing force-loaded PDLSCs to secrete the inflammatory cytokine IL-6, which accelerates OTM. This will help to reveal the mechanism of SMF accelerates tooth movement and should be evaluated for application in periodontitis patients.

Role of histone deacetylase 9 in human periodontal ligament stem cells autophagy in a tumour necrosis factor α-induced inflammatory environment.

Histone deacetylases (HDACs) play important roles in the post-translational modification of histones, which can affect the biological properties of cells, thereby altering disease progression and outcomes. However, it remains unclear how HDAC9, a class II HDAC, affects the autophagy of human periodontal ligament stem cells (hPDLSCs). We aimed to identify its role in autophagy in hPDLSCs in an inflammatory environment and to explore the potential regulatory mechanisms. A rat periodontitis model was induced by ligating the molars with silk thread. Expression of autophagy-related genes and TNF-α was elevated in this model. TNF-α was used to stimulate hPDLSCs to establish an inflammatory environment. In the TNF-α-stimulated hPDLSCs, the expression of ATG7, ATG12, Beclin-1, LC3 and HDAC9 was upregulated, and that of p62 was downregulated. When HDAC9 expression was inhibited, autophagy-related genes expression was downregulated, and p62 expression was upregulated in TNF-α-treated hPDLSCs, indicating that autophagy was inhibited under these conditions. ERK pathway inhibition significantly reduced HDAC9-mediated autophagy in TNF-α-treated hPDLSCs. These findings reveal that autophagy occurred in our rat periodontitis model and that HDAC9 regulated autophagy via ERK pathways in hPDLSCs in the inflammatory environment. HDAC9 is therefore a potential target for the treatment of periodontitis.

Static Magnetic Field Promotes Proliferation, Migration, Differentiation, and AKT Activation of Periodontal Ligament Stem Cells.

Periodontal ligament stem cells (PDLSCs) possess self-renewal and multilineage differentiation potential and exhibit great potential for the treatment of bone tissue defects caused by inflammation. Previous studies have indicated that static magnetic field (SMF) can enhance the proliferation and differentiation of mesenchymal stem cells (MSCs). SMF has been widely used to repair bone defects and for orthodontic and implantation treatment. In this study, we revealed that a 320 mT SMF upregulates the protein expression levels of cytokines such as MCM7 and PCNA in proliferating PDLSCs. Cell counting kit-8 results revealed that the SMF group had higher optical density values than the control group. The ratio of cells in the S phase to those in the G2/M phase was significantly increased after exposure to a 320 mT SMF. In scratch assays, the SMF-treated PDLSCs exhibited a higher migration rate than the sham-exposed group after 24 h of culture, indicating that the SMF promoted the migratory ability of PDLSCs. The activity level of the early differentiation marker alkaline phosphatase and the late marker matrix mineralization, as well as osteoblast-specific gene and protein expression, were enhanced in PDLSCs exposed to the SMF. Furthermore, AKT signaling pathway was activated by SMF. Our data demonstrated that the potential mechanism of action of SMF may enhance PDLSCs proliferation and osteogenic differentiation by activating the phosphorylated AKT pathway. The elucidation of this molecular mechanism may lead to a better understanding of bone repair responses and aid in improved stem cell-mediated regeneration.

Effect of silencing HDAC9 on the proliferation and differentiation of periodontal ligament stem cells / 口腔疾病防治

Objective @#To investigate the effect of silencing histone deacetylase 9 (HDAC9) expression on the proliferation and osteogenic differentiation of periodontal ligament stem cells (PDLSCs).@*Methods@# PDLSCs were isolated, cultured and identified in vitro. An siRNA construct specific for HDAC9 was transfected into PDLSCs (siHDAC9 group), and a nontargeting siRNA was used as a control (siNC group). The interference effect was determined by qRT-PCR. The cell cycle progression of PDLSCs was detected using flow cytometry. The proliferation activity of PDLSCs was detected via CCK-8 assay. Western blotting was used to detect the protein expression of proliferating cell nuclear antigen (PCNA). The mRNA expression of runt-related transcription factor 2 (RUNX2) and alkaline phosphatase (ALP) was investigated by qRT-PCR. The protein expression of RUNX2 was detected by western blotting. In addition, the formation of mineralized nodules was assessed by alizarin red staining. @*Results@#Compared with that in the siNC group, the mRNA expression of HDAC9 in the siHDAC9 group was lower (P < 0.01). Moreover, compared with those in the siNC group, the proliferation index (P<0.01), proliferation activity (P<0.05) and protein expression of PCNA (P<0.01) in the siHDAC9 group were all increased. Compared with the siNC group, the siHDAC9 group exhibited higher mRNA expression of RUNX2 and ALP (P < 0.05), and the protein expression of RUNX2 showed the same results (P < 0.01). The results of alizarin red staining showed that compared to the siNC group, the siHDAC9 group formed more mineralized nodules.@* Conclusion@#Silencing HDAC9 expression can promote the proliferation and osteogenic differentiation of PDLSCs.

Effect of miR-21 on the proliferation and osteogenic differentiation of human periodontal ligament stem cells / 口腔疾病防治

Objective @# To explore the effect of miR-21 on human periodontal ligament stem cells (PDLSCs) proliferation and osteogenesis and to provide a theoretical basis for the stem cell treatment of periodontitis.@*Methods@#hPDLSCs were isolated and cultured with the enzymatic tissue block method, and surface molecules (CD34, CD45, CD90 and CD105) were detected by flow cytometry. An miR-21 mimics (pre-miR-21) and inhibitor (anti-miR-21) were transfected into hPDLSCs by Lipofectamine 2000. The experiment groups: mimics-NC group, mimics group, inhibitor group, and inhibitor-NC group. The transfection efficiency of miR-21 was determined by qRT-PCR. Proliferation was detected by CCK-8 and flow cytometry. The osteogenic differentiation ability of hPDLSCs was determined by alizarin red staining. Western blot was used to detect the protein expression of osteogenic related genes: Runx2.@*Results@#The mRNA expression of miR-21in the mimics group was significantly higher than that in the mimics-NC group; additionally, the expression in the inhibitor group was significantly weaker than that in the inhibitor-NC group (P < 0.05). hPDLSCs proliferation and the S phase cell ratio in the mimics group were stronger than those in the mimics-NC group(P < 0.05); those in the inhibitor group were weaker than those in the inhibitor-NC group (P < 0.05). After alizarin red staining, the mimics group was found to have more mineralized modules than mimics-NC group, and the inhibitor group had fewer than that in the inhibitor-NC group. Runx2 protein expression in the mimics group was higher than that in the mimics-NC group (P <0.05), and expression was lower in the inhibitor group than in the inhibitor-NC group (P < 0.05).@*Conclusion@#miR-21can promote the proliferation and osteogenesic differentiation of hPDLSCs.