Periostin reverses high glucose-inhibited osteogenesis of periodontal ligament stem cells via AKT pathway

Catalpol Enhances Osteogenic Differentiation of Human Periodontal Stem Cells and Modulates Periodontal Tissue Remodeling in an Orthodontic Tooth Movement Rat Model

Purpose

This study examines the effects and mechanisms of catalpol (CAT) on the proliferation and osteogenic differentiation of cultured human periodontal ligament stem cells (hPDLSCs) in vitro and assesses the impact of CAT on periodontal remodeling in vivo using an orthodontic tooth movement (OTM) model in rats.

Methods

hPDLSCs were cultured in a laboratory setting, and their proliferation and osteogenic differentiation were assessed using the Cell-counting Kit-8 (CCK-8), Alizarin Red Staining (ARS), quantitative calcium assay, alkaline phosphatase (ALP) staining and activity assay, and immunofluorescence assay. Additionally, the expression of collagen type 1 (COL-1), ALP, and runt-related transcription factor-2 (RUNX-2) was evaluated through qRT-PCR and Western blot analysis. To verify the function of the estrogen receptor-α (ER-α)-mediated phosphatidylinositol-3-kinase-protein kinase B (PI3K/AKT) pathway in this mechanism, LY294002 (a PI3K signaling pathway inhibitor) and the ER-α specific inhibitor methyl-piperidine-pyrazole (MPP) were used. The osteogenic markers ER-α, AKT, and p-AKT (phosphoprotein kinase B) were identified through Western blot analysis. Eighteen male Sprague-Dawley rats were assigned to two groups randomly: a CAT group receiving CAT and a control group receiving an equivalent volume of saline. Micro-computed tomography (micro-CT) analysis was employed to evaluate tooth movement and changes in alveolar bone structure. Morphological changes in the periodontal tissues between the roots were investigated using hematoxylin and eosin (HE) staining and tartaric-resistant acid phosphatase (TRAP) staining. The expression of COL-1, RUNX-2, and nuclear factor-κB (NF-κB) ligand (RANKL) was assessed through immunohistochemical staining (IHC) to evaluate periodontal tissue remodeling. Tests were analyzed using GraphPad Prism 8 software. Differences among more than two groups were analyzed by one-way or two-way analysis of variance (ANOVA) followed by the Tukey's test. Values of p < 0.05 were regarded as statistically significant.

Results

In vitro experiments demonstrated that 10 μM CAT significantly promoted the proliferation, ALP activity, and calcium nodule formation of hPDLSCs, with a notable increase in the expression of COL-1, ALP, RUNX-2, ER-α, and p-AKT. The PI3K/AKT pathway was inhibited by LY294002, and further analysis using MPP suggested that ER-α mediated this effect. In vivo, experiments indicated that CAT enhanced the expression of COL-1 and RUNX-2 on the tension side of rat tooth roots, reduced the number of osteoclasts on the compression side, inhibited RANKL expression, and suppressed OTM.

Conclusion

CAT can promote hPDLSCs proliferation and osteogenic differentiation in vitro through the ER-α/PI3K/AKT pathway and enhance periodontal tissue remodeling in vivo using OTM models. These findings suggest the potential for the clinical application of catalpol in preventing relapse following OTM.

ED-71 ameliorates bone regeneration in type 2 diabetes by reducing ferroptosis in osteoblasts via the HIF1α pathway

Eldecalcitol (ED-71), a novel active form of vitamin D, shows potential in treating osteoporosis. However, its underlying mechanisms of action remain to be determined. This study aimed to investigate the effect of ED-71 on bone regeneration and to illustrate its mode of action. The in-vitro model was developed using rat primary osteoblasts cultured under high-glucose conditions, and these cells were treated with ED-71. Additionally, an in vivo model of cranial bone defects was established in type 2 diabetic rats, and ED-71 was administered by gavage. The results demonstrated that ED-71 prevented osteoblast cell death, enhanced rat primary osteoblasts' osteogenic capacity, and attenuated the overexpression of hypoxia-inducible factor 1α (HIF1α) induced by high glucose levels. Furthermore, ED-71 increased glutathione peroxidase 4 (GPX4) levels and inhibited ferroptosis in response to hyperglycemic stimulation. Notably, interference with the HIF1α activator and ferroptosis activator Erastin significantly reduced the therapeutic effects of edetate osteolysis. These findings were further tested in vivo experiments. These results suggest that ED-71 activates the HIF1α pathway in vivo and in vitro, effectively relieving the ferroptosis induced by high glucose. Significantly, ED-71 may improve osteogenic disorders caused by diabetes.

Phytic acid promotes high glucose-mediated bone marrow mesenchymal stem cells osteogenesis via modulating circEIF4B that sponges miR-186-5p and complexes with IGF2BP3

Diabetes-related hyperglycemia inhibits bone marrow mesenchymal stem cell (BMSC) function, thereby disrupting osteoblast capacity and bone regeneration. Dietary supplementation with phytic acid (PA), a natural inositol phosphate, has shown promise in preventing osteoporosis and diabetes-related complications. Emerging evidence has suggested that circular (circ)RNAs implicate in the regulation of bone diseases, but their specific regulatory roles in BMSC osteogenesis in hyperglycemic environments remain elucidated. In this study, in virto experiments demonstrated that PA treatment effectively improved the osteogenic capability of high glucose-mediated BMSCs. Differentially expressed circRNAs in PA-induced BMSCs were identified using circRNA microarray analysis. Here, our findings highlight an upregulation of circEIF4B expression in BMSCs stimulated with PA under a high-glucose microenvironment. Further investigations demonstrated that circEIF4B overexpression promoted high glucose-mediated BMSC osteogenesis. In contrast, circEIF4B knockdown exerted the opposite effect. Mechanistically, circEIF4B sequestered microRNA miR-186-5p and triggered osteogenesis enhancement in BMSCs by targeting FOXO1 directly. Furthermore, circEIF4B inhibited the ubiquitin-mediated degradation of IGF2BP3, thereby stabilizing ITGA5 mRNA and promoting BMSC osteogenic differentiation. In vivo experiments, circEIF4B inhibition attenuated the effectiveness of PA treatment in diabetic rats with cranial defects. Collectively, our study identifies PA as a novel positive regulator of BMSC osteogenic differentiation through the circEIF4B/miR-186-5p/FOXO1 and circEIF4B/IGF2BP3/ITGA5 axes, which offers a new strategy for treating high glucose-mediatedBMSCosteogenic dysfunction and delayed bone regeneration in diabetes.

Characterisation and Expression of Osteogenic and Periodontal Markers of Bone Marrow Mesenchymal Stem Cells (BM-MSCs) from Diabetic Knee Joints

Type 2 diabetes mellitus (T2DM) represents a significant health problem globally and is linked to a number of complications such as cardiovascular disease, bone fragility and periodontitis. Autologous bone marrow mesenchymal stem cells (BM-MSCs) are a promising therapeutic approach for bone and periodontal regeneration; however, the effect of T2DM on the expression of osteogenic and periodontal markers in BM-MSCs is not fully established. Furthermore, the effect of the presence of comorbidities such as diabetes and osteoarthritis on BM-MSCs is also yet to be investigated. In the present study, BM-MSCs were isolated from osteoarthritic knee joints of diabetic and nondiabetic donors. Both cell groups were compared for their clonogenicity, proliferation rates, MSC enumeration and expression of surface markers. Formation of calcified deposits and expression of osteogenic and periodontal markers were assessed after 1, 2 and 3 weeks of basal and osteogenic culture. Diabetic and nondiabetic BM-MSCs showed similar clonogenic and growth potentials along with comparable numbers of MSCs. However, diabetic BM-MSCs displayed lower expression of periostin (POSTN) and cementum protein 1 (CEMP-1) at Wk3 osteogenic and Wk1 basal cultures, respectively. BM-MSCs from T2DM patients might be suitable candidates for stem cell-based therapeutics. However, further investigations into these cells' behaviours in vitro and in vivo under inflammatory environments and hyperglycaemic conditions are still required.

Phytic acid improves osteogenesis and inhibits the senescence of human bone marrow mesenchymal stem cells under high-glucose conditions via the ERK pathway

Hyperglycaemia causes impairment of osteogenic differentiation and accelerates stem cell senescence, resulting in weakened osteogenesis and disordered bone metabolism. Phytic acid (PA) is an antioxidant that is reportedly beneficial to bone homeostasis. The present study aims to clarify how PA affects the osteogenic capacity and cellular senescence of bone marrow mesenchymal stem cells (BMSCs) exposed to high-glucose environments, as well as the potential molecular mechanisms. Our results indicate that osteogenic differentiation in BMSCs cultivated in high-glucose conditions is enhanced by PA, as evidenced by increased alkaline phosphatase activity and staining, Alizarin Red S staining, osteogenic marker in in vitro studies, and increased osteogenesis in animal experiments. PA also prevented high-glucose-induced senescence of BMSCs, as evidenced by the repression of reactive oxygen species production, senescence-associated β-galactosidase staining, and P21 and P53 expression. Furthermore, it was found that PA rescued the high-glucose-inhibited expression of phosphorylated extracellular regulated protein kinases (p-ERK). The inhibition of ERK pathway by the specific inhibitor PD98059 blocked the PA-enhanced osteogenesis of BMSCs and promoted cell senescence. Our results revealed that PA enhances osteogenic differentiation and inhibits BMSC senescence in a high-glucose environment. In addition, the activation of the ERK pathway seems to mediate the beneficial effects of PA. The findings provide novel insights that could facilitate bone regeneration in patients with diabetes.

Recent progress in bone-repair strategies in diabetic conditions

Bone regeneration following trauma, tumor resection, infection, or congenital disease is challenging. Diabetes mellitus (DM) is a metabolic disease characterized by hyperglycemia. It can result in complications affecting multiple systems including the musculoskeletal system. The increased number of diabetes-related fractures poses a great challenge to clinical specialties, particularly orthopedics and dentistry. Various pathological factors underlying DM may directly impair the process of bone regeneration, leading to delayed or even non-union of fractures. This review summarizes the mechanisms by which DM hampers bone regeneration, including immune abnormalities, inflammation, reactive oxygen species (ROS) accumulation, vascular system damage, insulin/insulin-like growth factor (IGF) deficiency, hyperglycemia, and the production of advanced glycation end products (AGEs). Based on published data, it also summarizes bone repair strategies in diabetic conditions, which include immune regulation, inhibition of inflammation, reduction of oxidative stress, promotion of angiogenesis, restoration of stem cell mobilization, and promotion of osteogenic differentiation, in addition to the challenges and future prospects of such approaches.

Hyaluronic Acid Induction Promotes the Differentiation of Human Neural Crest-like Cells into Periodontal Ligament Stem-like Cells

Periodontal ligament (PDL) stem-like cells (PDLSCs) are promising for regeneration of the periodontium because they demonstrate multipotency, high proliferative capacity, and the potential to regenerate bone, cementum, and PDL tissue. However, the transplantation of autologous PDLSCs is restricted by limited availability. Since PDLSCs are derived from neural crest cells (NCs) and NCs persist in adult PDL tissue, we devised to promote the regeneration of the periodontium by activating NCs to differentiate into PDLSCs. SK-N-SH cells, a neuroblastoma cell line that reportedly has NC-like features, seeded on the extracellular matrix of PDL cells for 2 weeks, resulted in the significant upregulation of PDL marker expression. SK-N-SH cell-derived PDLSCs (SK-PDLSCs) presented phenotypic characteristics comparable to induced pluripotent stem cell (iPSC)-derived PDLSCs (iPDLSCs). The expression levels of various hyaluronic acid (HA)-related genes were upregulated in iPDLSCs and SK-PDLSCs compared with iPSC-derived NCs and SK-N-SH cells, respectively. The knockdown of CD44 in SK-N-SH cells significantly inhibited their ability to differentiate into SK-PDLSCs, while low-molecular HA (LMWHA) induction enhanced SK-PDLSC differentiation. Our findings suggest that SK-N-SH cells could be applied as a new model to induce the differentiation of NCs into PDLSCs and that the LMWHA-CD44 relationship is important for the differentiation of NCs into PDLSCs.

Autophagy mediates cementoblast mineralization under compression through periostin/β-catenin axis

Repair of orthodontic external root resorption and periodontal tissue dysfunction induced by mechanical force remains a clinical challenge. Cementoblasts are vital in cementum mineralization, a process important for restoring damaged cementum. Despite autophagy plays a role in mineralization under various environmental stimuli, the underlying mechanism of autophagy in mediating cementoblast mineralization remains unclear. Here we verified that murine cementoblasts exhibit compromised mineralization under compressive force. Autophagy was indispensable for cementoblast mineralization, and autophagic activation markedly reversed cementoblast mineralization and prevented cementum damage in mice during tooth movement. Subsequently, messenger RNA sequencing analyses identified periostin (Postn) as a mediator of autophagy and mineralization in cementoblasts. Cementoblast mineralization was significantly inhibited following the knockdown of Postn. Furthermore, Postn silencing suppressed Wnt signaling by modulating the stability of β-catenin. Together our results highlight the role of autophagy in cementoblast mineralization via Postn/β-catenin signaling under compressive force and may provide a new strategy for the remineralization of cementum and regeneration of periodontal tissue.

Effect of periostin on bone metabolic and autophagy factors during tooth eruption in mice

This study aimed to investigate the effect of periostin (PN) on the expression of receptor activator of nuclear factor-κB ligand (RANKL), osteoprotegerin (OPG), microtubule-associated protein1 light chain 3B (LC3B), and Beclin1 in mouse alveolar bone specimens and cultured osteoblasts in vitro, to preliminarily explore the role of PN and autophagy in remodeling bone metabolism during tooth eruption. Mice at 5 days of age were injected with 75 ng/mL recombinant PN protein under the periosteum for 3 consecutive days according to the standard of 1 mL/100 g/day. Then, their mandibles were removed, and the expression of bone metabolic and autophagy factors was detected by immunohistochemistry. Mouse osteoblast-like cells cultured in vitro were treated with recombinant PN at a concentration of 75 ng/mL. The changes in the aforementioned indicators were compared again by immunofluorescence and western blotting 72 h after dosing. The results of the mouse samples showed that the protein expression of RANKL, LC3B, and Beclin1 decreased, accompanied by the decrease in RANKL/OPG ratio. However, OPG protein expression increased in the dosing group. Immunofluorescence and western blotting results of osteoblasts cultured in vitro showed that the protein expression of RANKL, LC3B, Beclin1, and the RANKL/OPG ratio in the experimental group decreased, but OPG expression increased. PN may regulate alveolar bone metabolism during tooth eruption by inhibiting the RANKL/OPG ratio and autophagy, which will provide a new research perspective for further exploration of the mechanisms during tooth eruption.

Osteogenesis of bone marrow mesenchymal stem cell in hyperglycemia

Diabetes mellitus (DM) has been shown to be a clinical risk factor for bone diseases including osteoporosis and fragility. Bone metabolism is a complicated process that requires coordinated differentiation and proliferation of bone marrow mesenchymal stem cells (BMSCs). Owing to the regenerative properties, BMSCs have laid a robust foundation for their clinical application in various diseases. However, mounting evidence indicates that the osteogenic capability of BMSCs is impaired under high glucose conditions, which is responsible for diabetic bone diseases and greatly reduces the therapeutic efficiency of BMSCs. With the rapidly increasing incidence of DM, a better understanding of the impacts of hyperglycemia on BMSCs osteogenesis and the underlying mechanisms is needed. In this review, we aim to summarize the current knowledge of the osteogenesis of BMSCs in hyperglycemia, the underlying mechanisms, and the strategies to rescue the impaired BMSCs osteogenesis.

Periostin in Osteoporosis and Cardiovascular Disease

Context

Osteoporosis (OP) and cardiovascular disease (CVD), prevalent disorders worldwide, often coexist and share common risk factors. The identification of common biomarkers could significantly improve patients' preventive care.

Objectives

The objectives are 1, to review periostin (Postn) involvement in osteoporosis and in CVD, and 2, identify if Postn could be a common biomarker.

Design

This is a scoping review on Postn in OP and CVD.

Methods

Databases were searched, in vitro and in vivo, for publications in English on Postn, bone, and the cardiovascular system, with no limit regarding publication date.

Results

Postn appears as a key factor in OP and CVD. Its role as a potential biomarker in both pathologies is described in recent studies, but a number of limitations have been identified.

Conclusions

Current evidence provides fragmented views on Postn in OP and CVD and does not encapsulate Postn as a common pivotal thread linking these comorbidities. A number of gaps impede highlighting Postn as a common biomarker. There is room for future basic and clinical research with Postn as a marker and a target to provide new therapeutic options for aging patients with concomitant OP and CVD.

Periostin plays a key role in maintaining the osteogenic abilities of dental follicle stem cells in the inflammatory microenvironment

OBJECTIVE

This study aimed to explore the effect of periostin in the osteogenic abilities of dental follicle stem cells (DFSCs) and DFSC sheets in the inflammatory microenvironment.

DESIGN

DFSCs were isolated from dental follicles and identified. A lentiviral vector was used to knock down periostin in DFSCs. 250 ng/ml lipopolysaccharide from Porphyromonas gingivalis (P.g-LPS) was used to construct the inflammatory microenvironment. Osteogenic differentiation was evaluated by alizarin red staining, quantitative real-time polymerase chain reaction (qRT-PCR), and western blot. The formation of extracellular matrix was assessed by qRT-PCR and immunofluorescence. The expressions of receptor activator of nuclear factor kappa-B ligand (RANKL) and osteoprotegerin (OPG) were measured by western blot.

RESULTS

Knockdown of periostin inhibited osteogenic differentiation and promoted adipogenic differentiation of DFSCs. In an inflammatory microenvironment, knockdown of periostin attenuated the proliferation and osteogenic differentiation of DFSCs. Knockdown of periostin inhibited the formation of extracellular matrix collagen I (COL-I), fibronectin, and laminin in DFSC sheets, but did not affect the expression of osteogenesis-related markers alkaline phosphatase (ALP) and osteocalcin (OCN). In the inflammatory microenvironment, knocking down periostin inhibited the expression of OCN and OPG in DFSC sheets, and promoted the expression of RANKL.

CONCLUSION

Periostin played a key role in maintaining the osteogenic abilities of DFSCs and DFSC sheets in the inflammatory microenvironment and might be an important molecule in the process of DFSCs coping with inflammatory microenvironment and promoting periodontal tissues regeneration.

Periodontal ligament cells from patients with treated stable periodontitis: Characterization and osteogenic differentiation potential

BACKGROUND AND OBJECTIVE

Periodontal ligament progenitor cells (PDL cells) isolated from patients with inflammatory periodontitis have impaired regenerative capacity, but it is unknown whether this capacity can be recovered upon treatment and stabilization of the periodontal condition. The study aimed to investigate the expression of surface markers and the proliferation and osteogenic potential of PDL cells isolated from patients with treated stable periodontitis (S-PDL cells), periodontally healthy individuals (H-PDL cells), and patients with inflammatory periodontitis (I-PDL cells).

METHODS

H-PDL, I-PDL, and S-PDL cells were isolated from the extracted teeth of individuals who (1) were periodontally healthy, (2) had inflammatory periodontitis, and (3) had treated stable periodontitis, respectively. The expression levels of surface markers and the proliferative and osteogenic capacities of the PDL cells were assessed.

RESULTS

PDL cells derived from all three sources exhibited mesenchymal stem cell (MSC) characteristics. They were positive for MSC-related markers and negative for a hematopoiesis-related marker. However, S-PDL cells had higher proliferation rates, higher expression levels of osteogenic markers, higher alkaline phosphatase activity, and more calcium nodules than I-PDL cells. But all of these parameters remained lower in S-PDL cells than in H-PDL cells.

CONCLUSIONS

S-PDL cells proliferated faster and had greater osteogenic potential than I-PDL cells, although these values remained lower than those in H-PDL cells.

Dental Follicle Stem Cells Promote Periodontal Regeneration through Periostin-Mediated Macrophage Infiltration and Reprogramming in an Inflammatory Microenvironment

Dental follicle stem cells (DFSCs) have been verified to promote periodontal regeneration in an inflammatory microenvironment. When coping with inflammatory stimulation, DFSCs highly express periostin, a bioactive molecule closely related to periodontal homeostasis. It is worth exploring whether and how periostin plays a role in the promotion of periodontal regeneration by DFSCs. By tracking the fate of DFSCs, it was found that DFSCs significantly contributed to periodontal regeneration in rat periodontal defects while they had a low survival rate. They highly expressed periostin and improved the immune microenvironment in the defect area, especially via the recruitment and reprogramming of macrophages. Silencing periostin attenuated the effects of DFSCs in promoting periodontal regeneration and regulating macrophages. Recombinant human periostin (rhPeriostin) could not only directly promote macrophage reprogramming through the integrin αM/phosphorylated extracellular signal-regulated kinase (p-Erk)/Erk signaling pathway, but it also exhibited the potential to promote periodontal regeneration in rats when loaded in a collagen matrix. These results indicated that periostin is actively involved in the process by which DFSCs promote periodontal regeneration through the regulation of macrophages and is a promising molecular agent to promote periodontal regeneration. This study provides new insight into the mechanism by which DFSCs promote periodontal regeneration and suggests a new approach for periodontal regeneration therapy.

3D Polycaprolactone/Gelatin-Oriented Electrospun Scaffolds Promote Periodontal Regeneration

Periodontitis is a worldwide chronic inflammatory disease, where surgical treatment still shows an uncertain prognosis. To break through the dilemma of periodontal treatment, we fabricated a three-dimensional (3D) multilayered scaffold by stacking and fixing electrospun polycaprolactone/gelatin (PCL/Gel) fibrous membranes. The biomaterial displayed good hydrophilic and mechanical properties. Besides, we found human periodontal ligament stem cell (hPDLSC) adhesion and proliferation on it. The following scanning electron microscopy (SEM) and cytoskeleton staining results proved the guiding function of fibers to hPDLSCs. Then, we further analyzed periodontal regeneration-related proteins and mRNA expression between groups. In vivo results in a rat acute periodontal defect model confirmed that the topographic cues of materials could directly guide cellular orientation and might provide the prerequisite for further differentiation. In the aligned scaffold group, besides new bone regeneration, we also observed that angular concentrated fiber regeneration in the root surface of the defect is similar to the normal periodontal tissue. To sum up, we have constructed electrospun membrane-based 3D biological scaffolds, which provided a new treatment strategy for patients undergoing periodontal surgery.

Thermoplasmonic Regulation of the Mitochondrial Metabolic State for Promoting Directed Differentiation of Dental Pulp Stem Cells

Regulating stem cell differentiation in a controllable way is significant for regeneration of tissues. Herein, we report a simple and highly efficient method for accelerating the stem cell differentiation of dental pulp stem cells (DPSCs) based on the synergy of the electromagnetic field and the photothermal (thermoplasmonic) effect of plasmonic nanoparticles. By simple laser irradiation at 50 mW/cm² (10 min per day, totally for 5 days), the thermoplasmonic effect of Au nanoparticles (AuNPs) can effectively regulate mitochondrial metabolism to induce the increase of mitochondrial membrane potential and further drive energy increase during the DPSC differentiation process. The proposed method can specifically regulate DPSCs' cell differentiation toward odontoblasts, with the differentiation time reduced to only 5 days. Simultaneously, the molecular profiling change of mitochondria within DPSCs during the cell differentiation process is revealed by in situ surface-enhanced Raman spectroscopy. It clearly demonstrates that the expression of hydroxyproline and glutamate gradually increases with prolonging of the differentiation days. The developed method is simple, robust, and rapid for stem cell differentiation of DPSCs, which would be beneficial to tissue engineering and regenerative medicine.

Rescuing effects of periostin in advanced glycation end-products (AGEs) caused osteogenic and oxidative damage through AGE receptor mediation and DNA methylation of the CALCA promoter

An in vitro model was established to simulate a diabetes-type environment by treating human periodontal stem cells with advanced glycation end-products (AGEs). Periostin (POSTN) plays a crucial role in maintaining the integrity of periodontal tissues. However, the role of POSTN in human periodontal stem cells stimulated by AGEs remains unknown. Diabetes mellitus is considered a metabolic disease, and DNA methylation of CpG islands is a biomarker of metabolic syndromes. Diabetes has been found to be closely related to the DNA methylation of certain genes. Here, we investigated the protective mechanism and effect of POSTN on osteogenesis and oxidative stress in the AGE environment, and further explored the CpG island methylation of specific genes potentially mediated by POSTN. The optimal concentration of AGEs was screened using CCK8. AGEs were found to contribute to oxidative stress. Conversely, reactive oxygen species production and malondialdehyde and superoxide activity indicated that the AGE + POSTN group decreased oxidative injury. According to an alkaline phosphatase assay, Alizarin Red S staining, and the expression of key genes and proteins involved in osteogenesis, POSTN mitigated the inhibitory effects of AGE on cell proliferation and osteogenic differentiation potential during osteogenic differentiation. In contrast, the growth and osteogenesis of human periodontal stem cells were notably suppressed by POSTN knockdown. Bisulfite sequencing PCR was used to evaluate the DNA methylation status. Moreover, AGE elevated the expression of DNA methyltransferas 1 (DNMT1) and inhibited the activation of CALAL promoter methylation, which was rescued by the addition of POSTN and 5-Azacytidine (5-AZA). In conclusion, POSTN attenuated the AGE-induced inhibition of osteogenesis in periodontal ligament stem cells by reducing AGE receptor levels and DNA methylation of the calcitonin-related polypeptide α (CALCA) promoter. Thus, POSTN is a promising candidate for dental bone regeneration, representing a novel therapeutic agent for diabetic patients. The mechanism underlying these processes may provide new insights into novel therapeutic targets for improving abnormal bone metabolism in patients with diabetes.

The Effect of Diabetes Mellitus on IGF Axis and Stem Cell Mediated Regeneration of the Periodontium

Periodontitis and diabetes mellitus (DM) are two of the most common and challenging health problems worldwide and they affect each other mutually and adversely. Current periodontal therapies have unpredictable outcome in diabetic patients. Periodontal tissue engineering is a challenging but promising approach that aims at restoring periodontal tissues using one or all of the following: stem cells, signalling molecules and scaffolds. Mesenchymal stem cells (MSCs) and insulin-like growth factor (IGF) represent ideal examples of stem cells and signalling molecules. This review outlines the most recent updates in characterizing MSCs isolated from diabetics to fully understand why diabetics are more prone to periodontitis that theoretically reflect the impaired regenerative capabilities of their native stem cells. This characterisation is of utmost importance to enhance autologous stem cells based tissue regeneration in diabetic patients using both MSCs and members of IGF axis.

AdipoRon Promotes the Osseointegration of Dental Implants in Mice With Type 2 Diabetes Mellitus

AdipoRon is an oral active synthetic small molecule with biological functions similar to adiponectin (APN). It is an APN receptor agonist that can improve insulin resistance and glucose intolerance. However, the role of AdipoRon in bone metabolism and related molecular mechanisms remains to be investigated. To explore the effect of AdipoRon on bone absorption and bone integration of type 2 diabetes mellitus (T2DM) mice with implants, we established surgery-induced model of osseointegration of dental implantation in T2DM mice of C57BL/6 db/db and normal mice homologous to diabetic mice. Micro-CT was used to analyze the femurs with the implant in the mice to detect the bone mass, H&E, and tartrate-resistant acid phosphatase (TRAP), and Safranin O-fast green staining was performed to analyze the bone formation and bone resorption. Bone integration-related markers as Rankl, bone morphogenetic protein 2 (BMP2), osteoprotegerin (OPG), osteopontin (OPN), and runt-related transcription factor 2 (Runx2) were also measured using immunohistochemistry. Our results indicated that diabetic mice showed a lower bone mass and decreased the osteoblast differentiation. AdipoRon attenuated diabetes-impaired bone volume (BV)/total volume (TV), trabecular thickness (Tb.Th), trabecular number (Tb.N), trabecular separation (Tb.Sp), and bone integration-related markers variation and promoted bone hyperplasia as well as repressed the osteoclast formation, especially in diabetic mice. AdipoRon may improve the osseointegration of dental implants in mice with T2DM by promoting osteogenesis and inhibiting bone resorption, and AdipoRon may serve as a promising oral strategy to improve the osseointegration ability of patients with diabetes.

TRIM16 protects human periodontal ligament stem cells from oxidative stress-induced damage via activation of PICOT

Periodontitis is a chronic inflammatory disease that result in severe loss of supporting structures and substantial tooth loss. Oxidative stress is tightly involved in the progression of periodontitis. Tripartite Motif 16 (TRIM16) has been identified as a novel regulatory protein in response to oxidative and proteotoxic stresses. The present study aimed to investigate the role of TRIM16 in human periodontal ligament stem cells (hPDLSCs) under oxidative stress. First, we found that the expression of TRIM16 decreased after exposure to H₂O₂. Then TRIM16 overexpression alleviated H₂O₂-induced oxidative stress by enhancing antioxidant capacity and reducing the amount of intracellular reactive oxygen species (ROS) and reactive nitrogen species (RNS). TRIM16 increased cell viability, inhibited cell apoptosis and the depolarization of the mitochondrial membrane potential in hPDLSCs. Furthermore, TRIM16 attenuated H₂O₂-induced suppression of osteogenic differentiation. Mechanistically, TRIM16 promoted the activation of protein kinase C (PKC)-interacting cousin of thioredoxin (PICOT), p-Akt and Nrf2, while knockdown of PICOT reversed TRIM16-mediated ROS resistance and decreased the expression of p-Akt and Nrf2. In conclusion, TRIM16 alleviated oxidative damage in hPDLSCs via the activation of PICOT/Akt/Nrf2 pathway, suggesting that TRIM16 could be a promising target to develop effective therapies for periodontitis.