Osteogenic effect of crocin in human periodontal ligament stem cells via Wnt/β-catenin signaling.

Crocin is a major class of medicinal components in saffron. This study aimed to determine whether crocin directly promotes the proliferation and osteogenic differentiation of human periodontal ligament stem cells (PDLSCs) in vitro and in vivo. CCK8 cell proliferation assay, reverse transcription quantitative polymerase chain reaction (RT-qPCR), Western blot analysis and Alizarin Red staining were performed in PDLSCs using crocin as a stimulant. DKK1 was used to selectively inhibit Wnt/β-catenin signaling, and Western blotting was performed to investigate the underlying mechanism. The PDLSCs were mixed with calcium phosphate cement and implanted into nude mice subcutaneously to study the effect of crocin on PDLSC osteogenic differentiation in vivo. The CCK-8 assay showed that crocin did not promote the proliferation of PDLSCs. Treatment with 400 μM crocin significantly promoted PDLSC mRNA levels of ALP, COL1 and OCN; RUNX2 and BMP2 protein expression; mineralized nodule formation in vitro and in vivo; and ALP activity in tissues in vivo. In addition, crocin significantly promoted the phosphorylation of β-catenin and cyclin D1. DKK1 inhibits Wnt/β-catenin activation and partially reverses crocin-mediated promotion of PDLSC osteogenic differentiation. Crocin may contribute to the regeneration of periodontal bone tissue.

Gu Y ，Bai Y 《-》

Erythropoietin enhances osteogenic differentiation of human periodontal ligament stem cells via Wnt/β-catenin signaling pathway.

Zheng DH ，Wang XX ，Ma D ，Zhang LN ，Qiao QF ，Zhang J ... -  《Drug Design Development and Therapy》

Lipopolysaccharide from Escherichia coli stimulates osteogenic differentiation of human periodontal ligament stem cells through Wnt/β-catenin-induced TAZ elevation.

Human periodontal ligament stem cells (PDLSCs), a type of dental tissue-derived mesenchymal stem cells (MSCs), can be clinically applied in periodontal tissue regeneration to treat periodontitis, which is initiated and sustained by bacteria. Lipopolysaccharide (LPS), the major component of the outer membrane of gram-negative bacteria, is a pertinent deleterious factor in the oral microenvironment. The aim of this study was to investigate the effect of LPS on the proliferation and osteogenic differentiation of PDLSCs, as well as the mechanisms involved. Proliferation and osteogenic differentiation of PDLSCs were detected under the stimulation of Escherichia coli-derived LPS. The data showed that E. coli-derived LPS did not affect the proliferation, viability, and cell cycle of PDLSCs. Furthermore, it promoted osteogenic differentiation with the activation of TAZ. Lentivirus-mediated depletion of TAZ (transcriptional activator with a PDZ motif) was used to determine the role of TAZ on LPS-induced enhancement of osteogenesis. PDLSCs cultured in osteogenic media with or without LPS and DKK1 (Wnt/β-catenin pathway inhibitor) were used to determine the regulatory effect of Wnt signaling. We found that TAZ depletion offset LPS-induced enhancement of osteogenesis. Moreover, treatment with DKK1 offset LPS-induced TAZ elevation and osteogenic promotion. In conclusion, E. coli-derived LPS promoted osteogenic differentiation of PDLSCs by fortifying TAZ activity. The elevation and activation of TAZ were mostly mediated by the Wnt/β-catenin pathway. PDLSC-governed alveolar bone tissue regeneration was not necessarily reduced under bacterial conditions and could be modulated by Wnt and TAZ.

Xing Y ，Zhang Y ，Jia L ，Xu X ... -  《-》

Kaempferol promotes proliferation and osteogenic differentiation of periodontal ligament stem cells via Wnt/β-catenin signaling pathway.

Kaempferol, a type of flavonoid, is widely present in fruits, vegetables and medicinal herbs. This study was designed to investigate the effects of kaempferol on proliferation and osteogenesis of periodontal ligament stem cells (PDLSCs) and to identify the related pathway. PDLSCs were isolated from extracted premolars and cultured in vitro. Cell-counting kit-8 (CCK-8) and colony formation assays were performed to determine the effect of kaempferol, at various concentrations, on the proliferation of PDLSCs. Alkaline phosphatase (ALP) activity was analyzed both quantitatively and qualitatively, and extracellular matrix mineralization was examined by alizarin red-S staining. In addition, the mRNA and protein expression levels of ALP, RUNX Family Transcription Factor 2 (RUNX2), Sp7 Transcription Factor (SP7; Osterix), Bone Gamma-Carboxyglutamate Protein (BGLAP; osteocalcin) and catenin beta 1 (CTNNB1; β-catenin) were monitored by qPCR and Western blot analysis. Additionally, the tankyrase inhibitor, XAV939, was used to determine the role of the Wnt/β-catenin pathway. The results illustrated that 10-6 M kaempferol markedly promoted the proliferation, ALP activity and mineral deposition of PDLSCs (P < 0.05). The expression levels of ALP, RUNX2, SP7, BGLAP and β-catenin were all upregulated (P < 0.05). After blocking the Wnt/β-catenin pathway with XAV939, the effects of kaempferol were apparently reversed. kaempferol enhanced proliferation and osteogenesis of PDLSCs by activating the Wnt/β-catenin signaling, which suggests the potential application of kaempferol for periodontal tissue regeneration.

Nie F ，Zhang W ，Cui Q ，Fu Y ，Li H ，Zhang J ... -  《-》

Nocardamine mitigates cellular dysfunction induced by oxidative stress in periodontal ligament stem cells.

The role of periodontal ligament stem cells (PDLSCs) in repairing periodontal destruction is crucial, but their functions can be impaired by excessive oxidative stress (OS). Nocardamine (NOCA), a cyclic siderophore, has been shown to possess anti-cancer and anti-bacterial properties. This study aimed to investigate the protective mechanisms of NOCA against OS-induced cellular dysfunction in PDLSCs. The cytotoxicity of NOCA on PDLSCs was assessed using a CCK-8 assay. PDLSCs were then treated with hydrogen peroxide (H2O2) to induce OS. ROS levels, cell viability, and antioxidant factor expression were analyzed using relevant kits after treatment. Small molecule inhibitors U0126 and XAV-939 were employed to block ERK signaling and Wnt pathways respectively. Osteogenic differentiation was assessed using alkaline phosphatase (ALP) activity staining and Alizarin Red S (ARS) staining of mineralized nodules. Expression levels of osteogenic gene markers and ERK pathway were determined via real-time quantitative polymerase chain reaction (RT-qPCR) or western blot (WB) analysis. β-catenin nuclear localization was examined by western blotting and confocal microscopy. NOCA exhibited no significant cytotoxicity at concentrations below 20 µM and effectively inhibited H2O2-induced OS in PDLSCs. NOCA also restored ALP activity, mineralized nodule formation, and the expression of osteogenic markers in H2O2-stimulated PDLSCs. Mechanistically, NOCA increased p-ERK level and promoted β-catenin translocation into the nucleus; however, blocking ERK pathway disrupted the osteogenic protection provided by NOCA and impaired its ability to induce β-catenin nuclear translocation under OS conditions in PDLSCs. NOCA protected PDLSCs against H2O2-induced OS and effectively restored impaired osteogenic differentiation in PDLSCs by modulating the ERK/Wnt signaling pathway.

He HP ，Zhao MZ ，Jiao WH ，Liu ZQ ，Zeng XH ，Li QL ，Hu TY ，Cheng BH ... -  《Stem Cell Research & Therapy》