Fluid shear stress promotes periodontal ligament cells proliferation via p38-AMOT-YAP.

Periodontal ligament (PDL) cells are a promising tool for periodontal regeneration therapy. Achieving a sufficient number of PDL cells is essential to PDL regeneration. In our study, appropriate flow shear stress (FSS, 1-6 dyn/cm2) promotes the proliferation of PDL cells. FSS remodels cytoskeleton and focal adhesion in a duration-dependent manner. FSS induces PDL cells to form the actin cap within 10 min, flattens the nuclei, and increases the nuclear pore size, which promotes nuclear translocation of Yes-associated protein (YAP). FSS activates p38, which plays a dual function in YAP regulation. p38 regulates the phosphorylation of Akt and cofilin, as well as induced F-actin polymerization to induce YAP activity. In addition, p38 inhibits pLATS and consecutively regulates angiomotin (AMOT) and YAP phosphorylation. AMOT competitively binds to F-actin and YAP to participate in FSS-mediated YAP nuclear translocation and cell proliferation. Taken collectively, our results provide mechanistic insights into the role of p38-AMOT-YAP in FSS-mediated PDL cells proliferation and indicate potential applications in dental regenerative medicine.

Wnt/ß-catenin plays a dual function in calcium hydroxide induced proliferation, migration, osteogenic differentiation and mineralization in vitro human dental pulp stem cells.

AIM: Calcium hydroxide is the gold standard material for pulp capping and has been widely used in clinical dentistry. Calcium hydroxide promotes proliferation, migration and osteogenic differentiation of dental pulp stem cells (DPSCs). However, the underlying mechanism is not clear. Our study investigated the role of Wnt/ß-catenin pathway in calcium hydroxide-induced proliferation, migration, osteogenic differentiation and mineralization of human DPSCs. METHODOLOGY: Protein and gene expression was detected by western blot (WB), immunofluorescence staining and quantitative real-time PCR (qPCR). Cell viability was analysed using the Cell Counting Kit-8 (CCK-8) assay. Wound-healing assay was used to analyse cell migration. The expression of alkaline phosphatase (ALP) was detected using ALP staining. Mineralization was analysed by alizarin red staining. RESULTS: Calcium hydroxide increased the protein expression of phosphorylated-GSK3ß/GSK3ß, ß-catenin and the gene expression of LEF-1. Inhibition of Wnt/ß-catenin abolished calcium hydroxide-induced proliferation and migration of DPSCs in 24 h. However, incubation with calcium hydroxide for 7 days and 14 days reduced Wnt/ß-catenin signalling. Inhibition of Wnt/ß-catenin promoted calcium hydroxide-induced osteogenic differentiation and mineralization in DPSCs. CONCLUSION: Wnt/ß-catenin pathway plays a dual role in calcium hydroxide-regulated DPSC behaviour. Incubation with calcium hydroxide promoted rapid proliferation and migration of DPSCs, while prolonged incubation negatively regulated osteogenic differentiation and mineralization.

Static magnetic field regulates proliferation, migration, and differentiation of human dental pulp stem cells by MAPK pathway.

Magnetic materials are now commonly used in dental clinics. These materials generally produce a static magnetic field (SMF). While it is known that SMF can affect cells' behaviors such as proliferation, migration, and differentiation, the mechanisms underlying these effects are still unclear. Our study investigates the role of the mitogen-activated protein (MAP) kinase pathway in SMF-induced proliferation, migration, osteogenic/odontogenic differentiation, and mineralization in human dental pulp stem cells (DPSCs). Human DPSCs were exposed to SMF of 1 mT and the phosphorylated MAP kinases were detected by Western blot analysis. Three MAP kinases inhibitors were pre-cultured with DPSCs and exposed to SMF for 24 h. Cell viability was analyzed using Cell Counting Kit-8. Cell migration was tested by a wound healing assay. Osteogenic/odontogenic differentiation was detected by ALP staining assay, ALP and DSPP Western blot analysis. Mineralization was studied by alizarin red staining analysis. SMF activated phosphorylation of c-Jun N-terminal kinase (JNK), P38 and extracellular signal-regulated kinase (ERK). The inhibition of JNK, P38, and ERK signaling decreased SMF-induced proliferation and migration. ERK and P38 play more important roles in SMF-induced ALP staining and protein expression. JNK was vital for SMF-induced DSPP expression. JNK, P38, and ERK all involved in SMF-mediated mineralization. Our study demonstrated that the MAPK pathway regulated SMF-induced proliferation, migration, osteogenic/odontogenic differentiation, and mineralization in human DPSCs.

Platelet-Derived Growth Factor Receptor-α and ß are Involved in Fluid Shear Stress Regulated Cell Migration in Human Periodontal Ligament Cells.

INTRODUCTION: Fluid shear stress (FSS) is the most common stress produced by mastication, speech, or tooth movement. However, how FSS regulates human periodontal ligament (PDL) cell proliferation and migration as well as the underlying mechanism remains unknown. METHODS: FSS (6 dyn/cm2) was produced in a flow chamber. Cell proliferation was tested by the 5-ethynyl-2'-deoxyuridine assay. Cell migration was tested by the wound healing assay. Gene and protein expression of platelet-derived growth factors (PDGFs) and matrix metalloproteinase (MMP)-2 were measured by reverse transcription-polymerase chain reaction and western blot analyses. RESULTS: We investigated the effect of 4 h of 6 dyn/cm2 FSS on proliferation and migration of PDL cells. FSS promoted PDL cell proliferation but inhibited migration. The gene and protein expression of PDGF receptor (PDGFR)-α and ß both decreased in response to FSS. Activating and inhibiting the PDGFRs did not affect the FSS-induced increase in cell proliferation. However, activating PDGFRs with PDGF-BB, which bound both PDGFR-α and ß, and PDGF-CC and DD, which had high affinities for PDGFR-α and PDGFR-ß, individually rescued FSS-inhibited migration. FSS also inhibited MMP-2 gene expression, which was the most important factor for matrix turnover and migration of PDLs. PDGF-BB, CC, and DD increased the FSS-induced decline in MMP-2 expression. These results indicate that MMP-2 is regulated by FSS and contributes to the FSS-induced decrease in cell migration. CONCLUSIONS: Our study suggests a role for PDGFR-α and ß in short-term FSS-regulated cell proliferation and migration. These results will help provide the scientific foundation for revealing the mechanisms clinical tooth movement and PDL regeneration.