RNA sequencing data of human periodontal ligament cells treated with continuous and intermittent compressive force.

Mechanical force regulates numerous biological functions. Application of different force types leads to different cell responses. This data article describes RNA sequencing data identifying gene expression of human periodontal ligament cells (hPDLs) treated with the continuous or intermittent compressive force. These data could be further utilized to investigate the controlling pathways that regulate hPDLs' behaviors by the different force types. Raw RNA sequencing data were deposited in the NCBI Sequence Read Archive (SRP136155) and NCBI Gene Expression Omnibus (GSE112122).

Intermittent compressive force promotes osteogenic differentiation in human periodontal ligament cells by regulating the transforming growth factor-ß pathway.

Mechanical force regulates periodontal ligament cell (PDL) behavior. However, different force types lead to distinct PDL responses. Here, we report that pretreatment with an intermittent compressive force (ICF), but not a continuous compressive force (CCF), promoted human PDL (hPDL) osteogenic differentiation as determined by osteogenic marker gene expression and mineral deposition in vitro. ICF-induced osterix (OSX) expression was inhibited by cycloheximide and monensin. Although CCF and ICF significantly increased extracellular adenosine triphosphate (ATP) levels, pretreatment with exogenous ATP did not affect hPDL osteogenic differentiation. Gene-expression profiling of hPDLs subjected to CCF or ICF revealed that extracellular matrix (ECM)-receptor interaction, focal adhesion, and transforming growth factor beta (TGF-ß) signaling pathway genes were commonly upregulated, while calcium signaling pathway genes were downregulated in both CCF- and ICF-treated hPDLs. The TGFB1 mRNA level was significantly increased, while those of TGFB2 and TGFB3 were decreased by ICF treatment. In contrast, CCF did not modify TGFB1 expression. Inhibiting TGF-ß receptor type I or adding a TGF-ß1 neutralizing antibody attenuated the ICF-induced OSX expression. Exogenous TGF-ß1 pretreatment promoted hPDL osteogenic marker gene expression and mineral deposition. Additionally, pretreatment with ICF in the presence of TGF-ß receptor type I inhibitor attenuated the ICF-induced mineralization. In conclusion, this study reveals the effects of ICF on osteogenic differentiation in hPDLs and implicates TGF-ß signaling as one of its regulatory mechanisms.

Prolonged release of iloprost enhances pulpal blood flow and dentin bridge formation in a rat model of mechanical tooth pulp exposure.

The aim of this study was to investigate the effect of prolonged release of iloprost, a prostacyclin analog, on angiogenesis and dental pulp healing in a rat model of mechanical pulp exposure. The profile of iloprost release from poly (lactic-co-glycolic) acid (PLGA) microspheres was evaluated, and expression of vascular endothelial growth factor (VEGF) mRNA was determined. The molars of rats were subjected to mechanical pulp exposure and 5 different forms of treatment: Ca(OH)2, PLGA (blank), iloprost, and iloprost/PLGA. Blood flow was determined at 0, 3, and 7 days using laser Doppler flowmetry. After 30 days, the tooth specimens were collected, and subjected to micro-CT and immunohistological analysis. The results showed that iloprost release from the microspheres was prolonged for 4 days, and that the treatment increased tooth blood flow for up to 7 days. At 30 days, an increase of mineralized tissue formation and dentin bridge formation was observed in the iloprost and iloprost/PLGA microsphere groups. VEGF expression was significantly increased in the iloprost/PLGA microsphere group relative to the other groups. In conclusion, this PLGA microsphere iloprost delivery system significantly increased dental pulp blood flow in a prolonged manner and increased tertiary dentin formation in this rat pulp injury model. Prolonged prostacyclin release could be a potentially useful approach for regeneration of dental pulp.

Mechanical stress induced S100A7 expression in human dental pulp cells to augment osteoclast differentiation.

OBJECTIVES: Mechanical injury of dental pulp leads to root resorption by osteoclasts/odontoclasts. S100 proteins have been demonstrated to be involved in inflammatory processes and bone remodeling. This study aimed to investigate the effect of mechanical stress on S100A7 expression by human dental pulp cells (HDPCs) and the effect of S100A7 proteins on osteoclast differentiation. MATERIALS AND METHODS: Isolated HDPCs were stimulated with compressive loading (2 and 6 hr), or shear loading (2, 6, and 16 hr). S100 mRNA expression and S100A7 protein levels were determined by real-time PCR and ELISA, respectively. Osteoclast differentiation was analyzed using primary human monocytes. The differentiation and activity of osteoclasts were examined by TRAcP staining and dentine resorption. In addition, the expression of S100A7 was analyzed in pulp tissues obtained from orthodontically treated teeth. RESULTS: Compressive and shear mechanical stress significantly upregulated both mRNA and protein level of S100A7. Dental pulp tissues from orthodontically treated teeth exhibited higher S100A7mRNA levels compared to non-treated control teeth. S100A7 promoted osteoclast differentiation by primary human monocytes. Moreover, S100A7 significantly enhanced dentine resorption by these cells. CONCLUSIONS: Mechanical stress induced expression of S100A7 by human dental pulp cells and this may promote root resorption by inducing osteoclast differentiation and activity.

Iloprost Induces Dental Pulp Angiogenesis in a Growth Factor-free 3-Dimensional Organ Culture System.

INTRODUCTION: Angiogenesis is a key determinant in dental pulp regeneration. Iloprost is a synthetic prostacyclin that promotes angiogenesis. A three-dimensional culture that mimics the in vivo condition has been used in tissue engineering. This study investigated the effect of iloprost on promoting dental pulp angiogenesis by using the tooth slice organ culture system. METHODS: Tooth slices with intact pulp tissue were cut from molars extracted from 12 patients. Dental pulp tissue viability was determined by live/dead staining. The tooth slices were cultured with iloprost for 1 or 3 days. The microvessel density and expression of vascular endothelial growth factor were determined by immunohistochemical staining. Collagen density was determined by using Masson trichrome and immunofluorescent staining. RESULTS: The pulp tissue in the tooth slices remained viable when cultured in serum-free medium. Iloprost increased the microvessel density as shown by a higher number of von Willebrand factor-positive cells. A significant increase in vascular endothelial growth factor expression was observed in the tooth slices cultured with iloprost. Iloprost stimulated collagen deposition, and this effect was abolished after inhibition of protein kinase A activity. CONCLUSIONS: Human tooth slices provide a valuable and easy-to-obtain model to investigate the effect of bioactive molecules used in dental pulp regeneration. This study showed for the first time that tooth slices could be kept viable under serum-free conditions for up to 3 days. Iloprost promoted angiogenesis, increased new vessel formation, and induced collagen deposition. This study proposes the clinical value of iloprost as a drug for inducing angiogenesis that can increase the success of pulp regeneration.