mTor plays an important role in odontoblast differentiation.

Signaling pathways responsible for dentin regeneration in a dental pulp are not fully understood. In this study, we determined the effects of the mammalian target of rapamycin (mTor) on the differentiation and mineralization of dental pulp stem cells. We hypothesized that the two known mTor complexes Torc1 and Torc 2 play pivotal roles in the differentiation of odontoblasts and that they modulate deposition of a mineralized extracellular matrix. Therefore, we investigated the effects of Torc1 and Torc 2 signaling on the differentiation and mineralization of stem cells from human exfoliated deciduous teeth (SHED). We used Western blot analysis to examine the expression of markers of dental differentiation in SHED (+/-) inhibition of either Torc1 or Torc 2 complex proteins raptor or rictor, respectively. In addition, the deposition of a mineralized matrix was determined under these conditions via alkaline phosphatase and alizarin red staining. Results show that the inhibition of Torc 1, via reduced expression of either raptor or mTor, severely restricts the synthesis of dentin sialoprotein and inhibits deposition of a mineralized matrix. Inhibition of Torc 2, via reduction of rictor, has the opposite effect, enhancing mineralization. This latter effect disappears when both rictor and mTor are inhibited, showing that the Torc 2 effect is Torc 1 dependent. These results strongly suggest an important role for mTor in dental pulp stem cell differentiation and provide evidence that the mechanisms involved in protein synthesis could prove an interesting target for dental pulp tissue engineering.

Kim JK ，Baker J ，Nor JE ，Hill EE ... -  《-》

Inhibition of Delta1 promotes differentiation of odontoblasts and inhibits proliferation of human dental pulp stem cell in vitro.

Dental pulp stem cells (DPSCs) have been receiving more attentions recently as an important biomaterial for tissue engineering. Notch signalling plays a key role in regulating self-renewal and differentiation of a variety of cells. The objective of this study is to investigate the effects of Notch-Delta1 RNA interference (RNAi) on the proliferation and differentiation of human dental pulp stem cells in vitro. In the present study, we performed gene knockdown of Notch ligand Delta1 in DPSCs using lentivirus-mediated Delta1-RNAi. Changes of proliferation in DPSCs/Delta1-RNAi were examined by cell cycle analysis, Cell viability assay (CCK-8) and Western blot analysis of proliferating cell nuclear antigen (PCNA). Cells were cultured in odontoblast differentiation-inducing medium, and the differentiation of cells was detected with Alkaline phosphatase ALP activity assay, Alizarin red S staining, calcium concentration measurement, and Western blot analysis of Dentine sialophosphoprotein (DSPP). Lentivirus-mediated Delta1-RNAi stably knocked-down the expression of Delta1 and Notch signalling, and some of DPSCs/Delta1-RNAi displayed changes in morphology or DSPP expression. The growth rate of Delta1-deficient DPSCs was significantly suppressed as compared with wild type DPSCs and control lentivirus vector transfected DPSCs. Furthermore, the differentiating capability of DPSCs/Delta1-RNAi into odontoblasts is much higher than the two control groups. Notch signalling plays a crucial role in regulating self-renewal and differentiation in DPSCs. The deficient Notch signalling inhibits the self-renewal capacity of DPSCs and tends to induce DPSCs differentiation under odontoblast differentiation-inducing conditions. These findings suggested that DPSCs/Delta1-RNAi might be applicable to stem cell therapies and tooth tissue engineering.

Wang X ，He F ，Tan Y ，Tian W ，Qiu S ... -  《-》

SHED differentiate into functional odontoblasts and endothelium.

Sakai VT ，Zhang Z ，Dong Z ，Neiva KG ，Machado MA ，Shi S ，Santos CF ，Nör JE ... -  《-》

Dentin-derived BMP-2 and odontoblast differentiation.

Casagrande L ，Demarco FF ，Zhang Z ，Araujo FB ，Shi S ，Nör JE ... -  《-》

Characterization of dental pulp stem cells isolated from canine premolars.

Dogs are commonly used animal models for regenerative endodontics research. Although several studies have used stem cells isolated from dog teeth to investigate the dentin/pulp regeneration in vivo, less attention has been paid for the characterization of these cells. Therefore, this study aimed to characterize the dental pulp stem cells isolated from dog teeth (cDPSCs) in order to further define the dog as an animal model for regenerative endodontics. Stem cells were isolated from freshly extracted premolars of 10-month-old Beagles. The isolated cells were investigated for their stem cell properties by analysis of their clonogenic and growth characteristics; expression of mesenchymal stem cell markers; and evaluation of their osteo/odontogenic, adipogenic, and neurogenic potential. A colony formation assay showed the existence of a clonogenic cell population in cDPSCs isolated. The growth curves revealed a higher proliferation rate of cDPSCs compared with hBMMSCs. cDPSCs expressed mesenchymal stem cell markers STRO-1, CD146, and Nanog. However, they were negative for CD73, CD105, and CD45. cDPSCs were able to differentiate into odontoblast-like cells as shown by increased alkaline phosphatase activity, dentin sialoprotein expression, and formation of mineralized nodules. cDPSCs also showed the neurogenic and adipogenic differentiation potential at a lower level compared with those of hDPSCs and hBMMSCs. The results of this study confirmed the stem cell properties of cDPSCs at a comparable level to those of hDPSCs and hBMMSCs. Overall, the data presented in this study provide evidence in supportive of using cDPSCs and dogs as an animal model in dental tissue engineering via stem cell-based approaches.

Dissanayaka WL ，Zhu X ，Zhang C ，Jin L ... -  《-》