OBJECTIVES: This study aimed to explore the impact of cell spreading area on odontoblast polarization and differentiation using micropatterned surfaces ge-nerated by photolithography. METHODS: Micropatterned surfaces with differential adhesive properties were prepared using polyethylene glycol diacrylate (PEGDA)-ba-sed photolithography. Human dental pulp stem cells (hD-PSCs) were isolated into single cells and cultured on micropatterned surfaces with areas of 1 800, 2 700, and 3 600 μm². Immunofluorescence staining was used to observe cell morphology and analyze the relocating of the golgi apparatus and nucleus. Alkaline phosphatase staining was preformed to examine odontogenic differentiation. RESULTS: The hDPSCs were successfully isolated and cultured on micropatterned surfaces mimicking the morphology of polarized odontoblasts. Phalloidin staining confirmed that the isolated hDPSCs successfully recapitulated the morphology of predesigned micropatterns. Immunofluorescence staining showed that the polarization and differentiation levels of the hDPSCs with a 3600 μm² area were significantly higher than those with 1 800 and 2 700 μm² areas (P<0.05). CONCLUSIONS The polarization and differentiation of single hDPSCs increased with the cell areas on micropatterned surfaces.
Cell Differentiation ; Humans ; Dental Pulp/cytology* ; Odontoblasts/cytology* ; Stem Cells/cytology* ; Cells, Cultured ; Cell Polarity ; Surface Properties

The expression of dentin sialophosphoprotein (DSPP) is the marker for cells differentiated into odontoblasts. This study attempted to analyze the DSPP promoter and build the reporter LacZ expression system driven by this promoter, which allows convenient and quick detection of odontoblast cells. First, we separated the human dental mesenchymal cells in which the expression of DSPP can be effectively induced by dexamethasone. Second, four 5' flanking regions of human DSPP gene (- 4 000-+54, -2 500-+54, -1 447-+54 and -1 027-+54) were analyzed, the results showed that the highest promoter activity lied in the -2 500-+54 region. The promoter activity is reduced when the 5' flanking region was extended from -2 500 to -4 000 bp upstream from the transcription start site; The promoter activity are also decreased when the 5' flanking regions were shorted from -2 500 to -1 447 bp and from -1 447 to -1 027 bp, indicating that potential suppresser elements are lied in the region between -4 000 and -2 500 bp and potential activator elements are lied in the region between -2 500 and -1 027 bp. Then we constructed the lentiviral report vector phDSPP-LacZ containing the -2 500-+ 54 promoter region in front of the LacZ gene. The expression of LacZ was detected using X-Gal staining in both human dental mesenchymal cells and immortalized human dental mesenchymal cells infected with phDSPP-LacZ. The phDSPP-LacZ lentiviral vector may provide a more convenient method to detect the expression of DSPP in human odontogenic differentiation, tooth development and tooth regeneration studies.
Cell Differentiation ; Extracellular Matrix Proteins ; genetics ; Genes, Reporter ; Humans ; Lac Operon ; Odontoblasts ; cytology ; Phosphoproteins ; genetics ; Promoter Regions, Genetic ; Sialoglycoproteins ; genetics

Dentin matrix protein 1 (DMP1) is essential to odontogenesis. Its mutations in human subjects lead to dental problems such as dental deformities, hypomineralization and periodontal impairment. Primarily, DMP1 is considered as an extracellular matrix protein that promotes hydroxyapatite formation and activates intracellular signaling pathway via interacting with αvβ3 integrin. Recent in vitro studies suggested that DMP1 might also act as a transcription factor. In this study, we examined whether full-length DMP1 could function as a transcription factor in the nucleus and regulate odontogenesis in vivo. We first demonstrated that a patient with the DMP1 M1V mutation, which presumably causes a loss of the secretory DMP1 but does not affect the nuclear translocation of DMP1, shows a typical rachitic tooth defect. Furthermore, we generated transgenic mice expressing (NLS)DMP1, in which the endoplasmic reticulum (ER) entry signal sequence of DMP1 was replaced by a nuclear localization signal (NLS) sequence, under the control of a 3.6 kb rat type I collagen promoter plus a 1.6 kb intron 1. We then crossbred the (NLS)DMP1 transgenic mice with Dmp1 null mice to express the (NLS)DMP1 in Dmp1-deficient genetic background. Although immunohistochemistry demonstrated that (NLS)DMP1 was localized in the nuclei of the preodontoblasts and odontoblasts, the histological, morphological and biochemical analyses showed that it failed to rescue the dental and periodontal defects as well as the delayed tooth eruption in Dmp1 null mice. These data suggest that the full-length DMP1 plays no apparent role in the nucleus during odontogenesis.
Animals ; Cell Nucleus ; genetics ; Codon, Initiator ; genetics ; Collagen Type I ; genetics ; Endoplasmic Reticulum ; genetics ; Extracellular Matrix Proteins ; genetics ; Familial Hypophosphatemic Rickets ; genetics ; Gene Targeting ; methods ; Genetic Vectors ; genetics ; Humans ; Introns ; genetics ; Methionine ; genetics ; Mice, Inbred C57BL ; Mice, Transgenic ; Mutation ; genetics ; Odontoblasts ; cytology ; Odontogenesis ; genetics ; Periodontal Diseases ; genetics ; Periodontal Ligament ; pathology ; Phosphoproteins ; genetics ; Promoter Regions, Genetic ; genetics ; Tooth Abnormalities ; genetics ; Tooth Eruption ; genetics ; Transcription Factors ; genetics ; Transgenes ; genetics ; Valine ; genetics ; Young Adult

Mesenchymal stem cells (MSCs) have been identified and isolated from dental tissues, including stem cells from apical papilla, which demonstrated the ability to differentiate into dentin-forming odontoblasts. The histone demethylase KDM6B (also known as JMJD3) was shown to play a key role in promoting osteogenic commitment by removing epigenetic marks H3K27me3 from the promoters of osteogenic genes. Whether KDM6B is involved in odontogenic differentiation of dental MSCs, however, is not known. Here, we explored the role of KDM6B in dental MSC fate determination into the odontogenic lineage. Using shRNA-expressing lentivirus, we performed KDM6B knockdown in dental MSCs and observed that KDM6B depletion leads to a significant reduction in alkaline phosphate (ALP) activity and in formation of mineralized nodules assessed by Alizarin Red staining. Additionally, mRNA expression of odontogenic marker gene SP7 (osterix, OSX), as well as extracellular matrix genes BGLAP (osteoclacin, OCN) and SPP1 (osteopontin, OPN), was suppressed by KDM6B depletion. When KDM6B was overexpressed in KDM6B-knockdown MSCs, odontogenic differentiation was restored, further confirming the facilitating role of KDM6B in odontogenic commitment. Mechanistically, KDM6B was recruited to bone morphogenic protein 2 (BMP2) promoters and the subsequent removal of silencing H3K27me3 marks led to the activation of this odontogenic master transcription gene. Taken together, our results demonstrated the critical role of a histone demethylase in the epigenetic regulation of odontogenic differentiation of dental MSCs. KDM6B may present as a potential therapeutic target in the regeneration of tooth structures and the repair of craniofacial defects.
Alkaline Phosphatase ; analysis ; Bone Morphogenetic Protein 2 ; genetics ; Bone Morphogenetic Protein 4 ; genetics ; Calcification, Physiologic ; genetics ; Cell Culture Techniques ; Cell Differentiation ; genetics ; Cell Lineage ; Dental Papilla ; cytology ; Epigenesis, Genetic ; genetics ; Gene Knockdown Techniques ; Homeodomain Proteins ; genetics ; Humans ; Jumonji Domain-Containing Histone Demethylases ; genetics ; Mesenchymal Stromal Cells ; physiology ; Odontoblasts ; physiology ; Odontogenesis ; genetics ; Osteocalcin ; analysis ; Osteopontin ; analysis ; Promoter Regions, Genetic ; genetics ; RNA, Small Interfering ; genetics ; Sp7 Transcription Factor ; Transcription Factors ; analysis ; genetics ; Transcriptional Activation ; genetics

Epithelial-mesenchymal interactions (EMIs) are critical for tooth development. Molecular mechanisms mediating these interactions in root formation is not well understood. Laser capture microdissection (LCM) and subsequent microarray analyses enable large scale in situ molecular and cellular studies of root formation but to date have been hindered by technical challenges of gaining intact histological sections of non-decalcified mineralized teeth or jaws with well-preserved RNA. Here,we describe a new method to overcome this obstacle that permits LCM of dental epithelia,adjacent mesenchyme,odontoblasts and cementoblasts from mouse incisors and molars during root development. Using this method,we obtained RNA samples of high quality and successfully performed microarray analyses. Robust differences in gene expression,as well as genes not previously associated with root formation,were identified. Comparison of gene expression data from microarray with real-time reverse transcriptase polymerase chain reaction (RT-PCR) supported our findings. These genes include known markers of dental epithelia,mesenchyme,cementoblasts and odontoblasts,as well as novel genes such as those in the fibulin family. In conclusion,our new approach in tissue preparation enables LCM collection of intact cells with well-preserved RNA allowing subsequent gene expression analyses using microarray and RT-PCR to define key regulators of tooth root development.
Animals ; Dental Cementum ; cytology ; metabolism ; Epithelial-Mesenchymal Transition ; physiology ; Gene Expression Regulation, Developmental ; Laser Capture Microdissection ; Mice ; Mice, Inbred Strains ; Odontoblasts ; metabolism ; Oligonucleotide Array Sequence Analysis ; Reverse Transcriptase Polymerase Chain Reaction ; Tooth Germ ; metabolism ; Tooth Root ; growth & development

AIMTo detect the expression of HSP25 in rat dental follicles both in vivo and vitro, and explore the underlying mechanism of HSP25 on the proliferation and differentiation of rat dental follicle cells (DFCs).

METHODOLOGYImmunohistochemistry was performed to detect the expression of HSP25 in mandibles of postnatal rats on days 1, 3, 5, 7, 9 and 11 in vivo. In vitro, the expression of HSP25 in DFCs was detected by an indirect immunofluorescence assay. Thiazolyl blue tetrazolium bromide (MTT) assay, flow cytometry and alkaline phosphatase (ALP) assay were used to identify the time-course effect mediated by different concentrations of recombinant murine HSP25 of 0, 1, 10, 50 and 100 ng/mL on rat DFCs.

RESULTSExpression of HSP25 was not detected in dental follicles of the rats until day 5 after birth, but became up-regulated in a time-dependent manner till day 11. HSP25 was detected in the cytoplasm of cultured rat DFCs. No significant difference could be observed in the proliferation of DFCs after stimulation with different concentrations of HSP25 on days 1, 2 and 3 (P > 0.05). HSP25 at concentrations of 50 ng/mL and 100 ng/mL up-regulated the ALP activity of DFCs on day 9 (P < 0.05).

CONCLUSIONHSP25-immunoreactivity increased chronologically during the development of dental follicles. The protein had no significant effect on cell proliferation but may play a role in cementoblast/osteoblast differentiation of DFCs.

Alkaline Phosphatase ; analysis ; Ameloblasts ; cytology ; Animals ; Cell Culture Techniques ; Cell Differentiation ; physiology ; Cell Proliferation ; Coloring Agents ; Cytoplasm ; ultrastructure ; Dental Sac ; cytology ; growth & development ; Flow Cytometry ; Fluorescent Antibody Technique, Indirect ; HSP27 Heat-Shock Proteins ; analysis ; physiology ; Odontoblasts ; cytology ; Rats ; Rats, Sprague-Dawley ; Tetrazolium Salts ; Thiazoles ; Tooth Germ ; cytology ; Up-Regulation ; physiology

OBJECTIVETo investigate the effect of adenovirus expressing human bone morphogenetic protein-7 (hBMP-7) on proliferation and differentiation of human dental pulp cells.

METHODSThe replication-deficient adenoviral vector encoding hBMP-7 gene was constructed by using homologous recombinant modality. The efficiency of transfection was evaluated by fluorescent microscopy and flow cytometry. The expression of hBMP-7 protein in adenovirus-infected dental pulp cells was determined by Western blot. The proliferation of cells was tested by MTT method, the activity of alkaline phosphatase was assayed, von Kossa staining was used to detect mineralized nodule formation, and the expression of DSPPmRNA in cells was detected using semi-quantitative RT-PCR.

RESULTSGreen fluorescent protein was visible under fluorescent microscopy. Higher transfection efficiency (91.1 +/- 1.0)% could be obtained at MOI of 75. Western blot from dental pulp cells infected with Ad-hBMP-7 for 48h detected protein expression of a hBMP-7 gene. The activity of alkaline phosphatase in cells was significantly higher than those of the control groups (P < 0.05). The cells infected with Ad-hBMP-7 had the ability of mineralization. DSPP mRNA expression of cells was in a time- and dose- dependent manner.

CONCLUSIONSAd-hBMP-7 can induce human pulp cells into odontoblasts, but has no obvious effect on their proliferation.

Adenoviridae ; genetics ; Bone Morphogenetic Protein 7 ; genetics ; metabolism ; Cell Differentiation ; Cell Proliferation ; Cells, Cultured ; Dental Pulp ; cytology ; Humans ; Odontoblasts ; cytology ; Transfection

OBJECTIVETo characterize the role of Smads proteins in alpha 2 (I) collagen (COL1A2) gene expression induced by bone morphogenetic protein-2 (BMP-2) in odontoblast cell line MDPC-23.

METHODSEndogenous Smad protein expression was determined by immunocytochemistry. Smads function and their role in COL1A2 gene expression were investigated in cotransfection experiments using promoter-luciferase reporter gene construct.

RESULTSMDPC-23 cells expressed Smad1, Smad5 and Smad6. BMP-2 promoted the activation of COL1A2 promoter reporter construct. Transient overexpression of Smad1 or Smad5 was enhanced, while overexpression of Smad6 inhibited BMP-2-induced COL1A2 promoter activity. BMP-2 inducibility could be blocked by overexpression of Smad1 or Smad5 dominant negative mutant.

CONCLUSIONSSmad signaling is functioning and appears to be involved in BMP-2-induced COL1A2 collagen transcription in MDPC-23. Smad signaling may play an important role in odontoblast differentiation and dentin extracellular matrix formation mediated by BMP-2.

Animals ; Bone Morphogenetic Protein 2 ; Bone Morphogenetic Proteins ; genetics ; Cell Line ; Collagen ; genetics ; Collagen Type I ; Mice ; Odontoblasts ; cytology ; metabolism ; Smad Proteins ; physiology ; Transforming Growth Factor beta ; genetics

OBJECTIVETo observe the temporal and spatial expression of Smad7 during human tooth germ development and evaluate the effect of Smad7 on tooth germ development.

METHODSThe expression of Smad7 and its changes at different stages of human tooth germ were detected by using immunohistochemical staining.

RESULTSSmad7 was expressed at all stages of tooth germ, but the distribution patterns at various stages were different. It indicated that temporal and spatial expressing mode of Smad7 during human tooth germ development was specific, which was similar to that of TGF-beta its signal transducer Smad2/3.

CONCLUSIONSmad7 might play an important role in TGF-beta intracellular signaling for modulating the differentiation of ameloblasts and odontoblasts.

Ameloblasts ; cytology ; Cell Differentiation ; DNA-Binding Proteins ; genetics ; metabolism ; physiology ; Fetus ; Humans ; Immunohistochemistry ; Odontoblasts ; cytology ; Odontogenesis ; Signal Transduction ; Smad7 Protein ; Tooth ; growth & development ; Tooth Germ ; embryology ; Trans-Activators ; genetics ; metabolism ; physiology ; Transforming Growth Factor beta ; genetics ; metabolism ; physiology

OBJECTIVETo study the roles of the Notch2-Delta signaling in the differentiation of dental pulp cells into odontoblasts in vitro.

METHODSA long-term culture system was used as a model for the study of proliferation and differentiation of pulp cells into preodontoblasts. The expression patterns of Notch2 and its ligand Delta in different phases of long-term cultured dental pulp cells were studied by immunohistochemistry and western blotting. Furthermore, the effects of rhBMP-2 on the expression of Notch signaling members were studied.

RESULTSNotch2 and its ligand Delta expressed in all phases of dental pulp cells and the sites and levels of their expression changed with different phases. rhBMP-2 could significantly up-regulated the expression of Delta in the phase of later cell nodule formation.

CONCLUSIONThis study demonstrated that Notch signaling pathway played roles in the differentiation of long-term cultured human dental pulp cells which formed nudules that were slightly mineralized and had ultrastructural features reminiscient of preodontoblasts, and it may be the mechanism that control pulpal cell's responsiveness to signaling molecules in the healing of wound pulp.

Bone Morphogenetic Protein 2 ; Bone Morphogenetic Proteins ; pharmacology ; Cell Differentiation ; Cells, Cultured ; Dental Pulp ; cytology ; metabolism ; Humans ; Immunohistochemistry ; Intracellular Signaling Peptides and Proteins ; Membrane Proteins ; biosynthesis ; physiology ; Odontoblasts ; cytology ; metabolism ; Receptor, Notch2 ; Receptors, Cell Surface ; biosynthesis ; physiology ; Recombinant Proteins ; pharmacology ; Signal Transduction ; Transforming Growth Factor beta