L型钙离子通道α 1亚基D亚型在发育小鼠磨牙牙胚成牙本质细胞中的表达

目的：研究成牙本质细胞分化不同阶段L型钙离子通道α1亚基D亚型的分布情况。方法：采用兔抗小鼠L型钙离子通道α1D亚基多克隆抗体进行牙胚免疫组织化学染色。结果：在前成牙本质细胞胞体，功能性成牙本质细胞的近矿化端以及成熟成牙本质细胞的胞体和突起上均发现有L型钙离子通道α1亚基D亚型分布，结论：成牙本质细胞可能通过L型钙离子通道α1亚基D亚型转运钙离子参与牙本质矿化过程。     

Calbindin-D28k与肌动蛋白在大鼠切牙成牙本质细胞的分布

目的 探讨Calbindin-D28k与肌动蛋白在大鼠下颌切牙成牙本质细胞中分布的相关性及其意义。方法 用免疫组化方法分别检测Calbindin-D28k与肌动蛋白在大鼠下颌切牙成牙本质细胞中的表达并观察比较。结果 大鼠下颌切牙唇侧区域的冠方2／3成牙本质细胞Calbindin-D28k与肌动蛋白表达均为阳性，且都集中于成牙本质细胞突；根尖区和舌侧成牙本质细胞均为阴性。结论 Calbindin-D28k与肌动蛋白在大鼠下颌切牙成牙本质细胞中的分布具有一致性，与牙本质的形成密切相关。     

波形蛋白标记观察人恒前磨牙成牙本质细胞突的分布

目的 :利用免疫酶组化染色技术 ,对人恒前磨牙成牙本质细胞突内的波形蛋白进行定位研究。方法 :将牙齿拔除后立即磨成薄片 ,10 0ml/L中性福尔马林液固定 72h ,10 0ml/L硝酸脱钙。石蜡包埋 ,制取6 μm厚的组织切片。采用SABC法进行免疫组化染色。 结果 :阳性染色的波形蛋白结构在牙本质小管内呈连续较直的长条状。在冠部至釉牙本质界 ,在根部达牙本质小管末端。其分布趋势是从牙本质内层到外层逐渐减少 ,阳性表达程度逐渐减弱。结论 :成牙本质细胞突贯通牙本质全层达牙本质小管末端。     

Dentin conditioning codetermines cell fate in regenerative endodontics

Introduction

Recent successes in dental pulp engineering indicate that regenerative treatment strategies in endodontics are feasible. Clinically, revascularization procedures render completion of root formation in immature teeth. The generation of a pulp-like tissue after seeding of dental pulp stem cells into dentin discs or cylinders and transplantation in vivo is possible. In this experimental setup, which mimics the situation in the root canal, the pretreatment of dentin might influence cellular behavior at the cell-dentin interface. Thus, the objective of this study was to investigate whether dentin conditioning can determine cell fate.

Methods

Dental pulp stem cells (DPSCs) were seeded into a growth factor–laden peptide hydrogel, transferred into dentin cylinders, and transplanted subcutaneously into immunocompromised mice. Before cell seeding, dentin cylinders were either pretreated with sodium hypochloride (NaOCl) or conditioned with EDTA. The constructs were explanted after 6 weeks and subjected to histological and immunohistochemical analysis.

Results

In dentin treated with NaOCl, resorption lacunae were found at the cell-dentin interface created by multinucleated cells with clastic activity. After conditioning with EDTA, DPSCs adjacent to the dentin formed an intimate association with the surface, differentiated into odontoblasts-like cells that expressed dentin sialoprotein, and extended cellular processes into the dentinal tubules. A vascularized soft connective tissue similar to dental pulp was observed inside the dentin cylinder.

Conclusions

Dentin conditioning considerably influences DPSC fate when seeded in close proximity to dentin. This information might be critical for optimized strategic planning for future regenerative endodontic treatment.     

BMP2在大鼠牙髓损伤修复中的表达及其对牙髓细胞的生物学效应

目的：从体内体外两方面探讨BMP2在牙髓损伤修复，尤其是牙髓细胞分化过程中的作用。方法：建立大鼠牙髓损伤修复模型和体外人牙髓细胞连续培养，采用免疫组织化学、MTT法和酶动力学等方法，检测BMP2在体内牙髓组织损伤修复过程中的表达，并比较不同浓度rhBMP2对体外人牙髓细胞连续培养各阶段细胞增殖活性及ALP活性的影响。结果：体内牙髓组织损伤修复过程中存在BMP2的表达，牙髓组织损伤修复的不同阶段其表达部位和强度发生变化；rhBMP2可提高体外培养人牙髓细胞的增殖活性，与其本身浓度有关，并可促进人虎髓细胞ALP活性，呈浓度依赖性；结论：BMP2是参与牙髓损伤修复，尤其是牙髓细胞的增殖和分化的重要因子之一。     

JNK MAPK is involved in BMP-2-induced odontoblastic differentiation of human dental pulp cells

Bone morphogenetic protein-2 (BMP-2) is a multi-functional growth factor belonging to the transforming growth factor β superfamily that has a broad range of activities that affect many different cell types. BMP-2 induces odontoblastic differentiation of human dental pulp cells (DPCs), but the underlying mechanism remains unclear. In this study, we investigated the potential role of the JNK mitogen-activated protein kinases (MAPK) pathway in BMP-2-induced odontoblastic differentiation of DPCs. The levels of phosphorylated and unphosphorylated JNK MAPK were quantified by Western blot analysis following treatment with BMP-2 and the JNK inhibitor SP600125. The role of JNK MAPK in the BMP-2-induced odontoblastic differentiation of DPCs was determined by measuring alkaline phosphatase (ALP) activity and by examining the expression of odontoblastic markers using quantitative real-time polymerase chain reaction analysis. The effect of JNK MAPK silencing on odontoblastic differentiation was also investigated. BMP-2 upregulated the phosphorylation of JNK in DPCs in a dose- and time-dependent manner. Early markers of odontoblastic differentiation, including ALP activity, osteopontin and dentin matrix protein-1, were not inhibited by the JNK inhibitor. However, the JNK inhibitor, SP600125, significantly inhibited late-stage differentiation of odontoblasts, including the gene expression of osteocalcin, dentin sialophosphoprotein and bone sialoprotein, and also reduced the formation of mineralized nodules in BMP-2-treated DPCs. Consistent with this observation, silencing of JNK MAPK also decreased late-stage odontoblastic differentiation. Taken together, these findings suggest that JNK activity is required for late-stage odontoblastic differentiation induced by BMP-2.     

Matrilin家族的研究进展

Matrilin家族即母系蛋白家族，是一个非胶原性细胞外基质蛋白家族，主要在骨和软骨组织中表达，参与形成细胞外基质，是多种骨发育异常疾病、骨关节炎的致病因子，多种细胞信号途经通过调节Matrilins的表达调控细胞外基质的性能。Matrilins可作为具有高分化增殖潜能细胞的标记。在牙体组织中，Matrilin-4特异性表达于成牙本质细胞，可能与牙本质形成、矿化及牙本质发育不全等疾病有关。     

Early in vivo and in vitro effects of amelogenin gene splice products on pulp cells

Recombinant amelogenin gene splice products A+4 and A-4, implanted in the pulp, induce the recruitment, proliferation, and differentiation of reparative cells. Our aim was to investigate the precocious events occurring in the pulp 1 d and 3 d after implantation of agarose beads alone or loaded with A+4 or A-4. Proliferation and cell recruitment towards an odonto/osteogenic phenotype were visualized by detection of the proliferation cell nuclear antigen (PCNA) and RP59. After implantation of beads alone or loaded with A+4, at day 3, pulp cells were moderately immunopositive for osteopontin (OP), whereas labeling was strongly positive upon treatment with A-4. Dentin sialoprotein (DSP) labeling was not detectable. Parallel in vitro studies were carried out on odontoblastic and mesenchymal progenitor cells in order to evaluate the effect of the amelogenin peptides on the expression of a series of marker genes involved in the odontoblastic/osteogenic/chondrogenic differentiation pathways. Altogether, our results suggest that the 'signaling' effects of the amelogenin peptides A+4 and A-4 may differ according to the type of target cells, their stage of differentiation, the time of treatment, and the type of amelogenin peptide (A+4 or A-4).     

Effects of aFGF,bFGF, TGFβ1 and IGF-I on odontoblast differentiation in vitro

In this work, we investigated the effects of aFGF and bFGF alone or combined with TGFβ1 or IGF-I on odontoblast differentiation. Trypsin-isolated dental papillae from day 17 mandibular first molar were cultured in semisolid-agar medium for 6 d. Our results demonstrated that aFGF, bFGF or combinations of these promoted cell polarization at the periphery of the dental Papillae. Moreover, simultaneous addition of aFGF and TGFβ1 to dental Papillae cultures induced both polarization and functional differentiation of odontoblast-like cells, as well as extracellular matrix deposition. Combination of aFGF or bFGF with IGF-I caused cell polarization at the surface of dental papillae, but matrix secretion was restricted to a few explants. In the presence of bFGF and TGFβ1, the explants had pronounced cell elongations but no matrix deposition. These results indicate that aFGF or bFGF is not able to induce odontoblast differentiation alone. However, both aFGF and bFGF can act synergistically with TGFβ1 and IGF-I to strengthen their inductive effects and promote gradients of cytological and functional changes in odontoblast-like cells.