Liu He, Li Wu, Shi Songtao, Habelitz Stefan, Gao Cen, Denbesten Pamela
University of California, San Francisco, Growth and Development, 521 Parnassus Avenue, Rm C734, Box 0640, San Francisco, CA 94143-0640, USA.
Arch Oral Biol. 2005 Nov;50(11):923-8. doi: 10.1016/j.archoralbio.2005.03.003. Epub 2005 Apr 13.
Previous studies on dental pulp cell culture have described heterogenous mixtures of cells that differentiate into odontoblasts and form mineralized dentin.
The aim of this study was to characterize the matrix extracellular phosphoglycoprotein (MEPE) expression by dental pulp stem cells (DPSC), related to cell differentiation.
DPSC differentiation to form mineralized nodules was characterized by Alizarin red staining and micro-Raman spectroscopy. Osteogenesis SuperArray analysis was used to broadly screen for osteogenesis-related genes altered by DPSC differentiation. Relative levels of expression of MEPE and DSP were determined by semiquantitative RT-PCR and Western blot.
Mineral analysis showed that as DPSC differentiated, they formed a carbonated hydroxyapatite mineral. Differentiation was initially marked by upregulation by Runx2, TGFbeta-related genes, EGFR and genes involved in collagen metabolism. ALP activity first increased, as DPSCs reached confluence but later decreased when cells further differentiated three weeks after confluence. MEPE was the only marker that was downregulated as DPSCs differentiated.
DPSC differentiation can be characterized by downregulation of MEPE as other markers of DPSC differentiation, such as DSP, are upregulated. Expression of MEPE related to DSP and can be used to monitor DPSC as they are used for studies of odontoblast differentiation, tissue engineering or vital pulp therapy. The downregulation of MEPE as DPSC differentiate, suggests that MEPE is an inhibitor of mineralization.
先前关于牙髓细胞培养的研究描述了可分化为成牙本质细胞并形成矿化牙本质的细胞异质混合物。
本研究旨在表征牙髓干细胞（DPSC）中与细胞分化相关的基质细胞外磷酸糖蛋白（MEPE）表达。
通过茜素红染色和显微拉曼光谱对DPSC分化形成矿化结节进行表征。利用成骨基因芯片分析广泛筛选DPSC分化后改变的成骨相关基因。通过半定量逆转录聚合酶链反应（RT-PCR）和蛋白质免疫印迹法测定MEPE和牙本质涎磷蛋白（DSP）的相对表达水平。
矿物质分析表明，随着DPSC分化，它们形成了碳酸羟基磷灰石矿物质。分化最初以Runx2、转化生长因子β（TGFβ）相关基因、表皮生长因子受体（EGFR）和参与胶原代谢的基因上调为特征。碱性磷酸酶（ALP）活性在DPSC达到汇合时首先增加，但在汇合后三周细胞进一步分化时降低。MEPE是DPSC分化过程中唯一下调的标志物。
DPSC分化的特征可以是MEPE下调，而DPSC分化的其他标志物如DSP上调。MEPE的表达与DSP相关，可用于监测DPSC用于成牙本质细胞分化、组织工程或牙髓活力治疗的研究。DPSC分化时MEPE下调，提示MEPE是矿化的抑制剂。
