牙髓干细胞（DPSC）是组织工程具有潜力的种子细胞，然而已有研究结果各相迥异，甚至有些研究表明其成骨和成牙能力有限。由于骨形成蛋白（BMP）被证明具有促进骨和牙本质形成的作用，本实验将经STRO-1分选的DPSC转染腺病毒介导的人BMP-2基因，并在无成骨环境诱导的条件下检测其牙向分化能力。检测内容有形态学观察、细胞增殖、碱磷酶活性及钙含量。实时定量PCR检测ALP、OCN、I型胶原、BSP、DSPP、DMP1的基因表达，Oligo基因芯片检测成牙相关基因的表达。实验结果表明只有经BMP2转染的细胞能分化为成牙本质细胞表型并产生矿化细胞外基质。相反，未经转染的细胞表现出未分化细胞的表型。结论：腺病毒可高效转染经STRO-1分选的DPSC，以此载体转染BMP2基因后，DPSC可在没有外源性成牙诱导环境中分化为成牙本质细胞表型。

Tissue Eng. 2007 Sep 9; [Epub ahead of print] 
   

STRO-1 Selected Rat Dental Pulp Stem Cells Transfected with Adenoviral-Mediated Human Bone Morphogenetic Protein 2 Gene Show Enhanced Odontogenic Differentiation.

   Yang X, Van Der Kraan PM, Van Den Dolder J, Walboomers XF, Bian Z, Fan M, Jansen JA.

    Department of Periodontology and Biomaterials, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands., Key Lab for Oral Biomedical Engineering of Ministry of Education, School and Hospital of Stomatology, Wuhan University, Wuhan, Hubei Province, People's Republic of China.

    Dental pulp stem cells harbor great potential for tissue-engineering purposes. However, previous studies have shown variable results, and some have reported only limited osteogenic and odontogenic potential. Because bone morphogenetic proteins (BMPs) are well-established agents to induce bone and dentin formation, in this study STRO-1-selected rat dental pulp-derived stem cells were transfected with the adenoviral-mediated human BMP-2 gene. Subsequently, the cells were evaluated for their odontogenic differentiation ability in medium not containing dexamethasone or other stimuli. Cultures were investigated using light microscopy and scanning electron microscopy (SEM) and evaluated for cell proliferation, alkaline phosphatase (ALP) activity, and calcium content. Real-time polymerase chain reaction (PCR) was performed for gene expression of Alp, osteocalcin, collagen type I, bone sialoprotein, dentin sialophosphoprotein, and dentin matrix acidic phosphoprotein 1. Finally, an oligo-microarray was used to profile the expression of odontogenesis-related genes. Results of ALP activity, calcium content, and real-time PCR showed that only BMP2-transfected cells had the ability to differentiate into the odontoblast phenotype and to produce a calcified extracellular matrix. SEM and oligo-microarray confirmed these results. In contrast, the non-transfected cells represented a less differentiated cell phenotype. Based on our results, we concluded that the adenovirus can transfect STRO-1 selected cells with high efficacy. After BMP2 gene transfection, these cells had the ability to differentiate into odontoblast phenotype, even without the addition of odontogenic supplements to the medium.