Department of Pedodontics, School of Stomatology, Fourth Military Medical University, Xi'an, Shaanxi, People's Republic of China.
J Cell Physiol. 2011 Aug;226(8):2081-90. doi: 10.1002/jcp.22538.
While dental mesenchymal stem cells are well-studied, the origin of these cells is still unclear. Bone marrow-derived cells (BMDCs) have the potential to engraft into several tissues after injury, but whether they can become dental tissue-specific progenitor cells under normal conditions and the relationship of these cells to the tissue-resident cells are unknown. Thus, we transplanted green fluorescent protein (GFP)-labeled BMDCs into irradiated wild-type mice. We found that the engraftment of BMDCs participated in the regeneration and differentiated into periodontal specific cells after injury. Under normal conditions, there were more BMDCs engrafting into the dental mesenchymal tissue than other organs, in which the expression of stromal cell-derived factor-1 (SDF-1) was significantly higher than in other organs, and the engraftment of cells increased with time. A small fraction of GFP+ cells maintained the mesenchymal stem cell phenotype positive for CD105, CD106, and CD90, which were significantly less than the tissue-resident stem cells; meanwhile, GFP+/CD45+ cells were rare. Isolation and characterization of the dental pulp cells showed that the number of GFP+/Ki67+ cells were greater than the GFP-/Ki67+ cells. In addition, some GFP+ cells differentiated into the dental-specific cells and expressed dental-specific proteins, and can be found in the odontoblast layer after implantation of the apical bud. In conclusion, these data suggest that bone marrow progenitor cells communicate with dental tissues and become tissue-specific mesenchymal progenitor cells to maintain tissue homeostasis.
虽然牙间充质干细胞已经得到了广泛的研究，但这些细胞的起源仍然不清楚。骨髓来源的细胞（BMDCs）在受伤后有可能植入到几种组织中，但它们是否能在正常条件下成为牙齿组织特异性祖细胞，以及这些细胞与组织驻留细胞的关系尚不清楚。因此，我们将绿色荧光蛋白（GFP）标记的 BMDC 移植到照射的野生型小鼠中。我们发现，BMDC 的植入参与了损伤后的再生，并分化为牙周特异细胞。在正常情况下，有更多的 BMDC 植入到牙间充质组织中，而其他器官则较少，其中基质细胞衍生因子-1（SDF-1）的表达明显高于其他器官，并且随着时间的推移，细胞的植入增加。一小部分 GFP+细胞保持间质干细胞表型，对 CD105、CD106 和 CD90 呈阳性，明显少于组织驻留干细胞；同时，GFP+/CD45+细胞很少。牙髓细胞的分离和鉴定表明，GFP+/Ki67+细胞的数量多于 GFP-/Ki67+细胞。此外，一些 GFP+细胞分化为牙特异性细胞，并表达牙特异性蛋白，在根尖芽植入后可以在成牙本质细胞层中找到。总之，这些数据表明，骨髓祖细胞与牙齿组织相互作用，并成为组织特异性间充质祖细胞，以维持组织内稳态。
