Baylor Department of Biomedical Sciences, Baylor College of Dentistry, Texas A&M Health Science Center, Dallas, Texas 75246, USA.
Stem Cells Dev. 2009 Jan-Feb;18(1):67-75. doi: 10.1089/scd.2008.0002.
Mesenchymal stem cells (MSC) and multipotent adult progenitor cells (MAPC) copurify from the bone marrow. Past studies have shown that bone marrow-derived cells transplanted into the periodontium obtain characteristics of several periodontal cells types, such as alveolar bone, periodontal fibroblasts, and cementoblasts. Bone marrow-derived cell populations are heterogeneous mixtures of different cell types. Characterization of each individual cell type in the bone marrow has not been completed. In this study, the MAPC were isolated from the bone marrow of 3-week-old rats by selecting attached cells that did not express leukocyte (CD45), erythroid (HIS49), or the MSC marker CD44. DiI-labeled male MAPC were injected into the periodontal ligament (PDL) of female adult rats. After 3 weeks, the morphology of the DiI-labeled cells was determined. Periodontal tissues sections that included alveolar bone, PDL, cementum, and dentin were also immunostained for collagen I and III after 3 days, 3 weeks, and 6 weeks following injection of male MAPC into the female PDL. Male and female cells were differentiated by fluorescent in situ hybridization tagging of the X and Y chromosomes. Our results show that DiI-labeled MAPC were spherical in shape before injection but after 3 weeks a portion of the injected MAPC obtained the characteristic spindle shape of PDL cells with an orientation parallel to the surrounding PDL cells. Consistent with the DiI results, male MAPC had a spherical shape on immunostained sections 3 days after injection and expressed collagen I and III at significantly reduced levels as compared with the endogenous female PDL. Six weeks after injection, the MAPC expressed both collagen I and collagen III at levels similar to the endogenous surrounding PDL and obtain a morphology characteristic of PDL. In conclusion, MAPC obtain PDL-like characteristics over a 6-week period after injection into the PDL.
间充质干细胞（MSC）和多能成体祖细胞（MAPC）从骨髓中共同分离出来。过去的研究表明，移植到牙周组织中的骨髓来源细胞获得了几种牙周细胞类型的特征，如牙槽骨、牙周成纤维细胞和成牙骨质细胞。骨髓来源细胞群体是不同细胞类型的异质混合物。骨髓中每个单独细胞类型的特征尚未完全确定。在这项研究中，通过选择不表达白细胞（CD45）、红细胞（HIS49）或 MSC 标志物 CD44 的附着细胞，从 3 周龄大鼠的骨髓中分离出 MAPC。用 DiI 标记的雄性 MAPC 注射到雌性成年大鼠的牙周韧带（PDL）中。3 周后，确定 DiI 标记细胞的形态。在雄性 MAPC 注射到雌性 PDL 后 3 天、3 周和 6 周，还对包括牙槽骨、PDL、牙骨质和牙本质在内的牙周组织切片进行了胶原 I 和 III 的免疫染色。雄性和雌性细胞通过 X 和 Y 染色体的荧光原位杂交标记进行区分。我们的结果表明，注射前 DiI 标记的 MAPC 呈球形，但 3 周后，一部分注射的 MAPC 获得了与周围 PDL 细胞平行排列的 PDL 细胞的特征性梭形形状。与 DiI 结果一致，雄性 MAPC 在注射后 3 天的免疫染色切片上呈球形，并且与内源性雌性 PDL 相比，胶原 I 和 III 的表达水平显著降低。注射后 6 周，MAPC 表达胶原 I 和胶原 III 的水平与内源性周围 PDL 相似，并获得类似于 PDL 的形态特征。总之，MAPC 在注射到 PDL 后 6 周内获得 PDL 样特征。
