Formation of bone-like mineralized matrix by periodontal ligament cells in vivo: a morphological study in rats
Formation of bone-like mineralized matrix by periodontal ligament cells in vivo: a morphological study in rats
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DOI：
10.1007/s00774-009-0039-9
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发表时间：
2009-03-01
影响因子：
3.3
通讯作者：
Nakamura, Hiroaki
中科院分区：
文献类型：
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作者：
Hiraga, Toru;Ninomiya, Tadashi;Nakamura, Hiroaki
牙周韧带（PDL）是一种独特的结缔组织，不仅连接牙骨质和牙槽骨以支撑牙齿，而且在重建牙周组织中发挥着重要作用。先前的研究表明PDL细胞具有成骨潜力；然而，他们缺乏精确的组织学检查。在这里，我们使用形态学技术研究了大鼠 PDL 细胞的骨样基质形成。大鼠和人 PDL 细胞表现出显着的碱性磷酸酶活性并在体外诱导矿化。 RT-PCR 分析显示 PDL 细胞表达成骨细胞标记物 Runx2、osterix 和骨钙素。这些结果表明 PDL 细胞与成骨细胞具有相似的表型。为了检查体内骨样基质的形成，将从绿色荧光蛋白（GFP）转基因大鼠中分离的PDL细胞用羟基磷灰石（HA）盘接种到野生型大鼠体内。植入五周后，HA 盘中的孔被 GFP 阳性细胞占据。 HA 孔表面也发现矿化基质形成。 12周时，部分孔内充满骨样矿化基质（BLMM），骨基质蛋白、骨桥蛋白、骨唾液蛋白和骨钙蛋白呈阳性。免疫组织化学检查显示，BLMM 上或内部的大多数成骨细胞和骨细胞样细胞均为 GFP 阳性，表明 BLMM 是由接种的 PDL 细胞直接形成的。在孔隙表面，还观察到嵌入牙骨质样矿化层中的夏皮纤维状结构。这些结果共同表明 PDL 细胞具有形成牙周组织的能力，可能成为牙周病再生治疗的有用来源。
Periodontal ligament (PDL) is a unique connective tissue that not only connects cementum and alveolar bone to support teeth, but also plays an important role in reconstructing periodontal tissues. Previous studies have suggested that PDL cells have osteogenic potential; however, they lack precise histological examinations. Here, we studied bone-like matrix formation by PDL cells in rats using morphological techniques. Rat and human PDL cells exhibited substantial alkaline phosphatase activity and induced mineralization in vitro. RT-PCR analyses showed that PDL cells expressed the osteoblast markers, Runx2, osterix, and osteocalcin. These results suggest that PDL cells share similar phenotypes with osteoblasts. To examine the bone-like matrix formation in vivo, PDL cells isolated from green fluorescent protein (GFP)-transgenic rats were inoculated with hydroxyapatite (HA) disks into wild-type rats. Five weeks after the implantation, the pores in HA disks were occupied by GFP-positive cells. Mineralized matrix formation was also found on the surface of HA pores. At 12 weeks, some of the pores were filled with bone-like mineralized matrices (BLMM), which were positive for the bone matrix proteins, osteopontin, bone sialoprotein, and osteocalcin. Immunohistochemical examination revealed that most of the osteoblast- and osteocyte-like cells on or in the BLMM were GFP-positive, suggesting that the BLMM were directly formed by the inoculated PDL cells. On the pore surfaces, Sharpey's fiber-like structures embedded in cementum-like mineralized layers were also observed. These results collectively suggest that PDL cells have the ability to form periodontal tissues and could be a useful source for regenerative therapies of periodontal diseases.