Cell biological study on physiological root resorption of deciduous teeth ; potentiality to support odontoclast differentiation on periodontal ligament fibroblasts derived from of human deciduous teeth

结果表明，人恒牙牙周膜成纤维细胞（HPLF）和乳牙成纤维细胞（HPLF-Y）与小鼠骨髓细胞（BMC）共培养时，能抑制破牙细胞（或破骨细胞）样细胞的形成，而人牙槽骨成骨细胞（hOB）对破牙细胞样细胞的形成无明显影响。与HPLF或HPLF-Y接触对破骨细胞样细胞（OC）形成的抑制作用比非接触条件下BMC与HPLF或HPLF-Y共培养更显著。用1 α 25（OH）_2维生素D_3（D_3）和地塞米松（Dex）预处理的HPLF和HPLF-Y对TRAP阳性的多核细胞（MNC）无抑制作用。在共培养体系中形成。用RT-PCR方法检测了D_3、Dex或两者联合作用后，HPLF-Y、hOB和人牙龈组织成纤维细胞（HGF）总RNA中巨噬细胞集落刺激因子（M-CSF）的mRNA水平。半定量RT-PCR结果显示，分泌型M-CSF（M-CSFs）mRNA在hOB和HGF上的表达明显高于膜结合型M-CSF（M-CSFm），而在HPLF-Y上两者mRNA表达水平相同。D_3处理后M-CSFm的mRNA表达增加，Dex处理后M-CSFm的mRNA表达增加更明显，D_3处理后M-CSFm的mRNA表达增加更明显。D_3和Dex对CSF无影响。Dex处理后HPLF-Y和HGF上M-CSFm mRNA表达量占总表达量的比例增加，而D3处理后M-CSFm mRNA表达量占总表达量的比例降低。这些结果提示，成纤维细胞和成骨细胞上M-CSFm/M-CSFs的mRNA水平比例不同，D_3、Dex等与骨代谢相关的可溶性因子改变了这一比例。

It was suggested that the fibroblasts derived from periodontal ligament of human permanent teeth (HPLF) and deciduous teeth (HPLF-Y) inhibit the formation of odontoclast (or osteoclast)-like cells using coculture system with mouse bone marrow cells (BMC), while the osteoblasts derived from human alveolar bone (hOB) has no effect on that compared to the culture of BMC alone. The inhibitory effects on the osteoclast-like cells (OC) formation in contact with HPLF or HPLF-Y were more significant than the coculture at non-contact condition between BMC and HPLF or HPLF-Y.On the other hand, pretreated HPLF and HPLF-Y with 1 α 25(OH)_2 vitaminD_3 (D_3) and dexamethasone (Dex) did not inhibited tartrate- resistant acid phosphatase (TRAP) positive multinucleated cells (MNC) formation in the coculture system. Then we performed RT-PCR to examine the mRNA level for macrophage colony stimulating factor (M-CSF), one of the essential factors for the differentiation of osteoclast precursor in early stage, on total RNA isolated from HPLF-Y, hOB and the fibroblasts derived from human gingival tissue (hGF) treated with D_3, Dex or both of them. As the result of semi-quantitative RT-PCR, the expression of mRNA for secreted form M-CSF (M-CSFs) was predominant over that for membrane-bound form M-CSF (M-CSFm) on hOB and hGF, however mRNA expression of both forms was same level on HPLF- Y.Moreover, the level of mRNA for M-CSFm increased by D_3 treatment and the effect was more remarkable in the presence of Dex while mRNA expression for M-CSFs was not affected by D_3 and Dex treatment. On the other hand, Dex treatment increased the ratio of M-CSFm mRNA level in total expression of both M-CSFs and M-CSFm on HPLF-Y and hGF, while it was reduced by D_3 treatment. These results suggest that the proportion of mRNA level of M-CSFm to that of M-CSFs on the fibroblast is different from osteoblast and that the ratio is altered by soluble factors related to bone metabolism such as D_3 and Dex.