MECHANISM FOR THE INHIBITION OF ODONTOCLAST FORMATION IN PULP TISSUE

我们的工作假设是牙髓组织中存在抑制破牙细胞形成的机制，可能是牙髓细胞产生了一些细胞因子来抑制破牙细胞的形成。首先，将牙髓细胞条件培养液(RPC-C2a细胞)加入破骨细胞培养体系中，观察其对破骨细胞形成的抑制作用。在条件培养液透析后，也观察到了这种抑制，支持了我们的假设。我们多次重复这个实验，然而，当我们增加条件培养液的量时，观察到刺激破骨细胞的形成。此外，用膜分离牙髓细胞和骨髓细胞的共培养实验显示了对破骨细胞形成的刺激作用。尽管结果复杂，但我们可以得出结论，牙髓细胞产生一些影响破骨细胞形成的细胞因子。这些细胞因子的特性仍有待研究。另一方面，各种影响破骨细胞形成和/或激活的细胞因子已有报道。我们利用RT-PCR对临床获得的人牙髓组织中各种细胞因子的表达进行了初步的实验，我们认为这种方法是有用的，这项实验正在进行中。我们用小鼠牙髓中的RNA做了同样的实验，我们发现了转化生长因子-β和IL-6的表达，但没有表达破骨细胞形成所必需的MCSF。现在，我们正在使用Northern blotting来确认我们的发现。

Our working hypothesis is the existence of the mechanism for the inhibition of odontoclast formation in pulp tissue, and it is possible that dental pulp cells produce some cytokines which inhibit odontoclast formation. First, we added the conditioned medium of dental pulp cells (RPC-C2A cells) into osteoclast-formation system using mouse bone marrow culture, and we observed the inhibition of osteoclast formation. After dialysis of the conditioned medium this inhibition was also observed, supporting our hypothesis. We repeated this experiment several times, however, stimulation of osteoclast formation was observed when we increased the amount of conditioned medium. Morever, co-culture experimant, in which dental pulp cells and bone marrow cells were separated with membrane demonstrated the stimulation of osteoclast formation. Although the results were complicated, we can conclude that dental pulp cells produce some cytokines which affect osteoclast formation. Characterization of such cytokines is remained to be investigated.On the other hand, various cytokines which affect the formation and/or activation of osteoclast have been reported. We did the preliminary experiment concerning the expression of various cytokines in human dental pulp tissues which were clinically obtained, using RT-PCR.We feel usefulness of this method and this experiment is underway. Using RNA from mouse dental pulp, we did the same experiment, and we found the expressions of TGF-beta and IL-6 but not MCSF which is necessary for osteoclast formation. Now, we are confirming our findings using Northern Blotting.