MECHANISM FOR THE INHIBITION OF ODONTOCLAST FORMATION IN PULP TISSUE

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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.