In vivo and in vitro study on tructure and function of dental pulp proteoglycan

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In in vitro study, observations on dental pulp tissues in PTHrP-deficient mice were executed. In these mice, accelerated alveolar bone formation was seen around the molar tooth germ and dental papilla was compressed by these bone tissues. Strong immuohistochemical staining for both versican and hyaluronan was seen in regions facing to invading bone tissues. In resin embedded sections, tissue metachromasia with toluidine blue staining showed a network structure among dental papilla cells and this network structure became fine in regions facing to invading bone tissues. These results indicated that, like aggrecan in cartilage, versican and hyaluronan have an ability to resist compressive forces in vivo. In situ hybridization using digoxigenin-labeled cRNA probes indicated that versican mRNA was distinctively increased in dental palilla of PTHrP-deficient mice compared to that in control (wild-type) mice. This phenomenon also supported functions of both molecules described above. We have already reported these results in meeting and now are preparing for papers.We also made an ultrastructural observation on macrophage-like cells emerging in monkey dental pulp after direct capping. These cells had many lysosome-like granules in cytoplasm and these granules contained and disposed dentin tips and capping materials including Dycal and resin filler. Further, lymph capillary-like vessels also contained these substances in the lumen. These results indicated that macrophages are directly involved in the disposal of capping material as a sigh of defense mechanism after direct capping. We have already reported these results in meeting and now are submitting papers.On the other hand, using this grant, we executed in situ hybridization and immunohistochemical study Of mouse condylar and limb bud cartilage and results were published in journals.