Tsukamoto-Tanaka Hiroko, Ikegame Mika, Takagi Ritsuo, Harada Hidemitsu, Ohshima Hayato
Division of Anatomy and Cell Biology of the Hard Tissue, Department of Tissue Regeneration and Reconstruction, Niigata University Graduate School of Medical and Dental Sciences, Niigata 951-8514, Japan.
Cell Tissue Res. 2006 Aug;325(2):219-29. doi: 10.1007/s00441-005-0138-4. Epub 2006 Apr 5.
Dental pulp is assumed to possess the capacity to elaborate both bone and dentin matrix under the pathological conditions following tooth injury. This study was undertaken to clarify the mechanism inducing bone formation in the dental pulp by investigating the pulpal healing process, after tooth replantation, by micro-computed tomography (mu-CT), immunocytochemistry for heat-shock protein (HSP)-25 and cathepsin K (CK), and histochemistry for both alkaline phosphatase (ALP) and tartrate-resistant acid phosphatase (TRAP). Under deep anesthesia, the upper right first molar of 4-week-old Wistar rats was extracted and immediately repositioned in the original socket. In control teeth at this age, the periphery of the coronal dental pulp showed intense ALP-positive and HSP-25-positive reactions, whereas there were no TRAP-positive or CK-positive cells. Tooth replantation weakened or terminated ALP-positive and HSP-25-positive reactions in the pulp tissue at the initial stages. At 3-7 days after operation, the ALP-positive region recovered from the root apex to the coronal pulp followed by HSP-25-positive reactions in successful cases showing tertiary dentin formation. In other cases, TRAP-positive and CK-positive cells appeared in the pulp tissue of the replanted tooth at postoperative days 5-10 and remained associated with the bone tissue after 12-60 days. Immunoelectron microscopy clearly demonstrated that CK-positive osteoclast-lineage cells made contact with mesenchymal cells with prominent nucleoli and well-developed cell organelles. These data suggest that the appearance of TRAP-positive and CK-positive cells is involved in the induction of bone tissue formation in dental pulp.
牙髓被认为在牙齿损伤后的病理条件下具有形成骨和牙本质基质的能力。本研究旨在通过微计算机断层扫描（μ-CT）、热休克蛋白（HSP）-25和组织蛋白酶K（CK）的免疫细胞化学以及碱性磷酸酶（ALP）和抗酒石酸酸性磷酸酶（TRAP）的组织化学来研究牙齿再植后牙髓愈合过程，以阐明诱导牙髓中骨形成的机制。在深度麻醉下，拔除4周龄Wistar大鼠的右上第一磨牙，并立即将其重新植入原牙槽窝。在这个年龄的对照牙齿中，冠部牙髓周边显示出强烈的ALP阳性和HSP-25阳性反应，而没有TRAP阳性或CK阳性细胞。牙齿再植在初始阶段减弱或终止了牙髓组织中的ALP阳性和HSP-25阳性反应。在术后3-7天，成功形成第三期牙本质的病例中，ALP阳性区域从根尖向冠部牙髓恢复，随后出现HSP-25阳性反应。在其他病例中，TRAP阳性和CK阳性细胞在术后5-10天出现在再植牙齿的牙髓组织中，并在12-60天后与骨组织相关。免疫电子显微镜清楚地表明，CK阳性破骨细胞系细胞与具有明显核仁和发达细胞器的间充质细胞接触。这些数据表明，TRAP阳性和CK阳性细胞的出现参与了牙髓中骨组织形成的诱导。
