Effects of Fibrillin Application on Periodontal Ligament Regeneration in Mouse Model of Tooth Replantation

福岡歯科大学2015年

Hertwig\u27s epithelial root sheath cells contribute to formation of periodontal ligament through epithelial-mesenchymal transition by TGF-β.

In tooth root development, periodontal ligament (PDL) and cementum are formed by the coordination with the fragmentation of Hertwig\u27s epithelial root sheath (HERS) and the differentiation of dental follicle mesenchymal cells. However, the function of the dental epithelial cells after HERS fragmentation in the PDL is not fully understood. Here, we found that TGF-β regulated HERS fragmentation via epithelial-mesenchymal transition (EMT), and the fragmented epithelial cells differentiated into PDL fibroblastic cells with expressing of PDL extracellular matrix (ECM). In the histochemical analysis, TGF-β was expressed in odontoblast layer adjacent of HERS during root development. Periostin expression was detected around fragmented epithelial cells on the root surface, but not in HERS. In the experiment using an established mouse HERS cell line (HERS01a), TGF-β1 treatment decreased E-cadherin and relatively increased N-cadherin expression. TGF-β1 treatment in HERS01a induced further expression of important ECM proteins for acellular cementum and PDL development such as fibronectin and periostin. Taken together, activation of TGF-βsignaling induces HERS fragmentation through EMT and the fragmented HERS cells contribute to formation of PDL and acellular cementum through periostin and fibronectin expression.福岡歯科大学2016年

Immunohistochemical expression of fibrillin-1 and fibrillin-2 during tooth development.

BACKGROUND AND OBJECTIVE:Oxytalan fibers are categorized as a microfibril assembly without elastin deposition, and are unique components in the periodontal ligament (PDL). However, little is known about their formation during PDL development. To clarify the mechanisms of oxytalan fiber formation in developing PDL, we performed immunohistochemical analysis to detect the direct expression of fibrillin-1 and fibrillin-2, which are major components of microfibrils.MATERIAL AND METHODS:Frozen sections of lower molars from mice at several stages of growth were prepared without chemical fixation and decalcification using the film transfer method. Immunostaining was performed with anti-fibrillin-1 and -2, and anticytokeratin antibodies.RESULTS:Fibrillin-1 was not expressed in the dental follicle during the crown forming stage. At postneonatal day 9, fibrillin-1 expression started with meshwork appearance between the epithelial cells from Hertwig\u27s epithelial root sheath at the root dentin surface. Fibirillin-2 was detected much earlier than fibrillin-1 expression. Fibrillin-2 was expressed with a liner appearance, running parallel to the root axis in PDL, and was partially co-expressed with cytokeratin 14 expression in Hertwig\u27s epithelial root sheath. Furthermore, we detected both fibrillin-1 and fibrillin-2 expression in human PDL. Fibrillin-1 was detected in fibers with a vertically oriented root axis in PDL. Fibrillin-2 was widely expressed in PDL, including around the epithelial cell rests of Malassez. Fibrillin-1 and fibrillin-2 were clearly co-expressed in thick fiber structures in human PDL.CONCLUSION:Our results suggest that both fibrillin-1 and fibrillin-2 expression is required to form thick oxytalan fibers in PDL. Based on the expression patterns for fibrillin-1 and fibrillin-2, they have different functions during tooth root and PDL development. Early expression of fibrillin-2 may regulate dental epithelial cell behavior during root and PDL development.福岡歯科大学2014年