MOLECULAR MECHANISMS OF HOMEOSTASIS AND MECHANICAL STRESS-RESPONSE IN PERIODONTAL LIGAMENT

牙周膜的再生和稳态是牙周组织再生中非常重要的功能。牙周膜成纤维细胞具有很强的成骨和成牙骨质能力，同时也具有较高的碱性磷酸酶活性。用骨形态蛋白（BMP）、地塞米松诱导牙周膜成骨。本研究旨在阐明咀嚼运动中牙周膜内环境稳定的分子机制。将原代培养的大鼠牙周膜细胞置于Flexer细胞应变装置中进行拉伸，观察拉伸对细胞增殖、分化及mRNA表达的影响（FX-4000 T/FLEXCELL/USA）拉伸至9和18%，频率为6个循环/分钟。 ...更多信息 结果表明：（1）与对照组相比，真实的牵张实验组胶原蛋白I（Coll-I）、纤维连接蛋白（FN）、碱性磷酸酶（ALP）、碱性成纤维细胞生长因子（b-FGF）、骨形态蛋白2（BMP-2）、骨形态蛋白4（BMP-4）的mRNA表达均发生了变化，12 h后mRNA表达量达到高峰。（2）与对照组相比，各实验组b-FGF、BMP-2、BMP-4 mRNA表达量均发生变化，24 h后mRNA表达量达到高峰。体外培养的牙周膜成纤维细胞在这些机械应力的作用下，细胞分化受到影响，细胞增殖和细胞密度发生改变。因此，机械应力或咀嚼力促进牙周膜再生，影响牙周膜的内环境稳定。少

Regeneration and homeostasis of the periodontal ligament are highly significant functions in relation to periodontal tissue regeneration. Fibroblasts of periodontal ligament have high potency of osteogenesis and cementogenesis, and also, indicate high alkaline phosphatase activity. Bone formation of periodontal ligament was induced by bone morphmetric protein(BMP), dexamethazone. The aim of this comprehensive study is to elucidate the molecular mechanisms of homeostasis in the periodontal ligament during mastication. Cell reaction, cell proliferation, cell differentiation and cell function in mRNA level, were examined in established primally cultured rat periodontal ligament cells, under the artificial mechanical stretching stress condition in vitro.Third passage primally cultured rat periodontal ligament cells were stretched in a Flexer cell Strain Unit (FX-4000T/FLEXCELL/USA) to 9 and 18 % elongation, at a frequency of 6 cycles/min. mRNA expression of the Type I collagen(Coll-I), Fib … More ronectin(FN), Alkaline phosphatase(ALP), Basic fibroblast growth factor(b-FGF), Bone morphologic protein2 (BMP-2), Bone morphologic protein4 (BMP-4) were examined by Real time Polymerase Chain-Reaction(RT-PCR) using Light Cycler system.Followings results were obtained in this project, (1)mRNA expression of Coll-I, FN, ALP were altered in all stretching experimental group compare with control group, and peak of mRNA quantity was recognized after 12 hrs. (2)mRNA expression of b-FGF, BMP-2,BMP-4 were altered in all stretching experimental group compare with control group, and peak of mRNA quantity was recognized after 24 hrs.In conclusion, we demonstrated that, primally cultured rat periodontal ligament cells, undergo osteoblastic differentiation upon receiving mechanical cyclic stretch. The cell differentiations of the cultured periodontal ligament fibroblasts were influenced by these mechanical stresses, and generated alteration of cell proliferation and cell density. So that reason, mechanical stress or mastication force accelerate the periodontal ligament regeneration, and influenced to the homeostasis of periodontal ligament. Less