生物刺激對骨性細胞之生理影響

將細胞外的力學刺激信號通過區域黏著激酶（FAK）進而促進進行骨分化的確切機制至今尚未闡明。根據細胞的來源和施加應力的類型也會導致不同的細胞反應。因此在齒槽骨的重建中，牙周韌帶組織周圍的骨前驅細胞及破骨前驅細胞的平衡是非常重要的。實驗中比較牙周韌帶細胞以及骨細胞在負壓以及正常壓力環境下培養不同的時間。在不同的實驗條件中，分別評估分析了細胞存活率、細胞週期、以及成骨蛋白生成。並且使用小片段干擾核苷酸的轉染技術來降低FAK的表現。從結果中可以發現，張力可以快速促進牙周韌帶細胞中FAK的磷酸化以及提高骨性蛋白的表現，但是在骨母細胞中皆無法得到同樣的表現。並且經過剔除FAK基因的牙周韌帶細胞也會同時抑制鹼性磷酸酶和骨鈣蛋白的分泌。這些結果都可以表明張力可以藉由活化牙周韌帶細胞FAK表現來調節免疫反應及成骨作用。此外，單獨培養和共同培養系統中，破骨細胞和骨母細胞在張力即正常環境條件下的培養均無顯著差異。然而在共同培養系統中，RAW264.7細胞在張力的環境下經過3，7，15天的培養後會較正常環境下分泌出更多的抗酒石酸性磷酸酶（TRAP）。此外更發現張力可以促進RANKL的分泌並且抑制骨保護素的合成。因此，RAW264.7培養於骨母細胞培養液並給予張力的刺激，也會促進TRAP的活性。

關鍵字

區域黏著激酶張力；牙周韌帶；骨母細胞；巨噬細胞

並列摘要

The exact mechanism by which focal adhesion kinase (FAK) translates mechanical signals into osteogensis differentiation in force-exposed cells has not been elucidated. The responses to different forces differ according to the origin of cells and the type of stress applied. Therefore, the recruitment of osteoclast- and osteoblast-progenitor cells, and the balanced activation of these cells around and within the periodontal ligament (PDL) are essential for alveolar bone remodeling. Cells within the PDL and MG63 were subjected to tensile forces under -100 kPa for different periods of time. At various times during the tensile force application, they were processed for the purpose of analyzing cell viability, cell cycle, and osteogensis protein. The effect of small interfering RNA (siRNA) transfection targeting on FAK was also evaluated. Tensile force enhanced a rapid increase in the phosphorylation of focal adhesion kinase (FAK) and up-regulated osteogensis protein expression in PDL cells, but not in MG63 cells. Transfecting PDL cells with FAK antisense oligonucleotide diminished ALP and osteocalcin (OC) secretion. These findings suggest that tension force activates FAK pathways in PDL cells, which down-regulate immune cytokine and up-regulate osteogenic protein. In addition, the mono-culture and co-culture systems, the two cell types cultured under tensile force and normal environment showed no significant differences (p > 0.05) at any time. However, in the co-culture system, a significant (p < 0.05) increase of 2.27-, 3.00-, or 3.27-fold production of tartrate-resistant acid phosphatase (TRAP) in RAW264.7 cells under tensile force was found when compared with the corresponding TRAP activity in RAW264.7 cells under normal environment at day 3, 7, or 15, respectively. Moreover, the results indicate that the tensile force up-regulated the secretion of RANKL and inhibited OPG synthesis. Therefore, RAW264.7 cells appear to increase their production of TRAP in the media of osteoblasts under tensile force, promoting TRAP activity nearly 2.8 times higher than in media of osteoblasts under normal environment for 3 days.

並列關鍵字

focal adhesion kinase (FAK) ； tensile force ； periodontal ligament (PDL) ； osteoblast ； osteoblast ； macrophages

參考文獻

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生物刺激對骨性細胞之生理影響

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