Effects of Arsenic Trioxide on Osteogenesis and Adipogenesis from Bone Marrow Mesenchymal Stem Cells

骨質疏鬆症一般被認為是細胞的骨生成作用與破骨細胞的骨吸收作用失去平衡，然而近年來的研究指出骨頭內的間質幹細胞分化成造骨細胞的能力減弱或是間質幹細胞分化成脂肪細胞的能力增強，這樣的結果往往會導致骨質疏鬆症，如糖尿病狀態。 砷為環境中普遍存在的毒性危害物質，我們的水源、空氣包括生物體內都有存在砷，因此人們很容易暴露到砷，砷主要經呼吸、皮膚及消化道吸收，進而 分佈於我們的組織和器官而造成傷害，如皮膚和骨頭，但過去的研究鮮少去探討砷會於骨生成的影響。 因此，本篇主是探討砷化物中的三氧化二砷對於間質幹細胞分化成造骨細胞和脂肪細胞的影響。首先我們選定了不造成細胞死亡的劑量：0.5 μM和1 μM，在此劑量下我們發現三氧化二砷會透過抑制AMPK、eNOS、BMP-2、ALP和OCN的表現來達到抑制骨生成，三氧化二砷對於脂肪細胞分化方面，0.5 μM及1 μM三氧化二砷有促進脂肪細胞分化的現象，而我們也發現在此劑量下三氧化二砷會透過ERK的磷酸化促進脂肪細胞的分化和抑制骨礦物化。在動物實驗上，我們將1 μM三氧化二砷在大鼠脛骨作局部注射和以0.5 ppm和5 ppm三氧化二砷水溶液對鼷鼠連續餵食六週，發現經三氧化二砷處理後，經細胞分化測試、骨密度測定和骨組織切片看到實驗動物的骨生成受到抑制。 綜合以上實驗結果，我們認為三氧化二砷0.5及1 μM劑量下有助於MSCs趨向分化成脂肪細胞同時也抑制了骨生成。In general, osteoporosis is a disease of bone which is caused by an imbalance between osteoblastic bone formation and osteoclastic bone resorption. However, the recent research showed that the ability of bone marrow mesenchymal stem cells differentiates into adipocytes is greater than osteoblasts and it was thought to cause into osteoporosis, such as diabetes. Arsenic is a common environmental toxicant including in water and air, and we expose to arsenic easily. Arsenic is mainly absorbed via breathing, skin and digestive tract, and then it distributes into our tissues and organs, such as skin and bone. However, few studies show the effects of arsenic to bone. Here we used arsenic trioxide to understand how it affects osteogenesis and adipogenesis of bone marrow mesenchymal stem cells. At first, we selected the arsenic trioxide dose(0.5 μM and 1 μM) that do not cause MSCs death. After 0.5 μM and 1 μM arsenic trioxide treatment, we found that arsenic trioxide inhibited bone formation via decreasing the expressions of AMPK、eNOS、BMP-2、ALP and OCN. Moreover, we also found that 0.5 μM and 1 μM arsenic trioxide can increase adipocyte differentiation and depressed bone formation via the phosphorylation of ERK. In animal test, we injected 1 μM arsenic trioxide into the tibia of rats and fed 0.5 and 5 ppm arsenic trioxide to mice for 6 weeks. The data of BMD, cell differentiation, and slices show the ability of bone formation in animal was inhibited. In Conclusion, we thought that 0.5 μM and 1 μM arsenic trioxide help MSCs favor adipogenesis and it also inhibited osteogenesis.目錄....................................3文摘要............................4文摘要............................6寫表.................................8一章 緒論.....................10二章 材料與方法.........20三章 結果......................30四章 討論.......................36圖.......................................42考文獻...............................6