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目的探讨长期动态机械拉伸力对类骨细胞分化及成熟的影响。方法利用机械形变发生装置拉伸类骨细胞,分析类骨细胞是否因拉伸力而使分化更趋成熟。应用Flexercell Strain Unit机械力拉伸装置对MG63及C2C12细胞株施加0～10%的拉伸形变72h。通过碱性磷酸酶(ALP)染色、RT-PCR反应及骨形态发生蛋白-2(BMP-2)添加测试来检测长期动态机械拉伸力对类骨细胞分化的影响。结果拉伸力使MG63细胞的ALP活性约增加2倍,RT-PCR检测显示骨标志物[骨钙素(OCN)及ALP]表达均因拉伸力作用而增加。而单独施加拉伸力并不能增加C2C12肌原细胞内ALP的活性。添加BMP-2培养能促进C2C12细胞向骨细胞分化,并增加细胞ALP的活性。在BMP-2刺激下拉伸力可使C2C12细胞内ALP的活性增加2倍以上。结论本研究确立10%拉伸力能促进类骨细胞向骨细胞分化。对于未分化的肌原细胞,拉伸力刺激并不能使其直接向骨分化,但却能使分化中的骨细胞加速分化或成熟。
Objective To investigate the effect of long-term dynamic mechanical tensile force on the differentiation and maturation of osteoblasts. Methods Tensile osteoblasts were pulled by mechanical deformable device to analyze whether osteoclasts matured due to tensile force. The strain of MG63 and C2C12 were applied 0 ~ 10% tensile strain 72h with Flexercell Strain Unit mechanical stretching device. Alkaline phosphatase (ALP) staining, RT-PCR and bone morphogenetic protein-2 (BMP-2) assay were used to detect the effect of long-term dynamic mechanical tensile force on osteoblast differentiation. Results Tensile strength increased the ALP activity of MG63 cells about 2-fold. RT-PCR showed that the expression of osteocalcin (OCN) and ALP increased with tensile force. Tensile force alone did not increase ALP activity in C2C12 myoblasts. The addition of BMP-2 could promote the differentiation of C2C12 cells into osteoblasts and increase the activity of ALP. Tensile strength stimulated by BMP-2 increased the activity of ALP in C2C12 cells by more than 2 folds. Conclusion This study established that 10% stretching force can promote the differentiation of osteoblasts to osteocytes. For undifferentiated myogenic cells, stimulation of tension does not make it directly to the bone differentiation, but it can differentiate the accelerated differentiation or maturation of bone cells.