THE EFFECT OF MECHANICAL STRESS ON CELLS ISOLATED FROM GINGIVA

1.机械应力促进人脐动脉和脐静脉内皮细胞增殖。使用Flexercell应变装置将细胞培养物暴露于循环机械应变。通过Flexercell使细胞经受24%的伸长，每天6、12、24小时。结果1.间断性加力（6、12 h/d）1-5 d促进脐动脉内皮细胞增殖，持续性加力1-9 d促进脐静脉内皮细胞增殖.在mRNA水平上检测了关键的血管生成因子VEGF及其受体（flt-1、KDR、flt-4）。将脐静脉内皮细胞置于上述相同的机械应力作用下，提取总RNA，用RT-PCR检测VEGF及其受体的表达。VEGF和KDR的mRNA表达水平升高，而flt-1和flt-4的mRNA表达水平降低，并呈时间依赖性.使人牙龈成纤维细胞经受与上述相同的机械应力，并计数细胞数。采用间歇性加力（每天6小时）1-2天，促进细胞增殖.纤维连接蛋白与组织修复过程有关。牙龈成纤维细胞暴露于机械应力（3%，6%伸长24小时）的纤维连接蛋白的合成进行了估计。3%的拉伸力显著促进纤维连接蛋白的合成。

1. The proliferation of human umbilical artery and vein endothelial cells was promoted by mechanical stress. The Flexercell strain apparatus was used to expose cell cultures to cyclic mechanical strain. The cells were subject to 24% elongation by the Flexercell for 6, 12, 24 hours per day. The proliferation of umbilical artery endothelial cells was promoted by intermittent force (6, 12 hours per day) for 1-5 days, while that of umbilical vein endothelial cells was promoted by continuous force for 1-9 days.2. A key angiogenic factor, VEGF and its receptors (flt-1, KDR, flt-4) were examined at mRNA levels. After umbilical vein endothelial cells were subject to the same mechanical stress described above, total RNA Was isolated and the expression of VEGF and its receptors was examined by RT-PCR. The mRNA levels increased in VEGF and KDR, but decreased in flt-1 and flt-4, in a time dependent manner.3. Human gingival fibroblasts were subject to the same mechanical stress described above and cell numbers were counted. The proliferation of the cells was promoted by intermittent force (6 hours per day) for 1-2 days.4. Fibronectin is concerned with tissue repairing process. The fibronectin synthesis by gingival fibroblasts exposed to mechanical stress (3%, 6% elongation for 24 hours) was estimated. By 3% elongation-force, the fibronectin synthesis was significantly promoted.