【摘要】 探讨在成骨细胞中 Integrins调节力学信号转导可能的分子机制和周期性双轴力学应变对成骨细胞增殖与合成功能的影响。将 3月龄雌性 SD大鼠颅顶骨分离的成骨细胞在含 10 %胎牛血清的 F- 12培养液中培养并接种在 Flexercell type I dish中。当细胞生长至亚融合状态 (Subconfluence) ,给细胞施加力学刺激 ,频率为 1Hz,力学刺激分别为 4 0 0、10 0 0、4 0 0 0 μ strain;作用时间分别为每天 30 m in,2 h,4 h,和 8h,共加载 2 d。以未受力学刺激的细胞为对照组 ,受力学刺激的细胞为实验组 ,并进行比较。采用流式细胞技术测定和分析 Integrinsα2 ,β1 ,β3在成骨细胞膜上的表达量、细胞周期分布与细胞增殖变化 ;采用同位素标记方法检测成骨细胞骨钙素、I型胶原 C端前肽 (PICP)和总蛋白的分泌量。结果表明 :(1)在 3月龄雌性 SD大鼠成骨细胞膜表面有 Integrinsα2 ,β1 ,β3的表达 ,β1的表达最高。 (2 )周期性双轴力学应变对 3月龄雌性 SD大鼠成骨细胞膜表面 Integrinsα2 ,β1 ,β3的表达量有明显上调作用 ,但不同强度、不同作用时间的力学应变对成骨细胞膜表面 Integrinsα2 ,β1 ,β3表达量上调的作用亦不相同 ,而 β3对力学刺激最敏感 ;在 4 0 0 0 μ strain力学刺激下 ,成骨细胞膜表面 Integrinsα2 ,β1更多还原

【Abstract】 The purpose of this paper is to investigate the probable molecular mechanism in mechano transduction of the regulation of integrins and the effects of cyclic biaxial mechanical strain on proliferation and synthetic function in the osteoblasts isolated from 3 month old female Sprague Dawley (SD) rats. The osteoblasts were cultured in F 12 medium contained with 10% fetal bovine serum(FBS) and grown to subconfluency in Flexercell type I dishes in a humidified incubator with 5% CO 2 and 95% air at 37℃. Mechanical strains were applied to the cells for periods of 30 min, 2?4 and 8 hours every day,lasting 2 days. The amplitude of mechanical strain applied to the cells were 400,1 000 and 4 000 μ strain respectively, at a frequency of one hertz(1 Hz). Unstrained cells were used as control. The expression of integrins α 2,β 1,β 3 on the membrane of osteoblasts and proliferation activity of osteoblasts were studied with Flow Cytometry(FCM). The content of osteocalcin?carboxyterminal propeptide of type I procollage(PICP)?total protein secreted by osteoblastes were detected with the isotope labelling method. The results showed that there are actual expressions of integrins α 2,β 1,β 3 on the membrane of osteoblasts without mechanical strain and that the expression of integrins β 1 is highest. The mechanical strain increased the expression of integrins α 2,β 1,β 3 on the membrane of osteoblasts, but the strain related up regulation of expression of integrins α 2,β 1,β 3 are different in various amplitude and different duration of mechanical stains. The up regulation of expression of integrins β 3 is most sensitive to mechanical strain. The up regulation of expression of integrins α 2,β 1,β 3 is higher at 4 000 μ strain than at 400,1 000 μ strain. The mechanical strain can elevate the proliferation activity and the synthetic function of osteoblast at 400,1 000 μ strain. However, the mechanical strain increased significant the proliferation in the osteoblasts and suppressed obviously the synthetic function in the osteoblasts. In the present study, the reaction of the osteoblasts in 3 month old rat to the mechanical stimulation suggested that 1) expressions of integrins α 2,β 1,β 3 were increased in a amplitude of strain dependent manner; 2) the changes of expression of integrins α 2,β 1,β 3 relate close to the changes of the proliferation and synthetic function of the osteoblasts. Low amplitude of strain can increase the proliferation and the synthetic function of the osteoblasts along with up regulationof expression of integrins α 2,β 1,β 3; while higher amplitude of strain elevated significantly the proliferation of osteoblasts and suppressed obviously the synthetic function of the osteoblasts along with up regulation of expression of integrins α 2,β 1,β 3. The amplitude of 4 000 μ strain is an optimal amplitude as stimulus for up regulation of expression of integrins α 2,β 1,β 3 on the membrane of osteoblasts and increase the proliferation activity, but decrease the synthetic function of osteoblasts in the present study.Accordingly it indicates that integrins have a important role in regulation of signal transduction pathway in osteoblasts as a result of mechanical strain.更多还原