周期性张应力对牙周膜成纤维细胞凋亡的影响

目的:在体外条件下,探讨周期张应力作用对人牙周膜成纤维细胞凋亡的影响及PI3k/Akt信号通路在细胞凋亡中的作用。方法:应用多通道细胞牵张应力加载系统,以HPDLFs(人牙周膜成纤维细胞)为对象构建细胞体外培养-力学刺激模型,对照组为0h,0h+LY294002,加力组1 h,6 h,12 h,12 h+LY294002,24 h,力值定为15%,频率为1/6HZ,即10循环/分钟。采用Hoechst33258染色检测细胞形态和凋亡情况,应用RT-PCR技术检测Bcl-2、Bax的表达情况。结果:Hoechst 33258细胞染色结果显示,对照组的细胞核为弥散均匀的圆形或椭圆形荧光,实验组的细胞核或细胞质内出现可见致密浓染的颗粒、新月体或环状荧,RT-PCR结果显示Bcl-2与Bax基因表达均呈现时间依赖性。12 h HPDLFs的细胞凋亡数达最高峰值(P<0.01),24 h细胞凋亡峰值开始下降,但仍高于未加力组(P<0.05)。与对照组相比加入LY294002后,Bcl-2/Bax比值较加载相同时间的加力组小(P<0.05)。结论:一定的时间范围内,周期性张应力能促进HPDLFs凋亡;随着时间的延长(24h),细胞凋亡受到抑制;PI3K/Akt信号传导通路可能参与在周期性张应力介导的HPDLFs的凋亡。

Effects of Cyclic Tensile Stress on Human Periodontal Ligament FibroblastsApoptosis

Objective: To investigate the effect of cyclic stretch on Human periodontal ligament fibroblasts apoptosis and PI3k/Akt signaling pathway involved.Methods: In vitro culture-tensile stimulate models of HPDLFs were established by using a multi-passage load adding system.Cyclic stretch was applied on the fibroblasts in different groups for 1,6,12,and 24 h,respectively.The loading was set for 15% surface elongation,with frequency 1/6 Hz.Meanwhile,the blank normal control group and negative control group,0h+LY294002 was established by static group.The cell apoptosis was determined by Hoechst 33258 staining.The expression of Bcl-2 and Bax mRNA was detected by RT-PCR.Results: Hoechst 33258 staining showed that after treatment with loading,the cell took the typical appearance of apoptosis with chromatin condensation and apoptotic bodies.RT-PCR displayed that the rate of Bcl-2 / Bax mRNA expression decreased in loaded HPDLFs group compared with that in unloaded HPDLFs(P < 0.01).The rate decreased to the lowest level at 12h following loading,and then enhanced gradually.Compared with that in the loading group,the HPDLFs apoptosis increased at corresponding time points in the LY294002 group(P <0.05).Conclusions: The cyclic stretch can promote the apoptosis of HPDLFs in a time-dependent manner,then the HPDLFs apoptosis was inhibited PI3K/AKT signaling pathway may participate in the regulation of apoptosis of HPDLFs induced by cyclic stretch.