静态单轴拉伸应变刺激对细胞有丝分裂方向的影响

Static Uniaxial Stretch Affect The Cell Mitosis Orientation

力学刺激对细胞发育具有重要意义,它如何对细胞分化及组织形态的发生产生影响是一个尚未完全阐明的问题.细胞的有丝分裂过程与细胞增殖、分化以及胚胎发育、组织器官形态形成和损伤组织的修复再生等特性密切相关,例如,细胞的有丝分裂方向就是影响细胞极性分化,乃至组织形态发生的因素之一.那么,力学刺激是否通过改变细胞有丝分裂方向从而影响细胞的分裂分化呢?以小鼠成骨细胞系MC3T3为模型,探讨了静态单轴拉伸应变刺激对细胞形态、应力纤维排布方向和有丝分裂方向的影响.结果显示,在4%及8%静态单轴拉伸应变条件下,48h之内细胞形态发生明显变化,细胞呈梭状,长轴沿应变方向排列,细胞骨架微丝呈束状平行排列,方向与应变方向相关.统计学分析表明,4%应变刺激48h后、8%应变6h后、8%应变12h后、8%应变24h后,及8%应变48h后,分别有49%,43%,54%,54%,和62%的细胞应力纤维排列方向与单轴拉伸应变方向的夹角在30!以内,以及50%,48%,56%,53%和62%的细胞有丝分裂方向与单轴应变方向夹角在30"以内.统计学分析表明,细胞形态、应力纤维排布及有丝分裂方向与拉伸方向相关,且应力纤维排列方向和有丝分裂方向之间呈现高的相关性,这种相关性在拉伸刺激48h后表现很明显,由此推测,存在力学刺激影响细胞形态及细胞应力纤维排布方向,控制有丝分裂方向的机制.

Cell division is one of the key roles in cell development, cell differentiation, embryogenesis and recovery of tissues. As a frequent stimulus, stress （or strain） plays an important role in the differentiation of the cells, morphology generation and function development of tissues. However, this stimulus was not studied enough. A uniaxial static stretch device was used to investigate the influence of a uniaxial stress on stress fibers and spindle orientation of cultured Murine osteoblast line （MC3T3）. The cells were seeded for 24 h on a thin rectangular silicon membrane in the uniaxial device before the static uniaxial stretch was applied to them. Five groups of the cells experiencing 4% strain for 48 h, 8% strain for 6 h, 8% strain for 12 h, 8% strain for 24 h, and 8% strain for 48 h were observed. After the stretching, the cells were incubated in fluorescent rhodamine-conjugated phalloidin and DAPI staining solution for 30 min. The stress fiber alignment and the cell division directions of the cells were recorded by CCD camera with an inverted fluorescent microscope （Olympus 71X） equipped with a green filter （554 nm）. In fact, the cells that were growing individually were counted because the interaction between cells may influence the cell alignment and the mitosis orientation. These cells were divided into three groups, 0^o-30^o, 30^o- 60^o, 60^o-90^o. The cells in each group were counted, then the distribution of the cell division directions were plotted in the circular graphs. It was showed that the morphology of the cells was regulated by 4% and 8% static uniaxial strain. Within 48 h, the uniaxial stress induced the stress fibers＇ alignment parallel to the stress direction while a random distribution of the long axial of the cells was seen in the control group. 49%, 43%, 54%, 54%, 62% of the cells under the five experimental conditions fall into the group I （0^o-30^o） according to the angles between the stretch directions and the stress fibers alignments. And, there are 50%, 48%, 56%, 53%, and 62% of the cells under the five stretch conditions in group I （0^o-30^o） according to the angles between the stretch and the cell division directions. Further statistic analysis indicates that the stress fibers＇ orientation and mitosis orientation show high relativity. The relativity was very high even 48 h after the stretch stimulus. These results suggest that the mechanical environment of the cells may play a role in the cell division orientation. The effect of cycle stress on cells mitosis orientation is worth further study.