Abstract:

BACKGROUND: In vivo study of cellular mechanics obtains poor results due to complexity of physiological environment and uncontrollable experiment conditions. 
OBJECTIVE: To study the cyclic tensile stress on fibroblasts apoptosis and its mechanism.
METHODS: In vitro culture-tensile stimulate models of fibroblast were established by using a multi-passage load adding system. Cyclic tensile stress was applied on the fibroblasts for 6, 12, and 24 hours, respectively, the load was set for 12% surface elongation, with frequency of 6 cycles per minute. A cycle of stress comprised 3 s stretch/3 s relaxation. At the same time, the normal control group was established. The cell apoptosis was determined by Hoechst 33258 staining, cell cycle was analyzed by flow cytometry, and the caspase-3 activity was detected by ELISA.
RESULTS AND CONCLUSION: The nucleus in the normal control group presented with dispersed uniformly round or oval-shaped fluorescent, while dense stain particles, crescent or ring fluorescence could be seen within the nucleus or cytoplasm in the load groups. Compared with the normal control group, load adding significantly prolonged cell cycles (P < 0.01). The cell cycle appeared to be notably shortened in the 12 and 24 hours groups than that of 6 hours group (P < 0.01); however, the 24 hours group appeared to be extended the cell cycle than that of the 12 hours group. The caspase-3 activity was obviously increased in of the load adding group that that of the normal control group (P < 0.01), especially in the 12 hours group, which was greater than that of the 6 hours group (P < 0.01). Cyclical tensile stress not only can induce fibroblast apoptosis in a time-dependent manner within 12 hours, but also can change the cell cycle. Caspase3 involves in this process.