The Effects Of Tensile And Compressive Stress On Proliferation And ALP Expression Of Rat Osteoblast-like Cells In Vitro

During orthodontic treatment, external forces are applied to teeth, which result in the remodeling of tissues and associated structures. Due to the great effects of mechanical forces on the remodeling process, study of the relationship between tissue response and mechanical factors through biomechanical methods is very important in this field.It is well known that osteoblasts play an important role in bone growth, remolding and shape formation. The bone remodeling is a complex and dynamic balancing process, which relies on the coupling between bone resorption and formation that involves osteoclasts and osteoblasts. Recent researches have demonstrated that osteoblasts not only promote bone formation, but also regulate the differentiation and maturation of osteoclasts.Mechanical stress plays a crucial role in bone remodeling, which affects activities and differentiation of osteoblasts and osteoclasts. So it is important to study the biological response and mechanism of osteoblasts to mechanical stress.The goal of this research work was to determine the effects of tensile stress and compressive stress on cell proliferation and alkaline phosphatase(ALP) expression of rat-derived osteoblast-like cell line ROS 17/2.8. And this study is useful to further research on the relationship of mechanical stress, cellular growth and functions.In this study, the rat osteoblast-like cells were cultured with DMEM medium. The cells were loaded with static mechanical stress (tensile and compressive stress) by the apparatus designed by us. Cell proliferation and alkaline phosphatase activity as a marker of osteoblasts were measured. Unstrained cells were used as control. The results show that:1. Static tensile stress could promote ALP activity and cell proliferation of rat osteoblast-like cells in vitro.2. Static compressive stress could promote ALP activity and cell proliferation of rat osteoblast-like cells in vitro.3. At the same condition, the level of cell proliferation and ALP activity of the tensile stress group was higher than that of the compressive stress group.In all, tensile and compressive stress both promoted cell proliferation, enhanced ALP activity. Besides, the two apparatus are reliable and can be used for further experiments of cells mechanical loading.