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Objective To investigate the role and influence of physiological loading and overloading on microgravity-induced osteoporosis,so as to find a reliable way to prevent or treat related-orthopedic disorders in astronauts induced by long-time space activity.Metbods The microgravity environment in space was simulated by tail-suspension experiment,then the osteoporosis models of mice were built.A total of 32 C57BL/6J mice were randomly and evenly separated into four groups:normal group (normal),tail-suspension group (TS),physiological loading group (loading) and overloading group (overloading).Periodic dynamic mechanical load was applied on the left tibia in loading group and overloading group during tail-suspension test.After four weeks,tibial mechanical properties,micro-parameters of bone trabecular,biochemical indices and osteogenesis-related gene expression in each group were compared and analyzed.Results A great loss of tibial cancellous bone,significantly lower tibial biomechanical expression,serious damage of microstructure and weaker osteogenic activity were found in tail-suspended mice as compared with those of normal group.Physiological loading could clearly improve mechanical properties of bones,microstructure of bone trabecular,osteogenic activity and relative gene expression (P ＜ 0.05).Overloading could also improve the condition of microgravity-induced osteoporosis,but the effect was not obvious (P ＞ 0.05).Conclusions Tail-suspension can successfully simulate microgravity environment and duplicate osteoporosis model.Physiological loading can effectively prevent the emergence and development of microgravity-induced osteoporosis,while overloading can also counter microgravity-induced osteoporosis,but the results have no significant differences.
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Osteoporosis (OP) is one of the bone metabolic diseases which seriously harms the health and lives of people. The main cause of OP is that the balance between bone formation and bone absorption, i.e. the balance of the bone remodeling process,is no longer exist. When the bone absorption dominates the process, it will lead to osteopenia, destruction of bone microstructure and increased rate of fracture. Previous studies have shown that casein kinase 2-interacting protein-1 (CKIP-1) plays an important role in the process of bone tissue proliferation and differentiation. It mainly interacts with Smad ubiquitination regulatory factor 1 (Smurf 1) to affect bone metabolism. This review analyzes and summarizes the impact of CKIP-1 on bone tissue osteogenic differentiation direction and its mechanism, which may provide new idea and research orientation for future clinical treatment of osteoporosis.
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Bone marrow mesenchymal stem cells (BMSCs) is a kind of multipotent adult stem cells,which is one of the most important seed sources of tissue engineering.Microgravity has inhibitory effects on osteogenic differentiation of BMSCs,which will cause bone mass reduction and changes of bone micro-structure that finally lead to osteoporosis.This process is regulated by multiple signaling pathways such as mitogen-activated protein kinase (MAPK) pathway,Notch pathway and Wnt/β-catenin pathway which co-regulated BMSCs osteogenic differentiation under microgravity.Studying the effects of microgravity on BMSCs into osteogenic differentiation can clarify the mechanism of bone loss,put forward new targets for the treatment of diseases and provide a useful reference for the development of China's space industry.