微重力导致骨质疏松的机制

Mechanisms by which microgravity causes osteoporosis

背景:在微重力环境中骨吸收和骨形成的失衡,导致航天员出现严重的骨质流失。现有研究表明,微重力环境下的骨质流失是由多种细胞、组织和系统共同作用的结果。目的:综述微重力对不同的细胞、组织或系统产生不同的生物学效应,总结微重力导致骨质疏松发生的机制。方法:在Pub Med、Web of Science和Cochrane图书馆数据库检索2000-2023年的相关文献,纳入标准为与微重力导致骨质疏松相关的组织工程研究和基础研究的所有文章,最终对85篇文献进行综述。结果与结论:(1)在微重力环境下,骨髓间充质干细胞更倾向于向成脂细胞分化,减少向成骨细胞分化,而微重力环境中的造血干细胞则更倾向于分化为破骨细胞,减少向红系分化;同时,微重力抑制成骨细胞增殖和分化、促进成骨细胞凋亡、改变细胞形态及降低成骨细胞矿化能力,显著增加破骨细胞数量和活性并且阻碍成骨细胞向骨细胞分化,促进骨细胞的凋亡。(2)在微重力环境下,人体会出现骨骼肌萎缩、微血管重塑、骨微循环障碍及内分泌紊乱等组织或系统的变化,这些变化会导致骨骼微环境下机械应力卸载,血液灌注不足以及钙循环紊乱等,对骨质疏松的发生产生了重要的影响。(3)目前,微重力导致骨质疏松的机制较为复杂,通过更深入的研究这些生理机制对于确保航天员在长期太空任务中的健康至关重要,并为预防和治疗骨质疏松症提供了理论依据。

BACKGROUND:The imbalance between bone resorption and bone formation in microgravity environments leads to significant bone loss in astronauts.Current research indicates that bone loss under microgravity conditions is the result of the combined effects of various cells,tissues,and systems.OBJECTIVE:To review different biological effects of microgravity on various cells,tissues,or systems,and summarize the mechanisms by which microgravity leads to the development of osteoporosis.METHODS:Databases such as PubMed,Web of Science,and the Cochrane Database were searched for relevant literature from 2000 to 2023.The inclusion criteria were all articles related to tissue engineering studies and basic research on osteoporosis caused by microgravity.Ultimately,85 articles were included for review.RESULTS AND CONCLUSION:(1)In microgravity environment,bone marrow mesenchymal stem cells tend to differentiate more into adipocytes rather than osteoblasts,and hematopoietic stem cells in this environment are more inclined to differentiate into osteoclasts,reducing differentiation into the erythroid lineage.At the same time,microgravity inhibits the proliferation and differentiation of osteoblasts,promotes apoptosis of osteoblasts,alters cell morphology,and reduces the mineralization capacity of osteoblasts.Microgravity significantly increases the number and activity of osteoclasts.Microgravity also hinders the differentiation of osteoblasts into osteocytes and promotes the apoptosis of osteocytes.(2)In a microgravity environment,the body experiences changes such as skeletal muscle atrophy,microvascular remodeling,bone microcirculation disorders,and endocrine disruption.These changes lead to mechanical unloading in the bone microenvironment,insufficient blood perfusion,and calcium cycle disorders,which significantly impact the development of osteoporosis.(3)At present,the mechanism by which microgravity causes osteoporosis is relatively complex.A deeper study of these physiological mechanisms is crucial to ensuring the health of astronauts during long-term space missions,and provides a theoretical basis for the prevention and treatment of osteoporosis.