Aerospace Medicine and Rehabilitation Laboratory, Faculty of Health and Life Sciences, Northumbria University, Newcastle-upon-Tyne, United Kingdom.
Harvard Medical School, Department of Neurology, Beth Israel Deaconess Medical Center Boston, MA, United States.
Life Sci Space Res (Amst). 2022 Aug;34:87-103. doi: 10.1016/j.lssr.2022.07.003. Epub 2022 Jul 29.
Space agencies are preparing to send humans to the Moon (16% Earth's gravity) and Mars (38% Earth's gravity), however, there is limited evidence regarding the effects of hypogravity on the skeletal system. A novel rodent partial weight-bearing (PWB) model may provide insight into how human bone responds to hypogravity. The aim of this study was to perform a systematic review investigating the effect of PWB on the structure and function of rodent bone. Five online databases were searched with the following inclusion criteria: population (rodents), intervention (PWB for ≥1-week), control (full weight-bearing), outcomes (bone structure/function), and study design (animal intervention). Of the 2,993 studies identified, eight were included. The main findings were that partial weight-bearing exposure for 21-28 days at 20%, 40%, and 70% of full loading causes: (1) loss of bone mineral density, (2) loss of trabecular bone volume, thickness, number, and increased separation, (3) loss of cortical area and thickness, and 4) reduced bone stiffness and strength. These findings predominately relate the tibia/femur of young/mature female mice, however, their deconditioning response appeared similar, but not identical, to male rats. A dose-response trend was frequently observed between the magnitude of deconditioning and PWB level. The deconditioning patterns in PWB resembled those in rodents and humans exposed to microgravity and microgravity analogs. The present findings suggest that countermeasures against bone deconditioning may be required for humans exploring the Lunar and Martian surfaces.
各航天机构正准备将人类送往月球（地球重力的 16%）和火星（地球重力的 38%），然而，关于微重力对骨骼系统影响的证据有限。一种新型的啮齿动物部分负重（PWB）模型可能有助于深入了解人类骨骼对微重力的反应。本研究旨在进行系统综述，调查 PWB 对啮齿动物骨骼结构和功能的影响。通过以下纳入标准，在五个在线数据库中进行了搜索：研究人群（啮齿动物）、干预措施（PWB 持续时间≥1 周）、对照（完全负重）、结果（骨骼结构/功能）和研究设计（动物干预）。在确定的 2993 项研究中，有 8 项研究被纳入。主要发现是，在 20%、40%和 70%的全负荷下，21-28 天的部分负重暴露会导致：（1）骨密度降低，（2）骨小梁体积、厚度、数量减少，分离增加，（3）皮质面积和厚度减少，以及（4）骨刚度和强度降低。这些发现主要与年轻/成熟雌性小鼠的胫骨/股骨有关，但它们的去适应反应与雄性大鼠相似，但不完全相同。在去适应程度和 PWB 水平之间经常观察到剂量反应趋势。PWB 引起的去适应模式与在微重力和微重力模拟环境中暴露的啮齿动物和人类的去适应模式相似。本研究结果表明，对于探索月球和火星表面的人类来说，可能需要采取对抗骨骼去适应的措施。
