Lawrence Elizabeth Anna, Aggleton Jessye, van Loon Jack, Godivier Josepha, Harniman Robert, Pei Jiaxin, Nowlan Niamh, Hammond Chrissy
School of Physiology, Pharmacology and Neuroscience, University of Bristol, Bristol, UK.
School of Anthropology and Archaeology, University of Bristol, Bristol, UK.
Bone Joint Res. 2021 Feb;10(2):137-148. doi: 10.1302/2046-3758.102.BJR-2020-0239.R1.
Vertebrates have adapted to life on Earth and its constant gravitational field, which exerts load on the body and influences the structure and function of tissues. While the effects of microgravity on muscle and bone homeostasis are well described, with sarcopenia and osteoporosis observed in astronauts returning from space, the effects of shorter exposures to increased gravitational fields are less well characterized. We aimed to test how hypergravity affects early cartilage and skeletal development in a zebrafish model.
We exposed zebrafish to 3 g and 6 g hypergravity from three to five days post-fertilization, when key events in jaw cartilage morphogenesis occur. Following this exposure, we performed immunostaining along with a range of histological stains and transmission electron microscopy (TEM) to examine cartilage morphology and structure, atomic force microscopy (AFM) and nanoindentation experiments to investigate the cartilage material properties, and finite element modelling to map the pattern of strain and stress in the skeletal rudiments.
We did not observe changes to larval growth, or morphology of cartilage or muscle. However, we observed altered mechanical properties of jaw cartilages, and in these regions we saw changes to chondrocyte morphology and extracellular matrix (ECM) composition. These areas also correspond to places where strain and stress distribution are predicted to be most different following hypergravity exposure.
Our results suggest that altered mechanical loading, through hypergravity exposure, affects chondrocyte maturation and ECM components, ultimately leading to changes to cartilage structure and function. Cite this article: 2021;10(2):137-148.
脊椎动物已经适应了地球上的生活及其恒定的重力场，重力场对身体施加负荷并影响组织的结构和功能。虽然微重力对肌肉和骨骼稳态的影响已有充分描述，从太空返回的宇航员中出现了肌肉减少症和骨质疏松症，但较短时间暴露于增加的重力场的影响却鲜为人知。我们旨在测试超重力如何影响斑马鱼模型中早期软骨和骨骼的发育。
在受精后三到五天，即颌骨软骨形态发生的关键事件发生时，我们将斑马鱼暴露于3g和6g的超重力环境中。暴露后，我们进行了免疫染色以及一系列组织学染色和透射电子显微镜（TEM）检查软骨形态和结构，原子力显微镜（AFM）和纳米压痕实验以研究软骨材料特性，并通过有限元建模来绘制骨骼雏形中的应变和应力模式。
我们未观察到幼虫生长、软骨或肌肉形态的变化。然而，我们观察到颌骨软骨的力学性能发生了改变，并且在这些区域我们看到软骨细胞形态和细胞外基质（ECM）组成发生了变化。这些区域也对应于超重力暴露后预计应变和应力分布差异最大的地方。
我们的结果表明，通过超重力暴露改变机械负荷会影响软骨细胞成熟和ECM成分，最终导致软骨结构和功能发生变化。引用本文：2021;10(2):137-148。
