Exposure to hypergravity during zebrafish development alters cartilage material properties and strain distribution

Abstract

Terrestrial 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, the effects of shorter exposures to increased gravitational fields are less well characterized. Here, we exposed zebrafish to 3 and 6g hypergravity from 3-5 days post fertilisation, when key events in jaw cartilage morphogenesis occur. We did not observe changes to growth, or morphology of cartilage or muscle. However, we observed altered mechanical properties of jaw cartilages. We model the impact of these material property changes using Finite Element Analysis and show strain distribution in the jaw is altered following hypergravity. In regions of predicted altered strain we observed local changes to chondrocyte morphology, suggesting altered gravity affects chondrocyte maturation, ultimately leading to changes to cartilage structure and function.

Skeletal Biology and Disease Modeling in Zebrafish

“…( 124 ) Although zebrafish have not been reared on the ISS, they have been exposed to increased gravitational forces (hypergravity). Exposure to 3 g to 9 g during zebrafish larval development led to altered chondrocyte maturation ( 125 ) and changes to mineralization and the transcription of skeletal genes. ( 126 ) These studies illustrate the versatility of zebrafish models to study loading effects on bone.…”

Control of the Autophagy Pathway in Osteoarthritis: Key Regulators, Therapeutic Targets and Therapeutic Strategies

“…The zebrafish model is also suitable for studying miR-mediated joint degeneration. In particular, zebrafish dicer1 mutant shows impaired craniofacial development and overexpression of SOX10 [ 69 ]. SOX9 controls miR140 and miR-29; miR92a regulates BMP signaling in zebrafish cartilage [ 41 , 70 ].…”

Potential of zebrafish as a model to characterise MicroRNA profiles in mechanically mediated joint degeneration

“…Finite element models for the developing zebrafish jaw have been published for wild-type fish (Brunt et al 2016;Brunt et al 2016), mutants (Lawrence et al 2018) and larvae exposed to different gravitational fields (Lawrence et al 2020). Cartilage material properties change during development, in response to mutations to chondrocyte genes or changes to gravitational force, and can be tested ex vivo by atomic force microscopy (AFM) or nanoindentation (Lawrence et al 2018(Lawrence et al , 2020, to provide further information and accuracy to FE models. Cavitation of the jaw joint between the Meckel's cartilage and the palatoquadrate to form a fluid-filled synovium (as opposed to a cellular interzone) occurs late in zebrafish (around 14 dpf) relative to onset of joint movement; this joint continues to mature, eventually forming a synovial joint with all of the tissues observed in a human synovial joint (Askary et al 2016).…”

“…FEA can be used to visualise patterns of strain by displaying them with colours to show areas of high and low strain, or degree of tissue deformation. Finite element models for the developing zebrafish jaw have been published for wild-type fish (Brunt et al 2016 ; Brunt et al 2016 ), mutants (Lawrence et al 2018 ) and larvae exposed to different gravitational fields (Lawrence et al 2020 ). Cartilage material properties change during development, in response to mutations to chondrocyte genes or changes to gravitational force, and can be tested ex vivo by atomic force microscopy (AFM) or nanoindentation (Lawrence et al 2018 , 2020 ), to provide further information and accuracy to FE models.…”

“…Finite Element modelling can be used to measure the response of specific cell populations, with areas of altered strain having been mapped previously (Fig. 3 h) and changes to chondrocyte morphology and ECM composition in these regions analysed (Lawrence et al 2020 ). Live imaging of transgenic reporter lines such as the wnt:GFP or the BMP:GFP reporter (Fig.…”