Histological assessments on the abnormalities of mouse epiphyseal chondrocytes with short term centrifugal loading

Abstract

We have examined the morphological changes in chondrocytes after exposure to experimental hypergravity. Tibial epiphyseal cartilages of 17-days-old mouse fetuses were exposed to centrifugation at 3G for 16 h mimicking hypergravitational environment (experimental group), or subjected to stationary cultures (control group). Centrifugation did not affect the sizes of epiphyseal cartilage, chondrocyte proliferation, type X collagen-positive hypertrophic zone, and the mRNA expressions of parathyroid hormone-related peptide and fibroblast growth factor receptor III. However, centrifuged chondrocytes showed abnormal morphology and aberrant spatial arrangements, resulting in disrupted chondrocytic columns. Through histochemical assessments, actin filaments were shown to distribute evenly along cell membranes of control proliferative chondrocytes, while chondrocytes subjected to centrifugal force developed a thicker layer of actin filaments. Transmission electron microscopic observations revealed spotty electron-dense materials underlying control chondrocytes' cell membranes, while experimental chondrocytes showed their thick layer. In the intracolumnar regions of the control cartilage, longitudinal electron-dense fibrils were associated with short cytoplasmic processes of normal chondrocytes, indicating assumed cell-tomatrix interactions. These extracellular fibrils were disrupted in the centrifuged samples. Summarizing, altered actin filaments associated with cell membranes, irregular cell shape and disappearance of intracolumnar extracellular fibrils suggest that hypergravity disturbs cell-to-matrix interactions in our cartilage model.The unique mechanical properties of the cartilage are conferred by its avascular composition and the complexity of its extracellular matrices including collagen fibrils, aggrecan, link proteins and so forth. Mesenchymal condensation, chondrocytic differentiation and subsequent matrix synthesis are genetically programmed, and regulated by microenvironmental influences such as soluble mediators, e.g., parathyroid hormone-related peptide (PTHrP) and fibroblast growth factor receptor III (FGFR3) (1, 2, 14). Currently, however, many investigators are paying attention to the fundamental role played by mechanical loading in chondrocyte regulation and cartilage dysfunction. Gravity, the force of attraction between all masses in the universe, can be understood as a source of loading upon chondrocytes and their surroundings. Altered gravity has been shown to affect

Skeletal Dysplasias Associated with Mild Myopathy—A Clinical and Molecular Review

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Biological application of focus ion beam-scanning electron microscopy (FIB-SEM) to the imaging of cartilaginous fibrils and osteoblastic cytoplasmic processes

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Effect of Short-Term Hypergravity Treatment on Mouse 2-Cell Embryo Development

“…The rocket carrying the satellite will generate 80-100 g of acceleration gravity for about 10 minutes in rising stage before to be into the orbit. In 2007 Feritas et al exposed the epiphyseal cartilages of 17-days-old mouse fetuses to centrifugation at 3 g for 16 h mimicking hypergravity environment, and found that the extracellular fibrils, cell shape and cell membranes were disrupted in the centrifuge samples, which indicated that hypergravity disturbs cell-to-matrix interaction in the cartilage model (Freitas et al 2007). In 2003, Sasagawa et al examined the embryonic development of the nematode Caenorhabditis elegans under hypergravity (200 g), the results showed that the embryos after fertilization developed normally whereas the number of eggs laid from an adult hermaphrodite decreased and their hatching rate was reduced under the hypergravity condition (Sasagawa et al 2003).…”