Standard Talk (15 mins) Australian Society for Fish Biology Conference 2022

Cartilage under pressure: what can we learn from deep-sea chondrichthyans? (#97)

Victoria Camilieri-Asch 1 2 , Flavia Medeiros-Savi 1 2 , Brittany Finucci 3 , Mason N. Dean 4 , Sinduja Suresh 2 5 6 , Marie-Luise Wille 1 2 5 6 , Jordan Davern 6 7 , Travis Klein 1 6 7 , Caroline Kerr 1 8 , Shaun P. Collin 1 8 , Dietmar W. Hutmacher 1 2 5 6
  1. Max Planck Queensland Centre (MPQC) for the Materials Science of Extracellular Matrices, Queensland University of Technology, Kelvin Grove, QLD, Australia
  2. Centre in Regenerative Medicine, School of Mechanical, Medical and Process Engineering, Queensland University of Technology, Kelvin Grove, QLD, Australia
  3. National Institute of Water and Atmospheric Research (NIWA), Hataitai, Wellington, New Zealand
  4. Department of Infectious Diseases & Public Health, Jockey Club College of Veterinary Medicine and Life Sciences, City University of Hong Kong, Kowloon Tong, Hong Kong, China
  5. ARC ITTC for Multiscale 3D Imaging, Modelling and Manufacturing (M3D Innovation), School of Mechanical, Medical and Process Engineering, Queensland University of Technology, Kelvin Grove, QLD, Australia
  6. Centre for Biomedical Technologies, Queensland University of Technology, Kelvin Grove, QLD, Australia
  7. ARC Centre for Cell and Tissue Engineering Technologies, Brisbane, QLD, Australia
  8. The Neuroecology Group, School of Agriculture, Biomedicine and Environment and AgriBiosciences Australia, La Trobe University, Melbourne, VIC, Australia

Cartilaginous fishes have evolved a unique skeletal system consisting mainly of unmineralised cartilage, a tissue that resembles the articular cartilage found in the joints of other vertebrates. Compared to other vertebrate taxa (including other fish groups), most of their skeleton is ‘tessellated’, i.e., made up of an unmineralised core covered by a thin layer of mineralised ‘tiles’ or tesserae.  While deep-sea species are able to withstand high hydrostatic pressures, ranging from 10 to 300 times greater than sea level depending on the depth they inhabit (typically <3000m), such extreme pressures would inevitably produce serious mechanical stress resulting in acute tissue damage when applied to the cartilage of terrestrial mammals.

We hypothesise that the extracellular matrix (ECM) secreted by cartilage cells (chondrocytes) within the skeleton of species found at different depths would show interspecific differences in microstructure, composition, and mechanical properties, and even site-specific differences in mineralisation and biophysical properties, to maintain tissue integrity according to functional load. The study uses a multimodal and multiscale approach to cross-correlate 2D histo-morphological and immunohistochemical data with 3D bioimaging, and biomechanical testing, in two main skeletal regions of interest (vertebrae and neurocranium) across representative species that occupy different depth profiles. Preliminary results reveal marked histological differences in the level of tissue mineralisation between areas, as well as varying collagen and proteoglycan contents in the ECM of unmineralised cartilage, potentially indicating characteristics adapted to an environmental gradient. Whether these observations are depth-related remain to be tested.

Ultimately, our characterisation and better understanding of such adaptations, in the structure, composition and mechanical properties of skeletal systems, which are exposed to high hydrostatic pressures, may inform future applications in cartilage tissue engineering and regenerative medicine, in addition to elucidating how many species are able to make large vertical movements within their depth range and maintain skeletal integrity.