Canalicular junctions in the osteocyte lacuno-canalicular network of cortical bone

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DOI

  • Nina Kølln Wittig
  • Malene Laugesen
  • ,
  • Mie Elholm Birkbak
  • ,
  • Fiona Linnea Bach-Gansmo
  • ,
  • Alexandra Pacureanu, ID27 Beamline, European Synchrotron Radiation Facility
  • ,
  • Stefan Bruns, Københavns Universitet, Technical University of Denmark
  • ,
  • Mette Høegh Wendelboe
  • ,
  • Annemarie Brüel
  • Henning Osholm Sørensen, Københavns Universitet, Technical University of Denmark
  • ,
  • Jesper Skovhus Thomsen
  • Henrik Birkedal

The osteocyte lacuno-canalicular network (LCN) is essential for bone remodeling because osteocytes regulate cell recruitment. This has been proposed to occur through liquid-flow-induced shear forces in the canaliculi. Models of the LCN have thus far assumed that it contains canaliculi connecting the osteocyte lacunae. However, here, we reveal that enlarged spaces occur at places where several canaliculi cross; we name these spaces canalicular junctions. We characterize them in detail within mice cortical bone using synchrotron nanotomography at two length scales, with 50 and 130 nm voxel size, and show that canalicular junctions occur at a density similar to that of osteocyte lacunae and that canalicular junctions tend to cluster. Through confocal laser scanning microscopy, we show that canalicular junctions are widespread as we have observed them in cortical bone from several species, even though the number density of the canalicular junctions was not universal. Fluid flow simulations of a simple model system with and without a canalicular junction clearly show that liquid mass transport and flow velocities are altered by the presence of canalicular junctions. We suggest that these canalicular junctions may play an important role in osteocyte communication and possibly also in canalicular fluid flow. Therefore, we believe that they constitute an important component in the bone osteocyte network.

Original languageEnglish
JournalACS Nano
Volume13
Issue6
Pages (from-to)6421-6430
Number of pages10
ISSN1936-0851
DOIs
Publication statusPublished - 25 Jun 2019

    Research areas

  • Canaliculi, Cortical bone, Lacuno-canalicular network, Nanotomography, Osteocytes

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