TY - JOUR
T1 - Canalicular Junctions in the Osteocyte Lacuno-Canalicular Network of Cortical Bone
AU - Wittig, Nina Kolln
AU - Laugesen, Malene
AU - Birkbak, Mie Elholm
AU - Bach-Gansmo, Fiona Linnea
AU - Pacureanu, Alexandra
AU - Bruns, Stefan
AU - Wendelboe, Mette Hoegh
AU - Bruel, Annemarie
AU - Sorensen, Henning Osholm
AU - Thomsen, Jesper Skovhus
AU - Birkedal, Henrik
PY - 2019/6/25
Y1 - 2019/6/25
N2 - 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.
AB - 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.
KW - osteocytes
KW - lacuno-canalicular network
KW - nanotomography
KW - canaliculi
KW - cortical bone
U2 - 10.1021/acsnano.8b08478
DO - 10.1021/acsnano.8b08478
M3 - Journal article
C2 - 31095362
SN - 1936-0851
VL - 13
SP - 6421
EP - 6430
JO - A C S Nano
JF - A C S Nano
IS - 6
ER -