Technical Approaches Leading to the Concept of Osteocytic Osteolysis

Lf, Bélanger; Bélanger, Charles H.; Semba, Teruhiko

doi:10.1097/00003086-196709000-00020

Cited by 22 publications

(16 citation statements)

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“…This FGF23 then acts on the gut and kidney to regulate phosphate uptake and reabsorption. Another mechanism by which osteocytes can regulate ion homeostasis is through remodeling of their perilacunar matrix [15,16], which can release calcium and phosphate from the lacunae and canaliculi into the circulation. Not only do viable osteocytes play multiple roles in diverse skeletal functions, but the dying (apoptotic) osteocyte is also thought to play important regulatory roles in controlling osteoclast activity [17].…”

Section: Introductionmentioning

confidence: 99%

Novel approaches for two and three dimensional multiplexed imaging of osteocytes

Kamel-ElSayed

Tiede-Lewis

et al. 2015

Bone

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Although osteocytes have historically been viewed as quiescent cells, it is now clear that they are highly active cells in bone and play key regulatory roles in diverse skeletal functions, including mechanotransduction, phosphate homeostasis and regulation of osteoblast and osteoclast activity. Three dimensional imaging of embedded osteocytes and their dendritic connections within intact bone specimens can be quite challenging and many of the currently available methods are actually imaging the lacunocanalicular network rather than the osteocytes themselves. With the explosion of interest in the field of osteocyte biology, there is an increased need for reliable ways to image these cells in live and fixed bone specimens. Here we report the development of reproducible methods for 2D and 3D imaging of osteocytes in situ using multiplexed imaging approaches in which the osteocyte cell membrane, nucleus, cytoskeleton and extracellular matrix can be imaged simultaneously in various combinations. We also present a new transgenic mouse line expressing a membrane targeted-GFP variant selectively in osteocytes as a novel tool for in situ imaging of osteocytes and their dendrites in fixed or living bone specimens. These methods have been multiplexed with a novel method for labeling of the lacunocanalicular network using fixable dextran, which enables aspects of the osteocyte cell structure and lacunocanalicular system to be simultaneously imaged. The application of these comprehensive approaches for imaging of osteocytes in situ should advance research into osteocyte biology and function in health and disease.

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Section: Introductionmentioning

confidence: 99%

Novel approaches for two and three dimensional multiplexed imaging of osteocytes

Kamel-ElSayed

Tiede-Lewis

et al. 2015

Bone

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“…These results suggest that cell dendrites can have important biomechanical functions that might not be recognized when only cell bodies (hence osteocyte lacunae) are considered. This bespeaks potentially important, but controversial [Parfi tt, 1977], aspects of osteocyte physiology -osteocytes are thought to have the capacity to modify the matrix of bone [Belanger et al, 1967], and the architecture of canaliculi containing the dendritic cell processes of osteocytes is known to be quite dynamic [Palumbo et al, 2004] and to potentially change over time [Okada et al, 2002].…”

Section: Distinguishing Osteocyte Cell Bodies From Dendrites In Affecmentioning

confidence: 99%

Osteocyte Lacuna Population Densities in Sheep, Elk and Horse Calcanei

Skedros¹

2005

Cells Tissues Organs

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Osteocytes, the most prevalent cell type in bone, appear to communicate via gap junctions. In limb-bone diaphyses, it has been hypothesized that these cellular networks have the capacity to monitor habitual strains, which can differ significantly between cortical locations of the same bone. Regional differences in microdamage associated with prevalent/predominant strain mode (tension, compression, or shear) and/or magnitude may represent an important ‘variable’ detected by this network. This hypothesis was indirectly addressed by examining bones subjected to habitual bending for correlations of osteocyte lacuna population densities (n/mm² bone area, Ot.Lc.N/B.Ar) with locations experiencing high and low strain, and/or prevalent/predominant tension, compression, and shear. We examined dorsal (‘compression’), plantar (‘tension’), and medial/lateral (‘shear’ or neutral axis) cortices of mid-diaphyseal sections of calcanei of adult sheep, elk, and horses. Ot.Lc.N/B.Ar data, quantified in backscattered electron images, were also evaluated in a context of various additional structural and material variables (e.g. % ash, cortical thickness, porosity, and secondary osteon population). Results showed significant differences in dorsal versus plantar comparisons with the highest Ot.Lc.N/B.Ar in dorsal cortices of sheep and elk (p < 0.0001); but this was a statistical trend in the equine calcanei (p = 0.14). There were no consistent transcortical (pericortical to endocortical) differences, and Ot.Lc.N/B.Ar in neutral axes was not consistently different from dorsal/plantar cortices. Correlations of Ot.Lc.N/B.Ar with structural and material parameters were also poor and/or inconsistent within or between species. These results provide little or no evidence that the number of osteocyte lacunae has a functional role in mechanotransduction pathways that are typically considered in bone adaptation. Although dorsal/plantar differences may be adaptations for prevalent/predominant strain modes and/or associated microdamage, it is also plausible that they are strongly influenced by differences in the bone formation rates that produced the tissue in these locations.

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“…While new functions of osteocytes have been discovered such as their role in phosphate metabolism , previous functions proposed for osteocytes have been rediscovered. This review will focus on rediscovering an earlier function of osteocytes, that of being able to remove and replace their perilacunar matrix, referred to by Belanger as "osteocytic osteolysis" (Belanger et al, 1967). Again, discoveries of osteocyte function regarding removal of their perilacunar matrix, is attributable to new technology, in this case the use of new imaging technologies such as Raman spectroscopy, atomic force microscopy, and synchrotron technology.…”

Section: Introductionmentioning

confidence: 99%