Senescent and apoptotic osteocytes and aging: Exercise to the rescue?

Sherk, Vanessa D.; Rosen, Clifford J.

doi:10.1016/j.bone.2019.02.006

Cited by 23 publications

(22 citation statements)

References 52 publications

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“…Prevention of the pro-inflammatory secretome of senescent cells in aged mice with a JAK inhibitor improved bone mass and strength (94). It has been hypothesized that exercise to increase mechanical strain on bone could improve the senescent phenotype in aging (95). It remains to been seen whether a lack of mechanical loading and a lack of adequate mechanosensory ability or pro-inflammatory senescent markers occurs first during aging in osteocytes.…”

Section: Mechanosensing and Inflammatory Signalsmentioning

confidence: 99%

The Role of Osteocytes in Inflammatory Bone Loss

Metzger

Narayanan

2019

Front. Endocrinol.

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Osteoimmunology investigations to-date have demonstrated the significant interactions between bone surface cells, osteoclasts and osteoblasts, and immune cells. However, there is a paucity of knowledge on osteocytes, cells embedded in the bone matrix, and their role in inflammation and inflammatory bone loss. Osteocytes communicate through various mechanisms; directly via dendritic processes and through secretion of proteins that can influence the formation and activity of osteoblasts and osteoclasts. Some osteocyte proteins (e.g., interleukin-6 and RANKL) also have roles within the immune system. In the context of mechanical loading/unloading, the regulatory role of osteocytes is well understood. More recent data on osteocytes in various inflammatory models suggest they may also aid in orchestrating inflammation-induced changes in bone turnover. In inflammatory conditions, osteocytes express multiple pro-inflammatory cytokines which are associated with increases in bone resorption and declines in bone formation. Cytokines are known to also influence cell population growth, maturation, and responsiveness via various signaling modalities, but how they influence osteocytes has not been greatly explored. Furthermore, osteocytes may play regulatory roles in orchestrating bone's response to immunological changes in inflammatory conditions. This review will address what is known about osteocyte biology in physiological conditions and in response to varying immunological conditions, as well as highlight key areas of interest for future investigations.

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Section: Mechanosensing and Inflammatory Signalsmentioning

confidence: 99%

The Role of Osteocytes in Inflammatory Bone Loss

Metzger

Narayanan

2019

Front. Endocrinol.

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“…Moreover, the LCN was shown to be the main actor in bone mechanical answer to loading 17,18,[23][24][25][26][27] . Indeed, it was recently shown that a significantly higher number of osteocytes was present around immediately loaded human dental implants with respect to control sites left to heal submerged (i.e.…”

mentioning

confidence: 99%

Jawbone remodeling: a conceptual study based on Synchrotron High-resolution Tomography

Iezzi

Mangano

Barone

et al. 2020

Sci Rep

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one of the most important aspects of bone remodeling is the constant turnover mainly driven by the mechanical loading stimulus. the remodeling process produces changes not only in the bone microarchitecture but also in the density distribution of the mineralized matrix-i.e. in calcium concentrations-and in the osteocyte lacunar network. Synchrotron radiation-based X-ray microtomography (microCT) has proven to be an efficient technique, capable to achieve the analysis of 3D bone architecture and of local mineralization at different hierarchical length scales, including the imaging of the lacuno-canalicular network. in the present study, we used microct within a conceptual study of jawbone remodeling, demonstratively focusing the investigation in two critical contexts, namely in the peri-dental and the peri-implant tissues. the microct analysis showed that a relevant inhomogeneity was clearly present in both peri-dental and peri-implant biopsies, not only in terms of microarchitecture and mineralization degree, but also considering the lacunar network, i.e. size and numerical density of the osteocyte lacunae. the correlated histological results obtained on the same samples confirmed these observations, also adding information related to non-mineralized tissues. Despite its demonstrative nature, it was concluded that the proposed method was powerful in studying jawbone remodeling because it revealed a direct correlation of its rate with the lacunar density, as achieved by the analysis of the osteocyte lacunar network, and an inverse correlation with the local bone mineral density, as revealed with the Roschger approach. Remodeling is a process enabling bone tissue to adapt to different physiological conditions and to replace damaged bone with newly-formed bone 1 , producing complete renewal of the entire skeleton mass about every 10 years 2. Several studies have been focused on regenerative properties of bone, but few of them were referred to the jaw sites. Conversely, it must be considered that the jawbone presents unique properties: thus, data regarding other skeletal bones, many of them referred to long bones 3-7 , may not be completely applicable to the jaw 8. Indeed, it is known since long time that the jawbone is remodeled faster than the other skeletal bones 9. This seems to be due to jaw morphogenesis: jaw arises from neural crest cells of the neuroectoderm germ layer and not of the mesoderm; 10 moreover, it undergoes intramembranous, instead of endochondral, ossification 11. Regarding the stem cells derived from the jaw, bone marrow stromal cells exhibit higher osteogenic potential and different characteristics respect to stem cells recruited in other skeletal bones 12-16. Consequently, because of the aforementioned features of the jawbone matrix, even if several studies have been focused on bone remodeling in other skeleton sites, there is a special need of specific investigations referred to the jawbone. One of the most important aspects of jawbone remodeling is the constant turnover mainly driven by the ...

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“…Axial ( Z ) apparent modulus of the proximal tibia has been recorded by numerous authors with values ranging from 2.5–3780 MPa which agrees well with our data. [ 5,6,12,17–31 ] It is noted that a number of studies report apparent modulus to be significantly less or greater than our study, which may be due to differences in experimental method, small samples sizes of predominantly young males or inclusion of cortical bone regions within cubes. [ 5,22,30,32,33 ] Studies such as those by Johnston et al, Nazemi et al, and Ashman et al have found apparent modulus from alternative methods (e.g., indentation testing, finite element simulations combined with neural networks or ultrasound testing).…”

Section: Resultsmentioning

confidence: 56%

Mapping the Multi‐Directional Mechanical Properties of Bone in the Proximal Tibia

Munford

Jeffers

2020

Adv Funct Materials

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The remodeling behavior of bone is influenced by its mechanical environment. By mapping bone's mechanical properties in detail, orthopedic implants with respect to its mechanical properties could stimulate and harness remodeling to improve patient outcomes. In this study, multiaxial apparent modulus and strength of cadaveric proximal tibial bone are mapped and predicted from computed tomography (CT) derived apparent density. Group differences are identified from testing order, subchondral depth, condyle, and sub-meniscal bone with covariates; age and gender. Axial modulus is 50% greater than the transverse modulus. Medial axial modulus is 30% greater than the lateral side. On the lateral side, axial modulus decreases by 50% from proximal to 25 mm distal. On the medial side, axial modulus remains relatively constant. Differences are quantified for density and multiaxial modulus across all subchondral depths, and different power law relationships are provided for each location. Density explains 75% of variation when grouped by subchondral depth and condyle. Yield strength is well-predicted across all test directions, with density predicting 81% of axial strength variation and no differences over subchondral depth. Quantified mapping of bone multiaxial modulus based on condyle and subchondral depth is shown for the first time in a clinically viable protocol using conventional CT.

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Senescent and apoptotic osteocytes and aging: Exercise to the rescue?

Cited by 23 publications

References 52 publications

The Role of Osteocytes in Inflammatory Bone Loss

The Role of Osteocytes in Inflammatory Bone Loss

Jawbone remodeling: a conceptual study based on Synchrotron High-resolution Tomography

Mapping the Multi‐Directional Mechanical Properties of Bone in the Proximal Tibia

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