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Long-lived murine osteocytes are embodied by craniofacial skeleton in young and old animals whereas they decrease in
Robert G Stigler1, Kathrin Becker2, Frank R Kloss1
1Department of Oral and Maxillofacial Surgery, Medical University Innsbruck, Innsbruck, Austria.
Gerodontology
|July 28, 2018
Summary
Bone aging differs between the mandible and femur due to osteocyte activity. Mandibular osteocytes ensure lifelong bone integrity, suggesting potential human relevance for craniofacial bone health.
Area of Science:
- Biomedical Science
- Skeletal Biology
- Aging Research
Background:
- Osteocytes are crucial for bone remodeling, fracture healing, and osseointegration.
- Age-related decline in ossification and regeneration capacity varies between mandible and femur.
- Mesenchymal stem cells from different skeletal origins may explain varying regenerative capacities in aged individuals.
Purpose of the Study:
- To investigate age-related differences in osteocyte density, lacunar density, and osteoid formation between murine mandibles and femurs.
- To test the hypothesis that distinct aging patterns exist in craniofacial versus postcranial bones.
- To explore the role of osteocytic activity in tissue-specific bone aging.
Main Methods:
- Histological analysis of mandibles and femurs from young and old male C57Bl/6 mice.
- Quantification of osteocyte-occupied lacunae.
- Assessment of osteoid formation using Masson-Goldner staining and BMP-2 expression analysis.
Main Results:
- Mandibular osteocyte density showed a modest decrease with age (91.12% young vs. 85.63% old).
- Femoral osteocyte density significantly decreased with age (93.28% young vs. 55.99% old).
- Old femurs exhibited reduced osteoid formation and decreased BMP-2 expression compared to young femurs.
Conclusions:
- Osteocyte activity dictates tissue-specific bone aging, with craniofacial bone (mandible) maintaining osteocyte function longer than postcranial bone (femur).
- Long-lived osteocytes in the craniofacial skeleton contribute to lifelong bone integrity.
- Preliminary human data suggest these findings are translatable to humans, highlighting the mandible's resilience in aging.
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