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Changes in trabecular bone turnover and bone marrow cell development in tail-suspended mice.
1Department of Orthopaedic Surgery, University of Occupational and Environmental Health, Kitakyushu, Japan. a-sakai@med.uoeh-u.ac.jp
Journal of Musculoskeletal & Neuronal Interactions
|March 11, 2005
Summary
Skeletal unloading causes rapid bone loss, but reloading can restore it if done within a week. Longer unloading periods lead to irreversible bone loss, highlighting the critical window for intervention.
Area of Science:
- Skeletal Biology
- Bone Physiology
- Spaceflight Research
Background:
- Skeletal unloading, such as during spaceflight, leads to significant trabecular bone loss.
- The tail-suspended mouse model is a key tool for studying the effects of unloading on bone.
Purpose of the Study:
- To investigate the impact of short-term (1-2 weeks) skeletal unloading on bone microarchitecture and remodeling in mice.
- To determine the efficacy of subsequent reloading in restoring bone mass and cellular activity after unloading.
Main Methods:
- Utilized the tail-suspended mouse model to induce hindlimb unloading.
- Performed histomorphometric analyses on murine tibiae to assess bone volume, formation, and resorption.
- Conducted bone marrow cell cultures to evaluate cellular responses to unloading and reloading.
Main Results:
- One week of unloading caused rapid trabecular bone loss, reduced bone formation, and increased osteoclast activity.
- Two weeks of reloading fully restored bone volume after one week of unloading but not after two weeks.
- Unloading affected bone marrow stromal cell differentiation, while reloading modulated marrow cell adhesion and osteoclast formation.
Conclusions:
- Tail suspension significantly impairs bone formation and enhances resorption, with effects on bone marrow cell differentiation.
- The duration of unloading is critical; early reloading can reverse bone loss, but prolonged unloading leads to persistent deficits.
- The tail-suspended mouse model is valuable for dissecting the cellular and physiological mechanisms underlying skeletal adaptation to unloading and reloading.