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Microgravity and bone cell mechanosensitivity.
J Klein-Nulend1, R G Bacabac, J P Veldhuijzen
1ACTA-Vrije Universiteit, Department of Oral Cell Biology, Amsterdam, The Netherlands. J.Klein_Nulend.ocb.acta@med.vu.nl
Advances in Space Research : the Official Journal of the Committee on Space Research (COSPAR)
|March 6, 2004
Summary
Bone cells sense mechanical stress via fluid flow, which triggers signaling molecules like nitric oxide (NO) and prostaglandins (PGs). Near weightlessness may impair this mechanosensation, contributing to bone loss in astronauts.
Area of Science:
- Biomedical Engineering
- Cell Biology
- Skeletal Physiology
Background:
- Bone adapts its mass and structure to mechanical loads through cellular processes.
- Osteocytes and lining cells sense mechanical stress via interstitial fluid flow.
- This fluid flow stimulates signaling pathways involving prostaglandins (PGs) and nitric oxide (NO).
Purpose of the Study:
- To investigate the impact of near weightlessness on bone cell mechanosensitivity.
- To determine if reduced gravity alters the early signaling response (NO, PGs) to mechanical stress.
- To elucidate the role of the cytoskeleton in bone cell mechanotransduction under altered gravity.
Main Methods:
- Utilizing a modified in vitro oscillating fluid flow apparatus (FlowSpace) on the International Space Station.
- Culturing bone cells with and without simulated gravity (near weightlessness).
- Applying mechanical loading to assess cellular responses, including NO and PG production.
Main Results:
- Near weightlessness conditions may alter cytoskeletal assembly and cell mechanosensitivity.
- Disruption of the actin-cytoskeleton abolishes cellular responses to mechanical stress.
- Fluid flow-induced NO and PG synthesis are key mediators of bone's adaptive response.
Conclusions:
- Altered mechanosensation in bone cells under near weightlessness could contribute to astronaut bone loss.
- The cytoskeleton plays a critical role in transducing mechanical signals in bone cells.
- Understanding these mechanisms is crucial for developing countermeasures against spaceflight-induced bone degradation.