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Probing the tissue to subcellular level structure underlying bone's molecular sieving function
A E Tami1, M B Schaffler, M L Knothe Tate
1Department of Biomedical Engineering, Orthopaedic Research Center, Lerner Research Institute, The Cleveland Clinic Foundation, Cleveland, OH 44195, USA.
Biorheology
|November 12, 2003
Summary
Bone acts as a molecular sieve, limiting solute transport. Mechanical loading enhances fluid flow, increasing the penetration of smaller molecules through the bone matrix and lacunocanalicular system (LCS).
Area of Science:
- Biomaterials Science
- Skeletal Biology
- Mechanobiology
Background:
- The lacunocanalicular system (LCS) is crucial for nutrient and waste transport to osteocytes within the dense bone matrix.
- Understanding bone's permeability is key to comprehending osteocyte viability and mechanotransduction.
Purpose of the Study:
- To characterize the permeability of the bone matrix and LCS.
- To investigate the effect of mechanical loading on solute transport in bone.
Main Methods:
- Transport of fluorescent probes (300 Da to 2,000,000 Da) in mechanically loaded and unloaded rat ulnae.
- Analysis of probe penetration into the mineral matrix and LCS.
Main Results:
- Bone mineral matrix restricts probes >300 Da.
- LCS pericellular space allows diffusion up to 10 kDa; convective flow enhances transport up to 70 kDa.
- Probes >70 kDa are excluded from bone regardless of loading.
Conclusions:
- Bone functions as a molecular sieve.
- Mechanical loading significantly modulates solute transport within bone via fluid flow.
- Findings support transport-modulated bone remodeling and have implications for osteocyte health.