Affiliations: Departments of Biomedical Engineering and Orthopaedic Surgery, Orthopaedic Research Center, Lerner Research Institute, The Cleveland Clinic Foundation, Cleveland, OH 44195, USA | Leni and Peter W. May Department of Orthopaedics, The Mount Sinai School of Medicine, New York, NY 10029, USA
Note: [] Corresponding author: M.L. Knothe Tate, Ph.D., Depts. of Biomedical Engineering and Orthopaedic Surgery, ND20, Orthopaedic Research Center, Lerner Research Institute, The Cleveland Clinic Foundation, 9500 Euclid Ave., Cleveland, OH 44195, USA. Tel.: +1 216 445 3223; Fax: +1 216 444 9198; E‐mail: [email protected].
Abstract: Transport of fluorescent probes between 300 and 2,000,000 Da was studied in mechanically loaded and unloaded ulnae of skeletally mature rats to characterize the permeability of the pericellular space of the lacunocanalicular system (LCS), and the microporosity of the bony matrix. The mineral matrix porosity allowed for penetration of the 300 Da probe but impeded transport of larger probes. The pericellular space of the LCS was permeable up to 10 kDa; above 10 kDa, diffusion was ineffective for transport through the pericellular space. Convective transport via load‐induced fluid flow increased penetration of all probes up to 70 kDa. Above this threshold, probes were excluded from bone, both with and without loading. This exploratory study suggests that bone acts as a molecular sieve and that mechanical loading modulates transport of solutes through the pericellular space that links osteocytes deep within the tissue to the blood supply and to osteoblasts and osteoclasts on bone forming and resorbing surfaces. This provides support for the postulate of transport modulated bone remodeling in which osteocytes are influenced by and modulate the local permeability of their surroundings as a means for survival (Knothe Tate et al. 1998, [28]) and has profound implications for osteocyte viability and intercellular communication in bone.
Keywords: Osteocytes, fluid flow, mechanotransduction, molecular sieve, mass transport
Journal: Biorheology, vol. 40, no. 6, pp. 577-590, 2003
