In Vivo Tracer Transport Through the Lacunocanalicular System of Rat Bone in an Environment Devoid of Mechanical Loading

Tate, Melissa L. Knothe; Niederer, Peter F.; Knothe, Ulf

doi:10.1016/s8756-3282(97)00234-2

Cited by 229 publications

(111 citation statements)

References 42 publications

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“…While the procedure was reproducible, it lacked the manufacturing precision that would have made it possible to distinguish subtle influences of defect size, implant compliance, and host femur compliance. 31 who found endosteal and periosteal evidence of microperoxidase (1,800 Da) diffusion in 60-day-old rats 2 h following injection. With intravascular volume estimated to be 5%-7% of body mass, the IV concentration of microperoxidase was approximately 1,700-2,300 mM.…”

Section: Discussionmentioning

confidence: 99%

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Novel explant model to study mechanotransduction and cell–cell communication

Hoffler

Hankenson

Miller

et al. 2006

Journal Orthopaedic Research

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To understand in situ behavior of osteocytes, we characterized a model of osteocytes in their native bone matrix and demonstrated real-time biologic activity of osteocytes while bending the bone matrix. Using 43 male Sprague-Dawley rats, dumbbell-shaped explants were harvested from stainless steel femoral implants after 6-12 weeks and incubated in culture medium or fixed. Sixteen specimens were used to determine bone volume density (BV/TV), volumetric bone mineral density (BMD) and histology for different implantation periods. Osteocyte viability was evaluated by L-lactate dehydrogenase (LDH) activity in 12 cultured explants. Confocal microscopy was used to assess tracer diffusion in three explants and changes in osteocyte pH of a mechanically loaded explant. From 6 to 12 weeks, explant BV/TV and volumetric BMD trended up 92.5% and 101%, respectively. They were significantly and highly correlated. Tissues were uniformly intramembranous and all bone cell types were present. Explants maintained LDH activity through culture day 8. Diffusion at 200 mM was limited to 1,209 Da. Explants appeared capable of reproducing complex bone biology. This model may be useful in understanding osteocyte mechanotransduction in the context of a physiologically relevant bone matrix. ß

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Section: Discussionmentioning

confidence: 99%

“…Probe molecular weights were selected based on recent literature 31 and previous experience with cell labeling. The confocal micrograph in Figure 7A demonstrated that the 950 Da tracer had accessed osteocyte lacunae within 10 min.…”

Section: Diffusion Analysismentioning

confidence: 99%

Novel explant model to study mechanotransduction and cell–cell communication

Hoffler

Hankenson

Miller

et al. 2006

Journal Orthopaedic Research

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“…123 It should be noted that 2/3 of the blood supply of cortical bone is provided by the endosteal surface. 80,102 It has also been shown that the variations and oscillations in IMP play an important role on the loading induced fluid flow developed in the interstices of the cortical bones as well as of the trabecular bones. 97,101,124 Therefore it is likely that the variations in the IMP not only affect the resident pluripotent stem cells but also serve as one of the players which are driving the fluid flow within the intersticies of cortical bone by way of generating pressure gradients between the envelopes of bone.…”

Section: Effects Of Physiological Activity and Loadingmentioning

confidence: 99%

The Mechanical Environment of Bone Marrow: A Review

2008

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Bone marrow is a viscous tissue that resides in the confines of bones and houses the vitally important pluripotent stem cells. Due to its confinement by bones, the marrow has a unique mechanical environment which has been shown to be affected from external factors, such as physiological activity and disuse. The mechanical environment of bone marrow can be defined by determining hydrostatic pressure, fluid flow induced shear stress, and viscosity. The hydrostatic pressure values of bone marrow reported in the literature vary in the range of 10.7-120 mmHg for mammals, which is generally accepted to be around one fourth of the systemic blood pressure. Viscosity values of bone marrow have been reported to be between 37.5 and 400 cP for mammals, which is dependent on the marrow composition and temperature. Marrow's mechanical and compositional properties have been implicated to be changing during common bone diseases, aging or disuse. In vitro experiments have demonstrated that the resident mesenchymal stem and progenitor cells in adult marrow are responsive to hydrostatic pressure, fluid shear or to local compositional factors such as medium viscosity. Therefore, the changes in the mechanical and compositional microenvironment of marrow may affect the fate of resident stem cells in vivo as well, which in turn may alter the homeostasis of bone. The aim of this review is to highlight the marrow tissue within the context of its mechanical environment during normal physiology and underline perturbations during disease.

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“…Moreover, patterns of cortical fluid flow are not only related to the differences in histological techniques and microscopic observation, but also with animal models and molecular size of makers used for labeling cortical fluid flow (Seliger, 1970;Kelly, 1973;Dillaman, 1984;Montgomery et al, 1988;KnotheTate et al, 1998). In our study, using ferritin as a fluid marker (molecular size of 0.01µm), flow pattern within the canaliculi-osteocytic lacunae system (canal diameter larger that 0.2µm) was well demonstrated but not the fluid pattern within the microporosity of the collagen-hydroxyapatite matrix due to their small size from 0.001 to 0.02µm (Pollack et al, 1984;Knothe et al, 1998). Flows within the matrix microporosity have only been implicated indirectly in some streaming potential analyses (Salzstein et al, 1987).…”

Section: Discussionmentioning

confidence: 60%

Histomorphological study on pattern of fluid movement in cortical bone in goats

et al. 1999

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Streaming potential is considered one of the most important mechanisms to moderate the function of osteoblasts and osteocytes in bone growth, remodeling and fracture repair. The present study was designed to demonstrate the fluid flow pattern in the cortical bone matrix in an animal model using undecalcified histological techniques. Immediately after injection of ferritin into the tibia nutrient artery of four adult goats, the animals were euthanized. Undecalcified transverse and longitudinal blocks of cortical bone obtained from the tibial diaphysis were immersed in Perl's reagent and embedded in methyl methacrylate. Sections were cut and ground to 30-50 µm thickness for histomorphological evaluation at different magnifications and focusing levels. A serial grinding technique was used to validate the observations made at different focusing levels. As expected, ferritin was observed in the interstitial compartment in both transverse and longitudinal sections. In osteons sectioned transversely, the pattern of centrifugal movement of ferritin marker was demonstrated as single or multiple halos around the Haversian canal. The most apparent halo in osteons with multiple halos was the one found closest to the Haversian canal. The total number of identifiable single or multiple halos increased or was altered when counting was made with higher magnification or at different focusing levels, respectively. Irregular and incomplete ferritin halos indicated structural complexity of the osteons. Overall, the pattern of ferritin movement was consistent with bulk interstitial fluid flow influenced by both hydrostatic pressure and transudation. This study demonstrated for the first time multiple concentric halos of the fluid flow marker ferritin around Haversian canals in the cortical interstitial compartment. The results suggest that the undecalcified technique might be a useful method for qualitative and quantitative studies on cortical fluid flow. Anat Rec 255: 380-387, 1999. 1999 Key words: fluid flow; cortical bone; ferritin transudation; undecalcification; histology; microscopy Mature cortical bone is structurally organized into osteons. Each osteon is roughly cylindrical in shape with concentric lamellae around the vasculature-containing Haversian canal. Between the lamellae lie the ellipsoidal lacunae where the osteocytes reside. Cortical bone has a hierarchical network of flow channels, i.e. the longitudinal Haversian and the transverse Volkmann's canals to the tiny lacunae-canaliculi channels around the bone cells, and the microporosity of the collagen-hydroxyapatite bone matrix (Cooper et al

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In Vivo Tracer Transport Through the Lacunocanalicular System of Rat Bone in an Environment Devoid of Mechanical Loading

Cited by 229 publications

References 42 publications

Novel explant model to study mechanotransduction and cell–cell communication

Novel explant model to study mechanotransduction and cell–cell communication

The Mechanical Environment of Bone Marrow: A Review

Histomorphological study on pattern of fluid movement in cortical bone in goats

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