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- Agholme, Fredrik, et al.
(författare)
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Anti-sclerostin antibody and mechanical loading appear to influence metaphyseal bone independently in rats
- 2011
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Ingår i: Acta Orthopaedica. - : Taylor and Francis. - 1745-3674 .- 1745-3682. ; 82:5, s. 628-632
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Tidskriftsartikel (refereegranskat)abstract
- Background and purpose: Sclerostin is produced by osteocytes and is an inhibitor of bone formation. Thus, inhibition of sclerostin by a monoclonal antibody increases bone formation and improves fracture repair. Sclerostin expression is upregulated in unloaded bone and is downregulated by loading. We wanted to determine whether an anti-sclerostin antibody would stimulate metaphyseal healing in unloaded bone in a rat model.Methods: 10-week-old male rats (n = 48) were divided into 4 groups, with 12 in each. In 24 rats, the right hind limb was unloaded by paralyzing the calf and thigh muscles with an injection of botulinum toxin A (Botox). 3 days later, all the animals had a steel screw inserted into the right proximal tibia. Starting 3 days after screw insertion, either anti-sclerostin antibody (Scl-Ab) or saline was given twice weekly. The other 24 rats did not receive Botox injections and they were treated with Scl-Ab or saline to serve as normal-loaded controls. Screw pull-out force was measured 4 weeks after insertion, as an indicator of the regenerative response of bone to trauma.Results: Unloading reduced the pull-out force. Scl-Ab treatment increased the pull-out force, with or without unloading. The response to the antibody was similar in both groups, and no statistically significant relationship was found between unloading and antibody treatment. The cancellous bone at a distance from the screw showed changes in bone volume fraction that followed the same pattern as the pull-out force.Interpretation: Scl-Ab increases bone formation and screwfixation to a similar degree in loaded and unloaded bone.
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- Agholme, Fredrik, et al.
(författare)
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Sclerostin Antibody Treatment Enhances Metaphyseal Bone Healing in Rats
- 2010
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Ingår i: JOURNAL OF BONE AND MINERAL RESEARCH. - : American Society for Bone and Mineral Research. - 0884-0431. ; 25:11, s. 2412-2418
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Tidskriftsartikel (refereegranskat)abstract
- Sclerostin is the product of the SOST gene Loss of-function mutations in the SOST gene result in a high bone-mass phenotype demonstrating that sclerostin is a negative regulator of bone mass Primarily expressed by osteocytes in bone sclerostin is reported to bind the LRP5/6 receptor thereby antagonizing canonical Wnt signaling and negatively regulating bone formation We therefore investigated whether systemic administration of a sclerostin neutralizing antibody would increase the regeneration of traumatized metaphyseal bone in rats Young male rats had a screw inserted in the proximal tibia and were divided into six groups given 25 mg/kg of sclerostin antibody or control twice a week subcutaneously for 2 or 4 weeks In four groups, the screws were tested for pull out strength At the time of euthanasia a similar screw also was inserted in the contralateral tibia and pull-out tested immediately Sclerostin antibody significantly increased the pull out force by almost 50% compared with controls after 2 and 4 weeks Also the screws inserted at the time of euthanasia showed increased pull out force Micro-computed tomography (mu CT) of the remaining two groups showed that the antibody led to a 30% increase in bone volume fraction in a region surrounding the screw There also was a general increase in trabecular thickness in cancellous bone Thus as measured by the amount of bone and its mechanical resistance the sclerostin antibody increased bone formation during metaphyseal repair but also in untraumatized bone
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| 10. |
- Agholme, Fredrik, et al.
(författare)
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The effects of Dickkopf-1 antibody on metaphyseal bone and implant fixation under different loading conditions
- 2011
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Ingår i: BONE. - : Elsevier Science B.V., Amsterdam.. - 8756-3282. ; 48:5, s. 988-996
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Tidskriftsartikel (refereegranskat)abstract
- The secreted protein Dickkopf-1 (Dkk1) is an antagonist of canonical Wnt signaling, expressed during fracture healing. It is unclear how it is involved in the mechanical control of bone maintenance. We investigated the response to administration of a Dkk1 neutralizing antibody (Dkk1-ab) in metaphyseal bone under different loading conditions, with or without trauma. In this three part experiment, 120 rats had a screw or bone chamber inserted either unilaterally or bilaterally in the proximal tibia. Mechanical (pull-out) testing, mu CT and histology were used for evaluation. The animals were injected with either 10 mg/kg Dkk1-ab or saline every 14 days for 14, 28, or 42 days. Antibody treatment increased bone formation around the screws and improved their fixation. After 28 days, the pull-out force was increased by over 100%. In cancellous bone, the bone volume fraction was increased by 50%. In some animals, one hind limb was paralyzed with Botulinum toxin A (Botox) to create a mechanically unloaded environment. This did not increase the response to antibody treatment with regard to screw fixation, but in cancellous bone, the bone volume fraction increased by 233%. Thus, the response in unloaded, untraumatized bone was proportionally larger, suggesting that Dkk1 may be up-regulated in unloaded bone. There was also an increase in thickness of the metaphyseal cortex. In bone chambers, the antibody treatment increased the bone volume fraction. The results suggest that antibodies blocking Dkk1 might be used to stimulate bone formation especially during implant fixation, fracture repair, or bone disuse. It also seems that Dkk1 is up-regulated both after metaphyseal trauma and after unloading, and that Dkk1 is involved in mechano-transduction.
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