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Published on: July 3, 2020
Differential expression of sclerostin in adult and juvenile mouse calvariae
Matthew D Kwan1, Natalina Quarto, Deepak M Gupta
1Stanford, Calif. From the Hagey Laboratory for Pediatric Regenerative Medicine, Division of Plastic and Reconstructive Surgery, Department of Surgery, Stanford University School of Medicine.
Background:
An understanding of the molecular mechanisms controlling bone formation is central to skeletal tissue engineering efforts. The observation that immature animals are able to heal calvarial defects while adult animals are not has proven to be a useful tool for examining these mechanisms. Thus, the authors compared expression of sclerostin, a bone inhibitor, between the calvariae of juvenile and adult mice.
Methods:
Parietal bone was harvested from juvenile (6-day-old; n = 20) and adult (60-day-old; n = 20) mice. Sclerostin transcript and protein levels were compared between the parietal bone of juvenile and adult mice using polymerase chain reaction, Western blotting, and immunohistochemistry. Finally, osteoblasts from the parietal bone of juvenile and adult mice were harvested and cultured under osteogenic differentiation conditions with and without recombinant sclerostin (200 ng/ml). Terminal osteogenic differentiation was assessed at 21 days with alizarin red staining.
Results:
Polymerase chain reaction, Western blot analysis, and immunohistochemistry all confirmed greater expression of sclerostin in the parietal bone of adult mice when compared with that of juvenile mice. Osteoblasts, whether from juvenile or adult parietal bones, demonstrated reduced capacity for osteogenic differentiation when exposed to recombinant sclerostin.
Conclusions:
Given the role of sclerostin in inhibiting bone formation, the authors' findings suggest that differences in expression levels of sclerostin may play a role in the differential regenerative capacity of calvariae from juvenile and adult animals. These findings suggest it as a potential target to abrogate in future tissue engineering studies.
Insights
Juvenile mice exhibit lower sclerostin levels, promoting bone healing. Adult mice show higher sclerostin, inhibiting bone formation, suggesting sclerostin as a target for skeletal tissue engineering.
Area of Science:
- Skeletal Biology
- Tissue Engineering
- Molecular Mechanisms of Bone Formation
Background:
- Understanding bone formation is crucial for skeletal tissue engineering.
- Immature animals heal calvarial defects better than adults, indicating age-related molecular differences.
- Sclerostin, a bone formation inhibitor, was investigated to explain these regenerative differences.
Purpose of the Study:
- To compare sclerostin expression in juvenile versus adult mouse calvariae.
- To investigate the role of sclerostin in the differential regenerative capacity of bone.
- To identify potential targets for improving skeletal tissue engineering.
Main Methods:
- Harvested parietal bone from juvenile (6-day-old) and adult (60-day-old) mice.
- Quantified sclerostin transcript and protein levels using PCR, Western blotting, and immunohistochemistry.
- Assessed osteoblast differentiation capacity with and without recombinant sclerostin.
Main Results:
- Adult mice demonstrated significantly higher sclerostin expression (transcript and protein) in parietal bone compared to juvenile mice.
- Osteoblasts from both age groups showed reduced differentiation when exposed to recombinant sclerostin.
- Sclerostin inhibits osteogenic differentiation in both juvenile and adult osteoblasts.
Conclusions:
- Differential sclerostin expression likely contributes to age-related differences in calvarial bone regeneration.
- Sclerostin inhibition may be a viable strategy for enhancing bone healing in tissue engineering.
- Targeting sclerostin could improve outcomes in skeletal regenerative medicine.
