Wnt/β-catenin signaling is required for distraction osteogenesis in rats

ABSTRACT

Overview: The Wnt signaling pathway plays crucial roles in embryonic skeletal development and postnatal bone regeneration. However, mechanisms of Wnt signaling functioning in distraction osteogenesis (DO) haven’t been well characterized. Materials and Methods: We established a DO model using Sprague–Dawley rat tibia. And a Wnt signaling blocking agent, recombinant rat Dickkopf-related protein 1 (rrDkk1), was locally applied in the distracted gap to study the role of Wnt signaling during DO process. Animals in the experimental group received rrDkk1 injections (dose = 25 μg/kg) once daily during distraction period and every third day during consolidation stage (n = 48). Animals in the control group received saline under the same injection strategy (n = 48). Animals at different time points during DO process (1, 3, 6, 12 days after distraction, 10 days and 6 weeks after consolidation) were killed and tissues in the distraction region were harvested for radiography, dual energy X-ray absorptiometry, micro-computed tomography (micro-CT), and histological analyses. Results: Most Wnt ligands, cofactors, receptors, and antagonists were widely expressed in the distraction callus and were significantly upregulated during DO process. After rrDkk1 administration, the majority of these factors were downregulated at the mRNA level, except sFRP and GSK-3β. At the protein level, both β-catenin and Lef-1 were also suppressed by rrDkk1. In the long term, restricted bone healing was observed in the distracted callus in the rrDkk1 injection group. These findings were confirmed by histological and micro-CT analyses. Conclusions: Our findings suggest that Wnt signaling participates in the process of DO, and clinical therapeutic approaches of DO may do well to avoid Wnt pathway suppression.

KEYWORDS:

• Bone regeneration
• distraction osteogenesis
• Dkk1
• tibia
• Wnt signaling

Declaration of interest

The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the article.

Funding

This study was supported by grants from the National Nature Science Foundation of China (Nos. 81271106, 81271178, and 30973346).

Additional information

Funding

This study was supported by grants from the National Nature Science Foundation of China (Nos. 81271106, 81271178, and 30973346).