TP508 Promotes Bone Regeneration on Distraction Osteogenesis via the Activation of Wnt/β-catenin Signaling Pathway

Introduction: TP508 is a thrombin peptide that participates in the inflammatory response and wound healing. Its role in the molecular mechanism of distraction osteogenesis remains unclear. This study established a tibia distraction osteogenesis (DO) model in rats and investigated the role and mechanism of TP508 in bone regeneration during DO. Method: Micro-computed tomography (Micro-CT) and hematoxylin-eosin (HE) staining were used to track osteogenesis. Western blot and quantitative real-time polymerase chain reaction (qRT-PCR) were performed to measure the expression of osteoblast-related factors, Wnt/β- catenin signaling-related proteins and genes. Immunohistochemistry was used to measure the expression of β-catenin in the cytoplasm and nucleus. Results: TP508 accelerated bone regeneration increased the expression of the osteoblast-related factors Alkaline phosphatase (ALP), runt-related transcription factor 2 (RUNX2), and osteocalcin (OCN). After the Wnt signaling was inhibited by LGK974, the expression of osteoblastrelated factors was downregulated, leading to a decrease in bone regeneration ability. More importantly, TP508 upregulated β-catenin and its target CYCLIN-D1 and could reverse the decreased osteogenic ability caused by LGK974. Conclusion: In conclusion, TP508 promotes bone regeneration in DO by activating the Wnt/β- catenin signaling pathway.