Different effects of Wnt/β‐catenin activation and parathyroid hormone on diaphyseal and metaphyseal in the early phase of femur bone healing of mice

Parathyroid hormone (PTH) and agents related to the manipulation of Wnt/β‐catenin signalling are two promising anabolic anti‐osteoporotic therapies that have been shown to promote the healing of bone fractures. Now, it is widely accepted that cortical bone and trabecular bone are two different compartments, and should be treated as separate compartments in pathological processes, such as fracture healing. It is currently unknown whether PTH and the activation of β‐catenin signalling would demonstrate different effects on cortical bone and trabecular bone healing. In the current study, single 0.6‐mm cortex holes were made in the femur metaphysis and diaphysis of mice, and then, PTH application and β‐catenin activation were used to observe the promoting effect on bone healing. The effects of β‐catenin and PTH signalling on fracture healing were observed by X‐ray and CT at 3, 6, and 14 days after fracture, and the levels of β‐catenin were detected by RT‐PCR assay, and the number of specific antigen‐positive cells of BRDU, OCN, RUNX2 was counted by immunohistochemical staining. While β‐catenin activation and PTH were found to demonstrate similar effects on accelerating metaphyseal bone healing, activation of β‐catenin showed a more striking effect than PTH on promoting diaphyseal bone healing. These findings might be helpful for selecting proper medication to accelerate fracture healing of different bone compartments.