Abstract:

Objective To discuss the effect of mangiferin （MGF） on the healing of hip fracture in the rats by regulating the Wnt/β-catenin signaling pathway， and to clarify the mechanism. Methods The hip fracture model in the SD rats was established. After successful modeling， the rats were divided into model group， MGF group， and MGF+XAV-939 （Wnt/β-catenin signaling pathway inhibitor） group， and sham operation group was set up， and there were 15 rats in each group. From the first day after surgery， the rats in each group received MGF or XAV-939 interventions every two days， totally for 14 times. Lane-Sandhu X-ray scoring method was used to detect the fracture healing in the second and fourth weeks after surgery； micro CT was used to detect the microstructural parameters of the bone， such as bone volume （BV）， number of bone trabeculae （Tb.N）， bone volume fraction （BV/TV）， and bone trabecular thickness （Tb.Th）； HE staining was used to observe the morphology of callus tissue of the rats in various groups； enzyme-linked immunosorbent assay （ELISA） was used to detect the levels of osteogenic markers bone alkaline phosphatase （BALP） and type Ⅰ procollagen N-terminal propeptide （PINP） and bone resorption markers tartrate resistant acid phosphatase-5b （TRACP-5b） and Carboxy-terminal terminalpeptide of type Ⅰ collagen （CTX） in serum of the rats in various groups；Western blotting method was used to detect the expression levels of β-catenin， Runt-associated transcription factor 2 （Runx2）， and bone morphogenetic protein-2 （BMP-2） in callus tissue of the rats in various groups. Results Compared with sham operation group， the rats in model group showed distinct fracture lines， an abundance of fibrous tissue at the fracture site， and no bony callus at the 2nd and 4th weeks after fracture， the Lane-Sandhu X-ray scores and microstructural parameters BV， Tb.N， BV/TV， and Tb.Th of the rats in model group were decreased （P<0.05），the serum level of BALP was decreased （P<0.05）， while the levels of PINP， TRACP-5b， and CTX were increased （P<0.05），and the expression levels of β-catenin， Runx2， and BMP-2 proteins in callus tissue were decreased （P<0.05）. Compared with model group， the rats in MGF group showed significantly increased new bone callus at 2nd weeks after fracture， almost no visible fracture line at the 4th weeks， faster fracture healing， and replacement of fibrous tissue by bone tissue at the fracture site， the Lane-Sandhu X-ray scores and microstructural parameters BV， Tb.N， BV/TV， and Tb.Th of the rats in MGF group were increased （P<0.05）， the serum level of BALP was increased （P<0.05）， the levels of PINP， TRACP-5b， and CTX were decreased （P<0.05），and the expression levels of β-catenin， Runx2， and BMP-2 proteins in callus tissue were increased （P<0.05）. Compared with MGF group， the rats in MGF+XAV-939 group showed only a small amount of new bone callus at the fracture site at 2nd and 4th weeks after fracture， with no formation of the marrow cavity， and the Lane-Sandhu X-ray scores and microstructural parameters BV， Tb.N， BV/TV， and Tb.Th of the rats in MGF+XAV-939 group were decreased （P<0.05）， the serum level of BALP was decreased （P<0.05）， the levels of PINP， TRACP-5b， and CTX were increased （P<0.05），and the expression levels of β-catenin， Runx2， and BMP-2 proteins in callus tissue were decreased （P<0.05）. Conclusion MGF can promote the healing of hip fracture in the rats， and its mechanism may be related to activation of Wnt/β-catenin signaling pathway.

Key words: Mangiferin, Hip fracture, Healing, XAV-939, Wnt/β-catenin signaling pathway