| Objective: Type 2 diabetes mellitus(T2DM)is a metabolic disease characterized by decreased or relative decreased insulin secretion due to the decreased ability of insulin to regulate glucose metabolism and the functional defect of islet β cells.When fractures occur in patients with type 2 diabetes,infection,poor bone quality and prolonged fracture healing may occur.The present study was to investigate the effect of a new type of degradable magnesium alloy on type 2 diabetic fracture in rats.A kind of degradable magnesium alloy(Mg-2Zn-0.5Nd-0.5Zr)was developed by Institute of Metals,Chinese Academy of Sciences.In order to make it more suitable for implantation in the body,the Institute of Metals,Chinese Academy of Sciences has optimized its process to make it have high strength,plasticity and high corrosion resistance.In order to study the therapeutic effect and mechanism of the modified degradable magnesium alloy on type 2diabetic fracture,we carried out cell and tissue experiments on the modified degradable magnesium alloy(" new degradable magnesium alloy "),and provided the basis for the clinical application of the new degradable magnesium alloy.Firstly,the relationship between the osteogenic effect of the new degradable magnesium alloy on osteoblasts induced by high glucose and PGC-1α/Fox O3 signaling pathway and mitochondrial autophagy was studied,and whether the mechanism of the new degradable magnesium alloy in up-regulating osteogenic effect was related to NIPA2 protein was studied.Secondly,to investigate the effect of new degradable magnesium alloy screw in the treatment of type 2 diabetic fracture.Methods: Firstly,the basic properties of the new degradable magnesium alloy and the preparation of magnesium alloy leaching solution were studied.In order to study the mechanism of osteoblast proliferation and differentiation promoted by new degradable magnesium alloy,osteoblasts were divided into control group,model group and magnesium alloy extract group according to different treatment factors.The CCK8 assay was used to detect cell viability in the different treatment groups.The osteoblasts were detected by ALP and alizarin red staining.The mitochondrial membrane potential was measured by immunofluorescence assay.Western blotting and real-time PCR were used to detect the expression of OSX,RUNX-2,Col-1,OPG,OCN,PGC-1α,Fox O3 a,pFox O3 a,p62,PINK1 and Parkin at the protein and gene levels.Then,in order to further study the related mechanism,the osteoblasts were further divided into control group,model group,NIPA2 si RNA group,NIPA2 si-con group,magnesium alloy extract group,NIPA2 si RNA+ magnesium alloy extract group and NIPA2 si-con + magnesium alloy extract group according to different treatment factors.ALP and alizarin red staining were used to detect the cells in each group.Western blot and real-time PCR were used to detect the contents of OSX,RUNX-2,Col-1,OPG,OCN,PGC-1α,Fox O 3a,p-Fox O3 a,p62,PINK1 and Parkin.Finally,to verify the new degradable magnesium alloy screw in the treatment of type 2 diabetic fractures.Firstly,the screw was designed and tested.Then the distal femoral fracture model of type 2 diabetic SD rats was established,and the fracture was fixed with screws.According to the different screw materials,it is divided into titanium screw group of the same model and new degradable magnesium alloy screw group.X-ray,Micro-CT and HE staining were used to observe the fixation effect of the same type titanium screw group and the new degradable magnesium alloy screw group on type 2 diabetic fractures at 6 weeks after operation.Western blot was used to detect the expression of NIPA2 and OSX protein in the same type of titanium screw group and the new degradable magnesium alloy screw group,and the content of RUNX-2,Col-1,OPG,OCN and other osteogenic activity indicators were detected.The expressions of CTX-1,OCN,ALP and TRAP in serum were detected by ELISA.Results: The new degradable magnesium alloy has better properties.In the osteoblast experiment,we found that compared with the model group,the proliferation level of cells in the magnesium alloy leaching solution group was significantly increased at 72 h(P<0.05);The activity of ALP and the formation of bone calcium nodules were obviously enhanced.OSX,RUNX-2,Col-1,OPG,OCN,PGC-1 α and Fox O3 a were up-regulated at the protein and gene levels(P <0.05).The depolarization of mitochondrial membrane potential was alleviated.The levels of p62,PINK 1 and Parkin were significantly decreased(P <0.05).Compared with the magnesium alloy extract group,the expression of ALP and the formation of bone calcium nodules in the NIPA2 si RNA + magnesium alloy extract group were significantly lower than those treated with magnesium alloy extract alone;The expression of OSX,RUNX-2,Col-1,OPG,OCN,PGC-1α,Fox O3 a and pFox O3 a were significantly decreased(P <0.05).At the same time,p62,PINK 1 and Parkin were increased(P <0.05).The results of X-ray,Micro-CT and HE staining showed that the new degradable magnesium alloy screw had the effect of promoting the healing of type 2diabetic fracture.Compared with the same type of titanium screw group,the expression levels of NIPA2 and OSX protein in the new degradable magnesium alloy screw group were significantly higher(P<0.05);The expression of RUNX-2,Col-1,OPG and OCN were significantly increased(P <0.05).Compared with the titanium screw group of the same model,the level of CTX-1 in the new degradable magnesium alloy screw group was significantly decreased,the level of OCN was significantly increased(P <0.05),the expression level of ALP was significantly increased,and the level of TRAP was significantly decreased(P <0.05).Conclusion: The new degradable magnesium alloy can regulate the activity of osteoblasts induced by high glucose and promote the proliferation and differentiation of osteoblasts,which is related to the up-regulation of NIPA2 protein expression,the activation of PGC-1α/Fox O3 signal pathway,the inhibition of mitochondrial autophagy and the promotion of the proliferation and differentiation of osteoblasts induced by high glucose.The new type of degradable magnesium alloy screw can promote the healing of type 2 diabetic fracture. |
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