| Objective:In the wake of accelerated pace of life and extended life expectancy,a growing number of patients are suffering from bone defects caused by accidents or diseases.The routine solution would be to fill a defective bone with alternative material and wait for the bone’s natural healing process to occur.The sources of bone substitutes generally include the bone provided by the body(e.g.autogenous bone and tooth),allograft,xenograft and synthetic bone graft.Each bone substitute has its own advantages and disadvantages.In terms of scope of application,availability and safety,synthetic bone graft is superior to other materials.The purpose of this study is to design a type of biocomposite composed of strontium,chitosan and multi-walled carbon nanotubes(“Sr-CNTs/CS biocomposite”),which can be prepared by solvent evaporation to support the growth of bone cells.Therefore,a strontium biological scaffold composed of chitosan and multi-walled carbon nanotubes was developed by solvent evaporation to promote the growth of osteoblasts.The osteogenic properties of Sr-CNTs/CS biocomposite were observed by biological experiments.In brief,the Sr-CNTs/CS biocomposite is an ideal candidate for clinical bone healing,since it has excellent mechanical properties,long-term multifunctional antibacterial activity and good performance in inducing osteogenesis.Methods:The carbon nanotubes with strontium concentrations of 0%,0.2%,1% and 2% were obtained by means of solution blending and freeze-drying,and labeled as Group A,Group B,Group C and Group D.All rats were randomly divided into 4 groups: Group A(implanted A scaffolds for parietal bone defect),Group B(implanted B scaffolds for parietal bone defect),Group C(implanted C scaffolds for parietal bone defect)and Group D(implanted D scaffolds for parietal bone defect).Twelve weeks after surgery,the rats were sacrificed by anesthesia overdose and cervical dislocation.Bone tissue was obtained from the area with parietal bone defect and treated for Masson’s trichrome staining and immunohistochemical(IHC)staining(platelet-derived growth factor-BB(PDGF-BB)and bone morphogenetic protein-2(BMP-2)).Count the number of the amount of newly formative bone under microscope.And the mean optical density(MOD)of immunohistochemistry staining determined with easiness using the Image Pro plus 7.0.SPSS 21.0 was used to analyze the results via variance analyisis and SNK test(P<0.05).Results:The soft tissues in the surgical sites of rats all healed well in the four groups.Large amounts of residual scaffolds were visible in the area filled with scaffolds.New tough tissues were visible at the edge of bone defect.Masson’s sections and immunohistochemical analysis PDGF-BB and BMP-2 showed that Group C had the highest content of PDGF-BB.The number of the newly formative bone in group A、B、C and D was 11.50±4.31、15.75±3.06、18.88±3.87 and 14.75±1.6.Their difference had statistic significance between group(P<0.05).Conclusion:The Sr-CNTs/CS scaffolds shows good osteogenic properties,but it also has some disadvantages such as inadequate degradation and incomplete osteogenesis.In relative terms,the osteogenesis was most obvious when the strontium content was 1%.It is necessary to determine the optimum strontium concentration by further study and improve the biocomposite in a way that makes it degrade more easily and form bones more completely. |
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