| Background:In the clinical work of Department of orthopedics and hand surgery,we often encounter cases of bone defects caused by trauma,tumor,infection,deformity and so on.For the treatment of bone defect,there are many clinical applications of autogenous bone graft,allograft bone graft,and metal prosthesis.But there are obvious shortcomings.Autologous bone graft is effective,but the source is limited,and it brings another damage to the donor area,and may increase the risk of hematoma,infection,and so on.Allograft bone graft is immune rejection,and potential cross infection is also daunting.Metal prosthesis,although occupies the mrchanical strength,but not biodegradable,may have loose,allergic reaction and other adverse consequences.Now,developing biodegradable materials with high strength,good biocompatibility and biodegradability is attracting more and more attention.It has great application prospects in tissue engineering and regenerative medicine.The ideal bone defect repair biomaterials need to meet the following conditions:(1)the compressive strength of the bone to bone support(2)the appropriate degradation rate and new bone growth rate,which is balanced(3)good biocompatibility,no rejection and inflammatory reaction(4)surface activity and good porosity,conducive to bone cell adsorption,proliferation,growth and nutrient uptake(5)has a certain biological activity,can induce bone formation,promote bone ingrowth,accelerate the healing of bone defect.In recent years,the biological materials commonly used in clinic include inorganic materials,natural organic polymer materials and chemical synthetic polymers.Inorganic materials include Bioglass and bone cement,in which bioactive glass is widely applied.Because its components are similar to human cortical elements,it can well combine bone tissue to facilitate ingrowth.At the same time,the calcium and silicon plasma released by the Bioglass can induce bone induction,which can promote bone regeneration.But its mechanical properties are poor and the plasticity is low.Plant protein(zein,wheat gliadin,etc.)is a natural polymer material.It belongs to polysaccharides or proteins.It is nontoxic,widely distributed,inexpensive,and has good degradability in vivo,widely used in tissue culture,but its physical properties are poor.Chemically synthesized polymer materials,including polycaprolactone and polylactic acid,have good mechanical properties and stability,low immunogenicity and good controllability,but low degradation rate.They also produce acidic substances in the micro ring,which are not good for new bone growth,but also lead to inflammatory response.It can be seen that single material is difficult to meet all the needs of treatment,and composite materials can make up for each other's shortcomings,so that the compressive strength,degradation and biocompatibility of scaffold materials are continuously improved,which can meet further clinical applications.There are many ways to prepare biomaterial scaffolds,including foam replication,freeze-drying,gas foam,solvent casting,particle leaching,phase separation and electrospinning.These traditional methods are economical and simple,but they can not effectively control the porosity,pore size and shape of the scaffold.3D printing technology is a new technology in 1980s,taking the 3D model in computer design is modeled by the software system,using laser beam or hot melt nozzle layer by layer can be printed,metal powder,ceramic powder,tissue as raw material,print out the bracket can control structure and porosity,in the field of Engineering preparation of a wide range of applications.Aims:We hope that the use of 3D technology,the preparation of a new bone repair scaffold,the structure can control the porosity,pore size and morphology of human,and change the content of calcium and magnesium silicate,stents,stent comparison of different calcium magnesium silicate content and physical properties in vivo and in vitro experiments and biological properties,reveal the composite scaffold the ratio,the best content,the compressive strength,biodegradability and biocompatibility has good performance,applied to the clinical treatment of bone defect in the hope of providing a new method for tissue engineering and regenerative medicine.Methods:We used 3D printing technology to prepare a new mesoporous material scaffold(MGPC).Its material consisted of mesoporous Bioglass,magnesium calcium silicate(mMCS),gliadin(GA)and polycaprolactone(PCL).Also,we change the content of calcium and magnesium silicate scaffold,prepared by three different groups of stents,GPC group(excluding calcium magnesium silicate(including 15%),15MGPC group and 30MGPC group(calcium silicate)containing 30%calcium magnesium silicate),to compare the performance of different bracket,so as to reveal the effects of calcium magnesium silicate concentration on the support performance the.In vitro,we through the mechanical measuring instrument of the stent group and tested for compressive strength;the immersion in Tris-HCl stent group for 2 weeks.The morphological observation of stent surface by scanning electron microscope,the changes of quality balance before and after stent immersion,to assess the degradation of the scaffold;at the same time,will not be the same with the generation of MC3T3-E1 cells into the scaffold group co culture in 6 hours,12 hours and 24 hours later,cell growth was observed by scanning electron microscope,measuring cell adsorption rate and the value of the level of reactive cells were observed on the stent,so as to evaluate the compatibility of different biological scaffolds.Finally,we combine the different stent group implanted in rabbit femoral defect model,in 1 months,2 months,was 3 months,and were generally by comparison and organization,to evaluate the different content of calcium and magnesium silicate scaffolds in vivo degradability,biocompatibility and osteoinductive effect.Results:Our experimental results show that materials with good porosity,pore size and well connectivity can be prepared by using 3D printing technology.With the increase of Mg CA silicate content,the porosity of the mesoporous composite scaffolds changed,but the compressive strength increased significantly.In Tris-HCl the degradation rate is gradually increased,in addition,the adsorption rate and the OD value of co cultured with scaffold MC3T3-E1 cells also increased with the calcium magnesium silicate content increased markedly.At the same time,the scanning electron microscopy(SEM)showed that the surface morphology of the scaffolds was normal,and the adsorption and diffusion of the cells were good.After the implantation of the rabbit femoral defect model in different stents,all the scaffolds were degraded and new bone formed as time went on.However,with the increase of mMCS content,the residual rate of scaffolds decreased,and the new bone formation area increased.By immunohistochemical staining,the expression of I collagen increased.Conclusion:According to our results,we can see that the structure of 3D printing MGPC materials with controllable(porosity,pore size and pore connectivity),good biocompatibility,high compressive strength,suitable degradation rate,can promote bone formation in vivo,and with the increase of the content of calcium and magnesium silicate,scaffold materials,compressive strength degradation,biocompatibility and bone formation obviously,show that the material has a broad application prospect on bone regeneration,it is a feasible method for treatment of bone defect. |
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