Three-dimensional Celluar Microenvironment Build And The Study Of Bone Repair Performance With High Strength And Low Modulus Bone Implants

In clinical orthopedics,the large bone defects are very common due to trauma,benign and malignant tumors,congenital and acquired malformation,nosocomial and out-of-hospital infection.However,how to promote osseointegration in clinical segmental bone defect have been the difficult and hot issues of bone reparative study.An ideal bone repair material should be with good ability on mechanics,possess osteoinductive activity and provide sufficient blood vessel supply,so as to stimulate osteogenic differentiation and angiogenesis,then to promote bone repair.Though porous titanium and its alloys have excellent mechanical and machinability properties,titanium alloys are inert materials with high Young's modulus and poor activity,their osseointegration were not ideal.Therefore,this selective district laser melt forming 3D printing was to build a kind of low modulus,high strength of porous titanium alloys segmental bone defect scaffolds.In the 3D printing,the three-dimension microenvironments will be constructed within the macro pores.According to the extracellular matrix structure characteristics,they could build similar 3D celluar microenvironments in the body to assist cells osteogenic differentiation and angiogenesis and improve the repair of nonunion of bone,which provide theoretical principle and experimental support for the research and development of new segmental bone defect implants.This study was based on 3D printing technology and functional surface modified methods to construct a composite porous titanium alloy scaffold material with good osseointegration effect.The main research contents and results are as follows:(1)Process optimization of 3D-printed porous Ti6Al4 V scaffolds and their biocompatibility evaluationBy studying the biological safety of 3D printing titanium alloy materials prepared by different processes,the parameters of 3D printing technology were optimized.And the porous titanium alloy scaffolds with precise controllable were constructed.The relative density,porosity,mechanical properties,morphology and composition analysis were also evaluated.The study found that the optimized elastic modulus of 3D printed titanium alloy scaffolds was close to that of natural bone and had good biocompatibility.(2)The application of biomimetic bone scaffold materials: HA/collagen modified 3D-printed porous Ti6Al4 V scaffolds in the repair of bone defects.This research proposed novel HA/collagen modified porous titanium alloy implant materials based on 3D printing and in-vitro biomimetic mineralization techniques.We found that the HA/collagen modified 3D-printed porous Ti6Al4 V scaffolds had good biological safety,osteogenic differentiation and angiogenic differentiation abilities in vitro cell and molecular biology experiments.At the same time,in vivo animal experiments showed that the HA/collagen modified porous titanium alloy scaffold could improve vascularization,osteogenic differentiation and osseointegration.Therefore,a biomimetic HA/collagen modified 3D printing porous titanium alloy scaffold could enhance angiogenesis,osteogenesis,and osteointegration,which provide a new method for developing a new generation of bone repair materials.(3)The application of gelatin methacryloyl(GelMA)hydrogels modified 3D-printed porous Ti6Al4 V scaffolds in the repair of bone defectsThis innovative project intended to combine laser selective district melt forming 3D printing with the "molecular brigade" technology,to build a kind of low modulus,high strength of porous titanium alloys segmental bone defect repair scaffolds.Experimental results in vitro indicated that the GelMA modified 3D-printed porous Ti6Al4 V scaffolds were biocompatible and could promote osteogenic differentiation.Implantation experiments in vivo further confirmed GelMA modified 3D-printed porous Ti6Al4 V scaffolds could promote the ability of bone repair around the implants,providing a new idea for the development of large segment bone defect repair implants.(4)Antibacterial performance of zinc-containing GelMA hydrogels modified 3D-printed porous Ti6Al4 V scaffoldsWe prepared zinc-containing GelMA hydrogel modified with porous titanium scaffolds and detected their antibacterial performance and biocompatibility by in vitro experiments.And the results showed that zinc-containing GelMA hydrogel modified porous Ti6Al4 V scaffolds had good antibacterial properties,which can reduce the risk of scaffolds infection.For the treatment of large segment bone defects caused by infection,it will be an potential carrier material.