Construction And Efficacy Assessment Of A Bionic Bone Repair Composite Scaffold For Inducing Bone Formation

Objective:Bone defects due to various etiologies have been a challenge for clinical treatment.The application of tissue engineering techniques to construct biologically active artificial bone replacement materials is a potential solution.With the gradual advancement of bone tissue engineering research,the construction of novel bone repair materials that can integrate and modulate adaptive mechanical properties,osseointegration,bone ingrowth,better matching of vascularization and bone regeneration,and reconstruct or even accelerate the repair process at the site of bone defects is the ultimate goal of current bone defect repair research.Biodegradable hydrogels,metal and ceramic scaffolds are the most commonly used artificial bone repair materials,but there are problems such as poor bioactivity,poor bone repair effect or mismatch of mechanical properties.Therefore,to address the key issues in the bone repair process,organic-inorganic composite to make bone tissue engineering scaffolds with adaptive mechanical properties,excellent osteoconductivity,osteoinductivity and vascular induced life can greatly advance the development and transformation of bone repair materials in the field of bone defect repair.Methods:Part I:construction of zirconia（ZrO₂）and methacrylate-based gelatin（GelMA）/alginate（SA）interpenetrating polymer network（GelMA/SA IPN）hydrogel（ZrO₂-GM/SA）composite scaffolds.The scaffolds were tested for biocompatibility,and hemolysis assay,cytotoxicity analysis,3D cell encapsulation activity,osteogenic capacity analysis and in vivo toxicity analysis were performed to investigate the effect of biocompatibility as well as osteoinductive activity.PartⅡ:The combination of microfluidic technology and photocrosslinking technology was used to construct GM&Ions-HA/WH bionic composite hydrogel microspheres by using GelMA hydrogel microspheres as the carrier and K⁺,Na⁺,Sr²⁺co-doped hydroxyapatite（Ions-HA）and Zn²⁺,Ce³⁺co-doped white phosphorite（Ions-WH）nanoparticles as a composite.PartⅢ:a bionic human umbilical cord-derived decellularized matrix（UC-d ECM）and GM&Ions-3HA/1WH（ECM-GM&Ions-3HA/1WH）composite hydrogel scaffold was constructed using double cross-linking technique,and the materialistic characterization and simple biocompatibility of the bionic composite scaffold were investigated.Material science characterization was performed for swelling experiments,degradation experiments,and characterization of mechanical properties;in vitro,its potential for application in bone regeneration applications was investigated by cytotoxicity experiments and co-culture of cells and scaffolds.Results:Part I:Compared with the porous bare ZrO₂scaffold and the optimized ZrO₂-GelMA composite scaffolds,the optimized ZrO₂-GM/SA composite scaffolds had high biocompatibility and cell adhesion properties;the constructed bionic ZrO₂-GM/SA composite scaffolds could promote the directed differentiation of MC3T3-E1 to osteoblasts and exhibits good biocompatibility and in vivo low toxicity.PartⅡ:Compared with GelMA hydrogel microspheres,GM&Ions-HA/WH hydrogel microspheres had excellent biocompatibility and cell adhesion properties;the constructed bionic bone defect repair unit can create a good anti-inflammatory environment;GM&Ions-HA/WH hydrogel microspheres scaffold enhanced the ability of MC3T3-E1to differentiate toward osteogenesis induction and improves the expression level of related genes and protein expression levels.PartⅢ:ECM-GM&Ions-3HA/1WH hydrogels demonstrated superior cytocompatibility and better cell adhesion compared with GM&Ions-3HA/1WH hydrogel,even the cells would extend towards the inside of the scaffold after co-culture with the scaffold for 7 days.Conclusions:Part I:The optimized ZrO₂-GM/SA composite scaffold has high mechanical properties,high biocompatibility and osteoinductive activity;and the composite scaffold is an ideal preosteoblast cell carrier with 3-dimensional culture of cells inside the technology,which is a potential osteoinductive active scaffold.PartⅡ:GM&Ions-HA/WH hydrogel microspheres with osteogenic and anti-inflammatory bionic microenvironment were successfully developed using photocrosslinking method and microfluidic technology.The highly bionic microspheres can effectively promote the adhesion,proliferation and osteogenic differentiation of MC3T3-E1 in vitro.PartⅢ:ECM-GM&Ions-3HA/1WH hydrogels have improved biocompatibility and bone ingrowth potential and have great potential for application in the field of bone defect repair.