The Construction And Bone Regeneration Of Iron Modified PLGA Microsphere Scaffold

Bone defect is one of the common surgical disease.A large number of bone substitutes are required for clinical treatment every year.However,most of the bone substitutes are lack osteoconductivity.And there is limited migration and homing efficiency of host cells.The new bone tissue grows via a creeping substitution mechanism after the implantation of bone substitutes.The rate of bone growth do not match the rate of implant resorption and incomplete repair during the creeping substitution process.The composition of nature bone is complex and contains a variety of trace metal elements,such as Mg,Sr,Zn and Fe.Bone grafting biomaterials dope with trace metal elements have a better performance of bone repair.Cell migration and homing efficiency can be improved after incubating with iron-base materials.In this work,iron was modified on the surface of PLGA microspheres based on the principle and characteristic of Pickering emulsion.And the effect of iron for bone regeneration in vitro and vivo was explored.First,ferric hydroxide?Fe?OH?₃?nanoparticle-coated poly?lactic-co-glycolic acid?microspheres?FePLGA?were designed via a Pickering emulsion.The morphology,element analysis and Fe content of the FePLGA microspheres were characterized by scanning electron microscopy?SEM?,X-ray photoelectron spectroscopy?XPS?and inductively coupled plasma atomic emission spectroscopy?ICP-AES?.And it indicated that FePLGA microspheres had a good cytocompatibility after culturing with mouse bone marrow stromal cells?mBMSCs?.Then,FePLGA microspheres were sintered to form porous microsphere scaffolds.Recombinant human bone morphogenetic protein-2?rhBMP-2?was immobilized on the scaffolds via a polydopamine coating to induce osteogenic differentiation.The cell viability,adhesion and migration of mBMSCs cultured on microsphere scaffolds were tested.The results indicated that the mBMSCs culture on scaffolds containing iron exhibited better adhersion,migration,proliferation and osteoblastic differentiation.And rhBMP-2significantly promoted osteogenic differentiation of mBMSCs.Moreover,the iron-containing,rhBMP-2-releasing scaffolds could enhance cell homing efficiency and promote bone formation and osteoconduction when implanted into critical size bone defect models of rabbit femur.Therefore,this new porous PLGA scaffold modified with iron and rh BMP-2 promotes bone repair by recruiting stem cells to the defect site and inside of scaffoldsIn summary,the iron modified and rhBMP-2 loaded microsphere scaffold can regulate cell migration,proliferation and osteogenic differentiation.And it can be used as multifunctional artificial bone substitute.