Design Of Fibrous Scaffolds Based On Bone Microenvironment For Bone Regeneration

Maxillofacial bone defect caused inflammation, congenital malformations andsurgical treatment is a common clinical manifestation of oral medical science andwhich makes the bone defect repair has been an important problem faced in thisfield. Currently, treatment of bone defects by using bone autograft, allograft,biological material and distraction osteogenesis technology has made a certainprogress. However, because of secondary injury, poor shape, immune rejection, hightechnical requirements, high costs and limited osteogenesis ability which limit theirmore widespread application. With the development of cell biology and biologicalmaterial science, building of artificial bone by tissue engineering technology forbone defect is becoming a hot spot of current research. Bone biochemicalmicroenvironment is the biological basis of bone tissue engineering, the design ofthe bone tissue engineering scaffold material and the selection of biological activitefactors. The understanding of bone biochemical microenvironment will greatlypromote the development of bone tissue engineering. Ideal bone tissue engineeringscaffold materials should have good osteoconduction and osteoinduction.Reconstruction and regeneration of bone extracellular matrix microenvironmentsystem and bone biochemical signaling molecule system are the designing aim ofbone tissue engineering, and finally repair bone defects quickly. Two mainingredients in the extracellular matrix are bone collagen and hydroxyapatite, thusbone tissue engineering scaffold material should include the two ingredients intheory. More over, through choosing appropriate bioactive factors to rebuild bonebiochemical signaling molecules can significantly improve the efficiency of bonerepair. Based on the above theory, we fabricate gelatin and hydroxyapatite modifiedpoly (lactic co glycolic acid) fibrous scaffold by electrostatic spinning method.Subsequently, we utilized confocal laser scanning microscopy (CLSM) and MTTassay to evaluate its cyto-compatibility in vitro. Besides, realtime quantitativepolymerase chain reaction (qPCR) analysis and alizarin red staining (ARS) wereperformed to assess the osteoinductive activity. To further test in vivo, we implantedfibrsous scaffolds in rat model. The results demonstrated that PGH scaffold couldbetter support osteoblasts adhesion, spreading, and proliferation and show bettercyto-compatibility than pure PLGA scaffold. Besides, qPCR analysis and ARSshowed that PGH composite scaffold exhibited higher osteoinductive activity owingto higher phenotypic expression of typical osteogenic genes and calcium deposition.The histology evaluation indicated that the incorporation ofGelatin/nanohydroxyapatite biomimetics could significantly reduce localinflammation. Our data indicated that PGH composite electrospun nanofiberspossessed excellent cytocompatibility, good osteogenic activity, as well as goodperformance in vivo, which could be versatile biocompatible scaffolds for bonetissue engineering.We also have prepared the biomimetic Gelatin/HA electrostatic spinningfibrous scaffold material. To improve the osteoinduction of scaffold, we added beta-glycerol phosphate disodium salt and ascorbic acid into Gelatin/HA fiber whichwere common ingredients in conditioned osteoinductive medium. We use scanningelectron microscope to observe the morphology of the scaffold before and aftercrosslinking. Through the establishment of rat critical-sized bone defect model, weevaluate the bone regeneration ability of the scaffolds in vivo. We determined therepair effects by MICRO CT and histological evaluation. Results showed that thedrug loaded nanofibers can repair bone defect quickly, and served as a template toguide bone regeneration and mineralization. Therefore beta-glycerol phosphatedisodium salt and ascorbic acid loaded Gelatin/HA scaffolds is a good autologousbone substitute material, can be used in clinical treatment for bone defect. Besides, by using the method of freeze-drying, we also fabricated EPO loadedGelatin/HA scaffold, which was a bone biochemical microenvironment hormonalsignaling molecules. We fabricated EPO loaded Gelatin/HA scaffold based on itsvery high specific surface area and porosity. We also use it to repair skull defect inrats. We established5mm critical-sized bone defect in rats skull and implanted EPOloaded scaffold into the defects. We assessed bone regeneration by MICRO CT andhistological evaluation. Results showed that EPO loaded scaffold could significantlypromote bone repair. EPO can stimulate proliferation and secretion of bone matrixof osteoblasts. Thus, EPO loaded Gelatin/HA scaffold is an excellent bone tissueengineering bone.