Preparation And Study Of Polymer Microspheres And The Of 3D Compound Scaffolds Loaded With And Slow Release Of BMPs And Osteogenetic Differentiation

BackgroundSo far,bone defect is a common clinical disease and the traditional treatment methods is incomplete,for examples,limited source and caused complications,especially for large bone defect.Baesd on the development of biomaterials and tissue engineering technology,the traditional model of bone defects has been changed and the shortcomings of traditional therapy have been improve.And it is expected to become an effective means to solve clinical bone defect repair.Bone defect repair scaffold is one of the hotspots of tissue engineering for bone repair.Ideal bone tissue engineering materials should have three-dimensional(3D)porous structure,mechanical strength,biodegradability,biocompatibility,good osteoinductivity,and so on.However,most biopolymers for application in bone tissue engineering do not show remarkable osteoinductivity.In addition,bone morphogenetic protein(BMP)is a osteoinductive growth factor,and it can add into biopolymers.Hence,a novel 3D polymer scaffold,which can loaded with and slow-released BMP,should been designed and prepared for osteogenic differentiation,for application in bone tissue engineering.Part 1:Preparation of polymer microspheres loaded with and released BMP-2 and BMP-7Objective: Novel microspheres based poly glycolic acid-lactide acid-ethylene glycol copolymer,which can loaded with and released BMP-2 and BMP-7,respectively,have been designed by double emulsion solvent evaporation method(W1/O/W2)in this study,for osteogenic differentiation of human osteoblasts h FOB1.19 in bone tissue engineering.Methods: The BMP-2 and BMP-7 microspheres of PGLA-PEG were prepared using a emulsion method.The size,encapsulation efficiency of BMPs and release of BMP-2 and BMP-7 from microspheres were investigated,respectively.The human osteoblasts(h FOB1.19)were cultivated with these microspheres for various tests,including cell proliferation and osteogenic differentiation.Results: The results showed the produced BMP-2 and BMP-7 microspheres based on PGLA-PEG can successfully loaded with and slow-release the BMP-2 and BMP-7,respectively.The human osteoblasts h FOB1.19 grew well with BMPs microspheres,similarly to that of cell culture plate control on day 10.The expressions of ALP collagen type-1(COL-1),osteocalcin(OC)and osteopontin(OPN)of cells with BMPs microspheres were higher than the cell culture plate control without BMPs.Conclusion: We successfully prepared novel PGLA-PEG microspheres,which can loaded with and released BMP-2 and BMP-7,respectively,for osteogenic differentiation of osteoblasts in bone tissue engineering.Part 2:Preparation of polymer composite scaffold simultaneously loaded with and released two BMPsObjective: 3D polymer scaffold,which can simultaneously released BMP-2 and BMP-7,have been designed in this study,for osteogenic differentiation of human osteoblast in bone tissue engineering.Methods: Firstly,the BMP-2 and BMP-7 microspheres of PGLA-PEG were prepared using a emulsion method.And the 3D porous scaffold of PGLA-PEG was also produced by phase separation.To form the composite scaffold loaded with BMPs,the two microspheres were fixed into scaffolds with methylene chloride fumigation technology,for investigation of slow-release effect of BMP-2 and BMP-7.The human osteoblast line cells(h FOB1.19)were seeded into these composite scaffolds for various tests,including cell proliferation and osteogenic differentiation.Results: The results showed the produced 3D composite scaffolds can successfully loaded with and slow-release the BMP-2 and BMP-7.The human osteoblasts h FOB1.19 grew better on 3D composite scaffolds than traditional PCL scaffolds on day 10 of cell culture,and had normal cell morphology.The expressions of ALP collagen type-1(COL-1),osteocalcin(OC)and osteopontin(OPN)of 3D composite scaffolds was higher than the scaffold without BMPs.Conclusion: We successfully prepared a novel PCL composite composite scaffold,which can simultaneously released BMP-2 and BMP-7,for osteogenic differentiation of OCT-1 cells in bone tissue engineering.Part 3:Preparation of phospholipid/polymer composite scaffold abundantly loaded with and released BMP-2 in the long termObjective: A novel PCL composite scaffold,which can loaded with abundant BMP-2 and long-term released slowly BMP-2,have been designed in this study,for osteogenic differentiation of human bone mesenchymal stem cells(BMSCs)in bone tissue engineering.Methods: Firstly,the BMP-2 was modified by soybean phospholipids to form BMP-2/PL compound(BMP-2/PL),for dispersion in methylene dichloride.PCL with B/P,was dissolved in methylene dichloride and produced to 3D scaffold,using an emulsion method,production.And the slow-release of BMP-2 from PCL-B/P scaffold was detected.The human BMSCs were seeded into these composite scaffolds for various tests,by comparation with the traditional scaffold,including cell proliferation with CCK-8 and osteogenic differentiation with ALP and RT-q PCR.Results: Compared with the traditional scaffolds(PCL-B),produced PCL composite scaffolds(PCL-B/P)in this study showed the well slow-release of BMP-2.The cell viability of BMSCs grew on PCL-B/P was better than that on PCL-B in 21 days of cell culture.The ALP content and expressions of collagen type-1(COL-1),osteocalcin(OC)and osteopontin(OPN)of 3D composite scaffolds(PCL-B/P)was higher than the PCL-B scaffold.Conclusion: We successfully prepared a novel PCL composite scaffold loaded with BMP-2 in bone tissue engineering.And this scaffold can released slowly BMP-2 for osteogenic differentiation of human bone mesenchymal stem cells(BMSCs),better than traditional scaffold.