The Synthesis And Characterization Of UPPE-PLGA-rhBMP2Scaffolds For Bone Regeneration

Part1Objective： To synthesis and detect a new kind of magnetic PLGA-BMP2microspheresthat can be used in bone tissue engineering scaffolds.Methods： Use the water-in-oil-in-water emulsion solvent evaporation method toprepare the microspheres. Use the scanning electron microscope (SEM) to observe themorphology of microspheres. Use the vibrating sample magnetometer (VSM) to test themagnetism of microspheres. Use the ELISA to detect the drug loading rate and slow releaseof microspheres.Results： The SEM images show that the microsphere showed a positive round with theparticle size between10-100um. The VSM results show that the microspheres aresuper-paramagnetic. The ELISA results show that the microspheres are slow release and its’drug loading rate is1±0.18ng/mg.Conclusion： The magnetic PLGA-BMP2microspheres were successfully synthesizedand can be used in the magnetic bone tissue engineering scaffolds. Part2Background： A novel unsaturated polyphosphoester (UPPE) was devised in ourprevious research, which has the potentials for bone regeneration scaffolds. Theunfavorable polymerization process of UPPE may adversely affect the bioactivity of osteoinductive molecules, such as recombinant human bone morphogenetic protein-2(rhBMP2).Objective: To investigate the possibility of maintain the bioactivity of rhBMP2byadding poly (lactic-co-glycolic acid)(PLGA)-rhBMP2microspheres to the synthesisprocess of UPPE scaffolds. The cytotoxicity and biocompatiblity of the newUPPE-PLGA-rhBMP2(UPB) scaffolds would be detected simultaneously.Methods: A W1/O/W2method was used to fabricate PLGA-rhBMP2microspheres. Usethe scanning electron microscope (SEM) to observe the morphology of microspheres. Usethe laser scanning confocal microscope (LSCM) to observe the rhBMP2on themicrospheres. Use the ELISA to detect drug loading rate and slow release of mic rospheres,and examine the activity of rhBMP2after the microspheres were treated at45℃.Thecytotoxicity and biocompatibility of UPB scaffolds were evaluated by the adsorption andapoptosis of bone marrow mesenchymal cells (BMMCs) seeded on the surface of scaffolds.The alkaline phosphatase (ALP) activity of seeded BMMCs was measured to evaluate thebioactivity of rhBMP2in scaffolds.Results: The microsphere showed a positive round with the particle size between10-100um, and rhBMP2evenly distributed on the microspheres. PLGA microspheres andUPB scaffolds have a burst and sustained release of rhBMP2. The cytotoxicity would begreatly reduced after the scaffolds were steeped in buffer solution for2hours, and cellscould be adsorbed and grown on the surface of soaked scaffolds. The ALP activity ofseeded BMMCs was significantly enhanced, indicated that the bioactivity of rhBMP2remainsConclusion: Our observations suggest that rhBMP2could be added into UPB scaffoldsand maintain its bioactivity in the form of PLGA-rhBMP2microspheres. UPB scaffoldshave a low cytotoxicity, and can be used in vivo.