Evaluation Of RhBMP-2 And Mesenchymal Stem Cells In Open Porous Biodegradable Polymeric Microspheres For Spinal Fusion Of Lumbar Intertransverse Process In Rat

[Abstract]Objective:To evaluate the efficacy of bone morphogenetic protein(BMP)-2-microspheres in inducing a posterolateral spine fusion in rat model.Methods:BMSCs were isolated from the bone marrow by density gradient centrifugation and fulling combined with adhering to cuture plastic in different time,Highly open porous biodegradable polymeric microspheres were fabricated for use as scaffold microcarriers for cell and rhBMP-2 delivery.A modified water-in-oil-in-water(W1/O/W2) double emulsion solvent evaporation and gas foaming method was employed for producing the microspheres.Attached cells on the microspheres scaffold were stained with Molecular Probes for cytological observation;BMSCs influenced by rhBMP-2-porous microspheres in cocultured with porous microspheres in vitro studied by the control group of rhBMP-2 adminstered only;Combination or used alone of rhBMP-2-porous microspheres and BMSCs-porous microspheres for posterolateral spine fusion in rats.Results:The method of density gradient centrifugation and fulling combined with adhering to cuture plastic in different time isolating BMSCs from bone marrow is simple,furthermore,the homozygosis of BMSCs is good and the injury of BMSCs is very little;BMSCs are compatible to grow,proliferate and differentiate in these porous microspheres; rhBMP-2-porous microspheres could induce BMSCs resulting in the more persisting and powerful effect of the proliferation,differentiation and bone formation in porous microspheres in vitro;All animals treated with rhBMP-2-porous microspheres alone or combination of BMSCs-porous microspheres demonstrated successful spinal fusion,four weeks postoperatively.Conclusions:The experimental study shows that the method of density gradient centrifugation and fulling combined with adhering to cuture plastic in different time,the porous microspheres for rhBMP-2 and/or BMSCs are the optimal methods and techniques for the construction of the bone tissue engineering.