The Study Of Silk/CA Coaxial Electrospinning Membrane Controlled-releasing BMP-2 Promoting The Bone Formation

Part ?:Preparation and characteration of Silk/CA coaxial electrospinning membraneObjective: Silk fibroin(SF)and polyethylene glycol(PEO)and cellulose acetate(CA)as raw material,the innerlayer of the CA,the outer layer of SF/PEO compound fiber were used for coaxial electrospinning fibers,at the same time adding nanometer hydroxyapatite(n HAP)and loading BMP 2(BMP-2),study its material characterization,and provide material basis for follow-up study.Methods:Coaxial electrospinning method was adopted to realize coaxial electrospinning silk/cellulose membrane layer and outside join n HAP and BMP-2 is divided into three groups.Different groups of surface microstructure of material and the diameter size was observed under scanning electron microscopy(SEM),the coaxial structure of the material observed under transmission electron microscope and n HAP mixed with situation,pure CA fibers characterized with Fourier transform infrared spectrometer and infrared spectrum of three groups of coaxial fiber with mechanical tester tests of three groups of materials and pure CA fiber tensile and tensile modulus calculation.Results: Electrospinning fibers is uniform and the surface of the porous structure with fiber diameter between 1-3 microns,infrared spectrum and transmission electron microscopy(SEM)shows that fiber with coaxial structure and n HAP is located in the outer layer.The mechanical tests found that the coaxial fibers were significantly more mechanical than the simple CA.Conclusions: Regenerated fibroin solution can be successfully preparation of coaxial electrospinning fiber membrane.The fiber membrane can load n HAP and BMP-2.To make use of SF,the modification of the pure CA can improve the mechanical properties of the electrospinning film.Part ?:The study of of silk/CA coaxial electrospinning membrane controlled-releasing BMP-2 promoting the bone formation both in vitro and in vivoObjective: The biocompatibility of the mesenchymal stem cells was developed by using the coaxial membrane and the mesenchymal mesenchymal cells.The induced differentiation of the mesenchymal stem cells in the mesenchymal stem cells was induced by the induction of the mesenchymal mesenchymal stem cells.The whole layer of cranial defect of SD rats was established,and the material was implanted into the bone defects to study its body's osteogenic properties.Methods:ELISA method was used to determine the release of materials containing BMP-2and release rate was calculated.The bone marrow mesenchymal stem cells extracted from SD ratswere cultured on the three groups of materials and observed under scanning electron microscopy(SEM)for the cell adhesion.Cell proliferation was determined by the method of CCK-8,Transwell plate was used forthe stem cells co-culturedwithmaterial osteogenetic differentiation.Then ALP and alizarin red staining were used to observe it.A full-thickness skull defect model of SD rats was established for in vivo study.After8 and 12 weeks since implantingthe three groups of material into the defect sites,we killed the rats to takeskull specimens out to observe the conditions of the new bone formation via Micro-CTthree-dimensional reconstruction and bone content analysis.Finally,we put the 12 weeks of skull specimens for tissue pathological dyeing.Results: The BMP-2 was released from membranes for 3 weeks,with a total release of about 17%.Scanning electron microscopy(SEM)and CCK-8 results showed that cell adhesion and good pseudopod extend on material.With the passage of time,an increase of cell populations was observed and the cell populations is most in group ?.Osteogenesis induced in vitro experiment,ALP activity and calcium nodule number area from less to more,the order is from group? to group ?.CT bone content analysis found that the increase in the number of new bone group over time and the amout of new bone of group ? was more than that of group?.The amout of new bone of group ? was more than that of group ? as well.The group ?had the mostamout of new bone,whose BV/TV is about 27%.Histological staining present the typical structure of new bone formation.Conclusion: SF/PEO can protect factor BMP-2 and realize sustained release of it.In vitro experiments showed that the material's pro-cellular properties,and the addition of n HAP could enhance it.Membranes loading BMP-2 canimprove the ability of inducing osteogenesis.The experimental results in vivoshowed that the materials had an osteogenic property.