具有定向孔结构的磷酸钙骨水泥复合支架的构建和性能

发布时间：2018-06-13 02:10

本文选题：磷酸钙骨水泥 + PLGA　；参考：《华南理工大学》2013年博士论文

【摘要】：采用定向冰晶-冷冻干燥法制备具有定向层状大孔结构的磷酸钙骨水泥（CPC）支架，通过灌注将聚乳酸羟基乙酸酯（PLGA）复合到CPC支架的孔壁表面后，获得了具有较高强度和柔韧性的PLGA/CPC复合支架。本文对所制备的PLGA/CPC支架进行了体外降解特性、细胞行为和体内成骨性能的研究，并对支架的组成和结构进行了优化，从而进一步改善其力学性能、细胞反应性和体内成骨性。显微观察表明，PLGA/CPC支架的孔壁表面覆盖着PLGA膜，在体外降解过程中，PLGA膜首先降解，使骨水泥基体逐渐暴露，从而有利于提高材料与细胞和骨组织的反应。PLGA/CPC支架的定向层状大孔结构有利于细胞的长入和增殖。将PLGA/CPC支架植入兔子的股骨缺损后，新生的骨组织沿着定向的层状大孔长入到支架的内部。由于PLGA/CPC支架表面包覆着PLGA膜，导致细胞反应性较差，植入初期，骨水泥骨传导性好的优点得不到发挥。为了改善PLGA/CPC支架的细胞反应性，本研究在氨气气氛下对PLGA/CPC复合支架进行等离子体表面处理，将胶原固定在PLGA/CPC支架孔壁PLGA膜的表面，改善支架的生物活性，得到Col/PLGA/CPC复合支架。经胶原表面改性后的支架的细胞种植率、粘附、增殖和分化均得到显著的提高。然而，植入兔子体内后发现，胶原改性对提高PLGA/CPC支架的成骨能力帮助并不大。为了适应一些对支架强度有更高要求的应用，本研究仿天然骨的皮质骨/松质骨双层结构制备了强度可控的核壳结构磷酸钙骨水泥基复合支架。通过设计模具，采用等静压处理的方法制备了致密的管状骨水泥壳层。在致密壳层的空腔内用定向冰晶-冷冻干燥法制备具有定向层状大孔结构的多孔磷酸钙骨水泥芯，并用PLGA进行增强，然后用胶原进行表面改性。外层致密、内层多孔的骨水泥复合支架的强度可以通过改变致密层和多孔层的厚度比例调节（5~90MPa），以满足不同骨缺损部位修复的要求。定向大孔主要在轴向上具有高度的连通性，横向连通性较低。因此，致密的骨水泥外层对支架多孔芯的孔隙连通性没有明显的影响。细胞实验表明，细胞在双层骨水泥复合支架上粘附和增殖良好。通过复合明胶微球改性PLGA/CPC支架的三维多孔结构。PLGA/CPC支架经过明胶微球（0%~30%）改性后，强度和孔隙率都有所变化，但分别保持在3.5~5MPa和62%~72%之间。经明胶微球改性后，支架的定向层状大孔被分割为尺寸较小的层状大孔。此外，明胶微球溶解后原位留下80~200μm左右的等轴状大孔。用20%明胶微球改性的支架的细胞种植率、增殖和分化改善效果最明显。明胶微球的改性并没有明显影响支架的轴向连通性，，细胞仍然可以顺利长入到支架的内部。将富血小板血浆（PRP）灌注到PLGA/CPC支架内部，制备了PRP-PLGA/CPC复合体。结果表明，PRP的复合大大地改善了PLGA/CPC支架的细胞反应。将PRP-PLGA/CPC复合支架植入到新西兰大白兔的股骨缺损后发现，PRP的复合明显促进了骨组织长入到支架的内部，加快血管的生成和材料的降解。此外，本研究首次将具有定向层状大孔结构的PLGA/CPC支架用于修复新西兰大白兔的桡骨节段性骨缺损。新生的骨组织沿着定向的层状大孔长入支架的内部，而没有受到其三维连通性有限的影响。PRP的复合对PLGA/CPC支架修复桡骨的节段性骨缺损具有显著的促进作用。
[Abstract]:Calcium phosphate cement (CPC) scaffold with directional layered macroporous structure was prepared by directional ice crystal and freeze drying. The PLGA/CPC composite scaffold with high strength and flexibility was obtained by compounding the poly (lactic acid hydroxyacetate) (PLGA) to the pore wall surface of the CPC scaffold by perfusion. The PLGA/CPC scaffold prepared in this paper was carried out in this paper. The study of the properties of degradation, cell behavior and osteogenesis in vivo, and optimization of the structure and composition of the scaffolds to further improve their mechanical properties, cell reactivity and osteogenesis in the body.
The microscopic observation shows that the surface of the hole wall of the PLGA/CPC stent is covered with PLGA membrane. In the process of degradation in vitro, the PLGA film is degraded first and the bone cement matrix is exposed gradually. Thus, the reaction of the material to the cell and bone tissue is beneficial to the directional layered macroporous structure of the.PLGA/CPC scaffold which is beneficial to the growth of the cells. The PLGA/CPC scaffold is implanted into the scaffold. After the rabbit's femur defect, the new bone tissue grows into the interior of the scaffold along the directional layered large pore. Because the PLGA/CPC stents are coated with PLGA membrane, the cell reactivity is poor and the advantages of the good conductivity of the bone cement bone are not played at the early stage of implantation. In order to improve the cell reactivity of the PLGA/ CPC scaffold, this study is in the ammonia atmosphere. The PLGA/CPC composite scaffold was treated by plasma surface treatment. Collagen was immobilized on the surface of the PLGA membrane of the hole wall of the PLGA/CPC stent. The bioactivity of the scaffold was improved and the Col/PLGA/CPC composite scaffold was obtained. The cell implantation rate, adhesion, proliferation and differentiation of the scaffold after the collagen surface modification were significantly improved. However, the implanted rabbit was implanted in the rabbit. It was found that collagen modification did not help to improve the osteogenic potential of PLGA/CPC scaffolds.
In order to adapt to the application of a high requirement for the strength of the scaffold, a calcium bone cement composite scaffold with controllable core shell structure was prepared by imitating the double layer structure of the cortical bone / cancellous bone of the natural bone. The compact tubular bone cement shell was prepared by the method of isostatic pressure treatment. The porous calcium phosphate cement core with directional layered macroporous structure was prepared by the directional ice crystal and freeze drying method, and enhanced with PLGA, then the surface was modified with collagen. The outer layer was dense and the strength of the porous bone cement composite scaffold of the inner layer could be adjusted by changing the thickness ratio of the dense layer and the porous layer (5~90MPa) to meet the difference. The requirement of bone defect repair is that the directional macropores mainly have high connectivity in the axial direction, and the lateral connectivity is low. Therefore, the dense bone cement outer layer has no obvious influence on the pore connectivity of the porous core of the scaffold. Cell experiments show that the cells adhere and proliferate well on the double bone cement composite support.
The strength and porosity of the three-dimensional porous structure.PLGA/CPC scaffold modified by compound gelatin microspheres were modified by gelatin microspheres (0%~30%), and the strength and porosity were changed, but they were kept between 3.5~5MPa and 62%~72%. After the modification of gelatin microspheres, the directional layered macropores of the scaffold were divided into smaller layered macropores. In addition, gelatin was used. After the microspheres were dissolved, the ISO axial large pores were left around 80~200 mu m in situ. The cell implantation rate, proliferation and differentiation of the modified scaffold with 20% gelatin microspheres were most obvious. The modification of gelatin microspheres did not obviously affect the axial connectivity of the scaffold, and the cells could still grow into the inner of the scaffold.
Platelet rich plasma (PRP) was perfused into the internal PLGA/CPC scaffold and the PRP-PLGA/CPC complex was prepared. The results showed that the PRP composite greatly improved the cell response of the PLGA/CPC scaffold. The PRP-PLGA/CPC composite scaffold was implanted into the femur defect of New Zealand white rabbits and found that the recombination of PRP significantly promoted the bone tissue to grow into the inside of the scaffold. In addition, it is the first time that PLGA/CPC scaffolds with directional layered macroporous structures have been used for the first time to repair the radial segmental bone defect of New Zealand white rabbits. The new bone tissue grows into the stent along the directional layered macropores, and is not affected by the limited three-dimensional connectivity of the.PRP. It has a significant promoting effect on repairing the segmental bone defect of the radius with PLGA/CPC stent.
【学位授予单位】：华南理工大学
【学位级别】：博士
【学位授予年份】：2013
【分类号】：R318.08

【参考文献】