磷酸钙相组成对类骨单位复合骨支架的影响（英文）

从组成上看,自然骨是一种无机与有机的复合材料;从结构上看,致密骨的基本结构单位为内壁血管化的骨单位。本研究基于组成与结构仿生的原理制备组织工程化支架,模拟具有复杂结构的密质骨的基本单位——骨单位。为此,通过静电纺丝和双螺杆挤出相结合的两步制造法,制备一种具有双层结构的聚己内酯/磷酸钙(PCL/Ca P)复合骨支架,其内层是由电纺纳米纤维组成的空心管,可贴附内皮细胞层形成与哈佛氏管相类似的结构;其外层是具有高孔隙率的螺旋状PCL/Ca P微丝,可复合前成骨细胞以模拟骨单位结构中的外层骨样组织。为进一步探索材料组成对于支架生物功能的影响,分别设计了外层为PCL,PCL/双相磷酸钙(PCL/BCP)和PCL/?-磷酸三钙(PCL/?-TCP)的复合支架,比较了材料组分变化对外层微丝结构及前成骨细胞(MC3T3-E1)活性的影响。相比于PCL和PCL/?-TCP,PCL/BCP微丝更能显著增强细胞的生长和钙的沉积,并成功获得可精确调控不同细胞的空间分布的双层复合支架,实现对复杂结构骨单位的模拟构建,显示出很好的应用前景。     

多壳层化中空微球两相陶瓷生物材料制备研究

利用硅灰石(CaSiO₃)和β-磷酸三钙(β-TCP)在骨损伤环境中降解速率存在显著性差异的基本特性, 以海藻多糖凝胶球为模板, 运用层-层包裹方法构建CaSiO₃、β-TCP交替包裹的多壳层化中空微球。首先, 将海藻酸钠与硅酸钠的混合水溶胶逐滴加入到温和搅拌的硝酸钙水溶液中, 形成由水合硅酸钙盐为壳层的海藻多糖基复合微球, 然后将该复合微球依次浸入到含β-TCP的海藻酸钠溶液和含CaSiO₃的海藻酸钠溶液中, 温和搅拌后将微球悬浮液分离, 再经真空冷冻干燥和850℃煅烧处理, 从而获得以CaSiO₃为最内壳层并具有双壳层或三壳层的中空微球。按类似步骤也可以制备以β-TCP为最内壳层的多壳层中空微球。运用SEM、EDX、XRD和FTIR对该类微球的微结构和组成进行了分析。运用弱酸性Tris缓冲液(pH=5.2)对双壳层中空微球的降解。实验证明, 缓冲液中硅、磷浓度变化特征与其外壳层、内壳层化学组成(即β-TCP或CaSiO₃)密切相关。本研究结果对构建降解速率阶段可调的复合陶瓷多孔生物材料以及研究原位骨再生效率与孔道网络演化规律之间关系等具有重要学术价值。     

机械活化增强多孔磷酸钙骨水泥支架的研究

本研究采用球磨对磷酸钙骨水泥(CPC)起始粉末进行机械活化处理, 以期改善CPC力学性能, 并探讨了其影响机理。采用激光粒度仪、比表面积测量仪和X射线衍射仪(XRD)表征球磨后的CPC粉末(Ball milling CPC, BCPC)。利用发泡法制备多孔BCPC支架, 采用万能力学试验机、XRD和扫描电子显微镜(SEM)表征多孔BCPC支架。结果显示, 球磨后的BCPC粉末平均粒径减小, 比表面积增大, 表观密度、堆积密度及紧密密度减小。BCPC支架孔隙率为(77.98 ± 0.58)%, 抗压强度为(4.11 ± 0.46) MPa, 相比CPC支架的(64.23 ± 2.32)%和(1.99 ± 0.43) MPa有显著提高。SEM结果显示BCPC支架具有数微米和数百微米的两种孔隙结构。XRD结果表明机械活化作用降低了DCPD、α-TCP、CaCO₃和HA的晶粒尺寸和结晶度, 促使DCPD向DCPA转化, 促进了各相磷酸钙盐的水化和HA的沉积, 提高了BCPC支架的力学性能, 为增强CaP基多孔材料的力学性能和扩展其临床应用提供了新途径。     

β-磷酸三钙/聚L-乳酸与大鼠骨膜成骨细胞复合骨修复材料的研究

采用溶液浇铸-模压成型-沥滤方法制备了β-TCP/PLLA多孔支架材料, 将支架材料与大鼠骨膜成骨细胞复合获得新型组织工程骨修复材料. 通过抗压强度及压缩模量的表征研究了支架材料的力学性能; 采用SEM观测、MTT法、碱性磷酸酶活性及骨钙素分泌量检测细胞复合材料的体外成骨特性; 通过裸鼠肌袋种植, 以组织学方法评价细胞复合材料的异位成骨能力. 结果表明: β-TCP/PLLA多孔支架材料孔隙率可调, 孔径为100～00μm, 孔道相互贯通; 材料抗压强度和压缩模量随孔隙率的增大而降低, β-TCP复合PLLA后材料的力学性能高于同孔隙率的纯PLLA多孔材料; 复合支架材料适宜骨膜成骨细胞粘附和生长, 无细胞毒性; 骨膜成骨细胞复合β-TCP/PLLA支架材料的体外成骨特性良好, 且具有体内异位成骨能力.     

原位自发泡制备磷酸钙/聚氨酯复合骨修复支架

磷酸钙/聚氨酯(CaP/PU)复合骨修复支架制备过程中随着材料体系粘度逐渐增大, 后期加入的发泡剂难于均匀分散, 影响支架孔隙率及孔结构均匀性。本研究在CaP/PU材料合成过程中将发泡剂水以磷酸氢钙结晶水合物(DCPD)的形式均匀复合在材料中, 在一定条件下释放结晶水与聚氨酯(PU)中的异氰酸根反应生成CO₂, 实现自发泡成型。实验结果显示, 90 ℃条件下自发泡制备的CaP/PU支架孔隙率高、孔结构均匀、贯通性好。将90 ℃发泡成型的CaP/PU多孔支架在110 ℃再熟化处理, 可提高支架的力学性能高达1倍以上。该方法简便易行, 为聚氨酯基多孔支架的制备提供了新思路。     

造孔剂和发泡剂结合法制备氟化羟基磷灰石多孔支架研究

本研究采用添加造孔剂和发泡剂相结合法制备多孔氟化羟基磷灰石, 合成具有大孔与小孔套连、3D方向上分布的多孔支架。通过化学沉淀法制备了氟化羟基磷灰石(FHA)粉体, 以碳酸氢铵为发泡剂、PMMA为造孔剂, 通过烘干和烧结工艺制备孔洞均匀且相互贯通、坯体致密的多孔支架。经X射线衍射分析, 支架的相组成是FHA和β-TCP。SEM观察结果显示支架孔洞形貌规整、大孔尺寸100~400 µm, 小孔尺寸10~50 µm。以HA和β-TCP为原料对造孔方法的普适性进行验证, 并对支架孔的形成及其影响因素进行了分析。     

多孔磷酸钙骨水泥组织工程支架的高分子灌注增强

利用棒状谷氨酸钠晶体作为造孔粒子,采用可溶盐造孔法,制备了三维连通的大孔径多孔磷酸钙骨水泥支架,分别将明胶(Gelatin) 、聚乳酸2羟基乙酸共聚物(PLGA) 、聚乳酸(PLA) 、聚己内酯(PCL) 、聚羟基丁酸戊酸酯(PHBV)灌注到多孔磷酸钙骨水泥(CPC)支架的孔隙中以改善支架材料的力学性能。结果表明,5 种高分子材料与水的接触角大小顺序为PHBV > PCL > PLA > PL GA > Gelatin , 复合支架材料的强度随高分子材料与水接触角的减小而增大;除PHBV外,其余4种均有明显的增强效果,其中Gelatin/CPC复合支架增强效果最好,强度达到2. 25 MPa±0. 02 MPa ,是CPC支架强度的25倍。经过增强的大孔径多孔磷酸钙骨水泥复合支架可用作骨组织工程支架材料。      

三维打印羟基磷灰石晶须增强复合骨修复支架

利用三维打印技术成功制备羟基磷灰石晶须(HAPw)增强的聚己内酯(PCL)复合骨修复支架。通过改变三维打印的挤出速度和挤出气压, 使不同含量HAPw均能在PCL基材中一致排列并均匀分布。PCL支架的机械强度随HAPw含量增加显著提高, 添加33wt%HAPw使PCL支架强度提升了高达3倍。此外, HAPw使PCL支架表面与水的接触角从近100º降低至约50º, 有效改善了细胞表面粘附。经过体外人类骨髓间充质干细胞(hBMSC)在支架上的培养实验, 发现添加HAPw的复合支架具有更好的生物相容性, 能够有效促进hBMSC的增殖生长, 且HAPw-PCL复合支架上细胞具有更高的碱性磷酸酶(ALP)活性和OCN、RUNX2等相关成骨基因表达, 显示出hBMSCs向成骨方向更好的分化及成骨活性。     

可注射镁基磷酸钙骨水泥的研究

采用MgO、KH₂PO₄、β-TCP、葡萄糖作为骨水泥的固相, 磷酸溶液作为液相, 制备可注射镁基磷酸钙骨水泥(IMPC)。考察液固比(LPR)、MgO含量、葡萄糖含量变化对IMPC胶凝性能和力学性能的影响。实验结果显示: 液固比和缓凝剂葡萄糖含量增大均会导致凝结时间变长和抗压强度下降, 但有益于可注射性; 随MgO含量增大, 凝结时间缩短, 可注射率降低, 但抗压强度提高。采用正交实验法确定MgO含量26wt%, 液固比0.30 mL/g, 葡萄糖含量6wt%时得到的IMPC综合性能良好, 水化过程缓和, 放热量低。该IMPC有望成为一种新型骨粘结材料。     

磷酸钙/BMP复合生物活性骨水泥水化性能及诱导成骨特性研究

采用微细α-磷酸三钙(α-TCP)粉料、辅助料与冻干牛骨形态发生蛋白(BMP)预先固相混合制备了新型磷酸钙(CPC)/BMP复合生物骨水泥.通过水化、凝固性能研究优化了配料成分、调和液和促凝剂组成;通过大鼠肌袋种植实验研究了骨水泥的异位成骨性能.结果表明:以α-TCP:CaHPO₄:CaO(0.95:0.025:0.025)为固相配料,以0.25mol/LNaH₂PO₄/Na₂HPO₄混合液([P]_T=0.5mol/L)作为调合液可制备性能优异的骨水泥材料,骨水泥初凝时间为6min,终凝时间为30min,固化强度达33MPa,达到临床手术的要求;α-TCP粉料粒度对骨水泥凝固性能影响显著,实验选用α-TCP粉料粒径d₅₀为1.3μm;骨水泥在Hank’s溶液中浸泡5天抗压强度可达最大值;骨水泥块经浸泡后内部生成针状羟基磷灰石晶体的网状结构.新型CPC/BMP复合骨水泥异位成骨作用明显,4周即能快速形成板层骨结构,证明该新型复合材料具有较强的诱导成骨活性.该生物活性骨水泥复合材料可望成为一类新型组织工程骨修复材料.     

Effect of testosterone incorporation on cell proliferation and differentiation for polymer–bioceramic composites

In the current study, we characterized the polycaprolactone (PCL), poly(lactic acid-co-glycolic acid) (PLGA), and biphasic calcium phosphate (BCP) composites coated with testosterone propionate (T) using Fourier transform infrared spectroscopy (FTIR) and powder X-ray diffraction (XRD). Osteoblastic cells were seeded with PCL/BCP, PCL/BCP/T, PLGA/PCL/BCP and PLGA/PCL/BCP/T scaffolds, and cell viability, proliferation, differentiation and adhesion were analyzed. The results of physic-chemical experiments showed no displacements or suppression of bands in the FTIR spectra of scaffolds. The XRD patterns of the scaffolds showed an amorphous profile. The osteoblastic cells viability and proliferation increased in the presence of composites with testosterone over 72?h, and were significantly greater when PLGA/PCL/BCP/T scaffold was tested against PCL/BCP/T. Furthermore alkaline phosphatase production was significantly greater in the same group. In conclusion, the PLGA/PCL/BCP scaffold with testosterone could be a promising option for bone tissue applications due to its biocompatibility and its stimulatory effect on cell proliferation.     

Biocompatibility and biodegradation studies of PCL/β-TCP bone tissue scaffold fabricated by structural porogen method

Three-dimensional printer (3DP) (Z-Corp) is a solid freeform fabrication system capable of generating sub-millimeter physical features required for tissue engineering scaffolds. By using plaster composite materials, 3DP can fabricate a universal porogen which can be injected with a wide range of high melting temperature biomaterials. Here we report results toward the manufacture of either pure polycaprolactone (PCL) or homogeneous composites of 90/10 or 80/20 (w/w) PCL/beta-tricalcium phosphate (β-TCP) by injection molding into plaster composite porogens fabricated by 3DP. The resolution of printed plaster porogens and produced scaffolds was studied by scanning electron microscopy. Cytotoxicity test on scaffold extracts and biocompatibility test on the scaffolds as a matrix supporting murine osteoblast (7F2) and endothelial hybridoma (EAhy 926) cells growth for up to 4?days showed that the porogens removal process had only negligible effects on cell proliferation. The biodegradation tests of pure PCL and PCL/β-TCP composites were performed in DMEM with 10?% (v/v) FBS for up to 6?weeks. The PCL/β-TCP composites show faster degradation rate than that of pure PCL due to the addition of β-TCP, and the strength of 80/20 PCL/β-TCP composite is still suitable for human cancellous bone healing support after 6?weeks degradation. Combining precisely controlled porogen fabrication structure, good biocompatibility, and suitable mechanical properties after biodegradation, PCL/β-TCP scaffolds fabricated by 3DP porogen method provide essential capability for bone tissue engineering.     

Bi-layered calcium phosphate cement-based composite scaffold mimicking natural bone structure

Abstract

In this study, a core/shell bi-layered calcium phosphate cement (CPC)-based composite scaffold with adjustable compressive strength, which mimicked the structure of natural cortical/cancellous bone, was fabricated. The dense tubular CPC shell was prepared by isostatic pressing CPC powder with a specially designed mould. A porous CPC core with unidirectional lamellar pore structure was fabricated inside the cavity of dense tubular CPC shell by unidirectional freeze casting, followed by infiltration of poly(lactic-co-glycolic acid) and immobilization of collagen. The compressive strength of bi-layered CPC-based composite scaffold can be controlled by varying thickness ratio of dense layer to porous layer. Compared to the scaffold without dense shell, the pore interconnection of bi-layered scaffold was not obviously compromised because of its high unidirectional interconnectivity but poor three dimensional interconnectivity. The in vitro results showed that the rat bone marrow stromal cells attached and proliferated well on the bi-layered CPC-based composite scaffold. This novel bi-layered CPC-based composite scaffold is promising for bone repair.     

Osteogenic differentiation of mesenchymal progenitor cells in computer designed fibrin-polymer-ceramic scaffolds manufactured by fused deposition modeling

Biomimetic scaffolds offer great potentials in the development of bone analogs for tissue engineering. The studies presented in this paper focus specifically on the osteogenic potential of the novel PCL/CaP matrices and its degradation behavior. Biodegradable Polymer-ceramic Scaffolds were fabricated using the solid free form fabrication technology: Fused Deposition Modeling (FDM). The scaffold architecture was characterized by a honeycomb-like design and a complete interconnectivity of the pores. Human mesenchymal stem cells (MSCs) were seeded together with fibrin glue into PCL/CaP scaffolds and cultured in vitro for periods of up to eight weeks. Cellular adhesion, proliferation and osteogenic differentiation were assessed in these constructs using a range of histological and microscopic techniques. In additional experiments, degradation was assessed by measuring mass loss, diameter change, molecular weight change and by scanning electron micrographs. MSCs were able to adhere, migrate, and differentiate along the osteogenic lineage with in these scaffolds. The PCL/CaP scaffolds showed up to 27 fold increased degradation of compared to PCL scaffolds.     

Novel approach to the fabrication of an artificial small bone using a combination of sponge replica and electrospinning methods

Abstract

In this study, a novel artificial small bone consisting of ZrO₂-biphasic calcium phosphate/polymethylmethacrylate-polycaprolactone-hydroxyapatite (ZrO₂-BCP/PMMA-PCL-HAp) was fabricated using a combination of sponge replica and electrospinning methods. To mimic the cancellous bone, the ZrO₂/BCP scaffold was composed of three layers, ZrO₂, ZrO₂/BCP and BCP, fabricated by the sponge replica method. The PMMA-PCL fibers loaded with HAp powder were wrapped around the ZrO₂/BCP scaffold using the electrospinning process. To imitate the Haversian canal region of the bone, HAp-loaded PMMA-PCL fibers were wrapped around a steel wire of 0.3 mm diameter. As a result, the bundles of fiber wrapped around the wires imitated the osteon structure of the cortical bone. Finally, the ZrO₂/BCP scaffold was surrounded by HAp-loaded PMMA-PCL composite bundles. After removal of the steel wires, the ZrO₂/BCP scaffold and bundles of HAp-loaded PMMA-PCL formed an interconnected structure resembling the human bone. Its diameter, compressive strength and porosity were approximately 12 mm, 5 MPa and 70%, respectively, and the viability of MG-63 osteoblast-like cells was determined to be over 90% by the MTT (3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide) assay. This artificial bone shows excellent cytocompatibility and is a promising bone regeneration material.     

In situ synthesis and characterization of porous polymer-ceramic composites as scaffolds for gene delivery

The use of three-dimensional scaffolds in gene delivery has emerged as a popular and necessary delivery vehicle for obtaining controlled gene delivery. In this report, techniques to synthesize composite scaffolds by combining natural polymers such as agarose and alginate with calcium phosphate (CaP) are described. The incorporation of CaP into the agarose or alginate hydrogels was performed in situ and the presence of CaP was confirmed by X-ray diffraction (XRD). The crystallite size of the CaP particles was determined to be 7.20 nm. Lyophilized, porous composites were examined under scanning electron microscopy (SEM) to estimate the size of the pores, an essential requirement for an ideal scaffold. The swelling properties of the composite samples were also investigated to study the effect of CaP incorporation on the behavior of the hydrogels. By incorporating CaP into the hydrogel, the aim is to synthesize a scaffold that is mechanically strong and chemically suitable for use as a gene delivery vehicle in tissue engineering.     

磷灰石-硅灰石/β-磷酸三钙复合多孔支架材料的制备和表征

以磷灰石-硅灰石玻璃陶瓷(AW)粉和β-磷酸三钙(β-TCP)粉为原料. 以硬脂酸为致孔剂. 经模压成型、1170℃烧结制备磷灰石-硅灰石/β-磷酸三钙复合多孔支架材料(AW/βTCP). 采用X射线衍射(XRD)、扫描电镜(SEM)、能谱(EDS)、诱导耦合等离子体原子发射光谱(ICP-AES)等方法分析支架的晶相组成、显微结构、物理性能、生物活性和降解性. 将大鼠骨髓间充质干细胞(rMSCs)与支架体外复合培养评价支架的生物相容性. 结果表明: 所制备的AW/β-TCP支架材料的抗压强度达14.3MPa. 孔隙率达66.9%. 孔径为100～700μm. 具有良好的生物相容性、生物活性和降解性. 可作为骨组织工程支架的候选材料.