Fabrication and characterization of electrospun poly-L-lactide/gelatin graded tubular scaffolds: Toward a new design for performance enhancement in vascular tissue engineering

In this study, a new design of graded tubular scaffolds have been developed for the performance enhancement in vascular tissue engineering. The graded poly-L-lactide (PLLA) and gelatin fibrous scaffolds produced by electrospining were then characterized. The morphology, degradability, porosity, pore size and mechanical properties of four tubular scaffolds (graded PLLA/gelatin, layered PLLA/gelatin, PLLA and gelatin scaffolds) have been investigated. The tensile tests demonstrated that the mechanical strength and also the estimated burst pressure of the graded scaffolds were significantly increased in comparison with the layered and gelatin scaffolds. This new design, resulting in an increase in the mechanical properties, suggested the widespread use of these scaffolds in vascular tissue engineering in order to prepare more strengthened vessels.     

Towards a Medium/High Load-Bearing Scaffold Fabrication System

This paper describes fabrication of scaffolds for load-bearing applications, with primary consideration from the manufacturing perspective. An extrusion device, inspired by the FDM process, was used to create scaffolds from a variety of different polymeric materials and mixtures. The effectiveness of these scaffolds to host cells for bone regeneration has been investigated. This ongoing work has generated significant insight into the future direction of research and the possibilities of developing scaffolds for medium/high load-bearing applications.     

用于软骨下骨修复的镁基支架

骨关节炎（osteoarthritis，OA）作为一种可以导致残疾的退行性疾病，常累及软骨下骨。受损的关节软骨和软骨下骨很难自愈，用于功能修复的组织工程支架是一种有前途的治疗方法。近年来，镁合金因其良好的机械和生物学性能被视为可降解多孔支架有希望的候选者。然而，目前对于适用于软骨下骨缺损修复的镁基支架的结构设计和优化方案还没有定论。归纳了镁合金用于骨软骨支架的研究进展，包括多孔支架的制造方法；添加合金元素和表面改性的优化策略；参数化与非参数化的结构设计；镁基支架的机械、降解和生物学性能及其影响因素。讨论了未来研究的潜在方向。旨在为多孔镁基支架的开发和临床应用提供参考。     

组织工程三维多孔支架制备方法

随着老龄化社会的到来,组织工程的研究已成为现代生物医用工程技术中最为活跃的研究领域之一。三维多孔的组织工程支架作为骨组织工程学的关键环节,已成为近年来研究的热点。本文就近年来国内外三维多孔组织工程支架制备方法进行综述,希望能为今后的研究提供参考．     

纳米支架在组织工程中的研究进展

纳米纤维支架技术是组织工程中为了支持细胞形成受损组织生物替代物的新兴技术。纳米支架能模拟天然的细胞外基质,作为三维的模板供细胞吸附、增殖以及分化。主要介绍了纳米纤维支架的结构特性、构建技术以及生物学效应。     

组织工程三维多孔支架制备技术的最新进展

理想的组织工程支架是由具有一定降解性能的高分子材料制成的,制备的支架除了要有一定的孔隙率和适于细胞生长的孔径外,还要有较高的机械性能和生物活性.为此介绍了用于组织工程中的可降解高分子材料,并详细阐述了最新的制备组织工程支架的方法:超临界CO2技术,计算机辅助成型技术,以及静电纺丝技术.     

聚氨酯改性及复合支架应用于血管组织工程

通过查阅近年来将聚氨酯作为血管组织工程支架材料的相关文献,介绍了聚氯酯改性的常用方法在血管组织工程支架中的应用情况,综述了聚氨酯表面改性支架和复合支架在血管组织工程中的应用.     

Preparation of PLGA-collagen hybrid scaffolds with controlled pore structures for cartilage tissue engineering

Scaffolds used for cartilage tissue engineering should have high mechanical strength and well-controlled pore structure to provide suitable microenvironments for functional tissue regeneration. In this study, hybrid scaffolds which had open and interconnected pore structure and high mechanical property were prepared by hybridization of PLGA mesh and collagen using ice particulates as porogen templates. Embossing ice particulates template was used to form open pore structures on the scaffold surfaces. Free ice particulates were used to generate interconnected bulk pores in the scaffolds. Hybridization with PLGA mesh provided the scaffolds with high mechanical property. Bovine articular chondrocytes were cultured in the hybrid scaffolds. The unique pore structures facilitated the homogeneous distribution of chondrocytes and cartilaginous matrices throughout the scaffolds. Subcutaneous implantation demonstrated cartilage-like tissue regeneration. The hybrid scaffolds should have a high potential for cartilage tissue engineering.     

Electrospun Nanofibers of Hydroxyapatite/Collagen/Chitosan Promote Osteogenic Differentiation of BMSCs

Bone tissue engineering, aiming at developing bone substitutes for repair and regeneration of bone defects instead of using autologous bone grafts, has attracted wide attention in the field of tissue engineering and regenerative medicine. Developing biomimetic biomaterial scaffolds able to regulate osteogenic differentiation of stem cells could be a promising strategy to improve the therapeutic efficacy. In this study, clectrospun composite nanofibers of hydroxyapatite/collagen/chitosan （ HAp/Col/CTS ） resembling the fibrous nanostructure and constituents of the hierarchically organized natural bone, were prepared to investigate their capacity for promoting bone mesenchymal stem cells （BMSCs） to differentiate into the osteogenic lineage in the absence and presence of the osteogenlc supplementation, respectively. Call morphology, proliferation and quantified specific osteogenic protein expression on the electrospun HAp/Coi/CTS scaffolds were evaluated in comparison with different controls including dectrospun nanofibrous CTS, HAp/CTS and tissue culture plate. Our remits showed that the nanofibrous HAp/Col/CTS scaffolds supported better spreading and proliferation of the BMSCs than other substrates （ P 〈 0.01 ）. Expressions of osteogenesis protein markers, alkaline phosphatase （ALP） and Col, were significantly upregulated on the HAp/Col/CTS than those on the CTS （P 〈0.01） and HAp/ CTS （P 〈 0. 05 ） scaffolds in the absence of the osteogeulc supplementation. Moreover, presence of osteogeulc supplementation also proved to enhance osteogeule differentiation of BMSCs on HAp/ Col/CTS scaffolds, indicative of a synergistic effect. This study highlights the potential of BMSCs/HAp/Col/CTS cell-scaffold system for functional bone repair and regeneration applications.     

软骨组织工程新进展

软骨组织工程技术为治疗骨、软骨疾病提供了一种新的方法，其主要技术路线是，通过种子细胞和生物活性支架的体外共培养实现软骨组织的再生，并最终完成组织的修复与重建。种子细胞的选择、支架的构建，培养条件的优化对软骨再生有重要作用，从而成为目前软骨工程领域的研究重点。     

骨组织工程聚左旋乳酸多孔框架快速成形研究

为制备用于骨组织工程的细胞载体框架结构 ,对快速成形技术制备聚左旋乳酸多孔框架结构的若干基础问题进行了研究。提出了聚左旋乳酸快速成形的精密挤出成形工艺 ,研究了此工艺制备多孔框架结构的设备与工艺过程 ,分析了制备的多孔框架结构应用于组织工程人工骨的可行性。制备的多孔框架结构具有合适的分子量、孔隙结构、孔隙率、机械强度和生物降解性能 ,可以用作骨组织工程的组织再生框架结构     

肝组织工程支架的仿生设计与有限元分析

为了解决细胞在细胞支架复合培养中难以植入的问题,提出了一种卷裹型支架.将平面多孔支架采用卷裹的方式成型,使细胞在整个支架内部形成螺旋状三维分布,支架表面的管道结构可使培养液在支架内部渗透,从而提高物质交换效率.提出了一种具有仿生参数的流道设计方案,从肝脏血管铸型中提取血管的形状数据,作为仿生学依据进行流道设计,具体为树状多层分支结构.用此流道结构仿生了动脉、静脉的血液循环功能,并利用多孔材料仿生了毛细血管的渗透功能.建立了不同形状参数的流场分析模型,进行流体与多孔材料的渗流分析.结果表明,仿生设计方案的流场分布最为均匀,且平均流速较高,间接表明营养物质的输送效率最高.该支架能够使细胞呈三维分布,并扩大培养液在支架内的有效分布范围,更好地维持细胞的存活、增殖和迁移,为向组织化方向发展奠定了一定的基础.     

CPP/PLLA软骨组织工程支架复合材料降解性能研究

采用溶媒浇铸/粒子滤取技术与气体发泡相结合的方法制备出CPP/PLLA软骨组织工程支架复合材料,测试了该支架复合材料的物理力学性能和降解性能.研究结果表明,CPP/PLLA软骨组织工程支架复合材料具有适宜的孔隙率,良好的降解性能和物理力学性能,以及三维连通、微孔、网状微观结构.因此,该复合材料有望成为软骨组织工程支架材料之一.     

3D Nanocomposite Hydrogel Scaffolds Fabricated by Rapid Prototyping for Bone Tissue Engineering

Colloidal gels made of oppositely charged nanoparticles are a novel class of hydrogels and can exhibit pseudoplastic behavior which will enable them to mold easily into specific shapes. These moldable gels can be used as building blocks to self-assemble into integral scaffolds from bottom to up through electrostatic forces. However, they are too weak to maintain scaffold morphology just depending on interparticle interactions such as Van der Waals attraction and electrostatic forces especially for bone tissue engineering. In this study, oppositely charged gelatin nanoparticles were firstly prepared by two-step desolvation method, followed by the mixture with water to form colloid gels. To solve the problem of weak mechanical performance of colloid gels, gelatin macromolecules were introduced into the prepared gels to form blend gels. The blend gels can be easily processed into three-dimensional （3D） porous scaffolds via motor assisted microsyringe （MAM） system, a nozzle-based rapid prototyping technology, under mild conditions. After fabrication the scaffolds were erosslinked by glutaraldehyde （ GA, 25 % solution in water by weight）, then the crosslinked gelatin macromolecules network could form to improve the mechanical properties of colloid gels. The average particle size and zeta potential of gdatin nanoparticles were measured by Nano- ZS instrument. The morphology and microstructures of scaffolds were characterized by macroscopic images. The mechanical properties of the scaffolds were studied by a universal material testing machine.     

Distribution of bone marrow stem cells in large porous polyester scaffolds

This work examined the optimal syringing depth during in vitro cell loading in order to even cell distribution after syringing a drop of cell suspension in cylinder poly（lactide-co-glycolide） （PLGA） porous scaffolds. The scaffolds of 10 mm height and 10 mm diameter were fabricated via room-temperature compression molding ＆ particulate leaching technique based on spherical porogens. In vitro tests were employed for such examinations： a global observation of a cell-loaded scaffold stained by the 3-（4,5-dimethylthiazol-2-yl）-2,5-diphenyltetrazolium bromide （MTT） technique and a quantitative measurement of spatial distribution of cells after slicing the cell-loaded scaffolds into layers. It was found that an even distribution of cells was soon achieved only if the initial cell suspension was seeded on the layer that was below the top surface but above the middle of scaffolds. The availability of in vitro osteoblastic differentiation of rat bone marrow stem cells in such a kind of spherical-pore PLGA scaffolds was meanwhile confirmed.     

Screening of functionalized self-assembling peptide nanofiber scaffolds with angiogenic activity for endothelial cell growth

Promotion of angiogenesis in tissue engineering is of vital significance to the survival of transplants,which leads the way of tissue regeneration.In this study,we screened six short peptides with potentially angiogenic activities to functionalize self-assembling peptide nanofiber scaffolds RADA16-I(Ac-(RADA)_4-CONH_2).Fluorescence microscopy images of endothelial cells morphology on peptide scaffolds exhibited good cell attachments and Survivals on these six functionalized peptide scaffolds, especially ...     

可降解高分子材料在心血管领域的研究与展望

细胞外基质材料的研究是组织工程中一个十分重要的环节 ,因此较系统地介绍了用于组织工程中的几种生物可降解高分子支架材料和三维多孔可降解组织工程支架材料的制备技术及发展 ,并指出了各自的优缺点 .同时结合这些材料综述了血管组织工程和心脏瓣膜组织工程的研究现状 ,以及对未来研究的展望     

新型前交叉韧带支架材料的构建及其生物相容性的实验研究

探讨以聚羟基丁酸己酯/聚左旋乳酸(PHB/PLLA1∶1)胶原杂化支架作为前交叉韧带组织工程载体材料的可行性。制备"三明治"样结构PHB/PLLA共聚物并测量其孔隙率等指标。以I型胶原对制备的PHB/PLLA支架进行杂化,获得PHB/PLLA胶原杂化支架。扫描电镜观察其表面结构。将兔皮肤成纤维细胞(SF)接种于PHB/PLLA胶原杂化支架,共培养5d后,扫描电镜下观察其在材料上生长情况。PHB/PLLA支架杂化后胶原填充于纤维空隙,分布比较均匀。体外培养的皮肤成纤维细胞成功种植在支架材料上,在材料上粘附、生长良好。说明构建的支架材料具有良好的三维构型和生物相容性,有望为前交叉韧带损伤的修复提供了一种新型的支架材料。     

小直径血管支架的仿生构建及其种子细胞

静电纺丝仿生天然细胞外基质(ECM)结构,所制备的高度多孔、高比表面积的纳米级(50～500nm)纤维赋予了丰富的分子架构和生化信号,为种子细胞提供理想的生长微环境.不同组分、纤维尺寸及取向和种子细胞类型,可以裁剪获得不同生化和力学性能的电纺支架细胞复合物.总结了血管组织工程仿生ECM的设计与构建,并强调与支架复合的种子细胞在血管组织工程的作用.     

造孔粒子形貌对磷酸钙骨水泥支架材料结构与性能的影响

采用可溶粒子造孔法,结合冷等静压成型技术,分别以立方体的氯化钠晶体和短棒状的谷氨酸钠晶体为造孔粒子制备出具有较高孔隙率和良好抗压强度的磷酸钙骨水泥组织工程支架材料,通过X射线衍射分析、扫描电镜分析及力学性能测试,研究了所制备的支架材料的物相组成及颗粒形貌对支架材料显微结构和力学性能的影响.结果表明:两种造孔粒子制得的支架材料的主晶相均是弱结晶的羟基磷灰石;造孔粒子的形貌决定了所制备的支架的孔隙形貌,并影响支架的孔隙率和力学性能;在造孔粒子加入量相同的情况下,谷氨酸钠晶体作为造孔粒子制备的支架的孔隙率更高,但强度更低;由于在制备过程中引入了等静压处理,支架材料具有良好的强度.