组织工程用壳聚糖研究进展

壳聚糖由于具有低细胞毒性、生物可降解性和生物活性而在组织工程中得到广泛的应用。综述了壳聚糖在软骨组织、骨组织、皮肤组织等方面的应用现状,重点分析了壳聚糖在组织工程移植应用中存在的问题及原因,并对这些问题的研究现状作了简述。最后提出了建立壳聚糖中的杂质蛋白的检测方法及壳聚糖纯化工艺,开发可达到组织工程医疗产品要求的组织工程用壳聚糖是研究重点之一。     

壳聚糖对骨组织工程中组织修复的影响

材料植入体内必然引起宿主体的应答,促进或抑制组织愈合。由于降解材料在体内的降解产物会随时间而变,产生的宿主体应答就会不同,进而会影响组织的愈合。而促进或抑制组织愈合的机制就成为新型医用高分子材料设计和制备的理论基础。壳聚糖是理想的骨组织修复材料之一,但至今还不清楚壳聚糖体内不同降解过程对组织修复的影响机制,也就无法设计出性能优良的壳聚糖基新材料。文章没有罗列壳聚糖基生物材料在骨组织工程中应用所取得的进展,而是重点阐述了壳聚糖在骨组织工程中应用的复杂性和对组织修复的影响,探讨了壳聚糖进一步用于骨组织工程所需要解决的问题。     

硫酸酯化壳聚糖衍生物在生物医学材料中的应用

壳聚糖具有优良的生物相容性和生物可降解性,被广泛地应用于生物医学领域。然而,壳聚糖的非水溶性和分子结构的高度结晶性能限制了其在组织工程中的更大作用的发挥。鉴于此,有必要对壳聚糖进行亲水改性研究。在壳聚糖衍生化改性中,硫酸酯化的壳聚糖尤为重要。它具有类肝素的抗凝效应等,这些都为壳聚糖大大扩展了其应用范围。本文就硫酸酯化壳聚糖衍生物在生物医学材料中的应用进行探讨。     

厦大研制出可将组织器官“种”在体外的医用支架材料

据报道，由厦门大学生物医学工程研究中心研发的“医用复合型组织工程支架材料”于近日通过福建省科技厅组织的专家鉴定。据项目负责人、厦门大学张其清教授介绍，医用复合型组织工程支架材料利用从贝类、螃蟹壳、虾壳等海产品中提取出的壳聚糖，与其他天然材料复合，制成多孔性的、具有生物活性的新型医用组织工程支架材料，并用从体内不同组织器官中提取出的细胞“种”到支架材料上，在体外构建出具有生命功能的不同的组织器官，植入到体内，用于病缺损部位（皮肤烧伤、骨骼缺损等）的修复治疗。     

可降解海藻酸钠-壳聚糖支架用于细胞黏附生长的研究

通过调节海藻酸钠与壳聚糖的比例制备了具有不同降解速度的组织工程支架,并以HepG2为细胞模型考察可降解支架对细胞黏附生长的影响.研究表明:壳聚糖含量越高,支架被溶菌酶降解的速度越快,但支架在培养液中的稳定性越高;MTT结果显示细胞在壳聚糖含量为100%和67%的支架中培养时活性较高,但活死染色显示细胞多以分散状态黏附在支架上,降低壳聚糖含量时细胞活性较低且多以聚集形式存在于支架空隙内部.通过调节海藻酸钠与壳聚糖的比例制备出可降解的组织工程支架,可以控制细胞的生长速度及黏附状态,有望为细胞的生长及功能发挥提供更适宜的环境.     

壳聚糖类复合材料应用于骨修复的研究进展

壳聚糖是天然多糖类高分子化合物甲壳素的脱乙酰产物,具有良好的生物相容性、可降解性和生物活性,可作为骨修复材料,并可应用于骨组织工程材料中的三维生长支架,作为种子细胞或活性生长因子的生物载体材料.综述了壳聚糖类复合材料在骨填充修复材料、骨组织工程和软骨组织工程方面应用的状况及前景.     

壳聚糖与丙交酯接枝共聚物的制备与表征

壳聚糖与聚乳酸是具有良好生物相容性的高分子材料,目前被广泛用于生物医学材料,特别是作为组织工程支架.本文以壳聚糖为原料,经过改性制备6-O-三苯甲基-2-邻苯二甲酰基-壳聚糖,作为大分子引发剂,以辛酸亚锡催化D,L-丙交酯接枝聚合,制备共聚物大分子.采用傅立叶变换红外光谱、核磁共振氢谱、碳谱对其结构进行表征,证实了共聚物的生成.热分析测试表明,共聚物具有不同于聚乳酸的热特性,熔点152.8℃.接触角测试表明共聚物具有较好的亲水性.凝胶色谱测定不同反应物配比对共聚物分子量的影响.壳聚糖与丙交酯的接枝共聚物具有较聚乳酸及壳聚糖更为优良的性能,可作为组织工程支架材料.     

壳聚糖智能水凝胶在生物材料领域的应用

壳聚糖智能水凝胶对于外界微小的物理化学刺激,如温度、pH、电场等能够感知并在响应过程中有显著的溶胀行为或响应性.介绍了壳聚糖智能水凝胶的制备及其在药物控释、伤口辅料和组织工程等方面的应用,并展望了其未来.     

壳聚糖温敏水凝胶的质-构关系及研究进展

壳聚糖温敏水凝胶是一种非化学交联智能水凝胶,其成胶性能取决于凝胶组分,形成特定的质-构关系。温和的制备条件和良好的生物活性,使壳聚糖水凝胶在组织工程、药物缓释,特别是细胞培养、液态栓塞剂等领域的研究应用取得了新进展。综述了壳聚糖温敏水凝胶的分类、成胶性能、相变机制及其在生物医药领域研究和应用的新进展。     

ADSCs-壳聚糖/明胶水凝胶工程化软骨的三维动态构建

组织工程软骨的体外构建被认为是一种有希望治疗关节软骨缺损的有效途径。为评估载脂肪干细胞(Adipose-derived stem cells,ADSCs)壳聚糖/明胶水凝胶支架,在体外动态构建组织工程软骨相对传统静态培养的优势,本研究用壳聚糖/明胶制备了软骨仿生支架,并检测其物理性质。在制备的水凝胶支架上以1×107cells/m L密度接种ADSCs后,分别置于转瓶及T-瓶的软骨诱导基中培养两周,通过试剂染色、代谢检测和电镜观察,考察了细胞的软骨分化能力、活性、生长分布、渗透深度、增殖及胞外基质分泌情况。结果表明,壳聚糖/明胶支架的平均孔径为118.25±19.51μm,孔隙率为82.60±2.34%,吸水率为361.28±0.47%,弹性模量为61.2±0.16 k Pa,具有良好生物相容性。ADSCs生长状态良好,可向软骨细胞分化,适于作为组织工程软骨构建的种子细胞。表征结果显示,转瓶内水凝胶支架中细胞蛋白多糖的表达更显著,细胞生长分布更加均匀,细胞外基质分泌基本填满整个支架。因此,转瓶载壳聚糖/明胶支架所提供的三维动态环境,是体外构建组织工程软骨的良好方法。     

Novel carboxymethyl derivatives of chitin and chitosan materials and their biomedical applications

Chitin and chitosan are natural biopolymers that are non-toxic, biodegradable and biocompatible. In the last decade, chitin and chitosan derivatives have garnered significant interest in the biomedical and biopharmaceutical research fields with applications as biomaterials for tissue engineering and wound healing and as excipients for drug delivery. Introducing small chemical groups to the chitin or chitosan structure, such as alkyl or carboxymethyl groups, can drastically increase the solubility of chitin and chitosan at neutral and alkaline pH values without affecting their characteristics; substitution with carboxyl groups can yield polymers with polyampholytic properties. Carboxymethyl derivatives of chitin and chitosan have shown promise for adsorbing metal ions, as drug delivery systems, in wound healing, as anti-microbial agents, in tissue engineering, as components in cosmetics and food and for anti-tumor activities. This review will focus on the preparative methods and applications of carboxymethyl and succinyl derivatives of chitin and chitosan with particular emphasis on their uses as materials for biomedical applications.     

Chitosan-Based Nanocomposite Scaffolds for Tissue Engineering Applications

This article reports the fabrication of three-dimensional porous chitosan and hydroxyapatite (HA)/chitosan composite scaffolds by the thermally induced phase separation (TIPS) technique, for bone tissue engineering. Different amounts of HA nanoparticles (10%, 20%, and 30% g/g) were added to the chitosan solution to produce HA/chitosan composite scaffolds of varying compositions. The morphology and pore structure of the scaffolds vis-à-vis composition were characterized using scanning electron microscopy (SEM) and an energy dispersive X-ray (EDX). Both pure chitosan and HA/chitosan composite scaffolds were highly porous and had interconnected pores. The pore sizes ranged from several micrometers to a few hundred micrometers. The HA nanoparticles were well dispersed and physically coexisted with chitosan in the composite scaffolds. However, some agglomeration of HA nanoparticles was observed on the surface of pore walls when a relatively large amount of HA was used. The composite 3D scaffolds are very promising for use in bone tissue engineering application.     

Effect of collagen II coating on mesenchymal stem cell adhesion on chitosan and on reacetylated chitosan fibrous scaffolds

The biocompatibility and biomimetic properties of chitosan make it attractive for tissue engineering but its use is limited by its cell adhesion properties. Our objectives were to produce and characterize chitosan and reacetylated-chitosan fibrous scaffolds coated with type II collagen and to evaluate the effect of these chemical modifications on mesenchymal stem cell (MSC) adhesion. Chitosan and reacetylated-chitosan scaffolds obtained by a wet spinning method were coated with type II collagen. Scaffolds were characterized prior to seeding with MSCs. The constructs were analyzed for cell binding kinetics, numbers, distribution and viability. Cell attachment and distribution were improved on chitosan coated with type II collagen. MSCs adhered less to reacetylated-chitosan and collagen coating did not improve MSCs attachment on those scaffolds. These findings are promising and encourage the evaluation of the differentiation of MSCs in collagen-coated chitosan scaffolds. However, the decreased cell adhesion on reacetylated chitosan scaffold seems difficult to overcome and will limit its use for tissue engineering.     

Fabrication and characterization of PCL/gelatin/chitosan ternary nanofibrous composite scaffold for tissue engineering applications

In the present study, we have fabricated a ternary composite nanofibrous scaffold from PCL/gelatin/chitosan, by electrospinning technique, using a solvent system—chloroform/methanol for polycaprolactone (PCL) and acetic acid for gelatin and chitosan, for tissue engineering applications. Field emission scanning electron microscopy (FE-SEM) was used to investigate the fiber morphology of the scaffold and it was found that the fiber morphology was influenced by the concentrations of PCL, gelatin, and chitosan in polymer solution during electrospinning. X-ray diffraction, Fourier transform infrared, and thermogravimetric (TG) analysis results showed some interactions among the molecules of PCL, gelatin, and chitosan within the scaffold. In-vitro cell culture studies were done by seeding L929 mouse fibroblasts on fabricated composite scaffold, which confirmed the cell viability, high cell proliferation rate, and cell adhesion on composite scaffold as indicated by MTT assay, DNA quantification, and FE-SEM analysis of cell-scaffold construct. Thus, the ternary composite scaffold made from the combination of PCL (synthetic polymer), gelatin, and chitosan (natural polymer) may find potential application in tissue engineering.     

A comparative study of the chondrogenic potential between synthetic and natural scaffolds in an in vivo bioreactor

Abstract

The clinical demand for cartilage tissue engineering is potentially large for reconstruction defects resulting from congenital deformities or degenerative disease due to limited donor sites for autologous tissue and donor site morbidities. Cartilage tissue engineering has been successfully applied to the medical field: a scaffold pre-cultured with chondrocytes was used prior to implantation in an animal model. We have developed a surgical approach in which tissues are engineered by implantation with a vascular pedicle as an in vivo bioreactor in bone and adipose tissue engineering. Collagen type II, chitosan, poly(lactic-co-glycolic acid) (PLGA) and polycaprolactone (PCL) were four commonly applied scaffolds in cartilage tissue engineering. To expand the application of the same animal model in cartilage tissue engineering, these four scaffolds were selected and compared for their ability to generate cartilage with chondrocytes in the same model with an in vivo bioreactor. Gene expression and immunohistochemistry staining methods were used to evaluate the chondrogenesis and osteogenesis of specimens. The result showed that the PLGA and PCL scaffolds exhibited better chondrogenesis than chitosan and type II collagen in the in vivo bioreactor. Among these four scaffolds, the PCL scaffold presented the most significant result of chondrogenesis embedded around the vascular pedicle in the long-term culture incubation phase.     

Preparation and cytocompatibility of silk fibroin / chitosan scaffolds

One challenge in soft tissue engineering is to find an applicable scaffold, not only having suitable mechanical properties, porous structures, and biodegradable properties, but also being abundant in active groups and having good biocompatibility. In this study, a three-dimensional silk fibroin/chitosan (SFCS) scaffold was successfully prepared with interconnected porous structure, excellent hydrophilicity, and proper mechanical properties. Compared with polylactic glycolic acid (PLGA) scaffold, the SFCS scaffold further facilitated the growth of HepG2 cells (human hepatoma cell line). Keeping the good cytocompatibility and combining the advantages of both fibroin and chitosan, the SFCS scaffold should be a prominent candidate for soft tissue engineering, for example, liver.     

Chitosan particles agglomerated scaffolds for cartilage and osteochondral tissue engineering approaches with adipose tissue derived stem cells

It is well accepted that natural tissue regeneration is unlikely to occur if the cells are not supplied with an extracellular matrix (ECM) substitute. With this goal, several different methodologies have been used to produce a variety of 3D scaffolds as artificial ECM substitutes suitable for bone and cartilage tissue engineering. Furthermore, osteochondral tissue engineering presents new challenges since the combination of scaffolding and co-culture requirements from both bone and cartilage applications is required in order to achieve a successful osteochondral construct. In this paper, an innovative processing route based on a chitosan particles aggregation methodology for the production of cartilage and osteochondral tissue engineering scaffolds is reported. An extensive characterization is presented including a morphological evaluation using Micro-Computed Tomography (μCT) and 3D virtual models built with an image processing software. Mechanical and water uptake characterizations were also carried out, evidencing the potential of the developed scaffolds for the proposed applications. Cytotoxicity tests show that the developed chitosan particles agglomerated scaffolds do not exert toxic effects on cells. Furthermore, osteochondral bilayered scaffolds could also be developed. Preliminary seeding of mesenchymal stem cells isolated from human adipose tissue was performed aiming at developing solutions for chondrogenic and osteogenic differentiation for osteochondral tissue engineering applications. An erratum to this article is available at .     

Preparation and cytocompatibility of silk fibroin/chitosan scaffolds

One challenge in soft tissue engineering is to find an applicable scaffold, not only having suitable mechanical properties, porous structures, and biodegradable properties, but also being abundant in active groups and having good biocompatibility. In this study, a three-dimensional silk fibroin/chitosan (SFCS) scaffold was successfully prepared with interconnected porous structure, excellent hydrophilicity, and proper mechanical properties. Compared with polylactic glycolic acid (PLGA) scaffold, the SFCS scaffold further facilitated the growth of HepG2 cells (human hepatoma cell line). Keeping the good cytocompatibility and combining the advantages of both fibroin and chitosan, the SFCS scaffold should be a prominent candidate for soft tissue engineering, for example, liver.     

Novel chitosan hydrogel formed by ethylene glycol chitosan, 1,6-diisocyanatohexan and polyethylene glycol-400 for tissue engineering scaffold: in vitro and in vivo evaluation

Traditional chitosan hydrogels were prepared by chemical or physical crosslinker, and both of the two kinds of hydrogels have their merits and demerits. In this study, researchers attempted to prepare one kind of chitosan hydrogel by slightly crosslinker, which could combine the advantages of the two kinds of hydrogels. In this experiment, the crosslinker was formed by a reaction between the isocyanate group of 1,6-diisocyanatohexan and the hydroxyl group of polyethylene glycol-400 (PEG-400), then the crosslinker reacted with the amidine and the hydroxyl group of ethylene glycol chitosan to form the network structure. Physical properties of the hydrogel were tested by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and biodegradation. Biocompatibility was assessed by cell implantation in vitro and the scaffold was used as a cartilage tissue engineering scaffold to repair a defect in rabbit knee joints in vivo. FTIR results show the formation of a covalent bond during thickening of the ethylene glycol chitosan. SEM and degradation experiments showed that the ethylene glycol chitosan hydrogel is a 3-D, porous, and degradable scaffold. The hydrogel contained 2 % ethylene glycol chitosan and 10 μl crosslinker was selected for the biocompatibility experiment in vitro and in vivo. After chondrocytes were cultured in the ethylene glycol chitosan hydrogel scaffold for 1 week cells exhibited clustered growth and had generated extracellular matrix on the scaffold in vitro. The results in vivo showed that hydrogel-chondrocytes promoted the repair of defect in rabbits. Based on these results, it could be concluded that ethylene glycol chitosan hydrogel is a scaffold with excellent physicochemical properties and it is a promising tissue engineering scaffold.