A triphasic ceramic-coated porous hydroxyapatite for tissue engineering application

Scaffolds which encourage the incorporation of a cell source for tissue engineering applications are critical determinants for clinical defects. Over the years, a number of biomaterials have emerged for cell support and growth, but only a few have demonstrated clinical efficacy. We therefore investigated an in-house-developed silica-based bioactive ceramic for its ability to support and sustain the growth of bone marrow-derived mesenchymal stem cells (BMSCs) in vitro. For this, MSCs aspirated from goat bone marrow were isolated and culture expanded on a novel triphasic ceramic composite coated hydroxyapatite (HASi) scaffold comprising hydroxyapatite, tricalcium phosphate and calcium silicate. The viability of cells that harbored on and within the material was ensured through fluorescence-activated cell sorting and confocal laser scanning microscope and for their anchorage sites by scanning electron microscopy. Interestingly, over the days in culture, cell-cell interactions gradually morphed into woven cell-sheets that spanned across the surface of the HASi, forming a canopy. To conclude, we have attempted to carry out the preliminary cytocompatibility studies of this novel ceramic to establish its appropriateness for bone tissue engineering application which is an important criterion in orthopaedic transplantation and regenerative surgery.     

Bone tissue engineering in osteoporosis

Osteoporosis is a polygenetic, environmentally modifiable disease, which precipitates into fragility fractures of vertebrae, hip and radius and also confers a high risk of fractures in accidents and trauma. Aging and the genetic molecular background of osteoporosis cause delayed healing and impair regeneration. The worldwide burden of disease is huge and steadily increasing while the average life expectancy is also on the rise. The clinical need for bone regeneration applications, systemic or in situ guided bone regeneration and bone tissue engineering, will increase and become a challenge for health care systems. Apart from in situ guided tissue regeneration classical ex vivo tissue engineering of bone has not yet reached the level of routine clinical application although a wealth of scaffolds and growth factors has been developed. Engineering of complex bone constructs in vitro requires scaffolds, growth and differentiation factors, precursor cells for angiogenesis and osteogenesis and suitable bioreactors in various combinations. The development of applications for ex vivo tissue engineering of bone faces technical challenges concerning rapid vascularization for the survival of constructs in vivo. Recent new ideas and developments in the fields of bone biology, materials science and bioreactor technology will enable us to develop standard operating procedures for ex vivo tissue engineering of bone in the near future. Once prototyped such applications will rapidly be tailored for compromised conditions like vitamin D and sex hormone deficiencies, cellular deficits and high production of regeneration inhibitors, as they are prevalent in osteoporosis and in higher age.     

Stem cell-based tissue engineering with silk biomaterials

Silks are naturally occurring polymers that have been used clinically as sutures for centuries. When naturally extruded from insects or worms, silk is composed of a filament core protein, termed fibroin, and a glue-like coating consisting of sericin proteins. In recent years, silk fibroin has been increasingly studied for new biomedical applications due to the biocompatibility, slow degradability and remarkable mechanical properties of the material. In addition, the ability to now control molecular structure and morphology through versatile processability and surface modification options have expanded the utility for this protein in a range of biomaterial and tissue-engineering applications. Silk fibroin in various formats (films, fibers, nets, meshes, membranes, yarns, and sponges) has been shown to support stem cell adhesion, proliferation, and differentiation in vitro and promote tissue repair in vivo. In particular, stem cell-based tissue engineering using 3D silk fibroin scaffolds has expanded the use of silk-based biomaterials as promising scaffolds for engineering a range of skeletal tissues like bone, ligament, and cartilage, as well as connective tissues like skin. To date fibroin from Bombyx mori silkworm has been the dominant source for silk-based biomaterials studied. However, silk fibroins from spiders and those formed via genetic engineering or the modification of native silk fibroin sequence chemistries are beginning to provide new options to further expand the utility of silk fibroin-based materials for medical applications.     

骨髓基质干细胞和软骨组织工程

关节软骨是透明软骨 ,它是一种特殊的结缔组织 ,由单一的软骨细胞、纤维和基质构成。软骨组织具有自身独特的生理学特点 ,无血管 ,无神经 ,无淋巴引流 ,在关节腔内仅靠滑液来获取营养 ,其代谢主要以无氧酵解为主等决定了它极其有限的再生能力。临床上由于创伤、炎症肿瘤等原因导致的关节软骨损伤、缺失极为常见 ,且常继发骨关节炎 ,严重影响关节的功能。目前临床上多通过自体或异体移植成形的软骨或具有成软骨潜能的组织如骨膜、软骨膜等来治疗关节软骨的缺损 ,这些组织移植后能生成透明软骨样组织 ,但其生物学性能、耐磨性、韧性均欠佳 ,易…     

纳米羟基磷灰石复合材料在骨组织工程中的应用

本文总结了纳米羟基磷灰石的主要制备方法,概括了纳米羟基磷灰石生物复合材料的研究进展及应用现状,并分析其发展前景。     

骨组织工程的研究进展

目的：了解组织工程骨的相关概念及其特点,以及在组织工程骨研究中种子细胞、支架材料、生长因子、组织工程骨的构建及其应用的最新研究进展。方法：查阅相关中外文献,了解组织工程骨最新的发展动态及临床应用进展。结果：组织工程骨对骨缺损的修复是积极有效的。结论：随着研究的深入,骨组织工程技术最终会解决骨缺损的治疗这一骨外科领域的难题。     

组织工程骨-假体界面微观结构与元素分析的意义

目的研究假体-组织工程骨界面的微观结构和钙磷元素及构成比动态变化及意义。方法取新西兰大白兔15只,将兔骨髓间充质干细胞培养、扩增及诱导后,与珊瑚羟基磷灰石复合构建组织工程骨;双侧股骨髁分别制作一0.5cm×1.2cm骨缺损,骨缺损中央植入0.2cmx1.0cm钛合金植入体,左侧植入体周围植入组织工程骨,右侧仅植入珊瑚羟基磷灰石为对照,于术后4周、8周和l2周分别行X线检查、扫描电镜及能谱分析观察植入体表面微观结构和钙磷元素百分含量及比值的变化。结果 X线检查示,实验组术后8-12周可见大量模糊的高密度骨痂影,缺损区与周围骨质间分界变模糊。对照组各时间点无明显变化;扫描电镜示,实验组术后8、12周植入体表面孔隙内有大量无定形物质,而对照组未见有无定形物质。能谱分析示,不同时间点实验组较对照组内钙、磷元素百分含量高,有显著性差异（〈0.05）,随着时间的变化实验组和对照组Ca、P百分含量都呈增高的趋势,但12周和8周相比无显著性差异（〉0.05）。实验组内钙磷比值随时间变化有逐渐增大趋势,8周时达峰值,8周后缓慢下降。结论假体-组织工程骨界面钙、磷元素及构成比的动态变化表明骨整合的形成,并随着时间的延长骨改建逐步增加。     

Biodegradable porous scaffolds for tissue engineering

 Three-dimensional scaffolds play an important role in tissue engineering as an adhesive substrate for implanted cells and a physical support to guide the formation of new organs. The scaffolds should facilitate cell adhesion, promote cell growth, allow the retention of differentiated cell functions, and be biocompatible, biodegradable, highly porous with a large surface-to-volume ratio, mechanically strong, and malleable. A number of biodegradable three-dimensional scaffolds have been developed for tissue engineering. This paper reviews some of the recent events in the development of these scaffolds. Received: March 6, 2002     

间充质干细胞在组织工程气管中的研究进展

组织工程学通过细胞或组织重建,修复缺损组织并保留其生物功能,成为气管替代治疗的新途径.种子细胞、生长因子及气管支架材料是组织工程气管的三大要素,学者们一直在寻求理想的种子细胞.间充质干细胞(MSCs)是一种具有高度自我更新能力和多向分化潜能的干细胞,广泛分布于骨髓、脐带、脂肪组织、心肌组织、大脑、肌肉和皮肤等,可向骨、软骨、脂肪、神经等多种细胞定向分化.MSCs具有增殖能力强、分化范围广、免疫调节等功能特点,能够修复损伤的组织,有望成为应用于组织工程气管的理想种子细胞.旨在对MSCs在组织工程气管中的应用作一综述.     

骨髓间充质干细胞与复合I型胶原和骨形态发生蛋白2的聚乳酸乙醇酸构建组织工程骨

目的探讨骨髓间充质干细胞(BMSC)体外分离培养后种植到复合Ⅰ型胶原和重组人类骨形态发生蛋白2(rhBMP-2)的聚乳酸乙醇酸(PLGA)生物支架上,构建组织工程骨的可行性.方法密度梯度离心法提取分离BMSC,倒置显微镜观察细胞形态,流式细胞分析法对细胞表面抗原进行鉴定.相分离法制备多孔三维PLGA生物支架,支架材料上复合Ⅰ型胶原和rhBMP-2,扫描电镜观察其超微结构.将第3代的BMSC接种于复合支架上,扫描电镜观察材料的细胞黏附性,将培养6 h 后的细胞-支架复合体植入SD大鼠肌袋内,于2个月后取材进行HE染色,观察其构建组织工程骨的情况.结果 BMSC可在体外分离扩增,表达CD29、CD44,不表达CD34和CD45.制备的PLGA支架孔隙率为90%,平均孔径为100 μm,与BMSC有较好的黏附性.2个月后动物体内细胞-支架复合体的大体观察和HE染色显示,BMSC种植到复合Ⅰ型胶原和rhBMP-2的PLGA生物支架上可构建骨组织.结论 BMSC可在体外长期、稳定培养,是理想的组织工程种子细胞.PLGA与干细胞有较好的黏附性,可用来做组织工程生物材料.BMSC种植到复合Ⅰ型胶原和rhBMP-2的PLGA生物支架上后,在动物体内可构建组织工程骨.     

骨髓间充质干细胞构建组织工程化小口径血管

目的采用在动物体外构建初级组织工程化血管、体内强化的方法,探讨构建小口径组织工程化血管的可能性.方法体外培养骨髓间充质干细胞(BMSC),用含全反式维甲酸(AT-RA)、双丁酰环磷酸腺苷(db-cAMP)的DMEM-LG培养液和含血管内皮细胞生长因子(VEGF)的培养液诱导BMSC分别向血管平滑肌样细胞和血管内皮样细胞分化.免疫荧光观察平滑肌样细胞β肌动蛋白的表达和内皮样细胞vWF的表达.电镜观察超微结构的改变.诱导的血管平滑肌样细胞和血管内皮样细胞,分层种植于胶原包埋聚乙醇酸(PGA)的复合支架表面,将细胞和支架复合体种植于动物皮下,于植入后第4、8周再次麻醉动物,取出植入皮下的组织工程化血管,行组织学检查、压力实验及免疫荧光检查.结果诱导14 d后,BMSC能够分化为血管平滑肌样细胞和血管内皮样细胞:β肌动蛋白和vWF呈阳性表达,电镜证实细胞出现了相应的形态学改变.人工血管组织学观察见管壁结构清晰.单纯支架组可承受100～150 mm Hg(1mm Hg=0.133 kPa)的血管腔内压力,实验组则均可承受200mm Hg的血管腔内压力不破裂.实验组皮下培养8周Brdu标记细胞的免疫荧光结果显示部分细胞核呈现明亮的黄绿色荧光.结论以动物皮下为生物反应器可构建出组织工程化血管,其大体结构和天然血管相似.     

Design and fabrication of porous biodegradable scaffolds: a strategy for tissue engineering

Current strategies of tissue engineering are focused on the reconstruction and regeneration of damaged or deformed tissues by grafting of cells with scaffolds and biomolecules. Recently, much interest is given to scaffolds which are based on mimic the extracellular matrix that have induced the formation of new tissues. To return functionality of the organ, the presence of a scaffold is essential as a matrix for cell colonization, migration, growth, differentiation and extracellular matrix deposition, until the tissues are totally restored or regenerated. A wide variety of approaches has been developed either in scaffold materials and production procedures or cell sources and cultivation techniques to regenerate the tissues/organs in tissue engineering applications. This study has been conducted to present an overview of the different scaffold fabrication techniques such as solvent casting and particulate leaching, electrospinning, emulsion freeze-drying, thermally induced phase separation, melt molding and rapid prototyping with their properties, limitations, theoretical principles and their prospective in tailoring appropriate micro-nanostructures for tissue regeneration applications. This review also includes discussion on recent works done in the field of tissue engineering.     

In vivo tissue engineering: dreams for the future

Both tissue-engineered organs and hybrid artificial organs are considered to be candidates for the satisfaction of future hopes. The author has been engaged in developing vascular prostheses-neointima formed on vascular prostheses was a product of tissue engineering in vivo. On the basis of the author's experiences, the advantages of in vivo tissue engineering technologies for future artificial organs and dreams for the future are described. The use of primitive young cells is an important point; they proliferate easily and can differentiate along with their environment. They also synthesize various kinds of cytokines and growth factors, which are useful for tissue engineering. Combined use of undifferentiated cells and growth factors can induce organogenesis, so we can aim for the creation of new organs in vivo. The rejuvenation phenomenon of cells, i.e., blastogenesis, is also useful. Extracellular matrix can control cell differentiation, migration, and formation of cell communities, so we must learn to modify extracellular matrices. We humans have an extremely important legacy in our bodies, although we do not know how to use it. We have accumulated many genes during our evolution, and such genes do not become extinct. Therefore we have many genes from our primitive ancestors. These primitive creatures had an extremely strong capability for tissue repair, and we must find a way to make practical application of these dormant traits. In the future human beings will be able to learn how to control and apply them for in vivo tissue engineering technologies.     

计算机辅助组织工程的发展和现状

计算机辅助技术在组织工程学中的应用已经成为一个新的研究课题——计算机辅助组织工程(CATE)。作者回顾了计算机技术、影像学技术、计算机辅助设计和制造(CAD/CAM)以及快速成型技术在组织工程学中的应用,主要介绍计算机辅助解剖建模、三维解剖显像、三维重建、基于CAD的解剖建模、计算机辅助组织分类、内植物植入及快速成型辅助外科重建的发展和应用。     

骨组织工程研究进展

植骨术是解决临床骨缺损这一棘手问题的主要方法。植骨术大致可分为自体植骨术、同种异体或异种植骨术和组织工程骨植骨术。前两种方法的弊端或局限性已众所周知 ,而当前骨组织工程研究显示极有希望的应用前景。本文从骨组织工程的基础研究、组织工程骨修复骨缺损的实验和临床初步研究以及骨组织工程的展望等四个方面介绍了目前骨组织工程的进展     

骨髓间充质干细胞在骨组织工程中的应用

间充质干细胞可以分化为成骨细胞、成纤维细胞、神经细胞等多种组织细胞。研究者从骨髓中分离提取骨髓间充质干细胞 ,并通过诱导和体外培养使之分化为成骨细胞 ,作为骨组织工程的种子细胞。     

计算机辅助组织工程在组织支架仿生建模和设计中的应用

计算机辅助组织工程(CATE)可以帮助进行复杂组织支架的建模,设计和制造,使很多用于改善替代材料力学及生物学性能的新方法得以实施。CATE通过获取组织的生物学、生物力学及生物化学信息,进行界面的设计、模拟和组织的制作。本文将讲述CATE在骨组织工程支架仿生设计中的应用:介绍运用CATE进行仿生建模,解剖结构重建,组织支架设计,定量CT分析,有限元分析和支架的自由挤压沉积制作。     

胶原-壳聚糖复合材料作为组织工程支架的研究

目的 本研究考察壳聚糖对于胶原膜理化性质的影响,选择合适比例的胶原-壳聚糖复合膜作为骨髓间充质干细胞（BMSCs）载体.方法 胶原溶涨液中添加一定比例的壳聚糖,交联并冷冻干燥制备多孔组织工程支架,研究壳聚糖对胶原膜形态学、孔隙率、机械强度、降解特性等理化性质的影响,并初步探讨了胶原-壳聚糖材料作为组织工程三维支架材料与BMSCs的相容性.结果 制备的胶原-壳聚糖支架孔径分布均匀;相对于单纯胶原海绵支架,胶原-壳聚糖复合材料支架降低体外降解速度,提高支架材料的力学性能,稳定支架的结构.BMSCs种植于胶原-壳聚糖（mCol∶mCS=9∶1）支架14 d时,SEM观察到细胞通过微绒毛与支架纤维复合,细胞相容性好.结论 胶原-壳聚糖复合支架有良好的细胞相容性,作为BMSCs诱导体外支架材料具有好的研究前景.     

间充质干细胞应用于软骨组织工程的研究进展

[摘要]本文主要回顾了不同来源的间充质干细胞作为种子细胞的软骨组织工程学研究进展，并讨论自体软骨细胞移植技术和诱导间充质干细胞成软骨分化的软骨组织再生技术各自的优缺点，并展望其临床应用前景。     

浓集自体骨髓基质干细胞组织工程复合物治疗早期股骨头坏死的实验疗效

目的研究浓集自体骨髓基质干细胞组织工程复合物治疗兔早期股骨头坏死的实验疗效，为临床应用提供依据。方法24只新西兰大白兔随机分为两组，建立右侧股骨头骨缺损模型，并用液氮从缺损内将股骨头冷冻坏死，A组为对照组，仅植入空白明胶海绵，B组为实验组，植入复合物。术后每组分别于2、4、6、8周各处死3只动物，做影像学及组织学检查。进行有关指标检测。结果①影像学结果：随着时间延长无论是X线、CT表现还是MRI表现，实验组钻孔区由低密度逐渐增高，8周时有骨小梁结构；对照组钻孔区无新骨形成表现。②组织学结果：A组2周标本缺损区内，充满坏死的组织碎片；4周标本，缺损区内为疏松的纤维肉芽组织；6周标本缺损区内为纤维组织；8周标本缺损区内仍为纤维组织，无新生骨组织。B组2周标本缺损区内，有大量的成骨细胞；4周标本，缺损区内有大量骨小梁及类骨质填充；6周标本缺损区内出现比较成熟的骨小梁；8周标本缺损区内骨小梁成熟，骨髓组织形成。结论浓集自体骨髓基质干细胞组织工程复合物对兔股骨头坏死有极好的修复作用。