聚羟基烷酸酯聚合物负载软骨细胞修复同种异体喉软骨缺损

背景：软骨组织工程基础研究相当深入,但在耳鼻咽喉科实际应用研究颇少,探索组织工程技术简便实用的喉软骨修复方法是值得研究的课题,目的：比较多孔海绵状聚羟基丁酸酯与聚羟基己酸酯共聚物生物材料负载软骨细胞体外培养形成的初期组织工程软骨组织与体内植入一定时期形成的较成熟组织工程软骨组织修复同种异体甲状软骨缺损的效果。方法：收集体外培养第3代乳兔（3d龄墩骨细胞,以多孔海绵状聚羟基丁酸酯与聚羟基己酸酯共聚物生物材料为细胞外基质,采用组织工程技术制备细胞一材料复合物,共同体外培养形成初级组织工程软骨组织后直接应用于成兔甲状软骨缺损的修复（实验组A,n=5）或将初级组织工程软骨组织体内植入一定时期形成较成熟组织工程软骨再应用于甲状软骨缺损的修复（实验组B,n=5）。设单纯聚羟基丁酸酯与聚羟基己酸酯共聚物材料修复组（对照A组,n=4）和单纯软骨细胞修复组（对照B组,n=4）作为对照。分别于术后4周（实验B组）和8周（实验A组、对照A组、对照B组）取材,对甲状软骨缺损修复效果进行大体和组织学评价。结果与结论：两者大体支架形态基本一致,修复区与原有软骨均相续平坦,无凹陷及缺损。但实验A组存在界面无细胞区,修复区基质分泌不丰富;实验B组界面区有细胞生长,基质分泌良好。两者炎细胞浸润均不明显。对照组修复区凹陷,呈暗红色软组织充填,组织学及特殊染色检查未发现软骨样结构及其分泌的基质成分。结果表明在有免疫力的动物体内,初级组织工程软骨组织直接应用与体内植入后再应用均能有效修复同种异体甲状软骨缺损,无明显免疫反应;相同时期内,应用较成熟组织工程软骨组织修复效果优于应用初级组织工程软骨组织。然而,直接应用初级组织工程软骨组织可节省时间、成本、工作量及操作环节,避免二次皮下手术的痛苦,是比较实用的方法之一。     

Treatment options for articular cartilage defects of the knee

The treatment of symptomatic articular cartilage defects of the knee has evolved tremendously in the past decade. Previously, there were limited treatment options available to patients who suffered from either partial-thickness or full-thickness cartilage lesions. Because articular cartilage has a limited capacity for healing, patients were often treated symptomatically until they became candidates for osteotomy or total joint replacement. Recently, both reparative and restorative procedures have been developed to address this significant source of morbidity in young active patients. Microfracture is a reparative technique that induces a healing response to occur in an area of articular cartilage damage. Osteochondral autografts and allografts in addition to autologous chondrocyte implantation are restorative techniques aimed at recreating a more normal articular surface. Both types of procedures have been developed to alleviate the symptoms associated with focal chondral defects, as well as limit their potential to progress to a diffuse degenerative arthritis. Treatment can vary depending on both cartilage defect and patient factors. This article summarizes the various treatment options that have recently become available.     

Mesenchymal cell transfer for articular cartilage repair

Mature articular cartilage has a poor reparative response to injury and its irreparable breakdown is the common feature of degenerative joint diseases. If articular cartilage lesions become symptomatic, the orthopaedic surgeon must decide on a treatment option. The treatment options include conversion of chondral lesions to osteochondral lesions, which facilitates migration of cells from the marrow space to effect repair. In recent years, a greater emphasis has been placed on tissue engineering strategies and thus several new treatment options have been introduced, including the use of cell transplantation. Several tissue sources and cell types can potentially be used for this type of therapy. These include autologous or allograft chondrocytes and mesenchymal progenitor cells from various tissues. These cells may be delivered to articular cartilage lesions by a variety of methods including direct cell injection to the lesion or seeding in a biodegradable scaffold prior to implantation. In this review, the potential of cell transplantation for articular cartilage repair and regeneration will be discussed. The authors will focus on the available technologies and the present limitations of cell-based therapies.     

组织工程化软骨细胞和骨髓间充质干细胞用于修复同种异体关节软骨缺损

背景:关节软骨几乎没有自身修复的能力,目前临床大多采用自体或异体软骨移植修复、软骨膜或骨膜移植修复、软骨细胞移植修复。由于自体软骨来源有限,异体软骨又存在慢性免疫排斥反应,最终可能导致预后不佳;软骨膜或骨膜移植修复的软骨易于退化,导致修复效果不佳。目的:总结组织工程化软骨细胞、骨髓间充质干细胞及两者共培养对同种异体软骨缺损修复作用的研究现状。方法:应用计算机检索PubMed数据库及中国期刊网全文数据库1994-01/2012-01有关组织工程化软骨细胞和骨髓间充质干细胞用于修复同种异体关节软骨缺损方面的文章,英文检索词为"cartilage defect,allograft,chondrocyte,mesenchymal stem cells,bone marrow mesenchymal stem cells",中文检索词为"软骨缺损,同种异体移植,软骨细胞,骨髓间充质干细胞"。排除重复性及非中英文语种研究,共保留35篇文献进行综述。结果与结论:随着体外细胞培养方法的不断改进,现已能够把软骨细胞从坚韧的软骨中分离出来,并获得大量高纯度的软骨细胞并繁殖出新生软骨细胞。软骨细胞培养增殖能力低,传代培养容易引起老化和去分化;而成体骨髓中骨髓间充质干细胞含量少,随传代次数的增多成软骨潜能明显降低。骨髓间充质干细胞和软骨细胞共培养,两种细胞相互促进增殖和分化,作为种子细胞可减少软骨细胞增殖传代次数并节省软骨细胞数量,与组织工程支架材料复合能有效修复关节软骨缺损。     

Osteochondral defects: present situation and tissue engineering approaches

Articular cartilage is often damaged due to trauma or degenerative diseases, resulting in severe pain and disability. Most clinical approaches have been shown to have limited capacity to treat cartilage lesions. Tissue engineering (TE) has been proposed as an alternative strategy to repair cartilage. Cartilage defects often penetrate to the subchondral bone, or full-thickness defects are also produced in some therapeutic procedures. Therefore, in TE strategies one should also consider the need for a simultaneous regeneration of both cartilage and subchondral bone in situations where osteochondral defects are present, or to provide an enhanced support for the cartilage hybrid construct. In this review, different concepts related to TE in osteochondral regeneration will be discussed. The focus is on the need to produce new biphasic scaffolds that will provide differentiated and adequate conditions for guiding the growth of the two tissues, satisfying their different biological and functional requirements.     

组织工程关节软骨：新生软骨与移植物周围正常软骨的整合及重塑

背景：由于关节软骨的组织再生能力非常低,因此创伤或退变疾病导致软骨缺损很难实现自身修复。 目的：通过资料分析了解关节软骨组织工程学的研究现状。 方法：以“Articular cartilage, Tissue engineering, Signaling molecules, Scaffolds”为英文检索词,“关节软骨,组织工程学,细胞来源,信号分子,支架”为中文检索词,检索 Pubmed 数据库、CNKI 数据库2000至2013年发表的相关文献。共检索到202篇文献,排除无关重复的文献,保留70篇进行综述。 结果与结论：软骨细胞和干细胞是当前软骨组织工程研究的主要细胞来源。多种细胞因子、激素类物质及生长因子会影响软骨细胞的合成及分解代谢过程。新型生物材料支架可为细胞提供一个适宜的环境,刺激细胞软骨基质合成,临时替代天然软骨基质的功能,直至新生软骨形成。而随着研究的不断深入,组织工程学关节软骨必将表现出良好的应用前景。     

Cell yield,chondrogenic potential,and regenerated cartilage type of chondrocytes derived from ear,nasoseptal, and costal cartilage

Functional reconstruction of large cartilage defects in subcutaneous sites remains clinically challenging because of limited donor cartilage. Tissue engineering is a promising and widely accepted strategy for cartilage regeneration. To date, however, this strategy has not achieved a significant breakthrough in clinical translation owing to a lack of detailed preclinical data on cell yield and functionality of clinically applicable chondrocytes. To address this issue, the current study investigated the initial cell yield, proliferative potential, chondrogenic capacity, and regenerated cartilage type of human chondrocytes derived from auricular, nasoseptal, and costal cartilage using a scaffold‐free cartilage regeneration model (cartilage sheet). Chondrocytes from all sources exhibited high sensitivity to basic fibroblast growth factor within 8 passages. Nasoseptal chondrocytes presented the strongest proliferation rate, whereas auricular chondrocytes obtained the highest total cell amount using comparable cartilage sample weights. Importantly, all chondrocytes at fifth passage showed strong chondrogenic capacity both in vitro and in the subcutaneous environment of nude mice. Although some significant differences in histological structure, cartilage matrix content and cartilage type specific proteins were observed between the in vitro engineered cartilage and original tissue; the in vivo regenerated cartilage showed mature cartilage features with high similarity to their original native tissue, except for minor matrix changes influenced by the in vivo environment. The current study provides detailed preclinical data for choice of chondrocyte source and thus promotes the clinical translation of cartilage regeneration approach.     

State of the art and future perspectives of articular cartilage regeneration: a focus on adipose-derived stem cells and platelet-derived products

Trauma, malposition and age-related degeneration of articular cartilage often result in severe lesions that do not heal spontaneously. Many efforts over the last centuries have been undertaken to support cartilage healing, with approaches ranging from symptomatic treatment to structural cartilage regeneration. Microfracture and matrix-associated autologous chondrocyte transplantation (MACT) can be regarded as one of the most effective techniques available today to treat traumatic cartilage defects. Research is focused on the development of new biomaterials, which are intended to provide optimized physical and biochemical conditions for cell proliferation and cartilage synthesis. New attempts have also been undertaken to replace chondrocytes with cells that are more easily available and cause less donor site morbidity, e.g. adipose derived stem cells (ASC). The number of in vitro studies on adult stem cells has rapidly increased during the last decade, indicating that many variables have yet to be optimized to direct stem cells towards the desired lineage. The present review gives an overview of the difficulties of cartilage repair and current cartilage repair techniques. Moreover, it reviews new fields of cartilage tissue engineering, including stem cells, co-cultures and platelet-rich plasma (PRP).     

组织工程软骨修复兔半月板损伤

背景半月板游离缘为无血运区,损伤不易自然愈合,需要在一定的条件促进下产生纤维组织愈合.目的采用组织工程软骨与纤维蛋白黏合剂治疗半月板无血运区的损伤,并进行的效果比较.设计随机分组,空白对照实验.单位深圳市第二人民医院动物实验室.对象①选择生后3～5 d青紫兰兔10只用于纤维软骨细胞的提取.②选择健康成年青紫兰兔36只,随机分为3组,空白对照组、纤维蛋白黏合剂治疗组和组织工程软骨组,每组12只.方法实验于2003-09/2004-03深圳市第二人民医院动物实验室完成.将10只生后3～5 d幼兔处死后提取纤维软骨细胞进行培养,制成软骨细胞含量约为12×108 L-1的组织工程软骨.将36只成年兔造成半月板(0.7×0 3)cm全层裂伤的无血运区损伤模型.空白对照组裂伤不用任何填塞处理,纤维蛋白黏合剂治疗组用纤维蛋白黏合剂注入裂口,组织工程软骨组用组织工程软骨注入裂口.3组动物分别于术后2,6,12周各处死4只,每次每组取8个半月板,行大体形态观察和组织学检查.主要观察指标兔半月板损伤模型标本大体形态观察和组织学检查.结果36只兔均进入结果分析.①兔半月板损伤模型标本大体观察结果空白对照组半月板损伤裂口均未愈合,未见组织填充;纤维蛋白黏合剂组及组织工程软骨组的全部半月板伤口均已被组织填充.②兔半月板损伤模型标本组织学检查结果空白对照组术后2～12周裂口边缘无软骨细胞增殖;纤维蛋白黏合剂组术后12周,缺损边缘有较多的成纤维细胞样细胞,与邻近组织连接较紧密,形成瘢痕组织愈合;组织工程软骨组术后12周,缺损处可见软骨陷窝及软骨囊,软骨细胞成团状.结论组织工程软骨在受体内可成活,可形成纤维软骨样愈合,形成软骨细胞特有的生物学标志,但修复的组织与邻近正常半月板组织及正常软骨的胶原排列有明显差异.     

Bioreactor studies of natural and tissue engineered cartilage

Bioreactors provide controlled environments for tissue cultivation and evaluation of the effect of specific biochemical and physical parameters on in vitro chondrogenesis. The hydrodynamic environment is expected to modulate the in vitro tissue formation in at least two ways: directly via hydrodynamic effects on cell morphology and function, and indirectly via flow-induced mass transfer of nutrients and metabolites. We investigated and compared the effects of three different hydrodynamic environments: static flasks (tissues fixed in place, static medium), mixed flasks (tissues fixed in place, unidirectional turbulent flow) and rotating bioreactors (tissues dynamically suspended in laminar flow) on the morphology and composition and metabolic function of engineered and natural cartilage over an in vitro culture period of 6 weeks. In general, engineered and natural cartilage responded in a similar manner. Static conditions were associated with increased rates of GAG release into tissue culture medium and the formation of an outer fibrous capsule in both engineered and natural cartilage. In contrast, dynamic laminar flow in rotating bioreactors provided efficient oxygen supply and resulted in the retention of newly synthesized macromolecules, the maintenance of cartilaginous tissue morphology, and the best overall tissue structure and composition for both engineered and natural cartilage.     

Stem cells as vehicles for orthopedic gene therapy

Adult stem cells reside in adult tissues and serve as the source for their specialized cells. In response to specific factors and signals, adult stem cells can differentiate and give rise to functional tissue specialized cells. Adult mesenchymal stem cells (MSCs) have the potential to differentiate into various mesenchymal lineages such as muscle, bone, cartilage, fat, tendon and ligaments. Adult MSCs can be relatively easily isolated from different tissues such as bone marrow, fat and muscle. Adult MSCs are also easy to manipulate and expand in vitro. It is these properties of adult MSCs that have made them the focus of cell-mediated gene therapy for skeletal tissue regeneration. Adult MSCs engineered to express various factors not only deliver them in vivo, but also respond to these factors and differentiate into skeletal specialized cells. This allows them to actively participate in the tissue regeneration process. In this review, we examine the recent achievements and developments in stem-cell-based gene therapy approaches and their applications to bone, cartilage, tendon and ligament tissues that are the current focus of orthopedic medicine.     

Gene transfer of a human insulin-like growth factor I cDNA enhances tissue engineering of cartilage

The repair of articular cartilage lesions remains a clinical problem. Two novel approaches to cartilage formation, gene transfer and tissue engineering, have been limited by short-term transgene expression in transplanted chondrocytes and inability to deliver regulatory signals to engineered tissues according to specific temporal and spatial patterns. We tested the hypothesis that the transfer of a cDNA encoding the human insulin-like growth factor I (IGF-I) can provide sustained gene expression in cell-polymer constructs in vitro and in vivo and enhance the structural and functional properties of tissue-engineered cartilage. Bovine articular chondrocytes genetically modified to overexpress human IGF-I were seeded into polymer scaffolds, cultured in bioreactors in serum-free medium, and implanted subcutaneously in nude mice; constructs based on nontransfected or lacZ-transfected chondrocytes served as controls. Transgene expression was maintained throughout the duration of the study, more than 4 weeks in vitro followed by an additional 10 days either in vitro or in vivo. Chondrogenesis progressed toward the formation of cartilaginous tissue that was characterized by the presence of glycosaminoglycans, aggrecan, and type II collagen, and the absence of type I collagen. IGF-I constructs contained increased amounts of glycosaminoglycans and collagen and confined-compression equilibrium moduli as compared with controls; all groups had subnormal cellularity. The amounts of glycosaminoglycans and collagen per unit DNA in IGF-I constructs were markedly higher than in constructs cultured in serum-supplemented medium or native cartilage. This enhancement of chondrogenesis by spatially defined overexpression of human IGF-I suggests that cartilage tissue engineering based on genetically modified chondrocytes may be advantageous as compared with either gene transfer or tissue engineering alone.     

聚羟基乙酸无纺网设计在软骨组织工程中的适用研究

目的观察接种同种异体软骨细胞后，一定设计的三维生物可降解材料聚羟基乙酸(PGA)无纺网在组织工程化软骨形成中的降解性。方法取乳兔肋软骨细胞，接种于PGA支架材料上，经体外培养，体内皮下种植或修复软骨缺损，一定时间取材，观察PGA纤维在工程化软骨形成过程中的降解情况。结果软骨细胞-PGA复合物体外培养1周，可见基质产生，未见纤维降解迹象；体内种植或修复软骨缺损4周后，新生软骨内仍有较多PGA纤维；8周时PGA纤维已基本消失；12周软骨细胞成熟，基质分泌丰富，未见任何PGA存留迹象。结论一定设计的PGA无纺网在组织工程化软骨形成过程中适合其生物降解性要求。     

Glycogen storage in tissue-engineered cartilage

Recent focus in cartilage tissue engineering has been to develop functional tissue that can survive after implantation. One such determinant is the ability of the engineered tissue to be able to sustain its metabolic activity post-implantation. In vivo, chondrocytes contain stores of intracellular glycogen to support metabolism and it is unknown whether these cells can store glycogen during tissue growth in vitro. Thus, the purpose of this study was to determine the appropriate nutrient conditions to elicit glycogen storage in tissue-engineered cartilage. Isolated bovine articular chondrocytes were seeded in scaffold-free, 3D culture and grown under different nutrient conditions (glucose concentrations and media volumes) for 4 weeks. Intracellular glycogen storage, glucose utilization and extracellular matrix (ECM) accumulation of the engineered tissues were then evaluated. Glucose concentration (5-10 mM) and media volume (1-4 ml) had no apparent effect on cartilaginous tissue formation. However, glucose consumption by the cells increased in proportion to the volume of medium provided. Lactate production was similarly affected but in direct proportion to the glucose consumed, indicating a change in glucose utilization. Similarly, under elevated medium volume, engineered tissues stained positive for intracellular glycogen, which was also confirmed biochemically (1 ml, 1 +/- 2; 2 ml, 13 +/- 4; 4 ml, 13 +/- 3 microg/construct). The storage of intracellular glycogen in engineered cartilage can be elicited by culturing the constructs in elevated volumes of medium (>or=1 ml medium/million cells), which might help to ensure appropriate metabolic function after implantation.     

以交联透明质酸钠为支架体外构建组织工程软骨简

背景：采用组织工程技术再生和重建软骨是目前修复软骨组织缺损效果最好、最有应用前景的方法。 目的：以体外培养的软骨细胞和交联透明质酸钠为支架材料,开发一套体外构建组织工程软骨的完整方案。方法：分离新西兰兔膝关节软骨细胞,制成细胞悬液滴加于交联透明质酸钠支架上,体外复合培养21 d,提取RNA进行RT-PCR检测,制备冰冻切片进行显微观察和免疫组织化学观察。 结果与结论：软骨细胞接种于交联透明质酸钠支架材料后,可贴附于支架上生长,并且大量细胞聚集成团,在支架材料的纤维间隙中生长或呈单层细胞附着于支架材料纤维。细胞-支架复合物表达软骨组织特异性蛋白聚糖基因和Ⅱ型胶原α1基因,以及软骨组织特异性蛋白Ⅱ型胶原蛋白,可维持软骨细胞表型。表明培养的细胞-支架复合物在体外培养可形成软骨细胞外基质,有望获得组织工程软骨组织。     

Distinct patterns of gene expression in the superficial,middle and deep zones of bovine articular cartilage

Hyaline articular cartilage will not heal spontaneously, and lesions in hyaline articular cartilage often result in degenerative joint disease. Considerable progress has been made with respect to the responsive stem cells, inductive signals and extracellular scaffolding required for the optimal regeneration of cartilage. However, many challenges remain, such as topographic differences in the functional zones of articular cartilage. We hypothesized that a distinct set of differentially expressed genes define the surface, middle and deep zones of hyaline articular cartilage. Microarray analysis of bovine articular cartilage from the superficial and middle zones revealed 52 genes differentially expressed ≥ 10‐fold and 114 additional genes differentially expressed ≥ five‐fold. However, no genes were identified with a ≥ five‐fold difference in expression when comparing articular cartilage from the middle and deep zones. There are distinct, differential gene expression patterns in the superficial and middle zones of hyaline articular cartilage that highlight the functional differences between these zones. This investigation has implications for the tissue engineering and regeneration of hyaline articular cartilage. Copyright © 2012 John Wiley & Sons, Ltd.     

SCI数据库关于运动状态下组织工程软骨生物力学变化的相关文章分析

背景：组织工程软骨研究是近年研究的热点,目前尚无对运动状态下组织工程软骨生物力学变化相关文章的文献计量分析。目的：通过运动状态下组织工程软骨生物力学变化相关文章文献的计量分析,总结概括目前研究的状况和前沿。方法：以美国科学情报研究所（ISI）开发的WebofScience网络数据库为数据源基础,对SCI收录的运动状态下组织工程软骨生物力学变化相关文章论文的情况,从论文的发表时间分布、国家地区分布、机构分布、期刊分布和被引频次分布等方面进行统计与分析。结果与结论：1990/2011共有运动状态下组织工程软骨生物力学变化相关文章文献82篇,文献呈年度递增,以美国发表论文最多,有58篇。得出了运动状态下组织工程软骨生物力学变化相关文章这一领域的研究动态和发展趋势,为中国深入研究组织工程软骨在运动状态下的生物力学变化提供可供借鉴的参考建议。     

无纺网与多孔海绵状材料作为软骨组织工程支架的适用性及体内降解性

背景：聚羟基乙酸无纺网与聚羟基丁酸酯-聚羟基己酸酯共聚物多孔海绵具有良好的塑形适应性、生物降解性与生物相容性。 目的：观察聚羟基乙酸无纺网与聚羟基丁酸酯-聚羟基己酸酯共聚物多孔海绵作为软骨组织工程支架的适用性及体内降解性。 方法：分别制备乳兔软骨细胞-聚羟基乙酸无纺网复合物、乳兔软骨细胞-聚羟基丁酸酯-聚羟基己酸酯共聚物多孔海绵复合物。在实验组成年兔两侧背部皮下分别植入制备的两种复合物,在对照组成年兔两侧背部皮下分别植入聚羟基乙酸无纺网与聚羟基丁酸酯-聚羟基己酸酯共聚物。 结果与结论：组织学观察显示,以聚羟基乙酸无纺网获取的组织工程软骨,植入4周时软骨细胞较小,软骨内有较多聚羟基乙酸纤维残留,8周时软骨细胞较成熟,包埋在陷窝内,聚羟基乙酸纤维消失,12周时软骨细胞成熟,基质分泌丰富,无聚羟基乙酸存留;以聚羟基丁酸酯-聚羟基己酸酯共聚物多孔海绵获取的组织工程软骨,植入4周时软骨细胞不成熟,软骨基质内似“杂质”样材料残留物较多,8周时软骨细胞较成熟,软骨基质内仍可见材料残留,12周时软骨基质材料残留基本消失。两组组织工程软骨特殊染色与免疫组织化学检测均显示再生软骨胶原与基质黏多糖生成良好,软骨中均检测出Ⅱ型胶原。表明两种材料作为软骨组织工程支架具有良好的适用性,其降解时间均达到组织工程软骨构建的要求。     

Tissue engineering for bone and cartilage repair

Huge bone defects that occur as a result of severe trauma or bone and oft tissue tumor are frequently difficult to achieve adequate union. Autogenous or allogeneic bone grafting and reconstruction using biomaterials are the traditional method used to repair bone defects, but it is not easy to reconstruct the structure and strength. Articular cartilage has very limited intrinsic healing capacity. Although numerous attempts to repair full-thickness articular cartilage defects have been conducted, no methods have successfully regenerated long-lasting hyaline cartilage. One of the most promising procedures for bone and cartilage repair is tissue engineering. New techniques of cell therapy for the treatment of bone and cartilage lesions are currently developed. This paper will summarize the current concepts of cell therapy for bone and cartilage repair and its future application.     

Advances in meniscal tissue engineering

Injuries and lesions to the meniscal cartilage of the knee joint are common. As a result of its limited regenerative capacity, early degenerative changes to the articular surface frequently occur, resulting in pain and poor function. Currently available surgical interventions include repair of tears, and partial and total meniscectomy but the results are inconsistent and often poor. Interest in the field of meniscal tissue engineering with the possibilities of better treatment outcomes has grown in recent times. Current research has focused on the use of mesenchymal stem cells, fibrochondrocytes, meniscal derived cells and fibroblast-like synoviocytes in tissue engineering. Mesenchymal stem cells are multipotent cells that have been identified in a number of tissues including bone marrow and synovium. Current research is aimed at defining the correct combination of cytokines and growth factors necessary to induce specific tissue formation and includes transforming growth factor-β (TGF-β), Platelet Derived Growth Factor (PDGF) and Fibroblast Growth Factor 2 (FGF2). Scaffolds provide mechanical stability and integrity, and supply a template for three-dimensional organization of the developing tissue. A number of experimental and animal models have been used to investigate the ideal scaffolds for meniscal tissue engineering. The ideal scaffold for meniscal tissue engineering has not been identified but biodegradable scaffolds have shown the most promising results. In addition to poly-glycolic acid (PGA) and poly-lactic acid (PLLA) scaffolds, new synthetic hydrogels and collagen sponges are also being explored. There are two synthetic meniscal implants currently in clinical use and there are a number of clinical trials in the literature with good short- and medium-term results. Both products are indicated for segmental tissue loss and not for complete meniscal replacement. The long-term results of these implants are unknown and we wait to see whether they will be proved to have benefits in delaying arthritic change and chondral damage.