TGF-beta1 immobilized tri-co-polymer for articular cartilage tissue engineering

Tri-co-polymer with composition of gelatin, hyaluronic acid and chondroitin-6-sulfate has been used to mimic the cartilage extracellular matrix as scaffold for cartilage tissue engineering. In this study, we try to immobilize TGF-beta1 onto the surface of the tri-co-polymer sponge to suppress the undesired differentiation during the cartilage growth in vitro. The scaffold was synthesized with a pore size in a range of 300-500 microm. TGF-beta1 was immobilized on the surface of the tri-co-polymer scaffold with 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC) as a crosslinking agent. Tri-co-polymer scaffolds with and without TGF-beta1 were seeded with porcine chondrocytes and cultured in a spinner flask for 2, 4, and 6 weeks. The chondrocytes were characterized by the methods of immunohistochemical staining with anti-type II collagen and anti-S-100 protein monoclonal antibody, and RT-PCR. After culturing for 4 weeks, chondrocytes showed positive in S-100 protein, Alcian blue, and type II collagen for the scaffold with TGF-beta1 immobilization. There is no observed type I and type X collagen expression in the scaffolds from the observation of RT-PCR. In addition, the scaffold without TGF-beta1 immobilization, type X collagen, can be detected after cultured for 2 weeks. Type I collagen was progressively expressed after 4 weeks. These results can conclude that TGF-beta1 immobilized scaffold can suppress chondrocytes toward prehypertrophic chondrocytes and osteolineage cells. The tri-co-polymer sponge with TGF-beta1 immobilization should have a great potential in cartilage tissue engineering in the future.     

The influence of scaffold material on chondrocytes under inflammatory conditions

Cartilage tissue engineering aims to repair damaged cartilage tissue in arthritic joints. As arthritic joints have significantly higher levels of pro-inflammatory cytokines (such as IL-1β and TNFα that cause cartilage destruction, it is critical to engineer stable cartilage in an inflammatory environment. Biomaterial scaffolds constitute an important component of the microenvironment for chondrocytes in engineered cartilage. However, it remains unclear how the scaffold material influences the response of chondrocytes seeded in these scaffolds under inflammatory stimuli. Here we have compared the responses of articular chondrocytes seeded within three different polymeric scaffolding materials (silk, collagen and polylactic acid (PLA)) to IL-1β and TNFα. These scaffolds have different physical characteristics and yielded significant differences in the expression of genes associated with cartilage matrix production and degradation, cell adhesion and cell death. The silk and collagen scaffolds released pro-inflammatory cytokines faster and had higher uptake water abilities than PLA scaffolds. Correspondingly, chondrocytes cultured in silk and collagen scaffolds maintained higher levels of cartilage matrix than those in PLA, suggesting that these biophysical properties of scaffolds may regulate gene expression and the response to inflammatory stimuli in chondrocytes. Based on this study we conclude that selecting the proper scaffold material will aid in the engineering of more stable cartilage tissues for cartilage repair, and that silk and collagen are better scaffolds in terms of supporting the stability of three-dimensional cartilage under inflammatory conditions.     

Comparison of different chondrocytes for use in tissue engineering of cartilage model structures

This study compares bovine chondrocytes harvested from four different animal locations--nasoseptal, articular, costal, and auricular--for tissue-engineered cartilage modeling. While the work serves as a preliminary investigation for fabricating a human ear model, the results are important to tissue- engineered cartilage in general. Chondrocytes were cultured and examined to determine relative cell proliferation rates, type II collagen and aggrecan gene expression, and extracellular matrix production. Respective chondrocytes were then seeded onto biodegradable poly(L-lactide-epsilon-caprolactone) disc-shaped scaffolds. Cell-copolymer constructs were cultured and subsequently implanted in the subcutaneous space of athymic mice for up to 20 weeks. Neocartilage development in harvested constructs was assessed by molecular and histological means. Cell culture followed over periods of up to 4 weeks showed chondrocyte proliferation from the tissue sources varied, as did levels of type II collagen and aggrecan gene expression. For both genes, highest expression was found for costal chondrocytes, followed by nasoseptal, articular, and auricular cells. Retrieval of 20-week discs from mice revealed changes in construct dimensions with different chondrocytes. Greatest disc diameter was found for scaffolds seeded with auricular chondrocytes, followed by those with costal, nasoseptal, and articular cells. Greatest disc thickness was measured for scaffolds containing costal chondrocytes, followed by those with nasoseptal, auricular, and articular cells. Retrieved copolymer alone was smallest in diameter and thickness. Only auricular scaffolds developed elastic fibers after 20 weeks of implantation. Type II collagen and aggrecan were detected with differing expression levels on quantitative RT-PCR of discs implanted for 20 weeks. These data demonstrate that bovine chondrocytes obtained from different cartilaginous sites in an animal may elicit distinct responses during their respective development of a tissue-engineered neocartilage. Thus, each chondrocyte type establishes or maintains its particular developmental characteristics, and this observation is critical in the design and elaboration of any tissue-engineered cartilage model.     

Characterizations of chondrocyte attachment and proliferation on electrospun biodegradable scaffolds of PLLA and PBSA for use in cartilage tissue engineering

The influence of physical characteristics of electrospun three-dimensional (3D) fibrous scaffolds based on polybutylene succinate-co-adipate (PBSA) and poly l-lactic acid (PLLA) on the culture of primary human chondrocytes (PHCs) in terms of cell attachment, proliferation, and re-differentiation was investigated. Physical characteristics assessed for two polymers electrospun at two different delivery rates (PBSA-3, PBSA-16, PLLA-3, and PLLA-16) including average fiber diameter, average pore diameter, porosity, and contact angle. Results demonstrated that 3D fibrous scaffolds are better for PHCs' attachment than two-dimensional (2D) casting films made of the same polymeric materials. It was also found that 3D fibrous scaffolds are appropriate architecture for the proliferation of PHCs than 2D casting films and dependent upon the polymer used. Histological analysis revealed that a significant amount of PHC was found to be growing only within layers of PLLA fibrous scaffolds. The mitochondrial ribonucleic acid (mRNA) expression of both aggrecan and type II collagen by PHCs cultured in tissue culture polystyrene for 28 days decreased significantly. The mRNA expression of both aggrecan and type II collagen by PHCs cultured in PBSA scaffolds increased from 14 to 28 days, whereas only mRNA expression of aggrecan cultured in both PLLA scaffolds increased from 14 to 28 days.     

Potential of 3-D tissue constructs engineered from bovine chondrocytes/silk fibroin-chitosan for in vitro cartilage tissue engineering

The use of cell-scaffold constructs is a promising tissue engineering approach to repair cartilage defects and to study cartilaginous tissue formation. In this study, silk fibroin/chitosan blended scaffolds were fabricated and studied for cartilage tissue engineering. Silk fibroin served as a substrate for cell adhesion and proliferation while chitosan has a structure similar to that of glycosaminoglycans, and shows promise for cartilage repair. We compared the formation of cartilaginous tissue in silk fibroin/chitosan blended scaffolds seeded with bovine chondrocytes and cultured in vitro for 2 weeks. The constructs were analyzed for cell viability, histology, extracellular matrix components glycosaminoglycan and collagen types I and II, and biomechanical properties. Silk fibroin/chitosan scaffolds supported cell attachment and growth, and chondrogenic phenotype as indicated by Alcian Blue histochemistry and relative expression of type II versus type I collagen. Glycosaminoglycan and collagen accumulated in all the scaffolds and was highest in the silk fibroin/chitosan (1:1) blended scaffolds. Static and dynamic stiffness at high frequencies was higher in cell-seeded constructs than non-seeded controls. The results suggest that silk/chitosan scaffolds may be a useful alternative to synthetic cell scaffolds for cartilage tissue engineering.     

Engineering bone-like tissue in vitro using human bone marrow stem cells and silk scaffolds

Porous biodegradable silk scaffolds and human bone marrow derived mesenchymal stem cells (hMSCs) were used to engineer bone-like tissue in vitro. Two different scaffolds with the same microstructure were studied: collagen (to assess the effects of fast degradation) and silk with covalently bound RGD sequences (to assess the effects of enhanced cell attachment and slow degradation). The hMSCs were isolated, expanded in culture, characterized with respect to the expression of surface markers and ability for chondrogenic and osteogenic differentiation, seeded on scaffolds, and cultured for up to 4 weeks. Histological analysis and microcomputer tomography showed the development of up to 1.2-mm-long interconnected and organized bonelike trabeculae with cuboid cells on the silk-RGD scaffolds, features still present but to a lesser extent on silk scaffolds and absent on the collagen scaffolds. The X-ray diffraction pattern of the deposited bone corresponded to hydroxyapatite present in the native bone. Biochemical analysis showed increased mineralization on silk-RGD scaffolds compared with either silk or collagen scaffolds after 4 weeks. Expression of bone sialoprotein, osteopontin, and bone morphogenetic protein 2 was significantly higher for hMSCs cultured in osteogenic than control medium both after 2 and 4 weeks in culture. The results suggest that RGD-silk scaffolds are particularly suitable for autologous bone tissue engineering, presumably because of their stable macroporous structure, tailorable mechanical properties matching those of native bone, and slow degradation.     

Chondrocyte aggregation and reorganization into three-dimensional scaffolds.

Articular cartilage has a very limited self-repairing capacity; thus, chondral lesions normally result in chronic degeneration and, eventually, osteoarthritis development. Currently, tissue engineering offers a new tool for the clinical treatment of osteochondral defects. The present investigation aimed to develop an in vitro engineered cartilage using a new class of semisynthetic scaffolds. Two nonwoven meshes of hyaluronan esters (Hyaff(R) derivatives) were seeded with sternal chick embryo chondrocytes cultured for up to 21 days, after which time they were assessed for both the cellular growth profile and histological features. Avian chondrocytes easily adhered and proliferated onto hyaluronan-based scaffolds, demonstrating a significant preference for the fully esterified benzylic form. Histochemical staining revealed the presence of a neosynthesized glycosaminoglycan-rich extracellular matrix, and immunohistochemistry confirmed the deposition of collagen type II. Moreover, ultrastructural observations supported evidence that chondrocytes grown onto a hyaluronan-derived three-dimensional scaffold maintained their unique phenotype and organization in a cartilage-like extracellular matrix. These findings support the further pursuit of a transplantable engineered cartilage using human chondrocytes for the regeneration of chondral lesions.     

Localization of type VI collagen in tissue-engineered cartilage on polymer scaffolds

Together, the chondrocyte and its pericellular matrix have been collectively termed the chondron. Current opinion is that the pericellular matrix has both protective and signalling functions between chondrocyte and extracellular matrix. Formation of a native chondrocyte pericellular matrix or chondron structure might therefore be advantageous when tissue engineering a functional hyaline cartilage construct. The presence of chondrons has not been previously described in cartilage engineered on a scaffold. In this paper, we describe a modified immunochemical method to detect collagen VI, a key molecular marker for the pericellular matrix, and an investigation of type VI collagen distribution in engineered hyaline cartilage constructs. Cartilage constructs were engineered from adult human or bovine hyaline chondrocytes cultured on sponge or nonwoven fiber based HYAFF 11 scaffolds. Type VI collagen was detected in all constructs, but a distinctive, high-density, chondron-like distribution of collagen VI was present only in constructs exhibiting additional features of hyaline cartilage engineered using nonwoven HYAFF 11. Chondron structures were localized in areas of the extracellular matrix displaying strong collagen II and GAG staining of constructs where type II collagen composed a high percentage (over 65%) of the total collagen.     

Comparative phenotypic analysis of articular chondrocytes cultured within type I or type II collagen scaffolds

Among the existing repair strategies for cartilage injury, tissue engineering approach using biomaterials and chondrocytes offers hope for treatments. In this context, collagen-based biomaterials are good candidates as scaffolds for chondrocytes in cell transplantation procedures. These scaffolds are provided under different forms (gel or crosslinked sponge) made with either type I collagen or type I or type II atelocollagen molecules. The present study was undertaken to investigate how bovine articular chondrocytes sense and respond to differences in the structure and organization of these collagen scaffolds, over a 12-day culture period. When chondrocytes were seeded in the collagen scaffolds maintained in free-floating conditions, cells contracted gels to 40-60% and sponges to 15% of their original diameter. Real-time polymerase chain reaction analysis indicated that the chondrocyte phenotype, assessed notably by the ratio of COL2A1/COL1A2 mRNA and alpha10/alpha11 integrin subunit mRNA, was comparatively better sustained in type I collagen sponges when seeded at high cell density, also in type I atelocollagen gels. Besides, proteoglycan accumulation in the different scaffolds, as assessed by measuring the sulfated glycosaminoglycan content, was found be highest in type I collagen sponges seeded at high cell density. In addition, gene expression of matrix metalloproteinase-13 increased dramatically (up to 90-fold) in chondrocytes cultured in the different gels, whereas it remained stable in the sponges. Our data taken together reveal that type I collagen sponges seeded at high cell density represent a suitable material for tissue engineering of cartilage.     

A new biodegradable polyester elastomer for cartilage tissue engineering

The objective of this study is to assess whether a new biodegradable elastomer, poly(1,8-octanediol citrate) (POC), would be a suitable material to engineer elastomeric scaffolds for cartilage tissue engineering. Porous POC scaffolds were prepared via the salt-leaching method and initially assessed for their ability to rapidly recover from compressive deformation (% recovery ratio). Controls consisted of scaffolds made from other materials commonly used in cartilage tissue engineering, including 2% agarose, 4% alginate, non woven poly(glycolic acid) (PGA) meshes, and non woven poly(L-lactide-co-glycolide) (PLGA) meshes. Articular chondrocytes from bovine knee were isolated and seeded onto porous disk-shaped POC scaffolds, which were subsequently cultured in vitro for up to 28 days. POC scaffolds completely recover from compressive deformation, and the stress-strain curve is typical of an elastomer (recovery ratio>98%). Agarose gel (2%) scaffolds broke during the compression test. The recovery ratio of 4% alginate gel scaffolds, PLLA, and PGA were 72, 85, and 88%, respectively. The Young's modulus of POC-chondrocyte constructs and cell-free POC scaffolds cultured for 28 days were 12.02+/-2.26 kPa and 3.27+/-0.72 kPa, respectively. After 28 days of culture, the recovery ratio of POC-chondrocyte constructs and cell-free POC scaffolds were 93% and 99%, respectively. The glycosaminoglycan (GAG) and collagen content at day 28 was 36% and 26% of that found in bovine knee cartilage explants. Histology/immunohistochemistry evaluations confirm that chondrocytes were able to attach to the pore walls within the scaffold, maintain cell phenotype, and form a cartilaginous tissue during the 28 days of culture.     

Proliferation of chondrocytes on porous poly(DL-lactide)/chitosan scaffolds

Porous poly(DL-lactide)(PDLLA)/chitosan scaffolds with well-controlled pore structures and desirable mechanical characteristics were fabricated via a combination of solvent extraction, phase separation and freeze-drying. These scaffolds were further evaluated for the proliferation of isolated rabbit chondrocytes in vitro for various incubation periods up to 4 weeks in order to finally use them for the cartilage tissue engineering. MTT assay data revealed that the number of cells grown on PDLLA/chitosan scaffolds measurably increased with the weight ratio of the chitosan component and was significantly higher than those collected from pure PDLLA scaffolds for the entire incubation period. Scanning electron microscopy examinations, histological observations and proteoglycan measurements indicated that the resulting PDLLA/chitosan scaffolds exhibited increasing ability to promote the attachment and proliferation of chondrocytes, and also helped seeded chondrocytes spread through the scaffolds and distribute homogeneously inside compared to pure PDLLA scaffolds. Immunohistochemical staining verified that these PDLLA/chitosan scaffolds could preserve the phenotype of chondrocyte and effectively support the production of type II collagen.     

Chitosan/polyester-based scaffolds for cartilage tissue engineering: Assessment of extracellular matrix formation

Naturally derived polymers have been extensively used in scaffold production for cartilage tissue engineering. The present work aims to evaluate and characterize extracellular matrix (ECM) formation in two types of chitosan-based scaffolds, using bovine articular chondrocytes (BACs). The influence of these scaffolds’ porosity, as well as pore size and geometry, on the formation of cartilagineous tissue was studied. The effect of stirred conditions on ECM formation was also assessed. Chitosan-poly(butylene succinate) (CPBS) scaffolds were produced by compression moulding and salt leaching, using a blend of 50% of each material. Different porosities and pore size structures were obtained. BACs were seeded onto CPBS scaffolds using spinner flasks. Constructs were then transferred to the incubator, where half were cultured under stirred conditions, and the other half under static conditions for 4 weeks. Constructs were characterized by scanning electron microscopy, histology procedures, immunolocalization of collagen type I and collagen type II, and dimethylmethylene blue assay for glycosaminoglycan (GAG) quantification. Both materials showed good affinity for cell attachment. Cells colonized the entire scaffolds and were able to produce ECM. Large pores with random geometry improved proteoglycans and collagen type II production. However, that structure has the opposite effect on GAG production. Stirred culture conditions indicate enhancement of GAG production in both types of scaffold.     

A porous PCL scaffold promotes the human chondrocytes redifferentiation and hyaline-specific extracellular matrix protein synthesis

The redifferentiation, proliferation, and hyaline-specific extracellular matrix (ECM) protein synthesis of chondrocytes cultured in a polycaprolactone (PCL) scaffold were analyzed. Gene expression of the type II collagen and aggrecan was assessed by real-time PCR in cells from PCL scaffolds, monolayer, and pellet cultures. The proliferative activity was assessed using Ki-67 immunodetection, and the chondrocytic differentiation was evaluated using S-100 immunodetection. The synthesis and deposition into scaffold pores of type II collagen and glycosaminoglycan were analyzed by immunohistochemistry and Alcian blue staining, respectively. All parameters were assessed throughout 28 days of cultures maintained in either fetal bovine serum-containing medium (FCM) or Insulin-Transferrin-Selenium-containing medium (ICM). Expression of the type II collagen gene was lower in FCM cultures than in ICM cultures for all culture systems (p < 0.05). Moreover, PCL scaffolds cultured in ICM were able to induce collagen gene expression more efficiently than pellet and monolayer cultures. Aggrecan gene expression did not vary significantly between mediums and three-dimensional system cultures, but in ICM cultures, the monolayer cultures had significantly higher levels of aggrecan gene expression than did either the PCL or pellet cultures. Chondrocytes cultured in PCL scaffolds or pellets with FCM did not proliferate to a great extent but did maintain their differentiated phenotype for 28 days. Levels of cartilage ECM protein synthesis and deposition into the scaffold pores were similar among PCL and pellet cultures grown in FCM and in ICM. In conclusion, chondrocytes seeded into PCL scaffolds, cultured in ICM, efficiently maintained their differentiated phenotype and were able to synthesize cartilage-specific ECM proteins.     

Mapping critical sites in collagen II for rational design of gene-engineered proteins for cell-supporting materials.

Collagen II is the most abundant protein of cartilage and forms a network of fibrils extended by proteoglycans that enables cartilage to resist pressure. The surface of the collagen fibril serves as a platform for the attachment of collagen IX, growth factors, and cells. In this study we examined the mechanism of the interaction of chondrocytes with recombinant versions of procollagen II, in which one of the four blocks of 234 amino acids that define repeating D periods of the collagen triple helix has been deleted. Analysis of the attachment of chondrocytes to collagen II variants with deleted D periods indicated that the collagen II monomer contains randomly distributed sites critical for cell binding. However, as was shown by spreading and migration assays, the D4 period, which is between residues 703 to 936, contains amino acids critical for cell motility. We also showed that binding, spreading, and migration of chondrocytes through three-dimensional nanofibrillar collagenous matrices are controlled by an interaction of the collagen triple helix with beta1 integrins. The results of this study provide a basis for the rational design of a scaffold containing genetically engineered collagen with a high density of specific sites of interaction.     

Extracellular matrix protein gene expression of bovine chondrocytes cultured on resorbable scaffolds

It has been demonstrated that using cultured chondrocytes that have been seeded onto various biomatrices can enhance the quality of the articular cartilage repair tissue. As tissue-engineering becomes increasingly more complex there is a need to understand how a specific biomaterial may influence gene expression. In this study several commonly used scaffold materials for cartilage tissue engineering were evaluated with respect to their influence on matrix gene expression. Primary cultures of bovine chondrocytes were established in monolayer then seeded onto polylactic acid (PLLA), polyglycolic acid (PGA), collagen matrices. The induction of collagen type I, collagen type II, and aggrecan was observed at various time points on these biomaterials using RT-PCR. The collagen type I gene was upregulated on collagen scaffolds throughout the culture period. PLLA and PGA showed initial induction followed by downregulation. Monolayer culture did not induce collagen I message. Collagen II genes were selectively upregulated after 72 and 96 h post seeding depending the scaffold material. Monolayer culture had strong induction of collagen II. The aggrecan protein was consistently expressed in all scaffold materials cultures and monolayer.     

三维环境下软骨细胞诱导滑膜间充质干细胞向软骨样细胞的分化

BACKGROUND: The co-culture of chondrocytes and synovial mesenchymal stem cells can induce the cartilage differentiation of synovial mesenchymal stem cells in vitro, but the cell differentiation induced by co-culture in vivo is rarely reported. OBJECTIVE: To investigate the chondrogenic differentiation of synovial mesenchymal stem cells co-cultured with chondrocytes on the chitosan/type I collagen composite scaffolds after being transplanted into the subcutaneous layer of Sprague-Dawley rats. METHODS: The synovial mesenchymal stem cells and chondrocytes harvested from the synovial membrane and articular cartilage of Sprague-Dawley rats were obtained by enzyme digestion method and cultured respectively. Passage 3 synovial mesenchymal stem cells and passage 2 chondrocytes, which were divided into four groups: group A (chondrocytes alone), group B (synovial mesenchymal stem cells alone), group C (ratio of synovial mesenchymal stem cells:chondrocytes=1:2) and group D (scaffold material without cells), were cultured on chitosan/type I collagen composite scaffolds and transplanted into the subcutaneous layer of rats followed by morphological observation and immunohistochemical staining at 4 and 8 weeks.   . RESULTS AND CONCLUSION: After 4 and 8 weeks, the discoid-like scaffold was visible. The immunohistochemical staining of type II collagen and the toluidine blue staining of aggrecan were significantly positive in groups A and C. These results show that the co-culture of synovial mesenchymal stem cells and chondrocytes on the scaffold in vivo can form cartilage-like tissues.      

Three-dimensional microenvironments retain chondrocyte phenotypes during proliferation culture

Although autologous chondrocyte implantation has already been in clinical use, chondrocyte dedifferentiation is problematic during proliferation culture. We attempted a three-dimensional (3D) collagen gel culture under chondrocyte proliferation with repeated passaging to prevent the chondrocytes dedifferentiation. Human auricular chondrocytes were cultured in 3D or conventional monolayer conditions, which reached a 1000-fold increase in cell numbers at passages 3 and 4, respectively. During multiplication, the chondrocytes in 3D culture showed greater suppression of collagen type I (COL1) and preservation of collagen type II (COL2) than those in monolayer. Tissue-engineered cartilage made of 3D cells also abundantly accumulated COL2 or proteoglycan and possessed favorable mechanical properties. The advantage of 3D cells may result from the similarity of microenvironments in cell-to-matrix adhesion or cell-to-cell contacts with that of native cartilage. The up-regulation of integrins and down-regulation of cadherins in the 3D cells mimicked the expression pattern of native cartilage, rather than that of monolayer cells. The silencing of integrin beta1 and Ob-cadherin expression by small interfering ribonucleic acid in the cultured chondrocytes led to the promotion of dedifferentiation and redifferentiation, respectively, indicating that the 3D collagen gel culture provided sufficient cell preparation and reduced chondrocyte dedifferentiation, which is regarded as a feasible strategy in autologous chondrocyte implantation.     

Three-dimensional tissue engineering of hyaline cartilage: comparison of adult nasal and articular chondrocytes

Adult chondrocytes are less chondrogenic than immature cells, yet it is likely that autologous cells from adult patients will be used clinically for cartilage engineering. The aim of this study was to compare the postexpansion chondrogenic potential of adult nasal and articular chondrocytes. Bovine or human chondrocytes were expanded in monolayer culture, seeded onto polyglycolic acid (PGA) scaffolds, and cultured for 40 days. Engineered cartilage constructs were processed for histological and quantitative analysis of the extracellular matrix and mRNA. Some engineered constructs were implanted in athymic mice for up to six additional weeks before analysis. Using adult bovine tissues as a cell source, nasal chondrocytes generated a matrix with significantly higher fractions of collagen type II and glycosaminoglycans as compared with articular chondrocytes. Human adult nasal chondrocytes proliferated approximately four times faster than human articular chondrocytes in monolayer culture, and had a markedly higher chondrogenic capacity, as assessed by the mRNA and protein analysis of in vitro-engineered constructs. Cartilage engineered from human nasal cells survived and grew during 6 weeks of implantation in vivo whereas articular cartilage constructs failed to survive. In conclusion, for adult patients nasal septum chondrocytes are a better cell source than articular chondrocytes for the in vitro engineering of autologous cartilage grafts. It remains to be established whether cartilage engineered from nasal cells can function effectively when implanted at an articular site.