Repair of articular cartilage defects with cultured chondrocytes in Atelocollagen gel

We attempted to repair full-thickness articular cartilage defects in rabbit knee joints with allogeneic cultured chondrocytes embedded in Atelocollagen gel. An articular cartilage defect was created on the patellar groove of the femur. The defect was filled with chondrocytes cultured in the collagen gel and covered with periosteal flap (G group). In three other experimental groups, the same defects were transplanted with chondrocytes in monolayer culture with periosteal flap (M group), periosteal graft only (P group), or left empty (E group). At 4, 12, and 24 weeks after operation, the reparative tissue was analyzed macroscopically and histologically. At 4 weeks after operation, the surfaces of the reparative tissue were smooth, and the defects were filled with reparative tissues that resembled hyaline cartilage in all four groups. However, the reparative tissues degenerated gradually with time in the M, P, and E groups. In contrast, in the G group, the reparative tissue retained its thickness, and there was a steady integration of the grafted tissue into the adjacent normal cartilage at 24 weeks after operation. The results suggest that transplantation of allogeneic chondrocytes cultured in Atelocollagen gel is effective in repairing an articular cartilage defect.     

Restoration of arthritic cartilage defects using autologous chondrocytes transplantation is superior to cartilage-paste graft in rabbits

This study compared the articular cartilage repair potential of cultured chondrocytes transplantation with bone-cartilage paste-graft in the resurfacing of full-thickness defects without breaching of the subchondral bone plate in rabbit knees. A 5 x 5-mm articular cartilage defect was created in the patellar groove of the femur. Three months following creation, the defect was filled with cultured autologous chondrocytes (group 1) or bone-cartilage paste (group 2). A control group of untreated defects was followed for 1 year. The reparative tissue was analyzed macroscopically, histologically, and by immunohistochemistry 3-12 months post-transplantation. The surfaces of the reparative tissue in group 1 were smooth, and the defects were filled with reparative tissue that resembled hyaline cartilage. The composition of the repair tissue more closely resembled cartilage, as demonstrated by cartilage-specific stains. In contrast, the reparative tissue in group 2 was fibrous and exhibited markers of mesenchymal stem cells and bone formation. Transplantation of cultured chondrocytes into a full-thickness defect in the rabbit generates a biologic substitute tissue that resembles native articular cartilage with living cells capable of synthesizing the surrounding cartilage matrix. In contrast, analysis of the healing response to the paste-graft technique failed to show cartilage-like characteristics. This information may be clinically applicable to direct the use of these treatments in chondral injuries.     

Effects of a cultured autologous chondrocyte-seeded type II collagen scaffold on the healing of a chondral defect in a canine model.

Using a previously established canine model for repair of articular cartilage defects, this study evaluated the 15-week healing of chondral defects (i.e., to the tidemark) implanted with an autologous articular chondrocyte-seeded type II collagen scaffold that had been cultured in vitro for four weeks prior to implantation. The amount and composition of the reparative tissue were compared to results from our prior studies using the same animal model in which the following groups were analyzed: defects implanted with autologous chondrocyte-seeded collagen scaffolds that had been cultured in vitro for approximately 12 h prior to implantation, defects implanted with autologous chondrocytes alone, and untreated defects. Chondrocytes, isolated from articular cartilage harvested from the left knee joint of six adult canines, were expanded in number in monolayer for three weeks, seeded into porous type II collagen scaffolds, cultured for an additional four weeks in vitro and then implanted into chondral defects in the trochlear groove of the right knee joints. The percentages of specific tissue types filling the defects were evaluated histomorphometrically and certain mechanical properties of the repair tissue were determined. The reparative tissue filled 88+/-6% (mean+/-SEM; range 70-100%) of the cross-sectional area of the original defect, with hyaline cartilage accounting for 42+/-10% (range 7-67%) of defect area. These values were greater than those reported previously for untreated defects and defects implanted with a type II collagen scaffold seeded with autologous chondrocytes within 12 h prior to implantation. Most striking, was the decreased amount of fibrous tissue filling the defects in the current study, 5+/-5% (range 0-26%) as compared to previous treatments. Despite this improvement, indentation testing of the repair tissue formed in this study revealed that the compressive stiffness of the repair tissue was well below (20-fold lower stiffness) that of native articular cartilage.     

Rabbit articular cartilage defects treated by allogenic chondrocyte transplantation

Articular cartilage defects have a poor capacity for repair. Most of the current treatment options result in the formation of fibro-cartilage, which is functionally inferior to normal hyaline articular cartilage. We studied the effectiveness of allogenic chondrocyte transplantation for focal articular cartilage defects in rabbits. Chondrocytes were cultured in vitro from cartilage harvested from the knee joints of a New Zealand White rabbit. A 3 mm defect was created in the articular cartilage of both knees in other rabbits. The cultured allogenic chondrocytes were transplanted into the defect in the right knees and closed with a periosteal flap, while the defects in the left knees served as controls and were closed with a periosteal flap alone, without chondrocytes. Healing of the defects was assessed at 12 weeks by histological studies. Allogenic chondrocyte transplantation significantly increased the amount of newly formed repair tissue (P=0.04) compared with that found in the control knees. The histological quality score of the repair tissue was significantly better (P=0.05), with more hyaline characteristics in the knees treated with allogenic chondrocytes than in the control knees. Articular cartilage defects treated with allogenic chondrocyte transplantation result in better repair tissue formation with hyaline characteristics than those in control knees.     

培养软骨移植修复关节软骨缺损的实验研究

目的：为探讨一种新的关节软骨缺损修复方法。方法：将体外培养２周形成软骨样组织,移植修复兔关节软骨全层缺损。于移植术后２、４、８周分别行功能评价、大体形态及组织学检查。结果：全部实验兔于术后２周内恢复正常活动。２周时移植修复组织由非成熟透明软骨组成。４周时部分移植组出现成熟透明软骨。８周时移植组关节软骨缺损全部由成熟透明软骨充填修复,修复组织与邻近关节软骨融合。培养软骨移植修复关节软骨全层缺损明显优于自身修复（Ｐ＜００１）。结论：本实验提示使用具有高有丝分裂率的软骨细胞,经离心管培养形成骺软骨样组织,植入关节软骨全层缺损后,软骨细胞生长良好,逐渐成熟和转化,能发挥良好的修复作用。     

Value of autologous chondrocyte transplantation in the reconstruction of experimental cartilage defects. Part I. Extent of defect, macroscopic appearance of reconstructed articular surface and microscopic analysis of predominant tissue]

Articular cartilage defect is one of the main reasons of osteoarthritis. Currently, tissue engineering techniques are the methods concerning better cartilage reconstruction. The aim of this part of the study was macroscopic evaluation of degree of defect feeling, macroscopic appearance of repair tissue and microscopic analysis of predominant tissue after autologous chondrocytes transplantation. Repair of partial thickness cartilage defect on distal part of femur was evaluated (25 adolescent rabbits). Procedures were performed in II groups: I--autologous chondrocytes transplantation under periosteal flap, II--periosteal graft. Chondrocytes were isolated from the cartilage specimens by enzymatic digestion and cultured in vitro. The regenerates were inspected 4, 8 and 12 weeks after the operation. Macroscopic analysis in group I, in most cases revealed filling of the defect with tissue resembling surrounding cartilage. In group II the defect was partially filled, and there was many fissures and cracks in all regenerates. In microscopic analysis in group I, after 4 and 8 weeks following the transplantation the tissue similar to juvenile hyaline cartilage predominated. After 12 weeks it resembled mature hyaline cartilage. In group II, in all cases fibrous cartilage was observed after 4, 8, 12 weeks. Obtained results indicate, that macroscopic and microscopic characteristics of repair tissue after autologous chondrocytes transplantation more closely resembled hyaline cartilage, than in periosteal graft group. 12 weeks after autologous chondrocytes transplantation the repair tissue reached maturity, and demonstrated microscopic characteristics of hyaline-like cartilage. The method of autologous chondrocytes transplantation provides potential for clinical application.     

自体软骨细胞团块植入修复兔陈旧性关节软骨缺损的实验研究

目的 观察自体软骨细胞团块植入对兔关节软骨缺损的修复作用. 方法 24只成年新西兰大白兔48侧膝关节,随机分为三组(n=16)并制备双膝关节股骨滑车软骨缺损模型.空白对照组无特殊处理,骨膜移植组将骨膜覆盖缺损并缝合于缺损两侧的股骨髁上,实验组将自体软骨细胞团块植入缺损中.术后3、6个月分别取材(n=8),进行大体和组织学观察,修复组织行Wakitani评分并进行比较. 结果实验组共成功取材11个缺损关节,9个为透明软骨修复,2个因植入细胞生长状态差未修复;骨膜移植组修复组织为纤维软骨或纤维组织,修复组织薄,基质异染弱;空白对照组仅有少量纤维组织填充缺损底部.修复组织Wakitani评分:实验组3.82分,骨膜移植组6.71分,空白对照组9.23分,差异有统计学意义(F=5.96,P=0.00). 结论自体软骨细胞团块植入能较好修复关节软骨缺损,修复的质量与植入细胞的质量有关.     

组织工程软骨移植修复兔膝关节软骨缺损

研究用组织工程的方法进行差了软骨缺损修复的基本原理。方法取新生兔关节－干骺复后体软骨,胶原酶消化,将所获软骨细胞种入９６孔板内几丁质纤维无纺布上。结果培养２１天时形成“膜状软骨”,至１１０天时形成直径为４．４ｍｍ的“圆盘状软骨”。经Ｓａｆｒａｎ“Ｏ”ｉｖｓ ｑｃ ｙｇｈ ｐｕ 其基质富含蛋白多糖,原位杂交法 产其软骨细胞表达Ⅱ型胶原ｍＲＮＡ。将培养２１天的“膜状软骨”移植于成年兔膝关节圆形全厚缺损     

组织工程技术修复同种异体兔关节软骨缺损实验研究

目的：探讨关节软骨缺损治疗的新途径。方法：把几丁糖作为软骨细胞培养的支架。将几丁糖与软骨细胞一起体外培养,然后移植修复同种异体兔的膝关节软骨缺损,并对关节软骨的修复过程进行术后16周大体、组织学、电镜观察及修复组织厚度测定。结果：几丁糖无纺网在术后2周开始降解吸收,术后10-12周完全吸收;术后第16周在实验侧关节软骨缺损处可见成熟的透明软骨,软骨缺损得到完全修复。结论：几丁糖泊生物学特性符合组织工程中对细胞培养支架的要求;几个糖负载软骨细胞移植修复同种异体兔膝关节软骨缺损,兔膝关节全层软骨缺损得到成功修复。为临床上关节软骨缺损的治疗提供了可能的途径。     

Current concepts in tissue engineering technique for repair of cartilage defect

Hunter's observation in 1743 that cartilage "once destroyed, is not repaired," has not essentially changed for 250 years. At present, there is no well-established procedure for the repair of cartilage defect with articular cartilage, which has the same biochemical and biomechanical properties as the surrounding normal intact cartilage. In 1994, transplantation of human autologous chondrocytes in suspension, as reported by Brittberg et al., provided a potential procedure for articular cartilage repair. We have improved their procedure and developed a new technique which creates new cartilage-like tissue by cultivating autologous chondrocytes embedded in Atelocollagen gel for 3 weeks before transplantation. These improvements maintained the chondrocyte phenotype, evenly distributed chondrocytes throughout the osteochondral defects, and decreased the risk of leakage of grafted chondrocytes into the defects. Good clinical results suggest that this technique should be a promising procedure for repairing articular cartilage defect.     

Xeno-implantation of pig chondrocytes into rabbit to treat localized articular cartilage defects: an animal model

Articular cartilage has only a limited ability to regenerate. The transplantation of autologous chondrocytes is currently used to treat focal defects in human articular cartilage, although use of organs, tissues, or cells from different species is being investigated as an alternative treatment. The object of this study was to use xeno-transplantation of cultured pig chondrocytes for the repair of rabbit chondral defects, and to analyze the significance of tissue rejection in this animal model. Partial chondral defects, including removal of cartilage tissue and a part of the subchondral bone, were created in the lateral femoral condyles of 30 adult New Zealand White rabbits. A periosteal flap was sutured to the native cartilage with the cambium layer facing the defect. As a control, culture medium was injected into the defect void of one group of rabbits while in a treatment group, chondrocytes, isolated from normal femoral pig cartilage, were injected into the defect void. All rabbits were killed by 24 weeks. Macroscopic changes of the cartilage were analyzed using Mankin's score. The distal femoral portion was studied histologically using hematoxylin and eosin, alcian blue, toluidine blue, and Mason's trichrome. Pig cells and pig genetic material were detected in the neo-synthesized tissue by immunohistochemical detection of SLA-II-DQ and polymerase chain reaction analysis of the gene SLA-II-DQB. The synovial membrane was studied histologically by hematoxylin and eosin staining. In the control group, on average, less than 25 percent of the chondral defect was filled. The repair tissue had an irregular surface with few cells similar to chondrocytes or fibroblasts and a minimal formation of extracellular matrix. In the treatment group, the chondral defect was approximately 90 percent filled with good integration between the neo-synthesized cartilage and the native cartilage. The repair tissue had a smooth surface with cells similar to chondrocytes and a hyaline-like extracellular matrix. The neo-synthesized cartilage was morphologically similar to hyaline cartilage. Importantly, there were no signs of graft-vs.-host rejections or infiltration by immune cells. In the neo-synthesized tissue, pig genetic material was detected in 27 +/- 5 percent of all cells. These cells containing pig genetic material were distributed throughout the neo-synthesized cartilage. We conclude that the xeno-transplantation of chondrocytes could be an alternative method for the repair of articular cartilage defects.     

Healing of canine articular cartilage defects treated with microfracture, a type-II collagen matrix, or cultured autologous chondrocytes.

The effects of three different treatments on the healing of articular cartilage defects were compared with use of a previously developed canine model. In the articular surface of the trochlear grooves of 12 adult mongrel dogs, two 4-mm-diameter defects were made to the depth of the tidemark. Four dogs were assigned to each treatment group: (a) microfracture treatment, (b) microfracture with a type-II collagen matrix placed in the defect, and (c) type-II matrix seeded with cultured autologous chondrocytes. After 15 weeks, the defects were studied histologically. Data quantified on histological cross sections included areal or linear percentages of specific tissue types filling the defect, integration of reparative tissue with the calcified and the adjacent cartilage, and integrity of the subchondral plate. Total defect filling (i.e., the percentage of the cross-sectional area of the original defect filled with any type of reparative tissue) averaged 56-86%, with the greatest amount found in the dogs in the microfracture group implanted with a type-II collagen matrix. The profiles of tissue types for the dogs in each treatment group were similar: the tissue filling the defect was predominantly fibrocartilage, with the balance being fibrous tissue. There were no significant differences in the percentages of the various tissue types among dogs in the three groups.     

Allograft of cultured chondrocytes into articular cartilage defects in rabbits--experimental study of the repair of articular cartilage injuries

Articular cartilage defects were created by dill holes, 2 mm wide and 3 mm deep, through the articular cartilage into the subchondral bone in the patellar groove of the femur in mature rabbits. The defects received graft of cultured chondrocytes and the matrix obtained from the primary culture of chondrocytes isolated from the articular cartilage or auricular cartilage in immature rabbits. The isolated cells were cultured for 10 to 14 days. For graft, the cultured chondrocytes together with the matrix were detached from the culture chamber using rubber policemen and centrifuged. The repair of the grafted defects or defects without graft (control) was histologically studied 2 to 12 weeks after operation. The defects without the graft were progressively filled with fibrous tissue containing spindle shaped cells, fibers perpendicular to the surface, and matrix showing weak metachromasia with toluidin blue at 8 weeks. The defects received articular cartilage cell graft were occupied by new cartilage tissue consisting colonylike crumps of chondrocytes 2 weeks after operation. The crumps showed strong metachromasia with toluidin blue and strong stainability for safranin-O. By 4-8 weeks, the defects were filled with homogeneous cartilage. At 12 weeks, arrangement of the chondrocytes of the superficial layer of the new cartilage became columnar as seen in the normal articular cartilage. The defects received elastic cartilage cell graft were filled by reformed cartilage with chondrocytes surrounded by elastic fibers 2-12 weeks after operation. The results indicate that allograft of cultured chondrocytes with matrix into the articular cartilage defects accerated the repair process of the defects by formation of the new cartilage derived from the grafted chondrocytes.     

Human autologous culture expanded bone marrow mesenchymal cell transplantation for repair of cartilage defects in osteoarthritic knees

OBJECTIVE: There is no widely accepted method to repair articular cartilage defects. Bone marrow mesenchymal cells have the potential to differentiate into bone, cartilage, fat and muscle. Bone marrow mesenchymal cell transplantation is easy to use clinically because cells can be easily obtained and can be multiplied without losing their capacity of differentiation. The objective of this study was to apply these cell transplantations to repair human articular cartilage defects in osteoarthritic knee joints. DESIGN: Twenty-four knees of 24 patients with knee osteoarthritis (OA) who underwent a high tibial osteotomy comprised the study group. Adherent cells in bone marrow aspirates were culture expanded, embedded in collagen gel, transplanted into the articular cartilage defect in the medial femoral condyle and covered with autologous periosteum at the time of 12 high tibial osteotomies. The other 12 subjects served as cell-free controls. RESULTS: In the cell-transplanted group, as early as 6.3 weeks after transplantation the defects were covered with white to pink soft tissue, in which metachromasia was partially observed. Forty-two weeks after transplantation, the defects were covered with white soft tissue, in which metachromasia was observed in almost all areas of the sampled tissue and hyaline cartilage-like tissue was partially observed. Although the clinical improvement was not significantly different, the arthroscopic and histological grading score was better in the cell-transplanted group than in the cell-free control group. CONCLUSIONS: This procedure highlights the availability of autologous culture expanded bone marrow mesenchymal cell transplantation for the repair of articular cartilage defects in humans.     

Repair of articular defects by perichondrial grafts. Experiments in the rabbit

A defect was created in the articular cartilage of the rabbit knee leaving the subchondral bone intact. The lesion was repaired by an autologous graft of costal perichondrium and fixed with fibrin glue. The result was compared with a nontreated defect in the contralateral knee. In 26 out of 30 knees, graft fixation proved to be adequate. In the grafted group the perichondrium developed macroscopically and histologically into normal hyaline cartilage. The nongrafted defects showed only limited repair.     

Regenerating hyaline cartilage in articular defects of old chickens using implants of embryonal chick chondrocytes embedded in a new natural delivery substance

Summary Partial and full thickness defects were created mechanically in articular cartilage and subchondral bone of the tibiotarsal joint condyles of 3-year-old chickens. The wounds were then repaired using embryonal chick chondrocytes embedded in a new biocompatible, hyaluronic acid-based delivery substance. Controls were similarly operated on but received either no treatment or implants of the delivery substance only. Animals were killed from 1 week to 6 months postoperatively. Sections from the two groups were examined and compared macroscopically, histologically, and histochemically. Results of 6-month follow-up showed that only the defects of the experimental chickens were completely filled with reparative hyaline cartilage tissue, with no signs of inflammation or immunologic rejection. Initially the entire defect cavity, whether partial thickness or full thickness up to the deep regions in the subchondral bone, was filled with cartilaginous reparative tissue. Relatively rapid maturation occurred under the tidemark; chondrocytes hypertrophied, were invaded with vascular elements and ossified. In the superficial areas, the reparative tissue remained cartilaginous and matured as typical hyaline cartilage tissue. These results indicate that aged chicken cartilage and its accompanying thin and spongy osteoporotic bone offer a favorable host environment for embryonal cell implants.     

Autologous bone marrow stromal cell transplantation for repair of full-thickness articular cartilage defects in human patellae: two case reports

This study assessed the effectiveness of autologous bone marrow stromal cell transplantation for the repair of full-thickness articular cartilage defects in the patellae of a 26-year-old female and a 44-year-old male. These two patients presented in our clinic because their knee pain prevented them from walking normally. After thorough examination, we concluded that the knee pain was due to the injured articular cartilage and decided to repair the defect with bone marrow stromal cell transplantation. Three weeks before transplantation, bone marrow was aspirated from the iliac crest of each patient. After erythrocytes had been removed by use of dextran, the remaining nucleated cells were placed in culture. When the attached cells reached subconfluence, they were passaged to expand in culture. Adherent cells were subsequently collected, embedded in a collagen gel, transplanted into the articular cartilage defect in the patellae, and covered with autologous periosteum. Six months after transplantation, clinical symptoms (pain and walking ability) had improved significantly and the improvement has remained in effect (5 years and 9 months posttransplantation in one case, and 4 years in the other), and both patients have been satisfied with the outcome. As early as 2 months after transplantation, the defects were covered with tissue that showed slight metachromatic staining. Two years after the first and 1 year after the second transplantation, arthroscopy was performed and the defects were repaired with fibrocartilage. Results indicate autologous bone marrow stromal cell transplantation is an effective approach in promoting the repair of articular cartilage defects.     

骨形态形成蛋白复合纤维蛋白载体修复全厚关节软骨缺损的实验研究

目的：用骨形态形成蛋白（BMP）复合纤维蛋白载体修复创伤性全厚关节软骨缺损,方法：60只新西兰家兔,体重2．5－3kg,雌雄不限,随机分为5组,每侧股骨髌髁关节面低速电钻钻一直径为4mm全厚关节软骨缺损,一侧缺损填充BMP／FS,对照侧缺损填充单纯FS,单纯BMP和空白组,膝关节不做固定,允许笼中自由活动,术后2,4,8,12周空气栓塞分批处死动物,大体观,组织学切片HE染色,S－100蛋白免疫组化染色和透射电镜观察实验结果,结果：术后4周,BMP／HF填充的部分关节软骨缺损由类透明软骨修复,术后8周,实验组缺损大部分由类透明软骨修复,而对照组则由纤维软骨或纤维组织修复,术后12周,实验组修复组织主要是透明软骨或类透明软骨,修复面较平整光滑,与周围组织愈合良好,但部分修复软骨面变薄,纤维化。结论：BMP／FS复合物促进了关节软骨的早期修复,并且最终的修复组织更接受正常的关节软骨,但术后12周修复的关节软骨出现退行性改变。     

Healing of defects in canine articular cartilage: Distribution of nonvascular α-smooth muscle actin-containing cells

The objective of this study was to evaluate the types of tissue resulting from spontaneous healing of surgically created defects in adult canine articular cartilage up to 29 weeks postoperatively, with specific attention directed toward the presence and distribution of cells containing the contractile actin isoform, alpha-smooth muscle actin. Two 4-mm diameter defects were made in the trochlear groove to the depth of the tidemark in 20 adult mongrel dogs. The areal percentage of specific tissue types in the reparative material was determined histomorphometrically. Immunohistochemistry was employed to evaluate the percentage of alpha-smooth muscle actin-containing cells. The results showed that approximately 50% of the chondrocytes in the superficial zone of the uninvolved articular cartilage expressed alpha-smooth muscle actin. A significantly lower percentage of alpha-smooth muscle actin-positive chondrocytes appeared in the uninvolved deep zone. Notably, the deep zone adjacent to the defect contained a greater percentage of such cells than in the uninvolved deep zone. Also of interest was that a greater percentage of nonvascular cells in the hyaline cartilage and fibrocartilage of the reparative tissue contained alpha-smooth muscle actin-positive cells, compared to the fibrous tissue in the defects. The findings of this study revealed that canine articular cartilage has some potential for spontaneous regeneration, including integration with the calcified cartilage zone. By 29 weeks, up to 40% of an areal cross section of an untreated full-thickness chondral defect was found to fill with hyaline cartilage, with up to 19% judged histologically similar to articular cartilage. The results warrant further consideration of the role of alpha-smooth muscle actin in chondrocytes in normal articular cartilage and in reparative tissue.     

骨髓基质细胞源性软骨细胞修复兔全层关节软骨缺损

目的观察体外诱导骨髓基质细胞(MSCs)源性软骨细胞在兔股骨滑车关节面全层软骨缺损修复中的作用. 方法高密度传代培养第3代诱导MSCs分化为软骨细胞,以酸溶性Ⅰ型胶原为载体,两者混合后形成凝胶样植入物(细胞浓度为5×106/ml).于36只新西兰大耳白兔一侧股骨滑车关节面造成3 mm×5 mm全层关节软骨缺损,凝胶样植入为实验侧;另一侧分别为单纯胶原植入组(18个膝关节)和空白对照组(18个膝关节).术后4、8、12、24、32和48周取材观察缺损修复情况及新生组织的类型.参照Pineda标准对新生组织评分. 结果实验侧术后4周,植入细胞类似软骨细胞,周围有异染基质,形成透明软骨样组织;8周,深层有软骨下骨形成,软骨细胞层较正常关节软骨厚;12周,新生软骨厚度减小,与正常软骨相近,细胞呈柱状排列,结构与正常关节软骨相似,软骨下骨形成,潮线恢复;24周,新生软骨厚度较正常薄,约占55%,表面平整,潮线附近仍有肥大的软骨细胞;32周,潮线附近无肥大软骨细胞;48周,组织结构与32周时基本相同,为类透明软骨.Pineda评分24、32和48周间无差异,与4周比较有统计学意义(P＜0.05).实验组2～48周期间关节功能良好.单纯胶原组与空白对照组缺损无修复,48周时软骨下骨外露,关节退变;关节功能逐渐减退,动度受限. 结论 MSCs源性软骨细胞移植体内可形成透明样软骨组织,24周后新生软骨特性稳定,48周时为透明样软骨,能维持良好的关节功能.