Chitosan-DNA介导关节基因转移的体外研究

目的探索体外Chitosan对关节软骨细胞、滑膜细胞的转染.方法分离培养兔正常滑膜细胞、软骨细胞,使用荧光质粒pEGFP-C3作为报道基因,制备Chitosan-DNA超微颗粒转染兔正常软骨细胞、滑膜细胞,荧光显微镜观察绿色荧光蛋白的表达.结果Chitosan能将DNA带入胞内,该DNA超微颗粒随时间的延长可缓慢进入胞内,其包被的DNA也可以被缓慢释放,且对软骨细胞的转染能力强.结论Chitosan 在体外可介导关节软骨细胞、滑膜细胞基因转移,为今后关节疾病非病毒基因转移的研究提供实验依据.     

骨形成蛋白家族成员2、7对小鼠胚胎肝干细胞分化的体外研究

目的 探讨骨形成蛋白2、7(BMP2、BMP7)对小鼠胚胎肝干细胞(HP14.5)定向诱导分化为肝细胞样细胞的影响.方法 将表达BMP2、BMP7、肝细胞生长因子(HGF)和绿色荧光蛋白(GFP)的重组腺病毒作为4个组分别感染HP14.5,诱导其分化,在病毒感染后的第1、4、7天通过检测荧光素酶报告基因读数,在第7天通过细胞免疫荧光染色,观察肝细胞标志物白蛋白(ALB)的表达情况;并在第4、7、10天通过PAS染色、尿素氮合成功能检测,观察诱导后HP14.5向肝细胞方向的分化成熟度.结果 BMP2组、HGF组荧光素酶读数较GFP对照组明显上升;免疫荧光染色显示,诱导7d后BMP2组、HGF组细胞质内表达肝细胞特有的ALB,而GFP对照组几乎无表达;糖原染色可见BMP2组、HGF组胞质存在紫红色颗粒,呈阳性反应;尿素合成功能检测显示BMP2组、HGF组培养液中尿素氮随时间而升高.BMP7组诱导后,细胞免疫荧光染色、荧光素酶活性、PAS染色和尿素合成检测均呈阴性或弱阳性反应.结论 BMP2具有一定的诱导HP14.5向成熟肝细胞分化的作用,并初步具备肝细胞的合成分泌功能,而BMP7对其无诱导作用.     

聚乳酸-羟基乙酸／磷酸三钙人工骨的体外构建

目的体外构建兔骨髓间充质干细胞与聚乳酸一羟基乙酸（PLGA）／磷酸三钙（TCP）及PLGA支架材料的复合体,初步评价人工骨构建效果。方法股骨骨穿获得兔骨髓,传代至3～4代,成骨诱导后进行成骨性能检测。同时转染腺病毒介导增强型绿色荧光蛋白（EGFP）后分别与PLGA及PLGA／TCP支架材料复合,采用激光扫描共聚焦显微镜和扫描电子显微镜对细肜支架复合物进行形态学观察。结果与结论种子细胞在两种支架上均可黏附、生长：PLGA／TCP复合支架材料较PLGA更有利于细胞生长,为下一步兔自体骨缺损修复提供了良好的实验基础。     

GFP转基因胎鼠神经干细胞的体外磁标记及MRI

目的 探讨超顺磁性氧化铁颗粒(superparamagnetic iron oxide, SPIO)标记绿色荧光蛋白(green fluorescent protein, GFP)转基因胎鼠神经干细胞(neural stem cells, NSCs)后对其生物学特性的影响及标记后MR成像效果.方法 采用多聚赖氨酸PLL(0.75 μg/ml)介导SPIO(25 μg Fe/ml)的方法标记GFP转基因胎鼠NSCs,用普鲁士蓝染色观察标记后NSCs内铁,比较标记和未标记NSCs的GFP表达、活力、增殖、凋亡及多向分化能力,并对标记的NSCs行MRI.结果 普鲁士蓝染色示标记NSCs胞质内见大量蓝色颗粒.标记与未标记细胞的活力、增殖、凋亡及多向分化能力经单因素方差分析后均显示2组细胞间无统计学差异(P值均＞0.05).MRI示1×105个/0.5 ml细胞管在T2*WI中可见明显低信号改变.结论 用PLL介导SPIO标记GFP转基因胎鼠NSCs是一种可行、安全、有效的细胞内标记方法.1.5T MR仪能够在体外观察到标记后的细胞,以T2*WI序列最为敏感.     

重组腺病毒Ad-mALR和Ad-hALR的构建及其对棕榈酸(PA)诱导的L02细胞凋亡的影响

目的 构建含肝再生增强因子(ALR)基因的重组腺病毒并探讨其抗凋亡功能.方法 采用基因重组法构建重组穿梭载体pAdTrack-TO4-mALR和pAdTrack-TO4-hALR,同源重组法构建重组腺病毒Ad-GFP-mALR和Ad-GFP-hALR,4轮扩增后获得高滴度Ad-GFP-mALR和Ad-GFP-hALR.将上述腺病毒感染L02细胞,通过绿色荧光蛋白(GFP)的表达了解其感染率;Western blotting法检测ALR及Bcl-2/Bax蛋白表达;CCK-8法检测细胞增殖活性;流式细胞仪检测ALR对棕榈酸(PA)诱导的L02细胞凋亡的影响.结果 重组腺病毒Ad-GFP-mALR和Ad-GFP-hALR构建成功,且均能高效感染并稳定表达于L02细胞.与非感染组和感染空载病毒组相比,过表达ALR能促进L02细胞的增殖,并抵抗PA诱导的L02细胞凋亡作用,明显降低Bax,增加Bcl-2蛋白的表达.结论 ALR对寸L02细胞具有促增殖及抗PA诱导的细胞凋亡的作用.     

绿色荧光蛋白在转基因动物研究中的应用

来源于水母(Aequorea Victoria)的绿色荧光蛋白(Green fluorescent protein, GFP),现已成为细胞生物学和分子生物学中应用最广泛的分子标记之一.其内源性荧光基团在受到紫外或蓝光激发时可发现清晰可见的绿光.由于检测方便,对生物体基本没有毒性,在很多领域已有取代LacZ,荧光素酶等传统标记方法的趋势,在制作转基因动物过程中更是如此.本文综述了GFP在标记目的基因、筛选阳性胚胎等方面的应用.     

不同细胞移植修复兔全层关节软骨缺损的比较研究

目的 :比较软骨细胞、骨髓基质细胞及成纤维细胞对全层关节软骨缺损的修复作用。材料和方法 :取幼兔的软骨细胞、骨髓基质细胞及成纤维细胞 ,共 3种有生成软骨潜力的细胞进行体外分离培养 ;以聚乳酸 (PLA)为载体 ,将培养的原代细胞植入PLA支架上 ,形成细胞 -PLA复合物。于 2 8只成年新西兰大白兔的股骨滑车关节面上造成直径 4 5mm、深 3 0mm的全层关节软骨缺损 ,将 3种细胞 -PLA复合物分别植入关节软骨缺损处。植入细胞 -PLA复合物为实验组 ,单纯植入PLA支架为对照组。术后 6周、12周观察缺损修复情况及新生组织类型。结果 :软骨细胞移植组为软骨样组织修复 ,分界明显 ,甲苯胺兰及Ⅱ型胶原染色阳性 ;软骨下骨部分重建 ;细胞排列紊乱。骨髓基质细胞移植组为软骨样组织修复 ,分界不明显 ,甲苯胺兰及Ⅱ型胶原染色阳性 ;软骨下骨重建良好 ,软骨下潮线恢复 ;细胞排列趋于正常。成纤维细胞移植组为纤维组织修复 ,甲苯胺兰及Ⅱ型胶原染色阴性 ;软骨下潮线消失。对照组为纤维组织修复。结论 :软骨细胞、骨髓基质细胞移植修复软骨缺损明显优于成纤维细胞及对照组。骨髓基质细胞与软骨细胞移植组的修复结果无统计学差异 ,但骨髓基质细胞修复组织的细胞排列有序 ,软骨下骨重建良好 ,与周围组织融合密切 ,更接近正?     

含绿色荧光蛋白基因的子宫内膜异位症体外模型的建立

目的 由腺病毒介导绿色荧光蛋白基因转染子宫内膜细胞,构建子宫内膜异位症体外模型.方法 取5例正常子宫内膜组织,分离子宫内膜基质细胞和腺上皮细胞,进行形态学观察和免疫荧光鉴定.用携带有绿色荧光蛋白基因的腺病毒转染细胞,比较转染后12、18、36、42h细胞的绿色荧光蛋白表达阳性率和凋亡率的差异.结果 分离培养获得高纯度的子宫内膜腺上皮细胞(90%)和基质细胞(接近100%).两种细胞均表达绿色荧光;与腺上皮细胞比较,基质细胞转染率明显增高(F=8.362,P=0.020),凋亡率明显降低(F=46.119,P<0.001);转染对细胞的凋亡率无明显影响(F=4.208,P=0.057).结论 利用腺病毒介导的绿色荧光蛋白基因载体转染子宫内膜腺上皮细胞和基质细胞,可获得相对稳定的体外荧光子宫内膜异位症模型.     

成肌干细胞在透明质酸凝胶载体中诱导分化为软骨细胞的研究

目的 探讨以透明质酸钠凝胶作为组织工程软骨载体、以成肌干细胞作为种子细胞诱导分化形成软骨细胞的可行性. 方法体外分离培养兔成肌干细胞,采用结蛋白(Desmin)细胞化学染色进行鉴定,并观察兔成肌干细胞在不同浓度透明质酸钠凝胶中的生长状态.在5%透明质酸钠凝胶中以骨形态发生蛋白2(BMP-2)诱导兔成肌干细胞,倒置相差显微镜观察细胞生长情况,并通过甲苯胺蓝染色、免疫细胞化学及RT-PCR技术对诱导后的细胞进行鉴定. 结果原代培养兔成肌干细胞Desmin细胞化学染色呈阳性表达,且在不同浓度透明质酸钠凝胶中均生长良好.BMP-2诱导培养1d后,成肌干细胞即开始于透明质酸钠凝胶中伸展生长,诱导培养10d后,细胞形态由梭形向多边多角形转化,甲苯胺蓝染色阳性,Ⅱ型胶原免疫荧光检测阳性,RT-PCR检测Ⅱ型胶原和聚焦蛋白聚糖mRNA呈阳性表达. 结论兔成肌干细胞可在适当浓度BMP-2诱导下分化为软骨样细胞,透明质酸钠凝胶可作为软骨组织工程的良好载体.     

地塞米松预培养兔BMSCs促进腺病毒介导BMP2转基因的高效表达

目前，骨形态发生蛋白2（BMP2）的基因治疗在骨组织工程中正成为广泛研究的热点。国外最新研究表明，以腺病毒为载体转染骨髓间充质干细胞（BMSCs）表达BMP2的效率取决于细胞的分化状态，1μmol／L地塞米松诱导培养人BMSCs后再进行腺病毒转染，其BMP2的表达量是单纯转染组的20倍。在此基础上，笔者首次利用同时表达绿色荧光蛋白（GFP）和BMP2的AdCMV—hBMP2-IRES—GFP-1转染兔BMSCs，通过流式细胞仪等方法，     

Real-time in vivo monitoring of viable stem cells implanted on biocompatible scaffolds

Purpose  Three-dimensional fibrous scaffolds provide an environment that enhances transplanted stem cell survival in vivo and facilitates imaging their localization, viability, and growth in vivo. To assess transplanted stem cell viability on biocompatible polymer scaffolds in vivo, we developed in vivo imaging systems for evaluation of implanted viable neural stem cells (NSC) and mesenchymal stem cells (MSC) on scaffolds using luciferase or sodium/iodide symporter (NIS) genes. Methods  Firefly luciferase stably expressing-C6 cell was established (C6-Fluc). The human neural stem cell, F3, was infected with adenoviral vector carrying luciferase gene (F3-Fluc) and MSC expressing NIS controlled by ubiquitin C promoter using lentiviral vector was established by treating blasticidine for 2 weeks (MSC-NIS). Chitosan and poly l-lactic acid (PLLA) scaffolds were used for in vivo image. In vivo expression of luciferase and human NIS was examined by bioluminescence image or ^99mTc-pertechnetate gamma camera image, respectively. The cell/scaffold complex was implanted into subcutaneous or abdominal area of BALB/C nude mouse. For quantitative evaluation of cell viability, regions of interest were drawn on ^99mTc-pertechnetate scintigraphy by manual. Results  The gradual increase of luciferase activity was observed in C6-Fluc seeded with chitosan according to the increase in the number of cells. C6-Fluc/chitosan complex subcutaneously implanted into nude mice showed longitudinal bioluminescence image until 34 days. Luciferase image of abdominal-injected C6-Fluc/PLLA complex was saturated in only 14 days, showing great cell growth due to abundant nutrients. F3 cells showed well-incorporated pattern with fibrous chitosan scaffold using scanning electron microscopy. F3 infected with Ad-Fluc showed >100-fold higher luciferase activity than luciferase activity in F3. Cell-number-dependent increase of luciferase activity was shown in F3-Fluc seeded on chitosan. F3-Fluc incorporation into chitosan after abdominal injection was clearly visible on bioluminescence image up to 11 days. Radionuclide imaging showed higher uptake by MSC-NIS on PLLA scaffolds than by MSC-NIS not seeded on a scaffold. Quantitative data showed significantly better survival of MSC-NIS on PLLA scaffolds than without scaffold at 72 h post-implantation, which concurred with histologic findings. Conclusion  These results suggest that NSC-Fluc and MSC-NIS cells incorporated within polymer scaffolds can be monitored on a long-term basis by serial in vivo imaging. We believe that a biocompatible scaffold-based imaging system could be used to assess stem cell viabilities in a non-invasive way to aid the development of regenerative therapeutics. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users. Soonhag Kim and Dong Soo Lee contributed equally to this investigation as corresponding authors and Do Won Hwang and Sung June Jang equally contributed as co-first author.     

A novel nano-structured porous polycaprolactone scaffold improves hyaline cartilage repair in a rabbit model compared to a collagen type I/III scaffold: in vitro and in vivo studies

Purpose

To develop a nano-structured porous polycaprolactone (NSP-PCL) scaffold and compare the articular cartilage repair potential with that of a commercially available collagen type I/III (Chondro-Gide^®) scaffold.

Methods

By combining rapid prototyping and thermally induced phase separation, the NSP-PCL scaffold was produced for matrix-assisted autologous chondrocyte implantation. Lyophilizing a water–dioxane–PCL solution created micro and nano-pores. In vitro: The scaffolds were seeded with rabbit chondrocytes and cultured in hypoxia for 6 days. qRT–PCR was performed using primers for sox9, aggrecan, collagen type 1 and 2. In vivo: 15 New Zealand White Rabbits received bilateral osteochondral defects in the femoral intercondylar grooves. Autologous chondrocytes were harvested 4 weeks prior to surgery. There were 3 treatment groups: (1) NSP-PCL scaffold without cells. (2) The Chondro-Gide^® scaffold with autologous chondrocytes and (3) NSP-PCL scaffold with autologous chondrocytes. Observation period was 13 weeks. Histological evaluation was made using the O’Driscoll score.

Results

In vitro: The expressions of sox9 and aggrecan were higher in the NSP-PCL scaffold, while expression of collagen 1 was lower compared to the Chondro-Gide^® scaffold. In vivo: Both NSP-PCL scaffolds with and without cells scored significantly higher than the Chondro-Gide^® scaffold when looking at the structural integrity and the surface regularity of the repair tissue. No differences were found between the NSP-PCL scaffold with and without cells.

Conclusion

The NSP-PCL scaffold demonstrated higher in vitro expression of chondrogenic markers and had higher in vivo histological scores compared to the Chondro-Gide^® scaffold. The improved chondrocytic differentiation can potentially produce more hyaline cartilage during clinical cartilage repair. It appears to be a suitable cell-free implant for hyaline cartilage repair and could provide a less costly and more effective treatment option than the Chondro-Gide^® scaffold with cells.     

Chondrogenesis in a hyaluronic acid scaffold: comparison between chondrocytes and MSC from bone marrow and adipose tissue

Treatment of focal lesions of the articular cartilage of the knee using chondrocytes in a hyaluronic acid (HA) scaffold is already being investigated in clinical trials. An alternative may be to use mesenchymal stem cells (MSC). We have compared articular chondrocytes with MSC from human bone marrow (BM) and adipose tissue (AT), all cultured in HA scaffolds, for their ability to express genes and synthesize proteins associated with chondrogenesis. The cells were expanded in monolayer cultures. After seeding into the scaffold, the chondrocytes were maintained in medium, while the two MSC populations were given a chondrogenic differentiation medium. Chondrogenesis was assessed by real-time RT-PCR for chondrocyte-associated genes, by immunohistochemistry and by ELISA for collagens in the supernatant. Redifferentiation of the dedifferentiated chondrocytes in the HA scaffold was shown by a modest increase in type II collagen mRNA (COL2A1) and reduction in COL1A1. BM-MSC expressed 600-fold higher levels of COL2A1 than chondrocytes after 3 weeks in the scaffold. The levels of aggrecan (AGC1) and COL1A1 were similar for chondrocyte and BM-MSC scaffold cultures, while COL10A1 was higher in the BM-MSC. AT-MSC expressed levels of COL2A1 and COL1A1 similar to chondrocytes, but less AGC1 and COL10A1. Surprisingly, little collagen II protein was observed in the scaffold. Instead, collagen II was found in the culture medium. Chondrogenesis in HA scaffolds was more efficient using BM-MSC than AT-MSC or chondrocytes. Some of the secreted collagen II escaped entrapment in the extracellular space and was detected in the culture medium.     

应用自体血清培养大鼠关节软骨细胞生物学行为研究

目的:比较自体血清与胎牛血清体外培养大鼠关节软骨细胞生物学行为的差异。方法:分离培养雄性8周Sprague-Dawley(SD)大鼠软骨细胞,分别在5%、10%自体血清和10%胎牛血清中进行单层传代培养,采用光镜观察细胞形态变化,绘制生长曲线评估细胞增殖速度,通过甲苯胺蓝染色,Ⅰ、Ⅱ型胶原免疫组织化学染色以及流式细胞仪分析细胞CD26、CD44及Ⅰ、Ⅱ型胶原表达以检测软骨细胞生物学行为的变化。结果:(1)在培养3代内,原代培养的软骨细胞形态呈多角形,而3代培养的细胞都为梭形,三组无明显差别;(2)5%自体血清培养的细胞的生长速度与10%胎牛血清培养的细胞接近,10%自体血清培养的软骨细胞的生长速度快于前两组;(3)甲苯胺蓝染色结果证明三组细胞均随传代数增加酸性粘多糖蛋白分泌量下降,且10%胎牛血清组比10%和5%自体血清培养组下降更明显,而10%与5%自体血清培养组之间无明显差异;(4)免疫组化染色和流式细胞仪检测结果表明10%与5%自体血清培养的软骨细胞Ⅱ型胶原表达高于10%胎牛血清培养的细胞(P<0.05),10%与5%自体血清组无显著性差异(P>0.05);随体外培养时间延长,三组细胞合成的Ⅱ型胶原均逐渐减少,Ⅰ型胶原表达逐渐增多。(5)流式细胞仪观察显示三组CD26表达虽有增加但无显著性差异,CD44表达均随传代数增加而逐渐增加,且在1、3代细胞之间具有显著性差异(P<0.05)。在3种培养条件下,相同代数的软骨细胞CD26和CD44表达无显著性差异。结论:本研究发现10%自体血清培养大鼠软骨细胞生长速度快,且仍可以较好保持细胞表型,推测在可能条件下使用浓度较高的自体血清可以缩短体外培养时间而达到较多细胞保持表型的目的。     

bBMP对体外培养人胎儿关节软骨细胞分化的促进作用

为了解运动创伤中肌肉、肌腱、关节囊中异位化骨的机制及软骨细胞在此过程中所起的作用，本研究用牛骨形态发生蛋白（ｂＢＭＰ）诱导体外不传代培养的胎儿关节软骨细胞，发现：在ｂＢＭＰ的诱导下，不传代培养的软骨细胞逐渐变为成骨细胞样形态，它们表达的碱性磷酸酶明显增加，细胞周围的钙沉积和基质沉积也明显增加。在ｂＢＭＰ的诱导下，关节软骨细胞开始表达具有成骨细胞特异性和骨基质特异性的骨钙素。这些结果表明，在ｂＢＭＰ的诱导下，胎儿关节软骨细胞已开始表达成骨细胞表型，并向成骨细胞样细胞方向分化。本研究提示，在异位化骨和各种软骨内化骨过程中，软骨细胞可能具有较活跃的参与骨形成的作用，可能不像以前所假设的那样仅分化为肥大软骨细胞，然后变性，最终坏死。     

Anatomy, biochemistry, and physiology of articular cartilage

Articular cartilage serves as a load-bearing elastic material that is responsible for the frictionless movement of the surfaces of articulating joints. Its ability to undergo reversible deformation depends on its structural organization, including the specific arrangement of the matrix macromolecules and the chondrocytes. Interactions between the matrix and chondrocytes are responsible for the biological and mechanical properties of articular cartilage and enable it to respond by effecting a balance between anabolism and catabolism as well as continual internal remodeling. Age-related changes in the function of chondrocytes may contribute to the initiation and progression of osteoarthritis.     

The effect of microRNA-21 on proliferation and matrix synthesis of chondrocytes embedded in atelocollagen gel

The objective of this study was to investigate the effect of microRNA-21 (miR-21) on the proliferation and matrix synthesis of chondrocytes embedded in atelocollagen gel. Articular cartilage was harvested aseptically from the knee and hip joints of rats. In the experimental group, double-stranded miR-21 was transfected into the chondrocytes, and in the control group, scrambled siRNA was used. After that, chondrocytes were cultured in atelocollagen gel for 3 weeks. At 1, 2, and 3 weeks after transfection, the cell numbers were counted, and the expression levels of Col2a1 and aggrecan were measured by real-time PCR. Histological analysis by toluidine blue staining was performed at 3 weeks. The cell number in the experimental group rapidly increased compared to the control group. The expression levels of Col2a1 and aggrecan in the experimental group were higher than in the control. Histological analysis revealed that many more cells with a metachromatic stain were present in the experimental group than in the control. This study demonstrated that miR-21 promotes high proliferation and matrix synthesis of chondrocytes embedded in atelocollagen gel.     

半月板纤维软骨细胞与壳聚糖/聚磷酸钙体外复合培养的实验研究

目的:观察半月板纤维软骨细胞在不同配比壳聚糖/聚磷酸钙(chitosan/calciumpolyphosphate,CS/CPP)支架材料上的生长状况,优选最佳配比CS/CPP生物材料作为组织工程半月板支架材料。方法:采用机械分离与酶连续消化相结合的方法体外分离兔半月板纤维软骨细胞,单层培养传代至第3代,并对其进行表型鉴定。采用共混-化学交联固化-冷冻干燥法将CS、醛基化海藻酸钠(aldehyde alginate,ADA)、CPP有机地结合起来,制备4种不同配比的新型组织工程半月板复合支架材料。将体外分离培养的第3代半月板细胞,通过二次沉淀接种法将其种植于不同配比的CS/CPP支架上,体外培养7天,采用相差倒置显微镜、SEM、HE染色观察细胞在支架上的形态、黏附、生长情况。结果:体外分离培养的第3代半月板细胞基本维持纤维软骨细胞的表型。相差倒置显微镜下可见,细胞在支架上黏附良好;扫描电镜下可见,细胞在支架上均匀分布,细胞多数呈多角形,并有基质分泌;HE染色结果显示,有细胞长入到三维支架材料内部。其中,半月板细胞在3:7的CS/CPP支架材料上单位面积内数目最多,生长最旺盛,细胞外基质分泌最多。结论:三维多孔的CS/CPP复合材料能促进半月板纤维软骨细胞的黏附、生长和增殖,其中3:7的CS/CPP支架材料细胞相容性和生物活性最好,最适于半月板纤维软骨细胞粘附和生长,并且能促进半月板细胞增殖和维持其表型,有望成为组织工程半月板良好的支架载体。     

Osteochondritis dissecans (OCD), an endoplasmic reticulum storage disease?: a morphological and molecular study of OCD fragments

Osteochondritis dissecans (OCD) fragments, cartilage and blood from four patients were used for morphological and molecular analysis. Controls included articular cartilage and blood samples from healthy individuals. Light microscopy and transmission electron microscopy (TEM) showed abnormalities in chondrocytes and extracellular matrix of cartilage from OCD patients. Abnormal type II collagen heterofibrils in “bundles” and chondrocytes with abnormal accumulation of matrix proteins in distended rough endoplasmic reticulum were typical findings. Further, Von Kossa staining and TEM showed empty lacunae close to mineralized “islands” in the cartilage and hypertrophic chondrocytes containing accumulated matrix proteins. Immunostaining revealed: (1) that types I, II, VI and X collagens and aggrecans were deposited intracellulary and (2) co‐localization within the islands of types I, II, X collagens and aggrecan indicating that hypertrophic chondrocytes express a phenotype of bone cells during endochondral ossification. Types I, VI and X collagens were also present across the entire dissecates suggesting that chondrocytes were dedifferentiated. DNA sequencings were non‐conclusive, only single nucleotide polymorphism was found within the COL2A1 gene for one patient. We suggest that OCD lesions are caused by an alteration in chondrocyte matrix synthesis causing an endoplasmic reticulum storage disease phenotype, which disturbs or abrupts endochondral ossification.