软骨细胞上清液诱导滑膜间充质干细胞微团培养成软骨

背景：滑膜间充质干细胞在体外具有多向分化的能力,有望成为软骨组织工程中治疗软骨缺损的种子细胞,在其向软骨细胞分化过程中,合适的生长因子起了重要作用。 目的：利用富含生长因子的软骨细胞上清液诱导滑膜间充质干细胞向软骨细胞分化,并对其鉴定。 方法：采用消化法分别获得SD大鼠滑膜间充质干细胞、软骨细胞。收集软骨细胞上清液离心、过滤冻存备用。培养滑膜间充质干细胞至第3代后离心成微团,并用软骨细胞上清液进行成软骨诱导分化,通过形态学观察、免疫组织化学法、RT-PCR检测进行鉴定。 结果与结论：滑膜间充质干细胞使用软骨细胞上清液成软骨诱导21 d后,微团可见似软骨样组织。免疫组化法进行Ⅱ型胶原鉴定,基质能被Ⅱ型胶原染色,细胞染色呈现棕黄色。RT-PCR结果显示诱导后的微团表达软骨特异性基因Ⅱ型胶原和蛋白聚糖。证实软骨细胞分泌的可溶性因子可以诱导大鼠滑膜间充质干细胞向软骨方向分化。中国组织工程研究杂志出版内容重点：干细胞;骨髓干细胞;造血干细胞;脂肪干细胞;肿瘤干细胞;胚胎干细胞;脐带脐血干细胞;干细胞诱导;干细胞分化;组织工程全文链接：     

滑膜间充质干细胞与软骨细胞三维条件下混合培养向软骨细胞的分化

背景：软骨细胞通过自分泌及旁分泌的作用可以为滑膜间充质干细胞向软骨细胞分化提供所需的生长因子及微环境,三维条件下更有利于细胞的黏附增殖与分化。目的：观察滑膜间充质干细胞与软骨细胞混合培养于壳聚糖/Ⅰ型胶原复合支架材料中向成软骨细胞分化的能力。方法：取SD大鼠滑膜组织及软骨组织,用酶消化法获得滑膜间充质干细胞及软骨细胞分别进行培养。取第3代滑膜间充质干细胞及第2代软骨细胞,将二者以1∶2的比例混合培养负载于壳聚糖/Ⅰ型胶原复合支架材料21 d,进行激光共聚焦扫描及免疫组织化学检测。结果与结论：培养72 h后,扫描电镜观察细胞黏附于支架材料表面,并可见细胞分泌大量基质成分。培养     21 d后,激光共聚焦扫描可见细胞在支架表面分布均匀,逐层扫描后细胞逐渐减少。免疫组织化学检测可见基质能被Ⅱ型胶原染色,细胞染色呈现棕黄色。结果表明壳聚糖/Ⅰ型胶原复合支架材料提供三维生长空间,利用软骨细胞分泌生长因子及细胞间的相互作用可以诱导滑膜间充质干细胞向软骨细胞分化。中国组织工程研究杂志出版内容重点：生物材料;骨生物材料; 口腔生物材料; 纳米材料; 缓释材料; 材料相容性;组织工程全文链接：     

基底膜基质/壳聚糖诱导骨髓间充质干细胞成软骨分化

背景：课题组前期研究发现基底膜基质能够定向诱导骨髓间充质干细胞向软骨方向分化,但其力学性能与实际应用有较大差距,还需要进一步研究。 目的：制备兼具适宜力学性能和优异生物相容性的壳聚糖/基底膜基质水凝胶支架用于软骨修复。 方法：以京尼平为交联剂,将壳聚糖溶液与基底膜基质按2︰1,1︰1,1︰3比例混合制成水凝胶,接种大鼠骨髓间充质干细胞,培养14 d。经材料力学测试、细胞增殖、活细胞染色、酶联免疫吸附测试以及阿尔新蓝染色等方法评价材料诱导细胞成软骨分化能力。 结果与结论：在基底膜基质内添加壳聚糖后,材料力学性能从0.48 kPa上升到1.78 kPa。标志性蛋白分泌结果显示,纯壳聚糖组早期诱导成软骨活性高于其他组,但后期诱导能力减弱,而含基底膜基质各组在后期能够保持较好的诱导活性,其中壳聚糖/基底膜基质=1︰1组材料具有一定的力学强度,且Ⅱ型胶原和Ⅹ型胶原的表达量在14 d较其他组高。结果表明实验制备的壳聚糖/基底膜基质水凝胶具有良好的力学性能,并能够促进骨髓间充质干细胞向软骨方向分化,可用于软骨组织工程研究。 中国组织工程研究杂志出版内容重点：干细胞;骨髓干细胞;造血干细胞;脂肪干细胞;肿瘤干细胞;胚胎干细胞;脐带脐血干细胞;干细胞诱导;干细胞分化;组织工程全文链接：     

胰岛素样生长因子Ⅰ转染对脂肪干细胞TWEAK/Fn14信号通路的影响

背景：胰岛素样生长因子Ⅰ具有诱导间充质干细胞向软骨细胞分化的能力,通过基因转染的方式将胰岛素生长因子Ⅰ转染入脂肪干细胞或许能够更好的促进脂肪干细胞向软骨细胞分化。 目的：探讨胰岛素样生长因子Ⅰ基因对脂肪间充质干细胞体外定向成软骨分化能力以及对TWEAK/Fn14信号通路的影响。 方法：构建慢病毒载体pLVX-IGF-I-IRES-ZsGreenl基因并转染第3代人脂肪间充质干细胞,诱导细胞向软骨分化。同时将pLVX-IRES-ZsGreenl转染的脂肪间充质干细胞设为绿色荧光蛋白/脂肪间充质干细胞组,单纯脂肪间充质干细胞设为对照组。 结果与结论：与绿色荧光蛋白/脂肪间充质干细胞组和对照组相比,胰岛素样生长因子Ⅰ/脂肪间充质干细胞组细胞中TWEAK mRNA表达水平降低,而胰岛素样生长因子Ⅰ,Col2al和Sox9 mRNA的表达水平增加,Col2a1表达水平增加,基质金属蛋白酶3以及TWEAK的表达降低。提示pLVX-IGF-I-IRES-ZsGreenl慢病毒转染脂肪间充质干细胞后可获得胰岛素样生长因子Ⅰ的高效表达,且能下调细胞TWEAK基因及蛋白表达,可促进体外培养的脂肪间充质干细胞转化为软骨细胞。 中国组织工程研究杂志出版内容重点：干细胞;骨髓干细胞;造血干细胞;脂肪干细胞;肿瘤干细胞;胚胎干细胞;脐带脐血干细胞;干细胞诱导;干细胞分化;组织工程     

外源性透明质酸对兔骨髓间充质干细胞定向分化为软骨细胞的影响

背景：透明质酸是关节腔滑液最主要的成分,对细胞的形态发生起着非常重要的作用,但其用于软骨缺损修复时对骨髓间充质干细胞的影响如何呢？ 目的：通过分析外源性透明质酸对兔骨髓间充质干细胞体外增殖及定向分化为软骨细胞的影响,探讨关节腔内环境对骨髓间充质干细胞的作用。 方法：全骨髓法+贴壁培养法分离培养兔骨髓间充质干细胞,取第4代细胞用于实验,实验组细胞加入透明质酸诱导液,以转化生长因子β3诱导组作为阳性对照,阴性对照组加入常规培养液。分别于诱导后第7,14,21 d行甲苯胺蓝染色检测蛋白聚糖表达,免疫组化染色及RT-PCR检测细胞Ⅱ型胶原表达。 结果与结论：经透明质酸诱导后,细胞增殖速度减慢,由长梭形变为多角形、椭圆形,细胞外基质呈甲苯胺蓝异染性和Ⅱ型胶原免疫组化阳性,RT-PCR检测示Ⅱ型胶原mRNA表达阳性,表现出软骨细胞的分化特点,但表达均比阳性对照组弱。结果提示,外源性透明质酸具有诱导兔骨髓间充质干细胞向软骨细胞分化的能力,但比转化生长因子β3的诱导能力弱,关节腔内环境对骨髓间充质干细胞向软骨细胞分化有正性促进作用,支持透明质酸作为软骨组织工程基质使用。     

人软骨细胞培养上清诱导脐血间充质干细胞向软骨细胞分化

背景：人脐血间充质干细胞作为软骨缺损修复的种子细胞日益受到关注,现有常用诱导方法无论是应用诱导培养基还是诱导因子,因其价格昂贵、用量大等因素限制了实际应用。 目的：验证人软骨细胞培养上清诱导人脐血间充质干细胞向软骨细胞分化的可行性。 方法：利用密度梯度离心法和贴壁培养法分离新生儿脐血,获取并培养人脐血间充质干细胞,流式细胞仪鉴定细胞表面抗原。切取股骨头置换或全髋关节置换患者透明软骨组织,体外分离培养软骨细胞,利用其培养上清培养人脐血间充质干细胞,培养2周后观察细胞表型外观变化,免疫组化染色检测Ⅱ型胶原表达结果。 结果与结论：密度梯度离心法与贴壁培养法可以分离获取人脐血间充质干细胞,流式细胞仪鉴定表面标记CD90,CD105高表达,不表达CD34,CD45。软骨细胞培养上清诱导2周后,人脐血间充质干细胞向多角形、圆形转变,Ⅱ型胶原免疫组化检测表达阳性。提示软骨细胞培养上清可诱导人脐血间充质干细胞表达Ⅱ型胶原,向软骨细胞分化。     

自体激活富血小板血浆干预兔骨髓间充质干细胞体外成软骨分化的研究

背景：自体富血小板血浆激活后可释放多种生长因子,可以促进骨髓间充质干细胞的增殖与分化。 目的：观察自体激活富血小板血浆对体外培养的兔骨髓间充质干细胞向成软骨细胞分化的影响。 方法：取兔股骨骨髓,全骨髓贴壁法分离培养骨髓间充质干细胞;取第3代骨髓间充质干细胞,分别应用体积分数10%自体激活富血小板血浆和体积分数10%胎牛血清培养液进行体外培养,观察其向成软骨细胞分化情况。 结果与结论：分离培养的兔骨髓间充质干细胞呈长梭形,传代后细胞生长迅速。流式细胞仪检测发现第3代细胞高表达CD29、CD44,而低表达CD45。免疫荧光细胞化学染色显示经自体激活富血小板血浆诱导的骨髓间充质干细胞表达Ⅱ型胶原;实时荧光定量PCR检测发现经自体激活富血小板血浆诱导的骨髓间充质干细胞Ⅱ型胶原α1链基因和聚集蛋白聚糖基因表达明显高于经胎牛血清诱导的骨髓间充质干细胞(P < 0.01)。可见自体激活富血小板血浆具有促进兔骨髓间充质干细胞向软骨细胞方向分化的潜能。     

不同方式诱导骨髓间充质干细胞的效果比较

背景：以往大多采用转化生长因子β1诱导骨髓间充质干细胞向软骨细胞分化,但诱导效果不佳。目的：对比分析骨髓间充质干细胞与关节软骨细胞共培养诱导、转化生长因子β1诱导骨髓间充质干细胞分化为软骨样细胞的效果。方法：获取SD大鼠关节软骨细胞和骨髓间充质干细胞,分别设置1∶2,1∶1,2∶1浓度组,以转化生长因子β1 诱导组为对照。经诱导培养20 d后MTT法检测细胞活力,阿利新蓝比色法检测氨基聚糖含量,Western Blot检测Ⅱ型胶原蛋白表达。结果与结论：转化生长因子β1组的吸光度值显著小于软骨细胞和骨髓间充质干细胞1∶1组和软骨细胞和骨髓间充质干细胞2∶1组(P < 0.05)。转化生长因子β1组的氨基聚糖含量和Ⅱ型胶原蛋白表达显著低于软骨细胞和骨髓间充质干细胞(1∶2,1∶1,2∶1)组。软骨细胞和骨髓间充质干细胞1∶1组与软骨细胞和骨髓间充质干细胞2∶1组之间各指标比较差异无显著性意义(P > 0.05)。结果表明关节软骨细胞与骨髓间充质干细胞共培养,可使骨髓间充质干细胞向软骨细胞分化,且骨髓间充质干细胞对软骨细胞诱导存在饱和现象。中国组织工程研究杂志出版内容重点：干细胞;骨髓干细胞;造血干细胞;脂肪干细胞;肿瘤干细胞;胚胎干细胞;脐带脐血干细胞;干细胞诱导;干细胞分化;组织工程     

髓核细胞共培养诱导骨髓间充质干细胞向类髓核细胞分化

背景：骨髓间充质干细胞近年来作为种子细胞被广泛应用于髓核组织工程。在诱导骨髓间充质干细胞向髓核细胞分化的过程中,需要提供适当的细胞外微环境以及生长因子。 目的：研究体外与髓核细胞非接触共培养和生物诱导剂条件下,兔骨髓间充质干细胞向类髓核样软骨细胞分化的可行性。 方法：用单层培养法分别分离培养兔骨髓间充质干细胞和髓核细胞。选用第3代的髓核细胞和骨髓间充质干细胞置于Transwell培养皿上下层构建共培养体系并加入转化生长因子β1为主的生物诱导剂诱导培养21 d,以高糖DMEM培养基单独培养的骨髓间充质干细胞作为阴性对照。 结果与结论：分离培养的兔骨髓间充质干细胞细胞表面CD29和CD44表达阳性,CD34、CD45的细胞表达阴性。与髓核细胞共培养诱导21 d后,可观察到骨髓间充质干细胞形态向多角形类圆形转变,胞质中分泌Ⅱ型胶原颗粒明显增多,RT-PCR结果表明诱导后细胞中Ⅱ型胶原mRNA表达明显增高。结果说明骨髓间充质干细胞在与髓核细胞共培养加生物诱导剂条件下可成功诱导分化为类髓核细胞。     

反转录病毒介导基质金属蛋白酶特异性组织抑制剂1基因转染骨髓间充质干细胞的成骨能力

背景：间充质干细胞成骨分化早期是成骨性细胞外基质细胞外间质的堆积,其主要成分均是基质金属蛋白酶特异性组织抑制剂1(tissue Inhibitor of Metalloproteinases 1,TIMP-1)作用的基质金属蛋白酶作用底物,通过增加TIMP-1的表达,是否可以抑制基质金属蛋白酶的活性,进而影响间充质干细胞的成骨分化能力？ 目的：观察反转录病毒介导TIMP-1基因转染骨髓间充质干细胞的成骨能力。 方法：设计In-Fusion引物扩增TIMP-1基因片段,与酶切后线性化的pBABE-Puro反转录病毒表达载体进行位点同源重组,构建TIMP-1基因反转录病毒表达载体,RT-PCR和测序验证,并使用GP-293细胞进行包装。通过密度梯度法分离人下颌骨来源骨髓间充质干细胞,流式细胞仪验证其表面标记。将TIMP-1反转录病毒包装液感染骨髓间充质干细胞并筛选稳定表达TIMP-1细胞株,RT-PCR和蛋白电泳验证其表达,并使用成骨诱导液诱导10 d,观察其对成骨能力的影响,RT-PCR验证其成骨相关基因的表达。 结果与结论：经测序证实,RT-PCR所获得的TIMP-1基因 cDNA 序列与NM_003254.2(624 bp)序列完全一致;通过表面标记鉴定证实成功分离了人骨髓间充质干细胞,并具良好的成骨、成脂能力;RT-PCR和Western Blot验证反转录病毒载体成功介导TIMP-1转染骨髓间充质干细胞,RT-PCR表明成骨诱导10 d时,TIMP-1基因感染组成骨增加,RUNX-2和COL1 mRNA表达增加。提示TIMP-1基因可通过反转录病毒成功转染人骨髓间充质干细胞,并能促进其成骨。     

滑膜间充质干细胞向透明软骨分化条件的体外研究

目的：研究TGFβ1、BMP-2、bFGF、IGF、BMP-7、ASA、Dex七种因素在滑膜间充质干细胞向透明软骨分化中起的作用。方法：酶消化法、有限稀释法获得滑膜间充质干细胞，并诱导其向脂肪细胞、软骨细胞和骨细胞分化。正交实验中纳入TGFβ1、BMP-2、bFGF、IGF、BMP-7、AsA、Dex七种因素。通过SPSS22.0统计软件设计L8(27)正交实验及表头，定义2水平条件。结果：滑膜间充质干细胞在成骨、成脂、成软骨分化后分别进行油红染色、碱性磷酸酶染色、甲苯胺蓝染色，染色结果均呈现为阳性。正交实验中直观观察、主体间方差分析显示TGFβ1作用最强。结论：滑膜间充质干细胞能够成功诱导向各种组织细胞分化，TGFβ1是七种因素中作用最明显的一种。     

Characterization of human adipose-derived stem cells and expression of chondrogenic genes during induction of cartilage differentiation

OBJECTIVES:

Understanding the changes in chondrogenic gene expression that are involved in the differentiation of human adipose-derived stem cells to chondrogenic cells is important prior to using this approach for cartilage repair. The aims of the study were to characterize human adipose-derived stem cells and to examine chondrogenic gene expression after one, two, and three weeks of induction.

MATERIALS AND METHODS:

Human adipose-derived stem cells at passage 4 were evaluated by flow cytometry to examine the expression of surface markers. These adipose-derived stem cells were tested for adipogenic and osteogenic differentiation capacity. Ribonucleic acid was extracted from the cells for quantitative polymerase chain reaction analysis to determine the expression levels of chondrogenic genes after chondrogenic induction.

RESULTS:

Human adipose-derived stem cells were strongly positive for the mesenchymal markers CD90, CD73, CD44, CD9, and histocompatibility antigen and successfully differentiated into adipogenic and osteogenic lineages. The human adipose-derived stem cells aggregated and formed a dense matrix after chondrogenic induction. The expression of chondrogenic genes (collagen type II, aggrecan core protein, collagen type XI, COMP, and ELASTIN) was significantly higher after the first week of induction. However, a significantly elevated expression of collagen type X was observed after three weeks of chondrogenic induction.

CONCLUSION:

Human adipose-derived stem cells retain stem cell characteristics after expansion in culture to passage 4 and serve as a feasible source of cells for cartilage regeneration. Chondrogenesis in human adipose-derived stem cells was most prominent after one week of chondrogenic induction.     

三维培养诱导人脂肪间充质干细胞微球的成软骨分化能力

背景：关节软骨损伤后修复结果不满意,需要新的手段,而脂肪间充质干细胞较适宜做种子细胞诱导软骨,然而怎么能够使诱导的软骨具有功能需要研究。 目的：采用三维培养体系诱导人脂肪间充质干细胞微球向软骨分化。 方法：无菌切取吸脂术后脂肪组织,分离培养人脂肪间充质干细胞,传至第3代进行流式细胞术分析,成骨成脂肪诱导等鉴定,同时也给予合适的培养条件用三维培养的方式向软骨细胞诱导,并行阿利辛蓝染色鉴定糖胺多糖的合成,苏木精-伊红染色进行组织学分析,免疫荧光检测Ⅱ型胶原表达,称质量测量软骨硬度。 结果与结论：分离的人脂肪间充质干细胞CD105,CD44,CD29均高表达,而 CD45,CD34低表达,并且成骨成脂诱导后细胞茜素红染色和油红O染色均为阳性。三维培养法诱导的软骨细胞可表达大量糖胺多糖及Ⅱ型胶原。结果证实,三维培养法诱导人脂肪间充质细胞向软骨分化后,具有软骨细胞的特性。中国组织工程研究杂志出版内容重点：干细胞;骨髓干细胞;造血干细胞;脂肪干细胞;肿瘤干细胞;胚胎干细胞;脐带脐血干细胞;干细胞诱导;干细胞分化;组织工程全文链接：     

Induction of intervertebral disc-like cells from adult mesenchymal stem cells

The potential of adult mesenchymal stem cells (MSCs) to differentiate towards cartilage, bone, adipose tissue, or muscle is well established. However, the capacity of MSCs to differentiate towards intervertebral disc (IVD)-like cells is unknown. The aim of this study was to compare the molecular phenotype of human IVD cells and articular chondrocytes and to analyze whether mesenchymal stem cells can differentiate towards both cell types after transforming growth factor beta (TGF beta)-mediated induction in vitro. Bone marrow-derived MSCs were differentiated in spheroid culture towards the chondrogenic lineage in the presence of TGF beta(3) dexamethasone, and ascorbate. A customized cDNA-array comprising 45 cartilage-, bone-, and stem cell-relevant genes was used to quantify gene expression profiles. After TGF beta-mediated differentiation, MSC spheroids turned positive for collagen type II protein and expressed a large panel of genes characteristic for chondrocytes, including aggrecan, decorin, fibromodulin, and cartilage oligomeric matrix protein, although at levels closer to IVD tissue than to hyaline articular cartilage. Like IVD tissue, the spheroids were strongly positive for collagen type I and osteopontin. MSC spheroids expressed more differentiation markers at higher levels than culture-expanded IVD cells and chondrocytes, which both dedifferentiated in monolayer culture. In conclusion, mesenchymal stem cells adopted a gene expression profile that resembled native IVD tissue more closely than native joint cartilage. Thus, these cells may represent an attractive source from which to obtain IVD-like cells, whereas modification of culture conditions is required to approach the molecular phenotype of chondrocytes in hyaline cartilage.     

Decorin moieties tethered into PEG networks induce chondrogenesis of human mesenchymal stem cells

A versatile approach to fabricate PEG-peptide copolymer gels was utilized to design niches to promote chondrogenic differentiation of human mesenchymal stem cells (hMSCs). The sequences RGD and KLER were chosen as motifs to modify PEG gels through a thiol-acrylate polymerization. The KLER sequence, a binding site from decorin protein, is known to bind strongly to collagen type II and is responsible for matrix organization, while RGD promotes general survival of encapsulated cells. hMSCs were encapsulated at 2 x 10(6) cells/mL into 10 wt % PEG gels with 1 mM CRGDSG in the presence or absence of 5 mM CKLERG. A scrambled sequence served as a control. The gels were cultured in control and chondrogenic media, containing 5 ng/mL TGFbeta(1) over a 6-week period. Cell/gel constructs were analyzed at various time points for glycosaminoglycan (GAG) content, type II collagen deposition, immunostaining, and gene analysis. After 14 days in chondrogenic cultures, cells in RGDS and KLER functionalized gels produced 2.5 times as much GAG/cell as those in gels containing only RGD. By day 28, hMSCs within the chondrogenic KLER gels produced 27-fold higher hydroxyproline than that of day 0, whereas cells in chondrogenic culture with RGDS alone produced twofold of initial. Immunostained images indicated that col II was more predominant in the KLER-derivatized gels than others, and enhanced chondrogenic differentiation in KLER containing gels was further supported by RT-PCR analysis of type II collagen and aggrecan expression. Collectively, these results demonstrate how incorporation of matrix-binding peptide interacts with hMSCs inducing chondrogenic differentiation and cartilage-specific ECM deposition.     

共沉默miR-221-3p/222-3p表达抑制骨髓间充质干细胞增殖及促成软骨分化

背景：基于干细胞的组织工程技术作为治疗骨关节损伤修复的有效手段,具有广泛的应用前景。研究表明miRNA在调控干细胞向软骨分化过程中具有重要的作用。 目的：探讨共感染慢病毒介导的反义miR-221-3p/222-3p(microRNA-221-3p,microRNA-222-3p)对人骨髓间充质干细胞成软骨分化的作用,为临床软骨损伤修复提供新的策略。 方法：利用miRNA基因芯片技术筛选转化生长因子β3诱导人骨髓间充质干细胞成软骨分化过程中不同阶段表达差异的miRNA,并利用荧光实时定量PCR(RT-qPCR)验证;构建慢病毒人反义miR-221-3p/222-3p载体(Lv-miR-221-3p-inhibition,Lv-miR-222-3p-inhibition)并共转染人骨髓间充质干细胞,空载体组(Lv-GFP)以及未转染组作为对照。利用CCK-8法检测沉默miR-221-3p/222-3p 6 d后细胞的增殖情况;通过番红O染色法、免疫组织化学方法以及RT-PCR验证各组软骨诱导21 d后软骨分化相关标志物的表达。 结果与结论：构建的Lv-miRNA-221-3p/222-3p inhibition 共转染人骨髓间充质干细胞,成功沉默了细胞中的miR-221-3p/222-3p表达水平;miRNA基因芯片与RT-qPCR验证结果显示miR-221-3p/222-3p在软骨分化后期表达明显降低;转染组与未转染组以及空载体组相比：①细胞增殖明显受到抑制。②番红Ｏ染色以及免疫组织化学显示软骨分化特征标志物硫酸软骨素以及Ⅱ型胶原表达增强。③RT-qPCR也证实硫酸软骨素以及Ⅱ型胶原的mRNA表达也明显上调。结果显示沉默人骨髓间充质干细胞miRNA-221-3p/222-3p,抑制了细胞增殖并促进了成软骨分化。  中国组织工程研究杂志出版内容重点：干细胞;骨髓干细胞;造血干细胞;脂肪干细胞;肿瘤干细胞;胚胎干细胞;脐带脐血干细胞;干细胞诱导;干细胞分化;组织工程     

Ultrastructural analysis of mouse embryonic stem cell-derived chondrocytes

Pluripotent embryonic stem (ES) cells cultivated as cellular aggregates, so called embryoid bodies (EBs), differentiate spontaneously into different cell types of all three germ layers in vitro resembling processes of cellular differentiation during embryonic development. Regarding chondrogenic differentiation, murine ES cells differentiate into progenitor cells, which form pre-cartilaginous condensations in the EB-outgrowths and express marker molecules characteristic for mesenchymal cell types such as Sox5 and Sox6. Later, mature chondrocytes appear which express collagen type II, and the collagen fibers show a typical morphology as demonstrated by electron-microscopical analysis. These mature chondrogenic cells are organized in cartilage nodules and produce large amounts of extracellular proteoglycans as revealed by staining with cupromeronic blue. Finally, cells organized in nodules express collagen type X, indicating the hypertrophic stage. In conclusion, differentiation of murine ES cells into chondrocytes proceeds from the undifferentiated stem cell via progenitor cells up to mature chondrogenic cells, which then undergo hypertrophy. Furthermore, because the ES-cell-derived chondrocytes did not express elastin, a marker for elastic cartilage tissue, we suggest the cartilage nodules to resemble hyaline cartilage tissue.     

Differentiation capacity of human chondrocytes embedded in alginate matrix

Healing capacity of cartilage is low. Thus, cartilage defects do not regenerate as hyaline but mostly as fibrous cartilage which is a major drawback since this tissue is not well adapted to the mechanical loading within the joint. During in vitro cultivation in monolayers, chondrocytes proliferate and de-differentiate to fibroblasts. In three-dimensional cell cultures, de-differentiated chondrocytes could re-differentiate toward the chondrogenic lineage and re-express the chondrogenic phenotype. The objective of this study was to characterize the mesenchymal stem cell (MSC) potential of human chondrocytes isolated from articular cartilage. Furthermore, the differentiation capacity of human chondrocytes in three-dimensional cell cultures was analyzed to target differentiation direction into hyaline cartilage. After isolation and cultivation of chondrogenic cells, the expression of the MSC-associated markers: cluster of differentiation (CD)166, CD44, CD105, and CD29 was performed by flow cytometry. The differentiation capacity of human chondrocytes was analyzed in alginate matrix cultured in Dulbecco?s modified eagle medium with (chondrogenic stimulation) and without (control) chondrogenic growth factors. Additionally, the expression of collagen type II, aggrecan, and glycosaminoglycans was determined. Cultivated chondrocytes showed an enhanced expression of the MSC-associated markers with increasing passages. After chondrogenic stimulation in alginate matrix, the chondrocytes revealed a significant increase of cell number compared with unstimulated cells. Further, a higher synthesis rate of glycosaminoglycans and a positive collagen type II and aggrecan immunostaining was detected in stimulated alginate beads. Human chondrocytes showed plasticity whilst cells were encapsulated in alginate and stimulated by growth factors. Stimulated cells demonstrated characteristics of chondrogenic re-differentiation due to collagen type II and aggrecan synthesis.     

Comparison of phenotypic characterization between "alginate bead" and "pellet" culture systems as chondrogenic differentiation models for human mesenchymal stem cells

Chondrogenesis involves the recruitment of mesenchymal cells to differentiate into chondroblasts, and also the cells must synthesize a cartilage-specific extracellular matrix. There were two representative culture systems that promoted the chondrogenic differentiation of human mesenchymal stem cells. These systems were adaptations of the "pellet" culture system, which was originally described as a method for preventing the phenotypic modulation of chondrocytes, and the "alginate bead" culture system, which was used to maintain encapsulated cells at their differentiated phenotype over time, and also it was used to maintain the cells' proteoglycan synthesis at a rate similar to that of primary chondrocytes. We performed test on the differences of phenotypic characterization with the two methods of differentiating human mesenchymal stem cells into chondrocytes. The typical gene for articular cartilage, collagen type II, was more strongly expressed in the "alginate bead" system than in the "pellet" culture system, in addition, specific gene for hypertrophic cartilage, collagen type X, was more rapidly expressed in the "pellet" system than in "alginate bead" culture system. Therefore, the "alginate bead" culture system is a more phenotypical, practical and appropriate system to differentiate human mesenchymal stem cells into articular chondrocytes than the "pellet" culture system.     

Differentiation Capacity of Human Chondrocytes Embedded in Alginate Matrix

Healing capacity of cartilage is low. Thus, cartilage defects do not regenerate as hyaline but mostly as fibrous cartilage which is a major drawback since this tissue is not well adapted to the mechanical loading within the joint. During in vitro cultivation in monolayers, chondrocytes proliferate and de-differentiate to fibroblasts. In three-dimensional cell cultures, de-differentiated chondrocytes could re-differentiate toward the chondrogenic lineage and re-express the chondrogenic phenotype. The objective of this study was to characterize the mesenchymal stem cell (MSC) potential of human chondrocytes isolated from articular cartilage. Furthermore, the differentiation capacity of human chondrocytes in three-dimensional cell cultures was analyzed to target differentiation direction into hyaline cartilage. After isolation and cultivation of chondrogenic cells, the expression of the MSC-associated markers: cluster of differentiation (CD)166, CD44, CD105, and CD29 was performed by flow cytometry. The differentiation capacity of human chondrocytes was analyzed in alginate matrix cultured in Dulbecco’s modified eagle medium with (chondrogenic stimulation) and without (control) chondrogenic growth factors. Additionally, the expression of collagen type II, aggrecan, and glycosaminoglycans was determined. Cultivated chondrocytes showed an enhanced expression of the MSC-associated markers with increasing passages. After chondrogenic stimulation in alginate matrix, the chondrocytes revealed a significant increase of cell number compared with unstimulated cells. Further, a higher synthesis rate of glycosaminoglycans and a positive collagen type II and aggrecan immunostaining was detected in stimulated alginate beads. Human chondrocytes showed plasticity whilst cells were encapsulated in alginate and stimulated by growth factors. Stimulated cells demonstrated characteristics of chondrogenic re-differentiation due to collagen type II and aggrecan synthesis.