脊索细胞促进骨髓间充质干细胞增殖及定向诱导分化的研究

目的 分离兔髓核脊索细胞及骨髓间充质干细胞(MSCs),通过共培养观察脊索细胞对MSCs增殖能力及细胞表型的影响.方法 4～6周龄新西兰兔4只,取胸腰段脊柱的髓核,用密度梯度离心法提取脊索细胞,同时取其股骨骨髓用Ficoll液分离得到MSCs,光镜观察脊索细胞和MSCs不同比例(1:2、1:1、2:1)共培养条件下细胞的生长,细胞计数试剂盒(CCK-8)法检测细胞增殖.脊索细胞和MSCs共培养(1:1)后行甲苯胺蓝染色及Ⅱ型胶原染色检测MSCs细胞表型的改变.对共培养后的MSCs进行相关基因表达的检测.结果 光镜下观察原代脊索细胞呈圆形或椭圆形,胞体大,细胞增殖不明显.MSCs呈梭形贴壁生长,旋涡状排列.CCK-8检测发现脊索细胞/MSCs1:1组细胞增殖明显高于其余各组.甲苯胺篮染色MSCs单独培养组呈阴性,共培养组呈阳性.Ⅱ型胶原染色MSCs单独培养组呈阴性,共培养组呈阳性.逆转录-聚合酶链反应(RT-PCR)检测发现共培养组蛋白聚糖及Ⅱ型胶原的表达分别为脊索细胞的2.00、1.35倍,而单独培养的MSCs则表达阴性.结论 在共培养条件下脊索细胞可以促进MSCs增殖,且细胞比例为1:1时更为显著;同时可以诱导其产生Ⅱ型胶原及聚集蛋白聚糖,表现出类软骨细胞表型.     

骨髓间充质干细胞结合藻酸盐治疗椎间盘退变的实验研究

目的观察骨髓间充质干细胞（Bone mesenchymal stem cell,BMSC）结合藻酸盐凝胶支架,治疗兔椎间盘退变的效果。方法将15只新西兰大白兔建立腰椎间盘退变模型,随机分为对照组、空白组和治疗组。体外培养兔BMSC,治疗组椎间隙注射BMSC结合藻酸盐凝胶支架,对照组注射藻酸盐凝胶,空白组注射生理盐水。应用核磁共振、免疫组化和生化分析,观察椎间盘退变的修复效果。结果治疗组影像学、病理组织学观察,以及蛋白多糖和Ⅱ型胶原的含量,均明显优于对照组和空白组,差异有统计学意义。结论 BMSC结合藻酸盐凝胶支架可用于治疗兔腰椎间盘退变。     

脊索细胞促进髓核软骨样细胞增殖及表型维持

目的分离纯化兔髓核中的细胞成分，观察脊索细胞形态及对软骨样细胞增殖及细胞表型的影响。方法6只4周龄新西兰兔胸腰段脊柱，获取髓核，0．2％Ⅱ型胶原酶消化法及不连续密度梯度法分离纯化脊索细胞及软骨样细胞。实验分为单纯软骨样细胞培养组（A组）及脊索细胞、软骨样细胞（1：1）共培养组（B组）。倒置相差显微镜观察两组细胞生长情况，测定两组原代及传代细胞成活率，MTT法测定两组第2代细胞增殖曲线，并以甲苯胺蓝染色和免疫细胞化学染色鉴定两组原代及传代细胞蛋白多糖及Ⅱ型胶原的表达。结果成功分离、纯化脊索细胞和软骨样细胞。细胞培养观察，原代脊索细胞直径10～15gm，胞浆内富含大小不等的囊泡；原代软骨样细胞直径4～6gm，胞浆内无囊泡。各代细胞成活率A组为89．0％～95．3％，B组为91_3％～96．3％，各代细胞成活率两组间比较差异无统计学意义（P〉0．05）。A组细胞培养3～4d进入对数生长期，B组细胞培养2d后进入对数生长期；培养4d后，B组细胞增殖能力高于A组，差异有统计学意义（P〈0．05）。A组3代以内细胞表达蛋白多糖及Ⅱ型胶原，B组细胞表型维持至5代。结论脊索细胞能促进髓核软骨样细胞的增殖及表型维持；脊索细胞可能在防止椎间盘退变中具有重要意义。     

脊索细胞培养基促进BMSCs增殖分化的研究

目的为研究椎间盘组织工程种子细胞,观察脊索细胞培养基对BMSCs增殖分化的影响。方法取4周龄日本大耳白兔胸腰段椎间盘分离培养脊索细胞,取双侧股骨分离培养BMSCs,用含15%FBS的DMEM/F12培养基培养脊索细胞,5 d后制备脊索细胞培养基。实验分为两组,实验组BMSCs中加入脊索细胞培养基培养,对照组BMSCs中加入含15%FBS的DMEM/F12培养基培养。使用细胞活力细胞毒性检测检测细胞增殖情况,采用免疫荧光及实时荧光定量PCR检测BMSCs蛋白多糖及Ⅱ型胶原表达情况。结果成功分离脊索细胞及BMSCs。细胞增殖检测示,培养5、7、9、14 d,实验组细胞数量明显多于对照组(P<0.05)。免疫荧光检测示对照组培养7、14 d细胞内均无或者有较少Ⅱ型胶原及蛋白多糖表达,实验组二者均有较多表达,且培养14 d时表达明显多于7 d。实时荧光定量PCR检测示,培养7、14 d实验组蛋白多糖和Ⅱ型胶原mRNA表达均显著高于对照组(P<0.05);实验组14 d蛋白多糖和Ⅱ型胶原mRNA表达显著高于7 d(P<0.05)。结论脊索细胞培养基可促进BMSCs增殖,并诱导BMSCs向类软骨细胞分化,为脊索细胞和BMSCs作为种子细胞治疗椎间盘退变提供了依据。     

脊索细胞对类软骨细胞增殖及基质合成代谢的影响

目的 观察非接触共培养条件下脊索细胞对类软骨细胞增殖及生物学特性的影响.方法 无菌条件下取4只4周龄日本大白兔胸腰段脊柱,获取髓核组织,酶消化法及不连续密度梯度法分离纯化的脊索细胞及类软骨细胞.取第2代类软骨细胞与脊索细胞按1:1的比例接种于共培养装置Transwell小室中,将单层培养的类软骨细胞设为对照组.培养1、3、7、10 d后倒置相差显微镜下观察细胞生长状况,免疫荧光法鉴定细胞表型,细胞计数试剂盒(CCK-8)法测定细胞增殖,逆转录-聚合酶链反应( RT-PCR)检测Ⅱ型胶原、蛋白多糖的表达.结果 成功分离纯化、获取脊索细胞及类软骨细胞.镜下观察见原代脊索细胞体积较大,呈圆形或椭圆形,直径10 ～ 15 μm,胞质内含较多大小不等的囊泡;原代贴壁的类软骨细胞体积较脊索细胞小,呈短梭形,直径4 ～6 μm.随着非接触共培养时间的延长,类软骨细胞增殖明显加快,以共培养7、10 d明显(P＜0.05);Ⅱ型胶原、蛋白多糖的表达量也逐渐增高.结论 脊索细胞能促进髓核类软骨细胞的增殖,其可能在阻止椎间盘退变的发生中具有一定意义.     

兔椎间盘髓核细胞体外生物学特性的实验研究

目的 对兔椎间盘髓核细胞进行体外培养,观察细胞的形态、表型及超微结构改变,研究其体外生物学特性.方法 取2周龄健康新西兰白兔椎间盘髓核组织,在含有15%灭活FBS的DMEM/F12培养液中培养,倒置相差显微镜下观察原代和传代细胞形态.分别在取材后、原代、第1代、第2代细胞培养期间,进行髓核细胞活力测定;爬片培养后进行甲苯胺蓝、HE、聚集蛋白聚糖番红O、Ⅰ型及Ⅱ型胶原免疫组织化学染色观察;MTT法绘制髓核细胞生长曲线,并行原代及第2代细胞透射电镜观察,对体外细胞的生物学特性进行研究.结果 倒置相差显微镜见原代髓核细胞呈类圆形,折光性较强;5 d开始有细胞贴壁,细胞呈多角形或短梭形;6～8 d细胞生长进入指数生长期;约17 d时,细胞长满瓶壁,可进行传代;随传代次数增加,细胞形态逐渐由多角形、短梭形向长梭形改变.髓核细胞活力测定在刚分离完成后细胞活力为95%～97%,原代培养期间为98%～100%,第1代培养期间仍能维持为100%,第2代细胞活力下降较为明显,为75%～80%.髓核细胞甲苯胺蓝染色呈强阳性:HE染色见细胞核、细胞质着色明显.第1代髓核细胞Ⅰ型胶原免疫组织化学染色呈阴性,Ⅱ型胶原免疫组织化学染色呈阳性,聚集蛋白聚糖番红O染色呈阳性;第2代细胞Ⅰ型胶原免疫组织化学染色呈阳性,Ⅱ型胶原免疫组织化学染色呈弱阳性,聚集蛋白多糖番红O染色着色较浅.MTT生长曲线与体外细胞培养时生长过程相符.透射电镜显示原代髓核细胞内线粒体少,胞质内有大量糖原颗粒,随传代次数增加,糖原颗粒减少,线粒体数量增多,细胞器开始肿胀.结论 明确了兔髓核细胞体外生物学特性变迁,为组织工程髓核的种子细胞研究提供了实验依据.     

骨髓基质细胞体外增殖后移植修复关节软骨缺损的实验研究

目的 :用组织工程的方法将骨髓基质细胞体外培养增殖后植入软骨缺损 ,观察关节软骨缺损的修复效果。方法 :抽取兔骨髓基质细胞体外培养增殖后 ,将其与Ⅱ型胶原凝胶相结合 ,植入到兔膝关节实验性关节软骨缺损中 ,对照组的缺损分别置入与髓腔血混合的Ⅱ型胶原凝胶、单纯Ⅱ型胶原凝胶或不作任何处理 ,术后 4、8、12周取材观察及组织学检查。结果 :术后 4周 ,实验组的缺损由透明样软骨样组织充填 ,术后 12周 ,软骨及软骨下骨组织基本修复 ;在对照组缺损 ,软骨下骨在术后 12周亦基本修复 ,但表层软骨主要由纤维组织修复。结论 :骨髓基质细胞来源丰富 ,采集方便 ,经体外培养增殖后 ,足量的未分化细胞与Ⅱ型胶原凝胶载体相结合 ,修复关节软骨缺损的效果较好。     

兔骨髓间充质干细胞在藻酸锶凝胶中体外三维培养的实验研究

[目的]观察兔骨髓间充质干细胞(BMSCs)于藻酸锶凝胶中体外三维培养的形态与活性变化,为藻酸锶凝胶复合干细胞应用于骨组织工程提供理论依据。[方法]分离培养原代兔BMSCs并扩增,取第3代BMSCs以细胞密度为5×105个/ml复合于藻酸锶凝胶中三维培养,每日于倒置相差显微镜下观察细胞形态,在不同时间点对其进行Live/Dead染色测细胞存活,CCK-8检测细胞增殖,并用扫描电镜观察凝胶的超微结构及细胞于凝胶上的黏附情况。[结果]藻酸锶凝胶质软、透明、渗透性较好;BMSCs接种于藻酸锶凝胶中初始形态为圆形、呈悬浮生长,后细胞逐渐贴壁生长并呈星形或多角形;接种第1 d和第14 d凝胶中活细胞率分别为(88.61±4.08)%和(92.16±2.10)%,两者间无显著统计学差异(P>0.05);第4、7、10、13 d时二维培养组中OD值显著高于三维培养组(P<0.05);扫描电镜示藻酸锶凝胶呈典型的"鸡蛋箱"样结构,孔隙直径大小平均为150μm;接种于凝胶中7 d后可见细胞均匀黏附于凝胶壁生长。[结论]藻酸锶凝胶是一种优良的细胞支架,将其复合种子细胞应用于骨组织工程具有广阔的前景。     

骨髓基质干细胞体外分化软骨细胞的实验研究

目的 探讨转化生长因子-β1(TGF-β1)和碱性成纤维细胞生长因子(b-FGF)对兔骨髓基质干细胞(BMSC)体外增殖、分化为软骨样细胞的影响。方法 24只兔等分为4组,抽取骨髓,分离基质干细胞,体外连续传代培养,A组为基础培养液,B、C、D组分别加入TGF-β1、b-FGF、TGF-β1和b-FGF,观察细胞生长情况及形态特征,阿新蓝染色,Ⅱ型胶原mRNA表达情况。结果B组细胞形态变化、C组增殖速度、D组增殖速度及形态变化均较A组加快。阿新蓝染色:原代阴性,传代细胞,A、c组淡染或阴性,B组呈蓝色,D组呈深蓝色。Ⅱ型胶原mRNA表达:A、c组未检出,B组阳性,D组有较强阳性表达。结论 兔BMSC在体外适当条件下可分化为软骨样细胞,TGF-β1能诱导BMSC向软骨方向分化,b-FGF不仅能促进BMSC的增殖,且能延长其生存时间。     

兔半月板纤维软骨细胞在纤维蛋白凝胶中体外培养的生物学特性

目的：研究兔半月板纤维软骨细胞的分离、培养及在纤维蛋白凝胶中三维培养时的生物学特性。方法：(1)分离、培养兔半月板纤维软骨细胞；(2)制备纤维软骨细胞与纤维蛋白凝胶复合物，在纤维蛋白中培养细胞；(3)通过倒置相差显微镜，HE染色、电镜检查作形态学观察；(4)通过测定生长曲线及ABPAS染色、Ⅰ、Ⅱ型胶原免疫组化检查，了解细胞生长特性及软骨基质的分泌情况。结果：(1)单层培养的纤维软骨细胞呈线形，部分呈多角形，在纤维蛋白中的纤维软骨细胞为圆形，表面细胞呈多角形；(2)细胞在纤维蛋白中培养时，对数生长期明显延长；(3)AB-PAS染色( )，Ⅰ、Ⅱ型胶原免疫组化检查( )。结论：兔半月板纤维软骨细胞在纤维蛋白凝胶中能够增殖，保持其表型和分泌胞外基质。     

非接触共培养脊索细胞诱导骨髓间充质干细胞向类软骨细胞分化的实验研究

目的:分离兔髓核脊索细胞(notochordal cells,NC)及骨髓间充质干细胞(mesenchymal stem cell,MSC),通过非接触共培养探讨NC对MSC细胞表型的影响。方法:4～6周龄新西兰兔8只,取胸腰段脊柱的髓核,用密度梯度离心提取NC,同时取其股骨骨髓用FICOLL液分离MSC,将NC和MSC等比例(1∶1)通过transwell培养板进行非接触共培养作为实验组,单纯MSC细胞培养作为对照组,光镜下观察细胞的生长情况。对两组的MSC行免疫组化及RT-PCR、Western-blot检测MSC细胞表型的改变情况。结果:原代NC呈圆形或椭圆形,细胞体积大,细胞增殖不明显;MSC贴壁生长,呈三角形或梭形,漩涡状排列。甲苯胺蓝染色:对照组MSC细胞核淡染,胞体染色不明显,染色阴性;实验组MSC可见从第3天开始胞体及胞外基质出现紫红色,第5天染色更加明显。Ⅱ型胶原免疫组化对照组MSC淡染,细胞形态不清楚;实验组第3天出现MSC内出现棕黄色深染,随着时间推移细胞染色加深呈阳性表现。RT-PCR检测,经过5d非接触共培养后实验组蛋白聚糖的基因表达为对照组的2.35倍(P<0.05),Ⅱ型胶原的基因表达为对照组的1.61倍(P<0.05),对照组Ⅰ型胶原的基因表达为实验组的2.56倍(P<0.05)。Western-blot检测后发现:经过5d非接触共培养,实验组蛋白聚糖的含量为对照组的1.61倍(P<0.05),Ⅱ型胶原的表达为对照组的10.04倍(P<0.05)(P<0.05)。结论:在非接触共培养条件下脊索细胞可以诱导骨髓间充质干细胞表型发生变化,向类软骨细胞方向分化,这将为组织工程化髓核的种子细胞筛选提供新选择。     

Culture of chondrocytes in alginate and collagen carrier gels

In this in vitro study, we compared the potential of collagen and alginate gels as carriers for chondrocyte transplantation and we studied the influence of demineralized bone matrix (DBM) on chondrocytes in the gels. Chondrocytes were assessed for cell viability, phenotype (histology), proliferation rate and sulfate incorporation.

Collagen gels showed a significant increase in cell numbers, but the chondrocytes dedifferentiated into fibroblast-like cells from day 6 onwards. In alginate gels, initial cell loss was found, but the cells maintained their typical chondrocyte phenotype. Although the total quantity of proteoglycans initially synthesized per cell in collagen gel was significantly higher, expressed per cell, the quantity in alginate gel eventually surpassed collagen. No effects of culturing chondrocytes in combination with DBM could be demonstrated on cell proliferation and sulfate incorporation.

The collagen and alginate gels have different advantages as carriers for chondrocyte transplantation. The high proliferation rate of chondrocytes in collagen gel may be an advantage, but the preservation of the chondrocyte phenotype and the gradually increasing proteoglycan synthesis in alginate gel is a promising method for creating a hyaline cartilage implant in vitro.     

辛伐他汀对兔髓核细胞的影响

目的 观察辛伐他汀对兔髓核细胞Ⅱ型胶原(ColⅡ)及聚集蛋白聚糖(Agg)表达的影响.方法 取兔髓核细胞进行原代培养,传至第3代行ColⅡ免疫组织化学鉴定后随机分为5组,以不同浓度辛伐他汀处理:A组:空白对照组;B、C、D、E组分别为0.1、0.2、0.4、0.8 μmol/L辛伐他汀组.运用半定量逆转录-聚合酶链反应(RT-PCR)检测ColⅡ、Agg含量的变化,并行细胞活力检测.结果 辛伐他汀浓度超过0.2 μmol/L时ColⅡ及Agg的表达增加,0.4 μmoL/L时达到高峰(P＜0.05),0.8 μmol/L时ColⅡ及Agg表达下降.0.8 μmol/L处理组影响细胞活力,0.1～0.4 μmol/L范围时细胞活性无明显影响(P＜0.05).结论 辛伐他汀可促进兔髓核细胞ColⅡ及Agg的表达,改善椎间盘退变进程;在＜0.4 μmol/L的较低浓度内对细胞活力无明显影响.     

Immunohistochemical identification of notochordal markers in cells in the aging human lumbar intervertebral disc

The fate of notochord cells during disc development and aging is still a subject of debate. Cells with the typical notochordal morphology disappear from the disc within the first decade of life. However, the pure morphologic differentiation of notochordal from non-notochordal disc cells can be difficult, prompting the use of cellular markers. Previous reports on these notochordal cell markers only explored the occurrence in young age groups without considering changes during disc degeneration. The aim of this study, therefore, was to investigate presence, localization, and abundance of cells expressing notochordal cell markers in human lumbar discs during disc development and degeneration. Based on pilot studies, cytokeratins CK-8, -18 and -19 as well as Galectin-3 were chosen from a broad panel of potential notochordal cell markers and used for immunohistochemical staining of 30 human lumbar autopsy samples (0–86 years) and 38 human surgical disc samples (26–69 years). In the autopsy group, 80% of fetal to adolescent discs (0–17 years) and 100% of young adult discs (18–30 years) contained many cells with positive labeling. These cells were strongly clustered and nearly exclusively located in areas with granular changes (or other matrix defects), showing predominantly a chondrocytic morphology as well as (in a much lesser extent) a fibrocytic phenotype. In mature discs (31–60 years) and elderly discs (≥60 years) only 25 and 22–33%, respectively, contained few stained nuclear cells, mostly associated with matrix defects. In the surgical group, only 16% of samples from young adults (≤47 years) exhibited positively labeled cells whereas mature to old surgical discs (>47 years) contained no labeled cells. This is the first study describing the presence and temporo-spatial localization of cells expressing notochordal cell markers in human lumbar intervertebral discs of all ages and variable degree of disc degeneration. Our findings indicate that cells with a (immunohistochemically) notochord-like phenotype are present in a considerable fraction of adult lumbar intervertebral discs. The presence of these cells is associated with distinct features of (early) age-related disc degeneration, particularly with granular matrix changes.     

Cell-based tissue engineering for the intervertebral disc: in vitro studies of human disc cell gene expression and matrix production within selected cell carriers.

BACKGROUND CONTEXT: Little is known about how disc cells attach, proliferate and form extracellular matrix (ECM) within carrier materials. Such information is needed to help formulate criteria for successful cell-carrier interactions in tissue engineering. PURPOSE: To compare proliferation, ECM production and gene expression in annulus cells cultured in a variety of cell carrier materials with potential application in tissue engineering of the disc. STUDY DESIGN: Human intervertebral disc cells from the annulus were used in a prospective study of proliferation, ECM production and gene expression within selected cell carriers. METHODS: Annulus cells from discs of 29 individuals were tested in collagen sponge, collagen gel, agarose, alginate or fibrin gel formulations. In situ hybridization assessed ECM gene expression of Types I and II collagen, aggrecan and chondroitin-6 sulfotransferase. Cell proliferation, cell shape, attachment and ECM production were evaluated. RESULTS: Collagen sponges provided the best microenvironment for disc cell ECM production and gene expression. Although collagen gels often could support good cell growth, such constructs did not result in either abundant ECM production or ECM gene expression, as shown by in situ hybridization. Growth and ECM production and gene expression in alginate, agarose and fibrin microenvironments were inferior. CONCLUSIONS: Tissue engineering techniques open new therapeutic possibilities for use of autologous disc cells, but fundamental questions on how these cells interact with cell carriers are unexplored. Results provide novel data on disc cell gene expression within diverse microenvironments. The collagen sponge proved to be a superior microenvironment.     

大鼠脂肪干细胞复合胶原-壳聚糖-硫酸软骨素三维支架构建组织工程软骨

目的 探讨大鼠脂肪干细胞复合胶原-壳聚糖-硫酸软骨素三维支架的优越性.方法 选用6周龄健康Wistar大鼠,分离出脂肪干细胞后行体外培养.将Ⅰ型胶原溶液与壳聚糖溶液混合后冷冻干燥,交联硫酸软骨素后再冷冻干燥得到复合三维支架,检测支架的孔径值、含水量及孔隙率.将接种的脂肪干细胞消化后分别接种到平面、微球和支架,软骨方向诱导培养.MTT检测细胞增殖情况,3周后倒置显微镜及扫描电镜观察细胞形态及在支架上的生长及黏附情况,并分析成软骨分化的情况.结果 5 d后MTT检测显示三维支架组及微球组细胞增殖速度较平面组快;三维支架组14 d后仍有细胞增殖.组织学分析显示细胞在支架上密集重叠生长,内层仍有残留支架结构.Ⅱ型胶原免疫组化检测结果显示,三维支架组及微球组表达呈强阳性,而平面组表达呈弱阳性.RT-PCR结果显示各组均有软骨特异性mRNA的表达.但平面组一直表达X型胶原,微球组培养至21 d时也表达X型胶原,而三维支架组则一直未表达.结论 复合胶原-壳聚糖-硫酸软骨素三维支架能促进细胞的增殖、分化,并能更好地维持软骨细胞的表型,可以作为组织工程构建软骨的最佳选择.     

Initial characterization of the metabolism of intervertebral disc cells encapsulated in microspheres.

Adult, canine intervertebral disc cells were isolated with a sequential digestion of pronase and bacterial collagenase. The nonchondrodystrophoid nucleus pulposus exhibits two populations of cells: large notochordal cells and smaller chondrocyte-like cells. The cells from the transition zone and anulus fibrosus are uniform in size, ranging from 17 to 21 microns. The isolated cells were encapsulated in alginate beads and cultured in Ham's F-12 medium containing 5% heat-inactivated fetal bovine serum. Alginate bead formation requires calcium ions and can be reversed with a suitable chelator, thus releasing viable cells. We observed that 58% of the newly synthesized proteoglycans formed large-molecular-weight aggregates with hyaluronic acid. The proteoglycans contained low amounts of keratan sulfate (KS) (less than 5% of the total glycosaminoglycans synthesized). The chondroitin sulfates (CS) consisted of 51-67% as 6-O-sulfate and 29-39% as 4-O-sulfate, with the remainder (4-10%) present as 4,6-sulfate for all three zones of the disc. The majority of cells synthesized significant amounts of matrix as evidenced by Alcian Blue staining. By immunohistochemical analysis, the matrix contained chondroitin 6-sulfate as demonstrated by monoclonal antibodies to the unsaturated disaccharides remaining on the proteoglycan core after chondroitinase ABC digestion. Keratan sulfate was also present in the majority of the matrices around cells. These results emphasize the similarity of the newly synthesized proteoglycans secreted by cells grown in alginate beads to those synthesized by the neonate disc. These experiments also demonstrate the usefulness of this method as a microculture technique for disc cells.     

Notochordal cells stimulate migration of cartilage end plate chondrocytes of the intervertebral disc in in vitro cell migration assays

Background contextIt was recently demonstrated that the postnatal transition from a notochordal to a fibrocartilaginous nucleus pulposus (NP) is accomplished exogenously by chondrocytes migrating from hyaline cartilage end plates (CEs) into the ectopic notochordal NP region. Although our previous in vivo studies showed evidences for the migration of CE chondrocyte from hyaline CEs into the notochordal NP, it is unknown whether CE chondrocytes of the intervertebral disc (IVD) really have a motile property. In addition, the effect of notochordal cells on this property has not been elucidated.PurposeThe purpose of this in vitro study was to demonstrate whether CE chondrocytes of the IVD are capable of migration, and whether there is any biological link between notochordal cells and CE chondrocytes that may regulate the CE chondrocyte migration.Study design/settingIn vitro cell migration assays were performed using rat IVDs.MethodsNotochordal cells and chondrocytes were obtained from the NP and CE tissues, respectively, and were cultured separately. The different numbers of notochordal cells and the supernatant (conditioned medium) that contained soluble factors produced by notochordal cells were used to demonstrate their effects on the migration of CE chondrocytes. Bovine serum albumin (BSA) and lysophosphatidic acid (LPA) were used as negative and positive controls, respectively.ResultsCompared with BSA, LPA, notochordal cells (N=4×, 2×, 1×, and 0.5×10⁵), and its conditioned media (unconcentrated and fivefold concentrated) significantly increased migration of CE chondrocytes (p<.05 in all comparisons). Particularly, notochordal cells and its conditioned media increased migration in a number- and concentration-dependent manner, respectively.ConclusionsThis study demonstrates that CE chondrocytes of the IVD are capable of migration and that soluble factors produced by notochordal cells stimulate the migration. These results provide a plausible explanation to the question of why CE chondrocytes of the IVD migrate into the ectopic NP region during the natural transition from the notochordal to fibrocartilaginous NP.