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.     

非接触共培养条件下山羊BMSCs向纤维环样细胞诱导分化的研究

[目的]建立山羊骨髓源性间充质干细胞(bone marrow mesenchymal stem cells,BMSCs)和纤维环细胞(annulus fibrosus cells,AFCs)非接触共培养体系,探讨BMSCs向纤维环样细胞诱导分化潜能,为组织工程修复纤维环缺损研究提供种子细胞。[方法]复苏第3代AFCs和BMSCs,观察细胞形态并绘制生长曲线。采用Transwell系统共培养AFCs和BMSCs,7 d后,检测BMSCs向纤维环样细胞分化情况。通过甲苯胺蓝染色检测聚集蛋白聚糖的表达,通过免疫细胞化学法检测Ⅰ型胶原蛋白的表达,realtime PCR检测Ⅰ型胶原、聚集蛋白聚糖和Sox-9 mRNA表达。[结果]非接触共培养7 d后,BMSCs形态转变为纤维环细胞样。非接触共培养组中BMSCs的聚集蛋白聚糖与Ⅰ型胶原染色呈阳性,与AFCs对照组结果一致,BMSCs对照组结果呈阴性。与AFCs对照组相比,共培养组中Ⅰ型胶原、聚集蛋白聚糖及Sox-9的mRNA表达量分别为0.86、1.13和0.91(P>0.05),而BMSCs对照组中未检测到其表达。[结论]建立稳定的山羊AFCs和BMSCs非接触共培养体系,共培养7 d后,BMSCs具有AFCs特性,表明共培养条件促进BMSCs诱导分化为纤维环样细胞。     

非接触性共培养BMSCs和髓核细胞时间差异性的实验研究

目的探讨在非接触性共培养环境下,BMSCs定向分化为类髓核细胞在共培养时间上的差异性,寻找适合体内移植的最佳时间。方法取6只8周龄健康新西兰大白兔(体重1.5～2.0 kg)骨髓及椎间盘髓核,分离、培养BMSCs和髓核细胞并进行免疫细胞化学鉴定。取原代髓核细胞和第2代生长良好的BMSCs体外建立非接触性共培养模型。观察共培养后第1、3、5代BMSCs的形态学变化并绘制生长曲线;RT-PCR检测共培养5、10、15 d BMSCsⅡ型胶原和蛋白聚糖mRNA表达;Western blot检测共培养5、10、15、20、25、30 d BMSCsⅡ型胶原和蛋白聚糖蛋白的表达。结果 BMSCs相对特异性标记物CD44、CD90表达阳性,造血细胞表面标记物CD34、CD45表达阴性。髓核细胞Ⅱ型胶原、蛋白聚糖表达阳性。共培养后2周BMSCs形态发生明显变化,呈多角形、不规则形;共培养后3代内,BMSCs生长速度无明显差异,随着传代次数增加,细胞增殖明显减慢。RT-PCR检测示共培养后10、15 d BMSCs蛋白聚糖和Ⅱ型胶原mRNA表达明显高于5 d时(P<0.05),而10 d与15 d时差异无统计学意义(P>0.05)。Western blot检测示共培养后随时间延长细胞表达Ⅱ型胶原和蛋白聚糖蛋白逐渐增加,5、10、15 d间差异有统计学意义(P<0.05),15 d后各时间点间比较差异无统计学意义(P>0.05)。结论在非接触性共培养环境下,BMSCs在髓核细胞诱导下可向类髓核细胞分化,表达Ⅱ型胶原和蛋白聚糖,在共培养15 d时达到相对稳定,此时较适合进行体内移植。     

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.     

髓内脂肪细胞对骨髓基质细胞成骨能力的影响

目的探讨在骨髓腔中,来源于骨髓基质细胞的脂肪细胞对骨髓基质细胞成骨能力的影响。方法将骨髓基质细胞以1×106个/ml浓度接种于24孔培养板中,共分为5组,分别加入0、103、104、105、106/ml浓度的脂肪细胞悬液,建立脂肪细胞和骨髓基质细胞共培养体系。共培养12d,每4d取细胞样本,检测细胞内碱性磷酸酶活性,利用原位杂交方法检测I型胶原mRNA表达,3H脯氨酸掺入实验检测骨髓基质细胞胶原合成能力。结果经过12d培养,不同时段的共培养体系中,随着脂肪细胞浓度上升,骨髓基质细胞内碱性磷酸酶相对活性下降,各实验组明显低于对照组(P<0.05或P<0.01);I型胶原mRNA表达减弱,对照组染色最深,实验组着色较淡;各实验组3H脯氨酸掺入实验min-1值均低于同期对照组(P<0.05或P<0.01)。结论髓内脂肪细胞干扰了骨髓基质细胞的成骨能力,可能与原发性骨质疏松症的发病有关。     

兔骨髓间充质干细胞与髓核细胞共培养后的营养效应和类髓核分化效应

目的:探讨兔骨髓间充质于细胞(BMMSCs)与髓核细胞(NPCs)共培养时BMMSCs的营养效应和类髓核分化效应及其动态变化规律.方法:应用1月龄新西兰大白兔的骨髓和髓核进行BMMSCs及NPCs的分离培养与鉴定,建立3个细胞培养组,BMMSCs与NPCs共培养组(实验组),BMMSCs单独培养组和NPCs单独培养组作为对照组.在培养的不同时间点(3、6、9、12、15、18、21d)分别检测细胞培养上清液中转化生长因子β1(TGFβ1)、血小板衍化生长因子(PDGF)的含量变化及BMMSCs与NPCs的增殖能力,采用RT-PCR法检测培养不同时间点BMMSCs与NPCs的蛋白聚糖Aggrecan及Ⅱ型胶原蛋白mRNA的表达变化.结果:分离培养的两种细胞经鉴定分别为BMMSCs及NPCs.从第3天开始的各个时间点,实验组上清液中TGFβ1、PDGF的含量较两对照组明显增高(P<0.05),且随时间的延长而逐渐增高,第15天达最高,TGFβ1、PDGF分别达815.81±25.69pg/ml和494.28±20.01pg/ml,此后第18d、21d逐渐下降.实验组细胞DNA含量在各个时间点上均较两对照组明显升高(P<0.05).从第3天开始的各个时间点,实验组NPCs的蛋白聚糖Aggrecan及Ⅱ型胶原mRNA的表达较对照组高(P<0.05);同时从第15天开始至第21天,实验组BMMSCs的蛋白聚糖Aggrecan及Ⅱ型胶原mRNA的表达较对照组高(P<0.05).结论:BMMSCs与NPCs共培养时BMMSCs可通过表达TGFβ1、PDGF等细胞因子发挥其营养效应,激活NPCs.促进其增殖及细胞外基质的合成;在共培养后期,BMMSCs在髓核局部微环境下,可发挥其类髓核分化效应,开始合成蛋白聚糖Aggrecan及Ⅱ型胶原蛋白.     

软骨寡聚基质蛋白对BMP 2诱导骨髓间质干细胞分化的影响

 目的 探讨过表达软骨寡聚基质蛋白（cartilage oligomeric matrix protein,COMP）对BMP-2诱导骨髓间质干细胞成骨及成软骨分化的影响。方法 用BMP-2诱导骨髓间质干细胞分化,通过脂质体转染含人COMP基因的质粒使骨髓间质干细胞过表达COMP,空载质粒作为对照。以RT-PCR检测成骨相关基因Ⅰ型胶原、RUNX2、骨桥蛋白、骨钙蛋白以及成软骨相关基因Ⅱ型胶原、SOX9、蛋白聚糖的表达变化;通过碱性磷酸酶染色观察成骨过程中的碱性磷酸酶活性,茜素红染色观察成骨终末阶段矿化结节的生成情况,阿利新蓝染色观察细胞基质蛋白多糖的合成情况。结果 COMP组目的基因COMP mRNA的表达显著升高;骨桥蛋白mRNA表达水平较对照组低,呈现出一致的下调趋势（P<0.05）;Ⅰ型胶原、RUNX2、骨钙蛋白mRNA表达水平在诱导早期均高于对照组（P<0.05）,但在诱导晚期均明显低于对照组（P<0.05）;成软骨指标（Ⅱ型胶原、SOX9、蛋白聚糖）的基因表达水平强于对照组,呈一致的上调趋势（P<0.05）;SOX9 mRNA表达水平高于对照组,仅在第7天时差异具有统计学意义（P<0.05）;细胞成骨染色（碱性磷酸酶染色、茜素红染色）均弱于对照组,而阿利新蓝染色强于对照组。结论 COMP能抑制BMP-2诱导骨髓间质干细胞成骨分化,促进BMP-2诱导骨髓间质干细胞成软骨分化。     

非接触式共培养下两种同源间充质干细胞对退变髓核细胞生物学影响的比较研究

【摘要】 目的：比较非接触式共培养条件下两种同源间充质干细胞对退变髓核细胞生物学功能的影响。方法：取同一腰椎间盘突出症患者骨髓间充质干细胞（BMSCs）、脂肪间充质干细胞（ADSCs）和退变髓核细胞（NPCs）,两种间充质干细胞分别与髓核细胞在Tanswell 6孔板中进行非接触式共培养,与ADSCs共培养的NPCs为A组,与BMSCs共培养的NPCs为B组,以单独培养的NPCs为对照组。共培养7d后,提取3组髓核细胞总RNA,进行反转录后,利用Real-Time PCR检测其Ⅱ型胶原、蛋白多糖和SOX-9基因的相对表达量。结果：非接触式共培养7d后,Ⅱ型胶原、蛋白多糖和SOX-9基因相对表达量对照组分别是1.03±0.28、1.21±0.40和0.94±0.34,A组分别是3.49±0.55、3.88±2.11和2.41±0.91,B组分别是7.60±1.89、6.26±2.96和4.55±1.88。与对照组相比,A、B组髓核细胞Ⅱ型胶原、蛋白多糖和SOX-9基因相对表达显著增加（P<0.05）;A、B两组间相比也有显著性差异（P<0.05）。结论：非接触式共培养条件下骨髓间充质干细胞和脂肪间充质干细胞对退变髓核细胞均有一定的激活效应;骨髓间充质干细胞对退变髓核细胞的激活效应更强,可能更加适合于椎间盘退行性疾病的生物学治疗。     

单纯Ⅱ型胶原酶消化法分离、培养人退变椎间盘髓核细胞的形态学观察

目的:探讨单纯Ⅱ型胶原酶消化法体外培养扩增人退变椎间盘髓核细胞的可行性。方法:收集20例人退变椎间盘髓核,单纯Ⅱ型胶原酶消化分离出髓核细胞并连续培养传代,倒置相差显微镜和HE染色观察细胞形态学变化,甲苯胺蓝染色检测髓核细胞内聚集蛋白聚糖的表达,免疫细胞化学法行Ⅱ型胶原染色,观察髓核细胞的类软骨表型表达情况。结果:单纯Ⅱ型胶原酶消化法可较好的分离培养人退变椎间盘髓核细胞,20例人退变椎间盘髓核,培养成功16例;原代髓核细胞平均7d贴壁,呈类圆形或多角形,P1代髓核细胞平均12h贴壁,呈大梭形或多角形,两代细胞融合95%所需时间分别为30d和7d,差异有统计学意义(P0.01);聚集蛋白聚糖和Ⅱ型胶原主要表达于原代和P1代髓核细胞浆内,被甲苯胺蓝染成天蓝色,免疫细胞化学染色主要表现为黄褐色沉淀,两代间聚集蛋白聚糖和Ⅱ型胶原的表达无统计学差异(P0.05)。结论:单纯Ⅱ型胶原酶消化法可简化髓核细胞分离步骤,提高培养效率;传一代后髓核细胞增殖速率提高,但仍维持类软骨表型,表达聚集蛋白聚糖和Ⅱ型胶原。     

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。     

兔脊索细胞体外培养及生物学特点观察

目的建立体外兔椎间盘脊索细胞藻酸盐凝胶培养模型,观察脊索细胞形态及生物学特点。方法采用胶原酶消化法及Percoll不连续密度梯度沉淀法体外分离收集原代椎间盘脊索细胞,于1.2%藻酸盐凝胶(低密度)中培养。倒置相差显微镜下观察细胞形态,经Ⅱ型胶原免疫荧光染色对细胞表型初步鉴定,并分别以细胞增殖和细胞毒性试剂-8(CCK-8)检测细胞在藻酸盐凝胶中的存活和增殖能力。结果成功分离获得原代椎间盘脊索细胞,可稳定表达Ⅱ型胶原。原代脊索细胞在藻酸盐凝胶中生长良好,但增殖缓慢。结论初步了解兔椎间盘脊索细胞体外生物学特性,为椎间盘退变机制及组织工程学髓核种子细胞的研究提供一定的实验依据。     

白介素-1β对髓核细胞MMP-1、2、9、13表达的影响

目的探讨IL-1β对人椎间盘髓核细胞表达基质金属蛋白酶MMP-1、2、9、13的作用。方法分离人椎间盘髓核细胞进行单层培养并利用甲苯胺蓝、番红O染色和Ⅱ型胶原免疫细胞化学染色进行鉴定,而后分别用10ng／ml和50ng／ml重组人IL—1β刺激体外培养的髓核细胞,RT-PCR检测基质金属蛋白酶-1、2、13的表达,定量PCR检测基质金属蛋白酶-9的表达。结果10ng／ml和50ng／ml重组人IL-1β均可促进髓核细胞基质金属蛋白酶-1、2、9、13的表达（P〈0．05）;基质金属蛋白酶-9、13表达随IL-1β浓度升高而升高（P〈0．05）。结论IL—1β可以促进人椎间盘髓核细胞表达基质金属蛋白酶-1、2、9、13,其加速了椎间盘基质分解的作用亦可能通过上述细胞因子的介导。     

Using notochordal cells of developmental origin to stimulate nucleus pulposus cells and bone marrow stromal cells for intervertebral disc regeneration

Purpose

Bone marrow stromal cells (BMSCs) have been proposed to complement the declining population of nucleus pulposus cells (NPCs) found in a degenerative intervertebral disc. Although able to stop degeneration, they could not produce enough matrix to restore a healthy state. Looking at development, when a large amount of matrix is produced, the disc also contains notochordal cells (NCs), potential progenitors or regulators of NPCs. The aim of the study was, therefore, to combine NCs to a BMSC/NPC mix and evaluate their effects on cell phenotype and matrix production, in long-term culture.

Methods

In a 3D hydrogel, NCs were co-cultured in different ratios with BMSCs and/or NPCs. Matrix production, cell morphology, and gene expression of disc markers were assessed after 4 weeks of culture.

Results

At day 28, BMSCs/NPCs highly expressed disc matrix markers (type II collagen and aggrecan) and produced disc matrix up to 30 % of values obtained for the positive control (BMSCs under TGFβ stimulation). The addition of NCs only slightly up-regulated marker expression (6–12× increase); an up-regulation not reflected at the matrix level. During the 4 weeks of culture, however, the NC phenotype changed drastically (morphology, disc marker expression).

Conclusion

In contrast to previously reported short-term studies, long-term co-cultures with NCs had no substantial effects on BMSCs and NPCs, most likely due to the loss of the NC native phenotype during culture. It, therefore, appears critical to maintain this specific phenotype for a long-term effect of the NCs.     

Sensitivity of notochordal disc cells to mechanical loading: an experimental animal study

The immature disc nucleus pulposus (NP) consists of notochordal cells (NCs). With maturation NCs disappear in humans, to be replaced by chondrocyte-like mature NP cells (MNPCs); this change in cell phenotype coincidences with early signs of disc degeneration. The reasons for NC disappearance are important to understand disc degeneration, but remain unknown, yet. This study investigated, whether loading induced a change from a notochordal nucleus phenotype to a chondrocyte-like one. An in vivo disc compression model with fixateur externe was used in 36 mature rabbits. Discs were compressed for different time periods (1, 28, 56 days), and compared with uncompressed control discs (56 days without treatment), and discs with sham compression (28 days). Nucleus cell phenotype was determined by histology and immunohistochemistry. NCs, but not MNPCs highly expressed bone-morphogenetic-protein 2 and cytokeratin 8, thus NC and MNPC numbers could be determined. A histologic score was used to detect structural endplate changes after compression (28 days). Control and sham compressed discs contained around 70% NCs and 30% MNPCs, to be decreased to <10% NCs after 28–56 days of loading. NC density fell sharply by >50% after 28–56 days of compression (P < 0.05 vs. controls). Signs of decreased endplate cellularity and increased endplate sclerosis and fibrosis were found after loading. These experiments show that NCs were less resistant to mechanical stress than MNPCs suggesting that increased intradiscal pressures after loading, and limited nutrition through structurally altered endplates could instigate the disappearance of NCs.     

骨形态发生蛋白-2对兔骨髓基质细胞向软骨细胞分化基因表达的影响

目的 观察骨形态发生蛋白-2(BMP-2)基因对兔骨髓基质细胞(MSCs)向软骨细胞分化mRNA表达的影响.方法 从兔骨髓细胞中分离提取BMP-2 mRNA,构建重组BMP-2真核表达质粒,并转染兔MSCs,采用荧光定量逆转录-聚合酶链反应(RT-PCR)方法检测各组MSCs内Ⅱ型胶原和蛋白多糖mRNA表达水平.结果 转染后2、4 d实验组MSCs内的Ⅱ型胶原和蛋白多糖mRNA表达量28.7±4.0、236.7±48.5及26.9±4.3、208.2±36.7,均明显高于转染后2、4 d的空白对照组(16.1±2.8、99.2±24.8及14.6±2.7、111.1±18.9)和空载体对照组(14.6±2.6、85.4±24.7及16.1±2.8、98.0±22.5)(P＜0.05).结论 重组真核表达载体BMP-2质粒能够诱导MSCs向软骨细胞分化.

Abstract：

Objective To observe the effect of bone morphogenetic protein-2 (BMP-2) on gene expression during the differentiation of marrow stromal cells (MSCs) into chondrocytes. Methods The BMP-2 mRNA was extracted from the rabbit bone marrow cells. The recombinant BMP-2 eukaryotic expression plasmids were constructed and transfected into MSCs. The mRNA expression of type Ⅱ collagen and proteoglycan was detected by using quantitative polymerase chain reaction (PGR) technique. Results At 2nd, and 4th day after transfection of plasmid pEGFP-C3-BMP-2 into MSCs, the mRNA expression levels of type Ⅱ collagen and proteoglycan in MSCs of experimental group were significantly higher than controls (P ＜ 0. 05 ). Conclusion Recombinant eukaryotic expression plastmid pEGFP-C3-BMP-2 can induce MSCs differentiation towards chondrocytes.     

Transplantation of mesenchymal stem cells in a canine disc degeneration model

Transplantation of mesenchymal stem cells (MSCs) is effective in decelerating disc degeneration in small animals; much remains unknown about this new therapy in larger animals or humans. Fas‐ligand (FasL), which is only found in tissues with isolated immune privilege, is expressed in IVDs, particularly in the nucleus pulposus (NP). Maintaining the FasL level is important for IVD function. This study evaluated whether MSC transplantation has an effect on the suppression of disc degeneration and preservation of immune privilege in a canine model of disc degeneration. Mature beagles were separated into a normal control group (NC), a MSC group, and the disc degeneration (nucleotomy‐only) group. In the MSC group, 4 weeks after nucleotomy, MSCs were transplanted into the degeneration‐induced discs. The animals were followed for 12 weeks after the initial operation. Subsequently, radiological, histological, biochemical, immunohistochemical, and RT‐PCR analyses were performed. MSC transplantation effectively led to the regeneration of degenerated discs. FACS and RT‐PCR analyses of MSCs before transplantation demonstrated that the MSCs expressed FasL at the genetic level, not at the protein level. GFP‐positive MSCs detected in the NP region 8 weeks after transplantation expressed FasL protein. The results of this study suggest that MSC transplantation may contribute to the maintenance of IVD immune privilege by the differentiation of transplanted MSCs into cells expressing FasL. © 2008 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 26:589–600, 2008     

组织工程化椎间盘构建及其生物学评定

目的 探讨人骨髓间充质干细胞(BM-MSCs)经诱导转化为人髓核细胞(NPs)并构建组织工程椎间盘的价值.方法 体外培养胎儿NPs及BM-MSCs并种植在聚乳酸-聚羟基乙酸共聚物(PLGA)支架上,倒置显微镜及扫描电镜进行形态学观察.将载有BM-MSCs和NPs的PLGA支架及BM-MSCs和NPs的细胞悬液植入新西兰大白兔椎间盘中,12周后对椎间盘信号强度按Thompson分级进行评定.分光光度法检测蛋白聚糖并免疫组化检测Ⅱ型胶原的表达.结果 BM-MSCs在与NPs共培养后由梭形、多角形变为成纤维细胞样,且两种细胞在PLGA支架表面贴附,形态正常,生长良好;载有BM-MSCs和NPs的PLGA支架在椎间MRI信号维持、蛋白多糖[PLGA支架组含量为(3.93±0.31)mg/100 mg,对照组为(3.52±0.26)mg/100 mg]及Ⅱ型胶原表达上较对照组差异均有统计学意义(P＜0.05).结论 共培养可促使BM-MSCs向NPs转化,PLGA支架为细胞提供良好的生长环境,其力学性能维持和空间结构保障可以满足BM-MSCs与NPs构建组织工程椎间盘的需要,有效延缓了椎间盘的退变.

Abstract：

Objective To investigate the value of bone marrow-mesenchymal stem cells(BMMSCs)transformed by nucleus pulposus(NPs)for construction of tissue engineering disc.Methods BMMSCs and fetal NPs were cultured in vitro,planted on polylactic acid-polyglycolic acid copolymer(PLGA),and observed with inverted microscope and scanning electronic microscope.PLGA scaffolds with adherent BM-MSCs and NPs,as well as BM-MSCs and NPs suspension were implanted into intervertebral discs of New Zealand white rabbits,respectively.Intervertebral signal intensity was evaluated by Thompson grading 12 weeks later.Proteoglycan and type Ⅱ collagen were determined by spectrophotometric method and immunohistochemistry,respectively.Results Spindle or multi-angular BM-MSCs turned into fibro-like phenotype coculture of BM-MSCs and NPs,which grew well with normal morphology when they attached on PLGA scaffolds.There was statistical difference in intervertebral signal intensity,and the expression of proteoglycan and type Ⅱ collagen between PLGA scaffolds group and control group(P＜0.05),the content of proteoglycan was(3.93 ± 0.31)mg/100 mg in the PLGA scaffolds group whereas(3.52 ± 0.26)mg/100 mg in the control group.Conclusions BM-MSCs can be induced into NPs by cocultivation,and PLGA scaffolds can provide good growing conditions,and maintain high mechanical properties and spacial structure which meet the requirement of tissue engineering disc to prevent degeneration.