胶原凝胶构建神经组织工程支架的实验研究

目的研究胶原凝胶支架对大鼠BMSCs增殖和分化的影响,探讨其作为神经组织工程支架的可行性。方法利用Ⅰ型胶原制备胶原凝胶支架。采用密度梯度离心法分离培养大鼠BMSCs,取第5代细胞制备胶原凝胶-BMSCs复合体。采用扫描电镜、HE染色观察胶原凝胶支架的形态结构及复合培养后细胞形态;MTT检测该支架对BMSCs增殖的影响。取绿色荧光蛋白(green fluorescent protein,GFP)阳性(GFP~+)BMSCs于胶原凝胶支架中培养24 h,通过激光共聚焦显微镜及活细胞工作站观察细胞生长及与材料的黏附情况。结果激光共聚焦显微镜及活细胞工作站观察示,GFP~+BMSCs均匀分布于胶原凝胶支架内,大部分GFP~+BMSCs呈梭形,部分细胞伸出突起,部分细胞间形成连接,提示BMSCs在三维空间中生长良好。扫描电镜示胶原凝胶支架为多孔纤维网状结构,BMSCs可黏附于该支架材料上,细胞形态良好。MTT检测示,BMSCs于胶原凝胶支架中培养后3、5、7 d的吸光度(A)值均高于单纯BMSCs培养,其中5、7 d时组间差异有统计学意义(t=4.472,P=0.011;t=4.819,P=0.009)。HE染色示,胶原凝胶支架呈均质淡粉染细丝样物质。BMSCs在胶原凝胶内培养24 h后均匀分布其中;7 d时BMSCs形态多样,部分细胞伸出细长突起,具有体外培养的神经元样形态。结论胶原凝胶支架制备简便,具有良好的生物相容性,可作为神经组织工程支架材料。     

多孔钽材料细胞毒性、生物相容性及体内成骨性研究

 目的 探讨国产多孔钽材料的细胞毒性和生物相容性,并通过兔骨内植入成骨示踪观察其成骨作用。方法 扫描电镜观察并测量多孔钽的形态学特征。来源于新西兰胎兔颅盖骨的成骨细胞以多孔钽浸提液（实验组）及完全培养基（对照组）培养,MTT法检测多孔钽的细胞毒性及其对增殖的影响。成骨细胞与多孔钽体外复合培养,观察成骨细胞的黏附、生长及增殖。雄性新西兰大白兔24只,制备股骨髁上多孔钽棒植入模型;4只动物于术后第5天和第19天分别肌肉注射荧光素钙黄绿素和茜素红,术后10 周取材,于488 nm（钙黄绿素激发光）和543 nm（茜素红激发光）波长处,激光扫描共聚焦显微镜观察多孔钽-骨界面成骨;20只动物于术后2、4、8和12 周取材行大体及硬组织切片观察。结果 多孔钽表面及断面可见均匀分布的三维立体连通孔隙结构。MTT法检测显示实验组与对照组细胞随培养时间的延长,其OD值的差异均无统计学意义。扫描电镜显示复合培养早期,细胞在多孔支架表面和孔壁上黏附,相互连接;晚期汇合成片并分泌细胞外基质覆盖材料表面。体内成骨实验显示植入的多孔钽棒与宿主骨结合紧密。硬组织切片显示术后2、4周时多孔钽-骨界面已出现新生骨及小血管,并向孔隙内生长;8、12周时多孔钽表面和孔隙内已长满新生骨组织,新生骨小梁已发育成熟并与材料直接接触。激光共聚焦扫描显微镜显示多孔钽-骨界面及孔隙内可见绿色荧光（钙黄绿素）和红色荧光（茜素红）标记的新生骨组织,红色荧光带位于绿色荧光带周围,早期均呈不连续性,晚期则融为一体。结论 国产多孔钽材料无细胞毒性,具有良好的生物相容性,多孔钽-骨界面为接触及传导性成骨并呈时间依赖性。     

微重力环境下体外构建组织工程化椎间盘

[目的]利用微重力培养环境,构建高质量组织工程化椎间盘。[方法]选用成年新西兰大白兔椎间盘细胞作为种子细胞,复合聚乳酸-羟基乙酸(PLGA)支架,分别在微重力培养环境和普通培养板环境下培养,利用倒置显微镜、MTT比色法、扫描电镜、组织学观察椎间盘细胞、支架和复合结构质量。[结果]体外单层培养的椎间盘细胞呈多角形符合传代要求,微重力环境比普通培养环境能更好地促进椎间盘细胞的增殖,同时椎间盘细胞在支架内分布更加均匀。[结论]微重力培养环境更适于椎间盘细胞在三维培养结构中均匀增殖,有利于构建高质量组织工程化椎间盘用于深入研究。     

可降解高分子丙交酯-乙交酯共聚物(PLGA)三维支架的细胞相容性和鼻软骨组织工程

目的 探讨可生物降解丙交酯-乙交酯共聚物(PLGA)(80∶20)三维多孔支架生物相容性及用于构建组织工程鼻软骨可行性,为临床鼻软骨缺损的修复提供新来源.方法 体外分离培养新生兔关节软骨细胞,采用计算机形态分析和MTT法检测兔软骨细胞在PLGA膜和支架表面粘附、扩展和增殖情况.将培养扩增的兔软骨细胞,按6×106 cels/ml浓度接种于预加工的人鼻软骨外形PLGA多孔支架内,抗坏血酸体外诱导培养4周,形成软骨样组织,倒置显微镜、组织切片、扫描电镜观察人工软骨的组织形态结构.结果 培养开始阶段,软骨细胞在PLGA膜表面粘附较差,以后逐渐增高,24小时接近于对照组;MTT法结果显示,软骨细胞在PLGA支架内培养7天时细胞绝对数量明显增加,而相对增殖率逐渐下降.肉眼观察,培养物为人鼻软骨外形的透明软骨样组织,具有一定弹性和硬度,表面有大量软骨基质形成;倒置显微镜下可见人工软骨周围有大量软骨细胞聚集和细胞外基质形成.组织切片及扫描电镜分析,多孔支架材料的网孔不完整,孔内有大量软骨细胞和细胞外基质,可见典型软骨陷窝样结构.结论 可生物降解PLGA制备的三维多孔支架具有较好生物相容性和可塑性,可用于组织工程鼻软骨体外构建,具有潜在的临床应用价值.     

脱细胞软骨基质来源的多孔支架复合山羊髓核细胞体内初步构建组织工程髓核的实验研究

[目的]探讨脱细胞软骨基质多孔支架复合PKH26标记的山羊髓核细胞体内异位构建组织工程髓核的可行性.[方法]制备脱细胞软骨基质来源的多孔支架,扫描电镜(scanning electron microscope,SEM)观察、天狼星红染色、HE染色观察、MTT毒性检测;分离山羊髓核细胞,通过倒置显微镜观察、番红O染色、Ⅱ型胶原免疫组化染色进行鉴定;将PKH26标记的山羊髓核细胞接种支架上,体外培养3d后进行LIVE/DEAD活性染色,将细胞支架复合物置入裸鼠皮下,培养6周,病理切片,荧光显微镜下观察,进行番红O、Ⅰ、Ⅱ型胶原免疫组化染色.[结果]扫描电镜观察支架孔隙相连通且分布均匀,天狼星红染色支架呈黄绿相间色,HE支架淡染,MTT检测细胞增殖曲线无统计学差异(P＞0.05);P1代髓核细胞呈软骨样细胞形态,番红O染色、Ⅱ型胶原免疫组化染色均阳性,PKH26标记后的细胞呈红色荧光;体外LIVE/DEAD染色细胞呈绿色荧光,体内培养6周后,带红色荧光的细胞填满支架孔隙,番红O、Ⅱ型胶原免疫组化染色阳性,Ⅰ型胶原免疫组化染色弱阳性.[结论]以脱细胞软骨基质多孔支架复合山羊髓核细胞在体内能够形成组织工程髓核样组织.     

仿生髓核组织工程支架材料的在体组织性能研究

[目的]初步评价自行设计构建的仿生髓核组织工程支架材料-CHCS支架的在体组织性能。[方法]以单层培养的传1代髓核细胞为种子细胞,体外初步构建细胞-CHCS支架复合体,并植入摘除髓核的椎间盘内,观察椎间隙的高度、相应节段生物力学性能以及组织学改变。[结果]成功构建了细胞-CHCS支架复合体,植入摘除髓核的椎间盘内,髓核细胞能够成功地合成和分泌PG等细胞外基质。在12周时,细胞-支架复合体初步形成了解剖学上的髓核样结构。8周后能有效缓解椎间隙高度的下降和抗压、屈曲、伸直强度的降低。[结论]所构建的细胞-支架复合体对于椎间盘的退变有一定的延缓作用。同时表明所构建的CHCS支架具有良好的在体组织性能。     

细胞复合β-磷酸三钙生物陶瓷修复软骨缺损的实验研究

[目的]通过将骨髓间充质干细胞（MCSc）诱导的具有软骨细胞、成骨细胞表型的细胞接种到三维多孔β-磷酸三钙（β-TCP）生物陶瓷支架材料上，体外构建骨软骨复合体，探讨以β-TCP为载体建造组织工程化软骨修复骨软骨缺损的可行性。[方法]将β-TCP多孔陶瓷加工成圆柱状，并将其作为构建人工软骨的细胞支架。在支架材料上分别接种从犬骨髓干细胞培养成的具有软骨细胞、成骨细胞表型的细胞，将细胞-支架复合体共同培养1周后，移植到犬关节软骨缺损处。植入后12、16周末取材，进行大体观察、组织学及组织化学等观察。[结果]复合体体内移植后，在犬关节软骨缺损处有新生软骨形成，形成的软骨基本保持了支架材料原有形态。[结论]β-TCP多孔陶瓷可作为支架材料，复合细胞后具有修复软骨缺损的作用。     

绿色荧光蛋白标记结合激光共聚焦显微镜三维重建技术观测组织工程骨的构建和体内移植

目的结合荧光蛋白标记技术和激光共聚焦显微镜三维重建技术观察体外构建的组织工程骨及其体内移植情况,为筛选优良的支架材料和三维构建方法提供技术支持。方法取2岁龄青山羊(体重约25kg)髂骨骨髓,利用密度梯度离心法结合贴壁培养法分离培养BMSCs,并通过流式细胞技术检测表面分子CD29、CD60L、CD45和CD44表达情况。将质粒pLEGFP-N1扩增、提取后酶切鉴定。用脂质体转染的方法将质粒转染到PT67包装细胞,G418筛选后扩增,获取病毒液。根据测定的滴度转染BMSCs,获得绿色荧光蛋白(green fluorescent protein,GFP)表达的BMSCs,扩增后作为种子细胞,以脱钙骨基质作为支架材料构建组织工程骨,并利用激光共聚焦显微镜观察种子细胞。将构建的组织工程骨移植到山羊股骨缺损处,利用激光共聚焦显微镜观察其存活和分布情况。结果获得的细胞呈成纤维细胞状,CD29和CD44呈阳性表达,CD60L和CD45呈阴性。质粒pLEGFP-N1用HindⅢ、BamHⅠ、SalⅠ和BglⅡ内切酶酶切后,凝胶电泳可见其相对分子质量约6900bp。将pLEGFP-N1转染到PT67包装细胞扩增后获取病毒液。根据测定的滴度(1.3×106cfu/mL)转染BMSCs,获得GFP表达阳性的BMSCs克隆。激光共聚焦显微镜三维立体成像技术观察到BMSCs在组织工程骨支架上分布、增殖和迁移。将构建的组织工程骨移植到山羊股骨缺损处,28d后激光共聚焦显微镜观察到GFP阳性细胞在移植区仍存在。结论荧光蛋白标记技术结合激光共聚焦显微镜三维重建技术可很好地观察支架上和移植体内的细胞,为组织工程产物三维培养的立体观察提供了可行方法 。     

基于细胞外基质来源的组织工程椎间盘双相支架裸鼠皮下异位构建椎间盘

[目的]探讨椎间盘细胞和细胞外基质来源的一体化纤维环-髓核双相支架在裸鼠体内异位构建组织工程一体化椎间盘的可行性,并采用PKH26荧光标记和小动物活体荧光成像系统无创评估组织工程化细胞-支架复合体在体内生长情况。[方法]纤维环细胞和髓核细胞分别标记PKH26荧光,分别接种入细胞外基质来源的一体化支架不同相中,扫描电镜、Dead/Live荧光染色观察细胞粘附及活性,植入裸鼠背部皮下,6周后利用分子小动物活体荧光成像系统评价组织工程化组织在裸鼠体内生长情况,取材进行荧光显微镜下观察、组织学染色。[结果]扫描电镜观察细胞粘附在双相支架上且周围有基质分泌,Dead/Live染色示细胞在双相支架上活性良好;6周后,活体荧光成像显示椎间盘细胞在支架内生长良好,从髓核往纤维环荧光强度减弱,细胞支架复合体在裸鼠体内形成椎间盘样组织,HE、番红O染色、甲苯胺蓝染色阳性。[结论]天然骨基质明胶和软骨基质来源的一体化纤维环-髓核支架复合椎间盘细胞能够在裸鼠皮下异位构建椎间盘样组织。     

软骨脱细胞基质仿生支架体外构建组织工程软骨

目的探索软骨脱细胞基质(ACM)仿生支架体外构建组织工程软骨的可行性。方法将软骨组织彻底粉碎后脱细胞处理,复合一定比例的明胶(GT)制备三维多孔支架。分析比较不同ACM/GT比例多孔支架的孔径、孔隙率、生物力学和降解速率,选取最适宜软骨体外再生的一组多孔支架用于体外构建。获取、培养猪关节软骨细胞,接种于ACM多孔支架上,体外培养8周后,行大体观察及组织学检测。结果 ACM多孔支架孔隙分布均匀,随ACM含量的增加,孔径和孔隙率逐渐增大,力学强度逐渐降低,其中,ACM:GT=5:5组在孔径和孔隙率方面均适宜体外软骨再生。大体观察和组织学检测显示,ACM支架可体外再生均质、典型的软骨组织。结论 ACM可制成适宜软骨再生的三维多孔支架,并可体外构建组织工程软骨。     

Tissue engineering of heart valves: in vitro experiences

BACKGROUND: Tissue engineering is a new approach, whereby techniques are being developed to transplant autologous cells onto biodegradable scaffolds to ultimately form new functional tissue in vitro and in vivo. Our laboratory has focused on the tissue engineering of heart valves, and we have fabricated a trileaflet heart valve scaffold from a biodegradable polymer, a polyhydroxyalkanoate. In this experiment we evaluated the suitability of this scaffold material as well as in vitro conditioning to create viable tissue for tissue engineering of a trileaflet heart valve. METHODS: We constructed a biodegradable and biocompatible trileaflet heart valve scaffold from a porous polyhydroxyalkanoate (Meatabolix Inc, Cambridge, MA). The scaffold consisted of a cylindrical stent (1 x 15 x 20 mm inner diameter) and leaflets (0.3 mm thick), which were attached to the stent by thermal processing techniques. The porous heart valve scaffold (pore size 100 to 240 microm) was seeded with vascular cells grown and expanded from an ovine carotid artery and placed into a pulsatile flow bioreactor for 1, 4, and 8 days. Analysis of the engineered tissue included biochemical examination, enviromental scanning electron microscopy, and histology. RESULTS: It was possible to create a trileaflet heart valve scaffold from polyhydroxyalkanoate, which opened and closed synchronously in a pulsatile flow bioreactor. The cells grew into the pores and formed a confluent layer after incubation and pulsatile flow exposure. The cells were mostly viable and formed connective tissue between the inside and the outside of the porous heart valve scaffold. Additionally, we demonstrated cell proliferation (DNA assay) and the capacity to generate collagen as measured by hydroxyproline assay and movat-stained glycosaminoglycans under in vitro pulsatile flow conditions. CONCLUSIONS: Polyhydroxyalkanoates can be used to fabricate a porous, biodegradable heart valve scaffold. The cells appear to be viable and extracellular matrix formation was induced after pulsatile flow exposure.     

Ⅰ型胶原半月板支架负载纤维软骨细胞体外培养

[目的]观察Ⅰ型胶原半月板支架对纤维软骨细胞的吸附作用及对细胞生物学性状的影响，评价其作为半月板组织工程支架的可行性及价值。[方法]构建Ⅰ型胶原半月板支架，将体外培养的兔半月板纤维软骨细胞吸附于该支架上三维立体培养，通过相差倒置显微镜、组织学、扫描电镜及免疫组织化学检测支架对半月板纤维软骨细胞的表型、增殖及功能的影响。[结果]Ⅰ型胶原能制成理想大小、形状的三维立体多孔半月板支架，纤维软骨细胞在支架孔壁贴附良好，维持表型稳定，分泌胞外基质。[结论]Ⅰ型胶原半月板支架细胞相容性良好，但力学性能相对较差，通过与其它生物材料复合以提高其机械力学强度，可望制得理想的半月板组织工程支架。     

胶原-透明质酸支架的制备及其与软骨细胞复合培养的实验研究

目的制备胶原-透明质酸支架,评价其与兔髁状突软骨细胞的生物相容性,探讨其应用于关节软骨组织工程的可行性。方法冷冻干燥法制备胶原-透明质酸复合多孔海绵支架材料,将其与碳化二亚胺[1-ethyl-3-（3-dimethyl aminopropyl）carbodiimide,EDC]进行化学交联。分别采用体积法和体外酶解实验测定支架材料孔隙率和降解率,扫描电镜观察交联前后支架材料的形态变化。取3周龄新西兰兔髁状突软骨细胞,体外培养5d后,甲苯胺蓝染色,倒置相差显微镜下观察行细胞鉴定。取消化后第2代软骨细胞接种至支架材料复合培养,倒置相差显微镜下观察细胞生长情况。复合培养1、3、5、7和10d后,PBS液清洗3次,置入24孔板并以0.25%胰酶和0.1%EDTA消化细胞,采集细胞进行细胞计数并绘制细胞生长曲线。另取部分样本继续培养5d,行组织学和扫描电镜观察。结果胶原-透明质酸支架材料经化学交联后,具有合适的三维多孔结构,孔隙率为83.7%,孔径100-120μm;交联后抗酶解能力显著增加。髁状突软骨细胞在其表面和内部贴附良好,形成细胞-材料复合体,细胞增殖实验显示,复合培养1d,材料中细胞数为3.7×104/支架,10d后增至8.2×104/支架。电镜观察见细胞周围有基质分泌。结论EDC交联后的胶原-透明质酸支架具有良好空间结构和生物相容性,可作为支架材料用于髁状突软骨组织工程的研究。     

组织工程软骨体外构建的相关实验研究

目的 探索组织工程软骨体外构建技术体系可行性.方法 种子细胞选用胎儿软骨细胞(口服药物流产胎儿,胎龄3～6个月).酶消化法获得第1代细胞,以50×106/ml浓度均匀接种于经聚乳酸(PLA)包埋聚乙醇酸(PGA)高分子聚合物支架,形成细胞-支架复合体,在体外静态培养.分别于2周、4周、8周进行大体观察、扫描电镜及组织学检测.结果 体外构建的组织工程软骨,随培养时间延长,色泽由2周时的乳白色逐渐呈现半透明,8周时接近正常软骨外观.扫描电镜显示软骨细胞与材料具有良好相容性,培养7天PGA纤维之间有基质沉积.HE染色示2周有大量软骨陷窝形成和均匀嗜碱性基质分泌,Safranin'O染色示基质有酸性蛋白多糖分布,Massons's trichome染色示基质有胶原成分,但含量较少,经免疫组织化学检测为特异Ⅱ型胶原.培养4周胶原成分开始明显增多,软骨陷窝形态接近成熟,8周细胞外基质蛋白多糖和Ⅱ型胶原含量丰富且分布均匀.结论 以成熟软骨细胞为种子细胞,运用组织工程技术在体外能构建出具有正常软骨组织结构特征的人组织工程软骨.     

以软骨细胞外基质与脱细胞骨基质构建组织工程骨软骨双层支架及其性能的研究

目的 探讨采用软骨细胞外基质(CECM)与脱细胞骨基质(ACBM)为材料制作新型组织工程骨软骨双层支架的可行性,并检测其性能.方法 双层支架的骨部分以犬松质骨制备的ACBM为原料,软骨部分以人CECM为材料,采用冷冻冻干法制备CECM/ACBM双层支架并交联.测定支架孔隙率,采用四甲基偶氮唑盐(MTT)法分析支架浸提液毒性.分离培养犬骨髓基质干细胞(BMSCs),成软骨诱导后种植到支架上,倒置显微镜、电镜、Dead/Live荧光染色观察细胞在支架的生长、分化情况.结果 扫描电镜及Micro-CT观察显示支架内孔洞相互贯通呈海绵状,CECM部分孔径(155±34)μm,孔隙率为91.3%±2.0%;ACBM部分具有大然骨的孔径和空隙率,骨软骨部分结合良好.培养1～6 d不同浓度支架浸提液与对照培养液吸光度值比较羌异均无统计学意义(P＞0.05).倒置显微镜、电镜检查结果表明BMSCs在支架上黏附良好,细胞基质分泌增加,Dead/Live荧光染色表明双层支架内细胞均呈绿色.结论 CECM/ACBM骨软骨双层支架具备良好的孔径和孔隙率,骨、软骨两层间结合良好,无毒,生物相容性良好,可作为支架载体用于组织工程骨软骨复合体的构建.

Abstract：

Objective To fabricate a novel bilayered scaffold constructed with cartilage extracellular matrix (CECM) and acellular bone matrix (ACBM) for osteochondral tissue engineering.Methods The bone layer of the osteochondral scaffold was prepared using canine bone cancellous bone columns, and the cartilage layer was fabricated using CECM.After CECM microfilaments were decellularized, the biphasic scaffolds were fabricated by soaking the ACBM columns into cylindrical silicon moulds with a 30 g/L CECM suspension using simple freeze-drying method.After the scaffolds were cross-linked, the porosity was measureed.MTT test was also done to assess cytotoxicity of the scaffolds.Canine bone marrow-derived mesenchymal stem cells (BMSCs) were induced by chondrogenic medium and seeded into novel scaffold.Cell proliferation and differentiation were analyzed using inverted microscopy, scanning electron microscopy (SEM)and Dead/Live staining method.Results SEM and Micro-CT revealed a 3-D interconnected porous structure, with the CECM pore diameter of 155 ± 34 μm and the porosity of 91.3% ± 2.0%.Cytotoxicity testing with MTT revealed no significant difference in absorbance among different extracts, showing no cytotoxic effect of the scaffold on BMSCs.Inverted microscopy and SEM showed that the novel scaffold could provide a suitable 3-D environment to support the adhesion, proliferation and differentiation of BMSCs to chondroeytes in culture with chondrogenic medium.Confocal microscopy of cell-scaffold constructs revealed cells with green fluorescence.Conclusion Since the novel CECM/ACBM bilayered integrated osteochondral scaffold has good mircostructure, non-toxicity and good biocompatibility, it may be a suitable candidate as an alternative cell-carrier for osteochondral tissue engineering.     

Tissue engineered cartilage generated from human trachea using DegraPol scaffold.

OBJECTIVE: To date numerous attempts have been undertaken to conquer the challenging problem of reconstructing long segmental tracheal defects, as yet without lasting success. Recently, employing concepts of tissue engineering in animals, cartilage-like constructs were transplanted in vivo. However, both the feasibility of fabricating tracheal replacements and the use of human tracheal chondrocytes (HTC) for tissue engineering are still under investigation. In this study, we optimized isolation and cultivation techniques for human tracheal cartilage, assessing the feasibility of seeding these cells onto a novel, three-dimensional (3-D) polyester-urethane polymer (DegraPol). METHODS: Human tracheal cartilage was harvested from the trachea of lung donors, digested in 0.3% collagenase II, and the condrocytes serially passaged every 7-9 days. Cells were also cultivated over agar plate during the total 6-8 weeks expansion phase. Thereafter, chondrocytes were seeded onto DegraPol (pore sizes 150-200 microm) with a seeding density of 2.4 x 10(7)/ml, and chondrocyte-polymer constructs maintained during in vitro static culture. RESULTS: HTC displayed stable proliferation kinetics in monolayer culture with positive expression of collagen type II. Following polymer seeding, both cellular proliferation and extracellular matrix (ECM) production, as measured by MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) and glycosaminoglycan assays, continued over extended culture. Active growth of HTC on DegraPol was further demonstrated by Alcian blue staining, with the histomorphological appearance of the construct resembling that of native cartilage. Scanning electron microscopy showed chondrocyte growth and ECM synthesis both on the surface and inside the porous scaffold, with a dense cell layer on the surface of the scaffold and a lower cell distribution in the scaffold's interior. CONCLUSIONS: The harvested chondrocytes from human trachea cartilage expand well in vitro and possess the ability to form new cartilage-like tissue when seeded onto DegraPol matrix. However, improved culture conditions are needed to permit cellular growth throughout cell-polymer constructs.     

柱状分层的胶原-羟基磷灰石复合支架负载软骨细胞体外培养

目的 观察具有柱状分层结构的胶原-羟基磷灰石（hydroxyapatite，HA）复合支架对软骨细胞的吸附作用及对软骨细胞生物学性状的影响，评价其作为软骨组织工程支架的可行性及价值。方法 以胶原复合HA逐层制备胶原-HA复合支架，体外培养新西兰大白兔关节软骨细胞并扩增，吸附于多孔胶原-HA复合支架材料上进行三维立体培养3周，通过倒置相差显微镜、组织学、扫描电镜及免疫组织化学检测支架对软骨细胞的表型、增殖及功能的影响。结果 胶原-HA复合支架为柱状，支架表层为胶原。平均孔径为147μm，孔隙率89％；中层为多孔胶原-HA复合；底层为HA，平均孔径为85μm，孔隙率85％。胶原-HA复合支架亲水性好，软骨细胞吸附于支架表面24h后，增殖并逐渐顺孔隙迁徙至支架内部，在孔壁贴附良好，表型维持稳定，分泌细胞外基质，Ⅱ型胶原免疫组织化学染色阳性。结论 具有柱状分层结构的胶原-HA复合支架其细胞相容性良好，较胶原纤维具有更强的力学性能，有望成为一种比较理想的软骨组织工程支架材料。     

Fetal tissue engineering from amniotic fluid

BACKGROUND: We have recently shown, in an animal model, that amniotic fluid can be a source of cells for fetal tissue engineering. This study was aimed at determining whether fetal tissue constructs could also be engineered from cells normally found in human amniotic fluid. STUDY DESIGN: Cells obtained from the amniotic fluid of pregnant women at 15 to 19 weeks of gestation (n=6) were cultured in Dulbecco's Modified Eagle's medium (Sigma Chemical, St Louis, MO) containing 20% fetal bovine serum and 5 ng/mL basic fibroblast growth factor in a 95% humidified, 5% CO(2) chamber at 37 degrees C. A subpopulation of morphologically distinct cells was then mechanically isolated from the rest and selectively expanded. The lineage of this subpopulation of amniocytes was determined by immunofluorescent staining with antibodies against standard intermediate filaments and surface antigens. Cell proliferation rates were determined by oxidation assay. After cell expansion, colonies of amniocytes were statically and dynamically seeded onto both unwoven, 1-mm-thick polyglycolic acid polymer scaffold and acellular human dermis for 72 hours. The resulting constructs were analyzed by scanning electron microscopy. RESULTS: Amniocytes stained positively for smooth muscle actin, vimentin, cytokeratin 18, and fibroblast surface protein, and negatively for desmin, cluster of differentiation 31, and von Willebrand's factor (Dako, Carpenteria, CA). These findings are consistent with a mesenchymal, fibroblast-myofibroblast cell lineage. Mesenchymal amniocytes could be rapidly expanded in culture, based on results of the proliferation assay. Scanning electron microscopy of amniocyte constructs revealed dense, confluent layers of cells surrounding the polymer matrices and firm cell adhesion to both PGA and Alloderm (Lifecell Corp, Branchburg, NJ) scaffolds. No evidence of cell death was observed. CONCLUSIONS: Subpopulations of fetal mesenchymal cells can be consistently isolated from human amniotic fluid and rapidly expanded in vitro. Human mesenchymal amniocytes attach firmly to both polyglycolic acid polymer and acellular human dermis. The amniotic fluid can be a valuable and practical cell source for fetal tissue engineering.     

骨髓间充质细胞与速固化磷酸钙支架共培养的实验研究

[目的]观察人骨髓间充质干细胞在速固化磷酸钙骨水泥支架中的增殖和生长情况。[方法]将速固化壳聚糖-磷酸钙骨水泥支架材料预先成形。采用全骨髓法分离人骨髓间充质细胞并在体外对细胞进行培养和扩增。72h首次换液,细胞融合80%传代,取第3代细胞用于实验。将细胞与磷酸钙骨水泥支架复合培养,分别利用四甲基偶氮唑蓝MTT法及扫描电镜等检测细胞在材料中的增殖和生长情况。[结果]用酶标仪检测OD值提示共培养后,支架内的细胞数量逐渐增加。扫描电镜结果显示支架材料内部为多孔结构,孔内见有细胞生长,细胞表面可见分泌颗粒。[结论]速固化壳聚糖-磷酸钙骨水泥对人骨髓间充质干细胞有较好的细胞相容性,细胞可在材料内黏附和增殖,是理想的骨组织工程支架材料。     

The placenta as a cell source in fetal tissue engineering

Purpose: This study was aimed at determining whether fetal tissue constructs can be engineered from cells derived from the placenta. Methods: A subpopulation of morphologically distinct cells was isolated mechanically from specimens of human placenta (n = 6) and selectively expanded. The lineage of these cells was determined by immunofluorescent staining against multiple intermediate filaments and surface antigens. Cell proliferation rates were determined by oxidation assays and compared with those of immunocytochemically identical cells derived from human amniotic fluid samples (n = 6). Statistical analysis was by analysis of variance (ANOVA). After expansion, the cells were seeded onto a polyglycolic acid polymer/poly-4-hydroxybutyrate scaffold. The resulting construct was analyzed by both optical and scanning electron microscopy. Results: The immunocytochemical profile of expanded placental cells was consistent with a nontrophoblastic, mesenchymal origin. Their proliferation rate in culture was not significantly different when compared with mesenchymal fetal cells isolated from human amniotic fluid; however, it was greater than previously reported rates for similar cells obtained from postnatal or adult tissues. Construct analysis showed dense layers of cells firmly attached to the scaffold without evidence of cell death. Conclusions: Subpopulations of nontrophoblastic, mesenchymal cells can be isolated consistently from the human placenta. These cells proliferate as rapidly as fetal mesenchymal amniocytes in vitro and attach firmly to polyglycolic acid scaffolds. The placenta can be a valuable and practical source of cells for the engineering of select fetal tissue constructs. J Pediatr Surg 37:995-999.