全骨髓贴壁接触培养SD大鼠骨髓间充质干细胞

背景：体外分离培养出生长状态好、高纯度、增殖能力强和数量充足的大鼠骨髓间充质干细胞,是将其作为种子细胞用于组织和细胞移植的重要前提。 目的：建立简便、快速、有效的SD大鼠骨髓间充质干细胞体外分离培养方法,并观察其生物学特性。 方法：采用全骨髓法将SD大鼠双侧股骨和胫骨骨髓细胞进行体外分离培养,贴壁接种法进行细胞纯化、传代。观察细胞生长形态及特征,绘制细胞生长曲线,检测细胞表面标记物,采用体外诱导剂诱导细胞分别向成骨、成软骨、成脂方向分化。 结果与结论：全骨髓贴壁接种法分离培养的骨髓间充质干细胞生长旺盛、纯度高,细胞生长形态呈长梭形,极性排列,细胞生长呈S形生长曲线,群体倍增时间为29 h,细胞在连续传10代后仍具有较强的增殖能力。第3代骨髓间充质干细胞的表面标记物CD44、CD29、CD90均呈阳性表达,CD45、CD34、CD11b则呈阴性表达。第3代骨髓间充质干细胞分别经成骨、成软骨、成脂诱导剂诱导后,茜素红染色、碱性磷酸酶染色、von-kossa矿化结节染色、甲苯胺蓝染色和油红O染色均呈阳性。结果验证全骨髓贴壁接种法是一种简便可靠的体外分离培养方法,能获得纯度较高的骨髓间充质干细胞,经实验鉴定第3代骨髓间充质干细胞生物活性最佳,且具有多向诱导分化能力,适合作为后续实验的种子细胞。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;组织工程全文链接：     

SD乳鼠骨髓间充质干细胞体外改良筛选法培养及鉴定

目的评估应用SD乳鼠骨髓的改良筛选法分离培养骨髓间充质干细胞(bone marrow mesenchymal stem cell,BMSCs)的可行性及优势,探讨一种简单高效的BMSCs体外分离、纯化及扩增的方法。方法选择7d龄SD大鼠6只,无菌解剖大鼠双侧股骨,于完全培养基浸泡、剪碎,反复吹打暴露骨髓腔,高速震荡3min后取上清液接种于培养瓶中,24h后半量换液,48h后全量换液,以后隔天换液。应用CCK-8法测定生长曲线;成骨分化诱导3周后进行茜素红染色,成脂分化诱导4周后进行油红“O”染色;应用流式细胞仪鉴定细胞表面抗原。结果原代培养的BMSCs细胞生长曲线呈“S”形,接种1d后有少量细胞贴壁,第3~6天为对数增殖期,第7天进入平台期。BMSCs经成骨诱导3周后茜素红染色细胞外基质中可见深红色团块状矿化结节;经成脂肪诱导4周后胞浆内充满“串珠状”红色脂滴。流式细胞仪检测BMSCs表面抗原CD29、CD44、CD90阳性,CD34和CD45阴性。结论应用7d龄SD乳鼠的改良全骨髓自然贴壁筛选法可以高效分离纯化出BMSCs。     

小鼠骨髓间充质干细胞的分离培养及形态学观察

目的建立一种简单实用的小鼠骨髓间充质干细胞(MSCs)的分离培养方法,通过了解其细胞生物学特性,为MSCs的应用提供实验依据。方法采用差速贴壁法体外分离、扩增MSCs,倒置显微镜观察原代及传代细胞的形态及生长过程。结果在小鼠骨髓间充质干细胞的培养过程中,血液系细胞在换液过程被去除,成纤维细胞污染经差速贴壁法也可去除。获得的骨髓间充质细胞形态较均一,生长状态良好。结论采用差速贴壁培养法可获得一定纯度的MSCs,此法简单、实用,并且获得的细胞生长状态良好,增殖能力强.     

不同接种密度骨髓间充质干细胞/骨基质明胶复合体修复大鼠桡骨缺损

背景:在构建种子细胞与载体材料的复合体时,种子细胞的接种密度是影响复合体成骨能力的一个重要因素,目前关于种子细胞的接种密度认识尚不统一。目的:构建骨髓间充质干细胞/骨基质明胶复合体,观察构建复合体骨髓间充质干细胞的最适接种密度。方法:体外单层培养SD大鼠骨髓间充质干细胞,以不同的细胞密度将骨髓间充质干细胞接种到异种骨基质明胶上,构建骨髓间充质干细胞/骨基质明胶复合体,通过扫描电子显微镜观察细胞在骨基质明胶中的黏附生长情况。制备SD大鼠双侧桡骨骨干5mm节段性骨缺损模型。随机分成4组,采用骨髓间充质干细胞/骨基质明胶复合体修复骨缺损,所用的接种细胞密度分别为1×108L-1、5×108L-1、1×109L-1、5×109L-1。各组于第2,4,8,12周取材,通过大体观察大鼠的术肢活动情况,X射线放射学、组织学,免疫组织化学等检测方法,对骨缺损的修复情况进行评价。结果与结论:4种细胞密度与骨基质明胶复合培养24h,骨髓间充质干细胞在骨基质明胶上的黏附率随着细胞接种密度的增高而增高,当密度为1×109L-1时,黏附率最高为(76.00±2.94)%,继续增加细胞密度其黏附率反呈下降趋势。复合培养7d,扫描电子显微镜观察结果显示,材料上均有细胞黏附生长。X射线放射学评分显示,同一组别8,12周评分均高于2周评分(P0.01);第4,8,12周1×109L-1组与5×109L-1组差异无显著性意义(P0.05),均高于其余两组(P0.01)。组织学评分结果表明,同一组别8,12周评分均高于2周评分(P0.01)。结果提示,在构建骨髓间充质干细胞/骨基质明胶复合体时,骨髓间充质干细胞接种密度维持在1×109L-1最佳。     

婴幼儿骨髓间充质干细胞体外培养及基本生物学特性的实验研究

目的 建立一种体外分离和培养婴幼儿骨髓间充质干细胞（bone marrow mesenchymal stem cells，BMSCs）的方法，并探讨其基本生物学特性。方法 麻醉、无菌条件下行胸骨穿刺抽取先天性心脏病婴幼儿骨髓3mL-5mL，经密度梯度离心获得单个核细胞（Percoll分离液，γ为1．073），接种入含10％胎牛血清的低糖DMEM培养液，测定其生长曲线，流式细胞仪检测婴幼儿BMSCs表面标记，并观察其形态、贴壁率、集落形成能力和超微结构的变化。结果 培养的要幼儿BMSCs 3h-4h后开始贴壁，贴壁率为65％-80％；2d-3d可见集落形成；10d左右汇合90％以上。BMSCs随着传代次数增加集落形成率逐渐降低。培养期间细胞形态均一，基本上为梭形成纤维细胞样形态。婴幼儿BMSCs表面标记CD29、CD44、CD71、CD90表达阳性，CD3、CD14、CD34、CD45、HLA-DR不表达。透射电镜观察，婴幼儿BMSCs具有BMSCs典型的超微结构。结论 成功地建立了一种体外分离培养先天性心脏病婴幼儿BMSCs的方法，获得的细胞形态均一，生长稳定，增殖较快，能为体外构建组织工程化先天性心脏病修复材料提供重要的种子细胞的来源。     

大鼠骨髓间充质干细胞分离鉴定方法及生物学特性北大核心

背景:如何能简便高效地获得均质性的骨髓间充质干细胞群是软骨组织工程研究的重点。目的:分离培养大鼠骨髓间充质干细胞,观察其生物学特性。方法:抽取30只SD大鼠股骨以及胫骨骨髓,采用全骨髓贴壁培养法体外分离培养骨髓间充质干细胞,流式细胞仪测定细胞表面标记物的表达,细胞计数法观察细胞生长增殖能力,MTT法检测细胞存活率。结果与结论:(1)刚分离培养的细胞呈圆形、椭圆形,部分细胞呈三角形,接种12-15 d后,细胞开始融合,传代后细胞增殖速度加快,传代2 h后细胞均匀分布在瓶底;(2)随着传代次数的增加,细胞增殖能力出现下降趋势,第1-5代细胞存活率均超过95%,显著高于第6代和第7代(P<0.05);(3)骨髓间充质干细胞表面CD34呈阴性表达,CD44呈阳性表达;(4)结果表明,采用全骨髓贴壁法可有效分离大鼠骨髓间充质干细胞,获得的细胞生长稳定,增殖能力强,可选用前5代细胞作为软骨组织工程的种子细胞。     

大鼠骨髓间充质干细胞的纯化、冻存及成瘤性分析

背景：骨髓间充质干细胞在骨髓中的含量极低,体外的长期培养过程中易丧失干细胞潜能以及体内移植后安全性等问题的存在,限制了骨髓间充质干细胞在临床上的广泛应用。 目的：探索体外分离纯化、冻存大鼠骨髓间充质干细胞的最适方法,并观察以此方法培养的骨髓间充质干细胞移植体内后是否具有成瘤性。 方法：分别采用差速贴壁结合24 h首次换液、24 h首次换液、48 h首次换液的方法纯化培养骨髓间充质干细胞,筛选最适纯化方法进行后续实验。配制含体积分数为10%,20%,30%,40%,50%胎牛血清的细胞冻存液冻存细胞,复苏后计算细胞存活率,测定复苏后细胞的生长曲线及成脂诱导能力。将第3,15代骨髓间充质干细胞进行裸鼠肌肉、肝脏局部注射体内移植,45 d后取注射部位行病理组织标本检查。 结果与结论：差速贴壁结合24 h首次换液法所获得骨髓间充质干细胞纯度最高,而细胞增殖能力与其他两组无明显差别,因此选用该方法纯化骨髓间充质干细胞,然后进行传代培养;含体积分数为30%血清冻存液既可保证细胞活性与增殖能力,又可保证干细胞特性及多向分化潜能。骨髓间充质干细胞传至15代仍保持间充质干细胞特性,骨髓间充质干细胞移植入裸鼠肝脏45 d后仍可在肝脏局部存活,生长状态与体外培养相似,无异型性及向周围浸润生长,提示体外长时间培养15代以内的骨髓间充质干细胞可在裸鼠体内存活且无成瘤性。     

犬骨髓间充质干细胞片层的体外培养与制备

背景:传统的组织工程方法在收获和转移细胞方面存在诸多不足,且难以形成致密的组织,明显限制了组织工程学的发展。目的:探讨犬骨髓间充质干细胞片层的体外培养与制备方法。方法:实验犬麻醉后抽取骨髓,采用密度梯度离心法体外分离骨髓间充质干细胞。取传至第4代细胞,按1×109L-1密度接种于直径3.5cm的温度反应性培养皿中,置于37℃、体积分数为5%的CO2饱和湿度培养箱内培养,待细胞增殖融合时再将培养皿的温度降至20℃培养20min,倒置显微镜下观察细胞形态学变化及细胞片层形成情况。结果与结论:犬骨髓间充质干细胞原代培养24h呈椭圆形或多角形,72h多数细胞伸展贴壁,7d时形成细胞集落,12d时细胞呈长梭形,完全融合,细胞界限不清。温度反应性培养皿中的骨髓间充质干细胞在降温至20℃时,细胞形态发生变化,呈短梭形,且逐步从培养皿底分离,形成含细胞外基质的完整的细胞片层。证实密度梯度离心法可成功分离培养犬骨髓间充质干细胞,通过改变应用温度反应性培养皿的温度,能获取完整的细胞片层。     

C57BL/6小鼠骨髓单核细胞分离、培养、纯化及向破骨细胞的分化

背景：目前骨髓单核细胞的分离提取国内外文献报道,大多是利用RAW264.7细胞诱导分化为破骨细胞。 目的：探讨分离、培养、纯化和鉴定C57BL/6小鼠骨髓单核细胞的方法,观察小鼠骨髓单核细胞体外生长特征,诱导其向破骨细胞分化。 方法：无菌分离C57BL/6小鼠股骨和胫骨,取出骨髓细胞,提取过程中先用红细胞裂解液去除红细胞;骨髓细胞过夜培养后(大于16 h),第2天分离出悬浮细胞,在含有巨噬细胞集落刺激因子的培养基中继续培养获得贴壁的小鼠骨髓单核细胞。通过换液对小鼠骨髓单核细胞进行纯化和扩增培养。进行形态学观察,测定生长曲线,用流式细胞仪检测原代小鼠骨髓单核细胞细胞表面抗原,加入巨噬细胞集落刺激因子和核因子κB受体活化因子配基诱导分化为破骨细胞。 结果与结论：新分离的小鼠骨髓单核细胞呈小圆形,两端伸出触角,培养5 d后,细胞成椭圆形,两端的触角更明显,增殖依赖巨噬细胞集落刺激因子。流式结果显示分离的小鼠骨髓单核细胞纯度较高,能够诱导分化为破骨细胞。利用间充质干细胞与单核细胞的贴壁能力不同及巨噬细胞集落刺激因子显著促进单核细胞贴壁增殖的特性能有效分离获得稳定生长的小鼠骨髓单核细胞。培养的小鼠骨髓单核细胞性状稳定,表型稳定均一,适于做进一步研究。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：     

小鼠骨髓间充质干细胞分离培养方法的建立

目的建立培养小鼠骨髓间充质干细胞(none mesenchymal stem cells,BMSCs)的分离培养方法。方法采用全骨髓体外分离并采用差速贴壁法纯化扩增C57BL/6小鼠BMSCs,形态学观察细胞生长情况,流式细胞仪检测其表面抗原情况并观察其多项分化潜能。结果使用该方法纯化扩增的BMSCs形态均一,生长良好,表达CD29、CD44和Sca-1,不表达CD11b、CD45和CD34,并具有成骨成脂潜能。结论通过全骨髓贴壁法可以成功的分离培养出小鼠BMSCs。     

小鼠精原干细胞冷冻保存

目的 探索小鼠精原干细胞(SSCs)冷冻保存方法 以及解冻后体外快速增殖的条件. 方法 实验以6d龄雄性昆明小白鼠为材料,两步酶消化法分离小鼠睾丸生殖细胞,Percoll非连续密度梯度离心法富集小鼠精原干细胞,随后加入不同的冷冻液以及采用不同的降温速率冷冻小鼠精原干细胞.以MEMα为基本培养基,加入10%胎牛血清和100μg/L的胶质细胞源性神经营养因子, WST-8比色法分析培养SSCs 复苏后的增殖率,运用碱性磷酸酶细胞化学染色和RT-PCR技术,对培养的SSCs进行鉴定. 结果 冷冻液中添加10%二甲基亚砜、10%胎牛血清、0.07mol/L蔗糖时,以1℃/min程控降温方式冷冻小鼠SSCs,细胞解冻后活率最高,达84%以上;采用非程控降温方式冻存SSCs,尽管细胞解冻后活率相对于程控降温方式略低,但具有方法 简单、易于操作、无需昂贵仪器的优点,复苏后SSCs贴壁时间为8～12h,24h可见细胞分裂,48h细胞出现迅速增殖,96h可见较多含20～25细胞的细胞团,此时精原干细胞增殖近5倍. 结论 本实验所用培养条件,可以使经长期冷冻的SSCs短期快速增殖.     

Retinol transport in cultured fat-storing cells of rat liver. Quantitative analysis by anchored cell analysis and sorting system

It is difficult to study the mechanism of specific transport of vitamin A in fat-storing cells (FSC) in vivo. In this study, transport of vitamin A added to the medium was quantitatively analyzed in cultured FSCs by means of the spontaneous fluorescence emitted by vitamin A. By density-gradient centrifugation with 38% Percoll, an FSC-rich fraction was separated from normal rat liver cells. The FSCs were observed to retain cytoplasmic fat droplets even on days 3 and 4 of culture. The FSCs containing fat droplets were selected for this experiment by checking their emission of vitamin A fluorescence. To analyze the vitamin A content of isolated cells, we employed a newly developed anchored cell analysis and sorting system (ACAS 470), which provides fluorescence analysis and sorting of adherent cells under the phase contrast microscope by utilizing a laser with its irradiation range narrowed to 1 micron. Vitamin A fluorescence was detectable by this system even in the cultured FSCs. After 24 hours of culture of FSCs in medium with 1 x 10(-6) M vitamin A added, the strength of fluorescence per FSC was 24.3 +/- 11.2 x 10(5)/cell for control, 61.5 +/- 17.6 x 10(5)/cell for retinyl acetate, 26.0 +/- 12.6 x 10(5)/cell for retinyl palmitate, and 59.0 +/- 15.1 x 10(5)/cell for retinol. Thus, retinol and retinyl acetate were transferred to FSCs in significant amounts without the participation of retinol-binding protein. Furthermore, an extended examination was made of the mechanism of the retinol transport observed in this study. Transport was never inhibited by the presence of vitamin E or azide. Retinol may be transferred by passive transport attributable to the concentration gradient rather than by active transport or through cell membrane damage by retinol itself. There was a tendency for inhibition of the transport of retinol into the cells in fetal calf serum. This inhibition may have occurred because the retinol-binding protein or other serum proteins had decreased the concentration of free retinol.     

全骨髓直接贴壁分离人骨髓间充质干细胞的生物学特性****☆

背景：体外分离培养骨髓间充质干细胞成为实验研究和临床应用的关键环节。 目的：采用全骨髓培养法分离人骨髓间充质干细胞,建立一种简单、有效的分离培养骨髓间充质干细胞的方法。 方法：通过全骨髓培养法分离培养人骨髓间充质干细胞,并通过传代进行纯化和扩增培养。分别在特定诱导体系中诱导人骨髓间充质干细胞向脂肪、成骨及软骨细胞分化。 结果与结论：采用全骨髓培养分离法能获得90%以上纯度的骨髓间充质干细胞;流式细胞仪检测结果显示,贴壁细胞均表达CD73、CD90、CD105,不表达造血细胞表型CD34、CD45和HLA-DR;细胞倍增时间为(24.04±0.49) h;细胞周期分析表明：G0~G1期和S+G2+M期所占比例分别为71.63%和28.37%;诱导分化结果显示,人骨髓间充质干细胞能够向脂肪、骨和软骨细胞分化。说明全骨髓分离培养法是一种较好的分离人骨髓间充质干细胞的方法。     

Milk of cow (Bos taurus), buffalo (Bubalus bubalis), and goat (Capra hircus): a better alternative than fetal bovine serum in media for primary isolation, in vitro cultivation, and maintenance of Leishmania donovani promastigotes

Tyndalized milk of goat, cow, and buffalo was found to be a potential substitute for fetal bovine serum (FBS) in the medium for the cultivation of Leishmania donovani promastigotes. The numbers (means) of promastigotes reached 2.6 x 10(7), 2.3 x 10(7), and 2.1 x 10(7)/ml, respectively, in the medium supplemented with 10% milk of goat, cow, and buffalo, in comparison to 1.9 x 10(7)/ml in the control with 10% FBS. In primary isolation, the milk-supplemented medium showed that 22 out of 26 samples were positive for promastigotes (84.6%) and the cells were maintained successfully during the observed period of 6 months.     

The optimal hepatocyte density for a hollow-fiber bioartificial liver

A bioartificial liver (BAL) based on viable porcine hepatocytes can serve as a bridge to liver transplantation in patients with acute liver failure (ALF). To support liver functions, an adequate mass of hepatocytes is needed, which depends upon the cell density in the BAL device. This study evaluated the optimal density of hepatocytes within BAL devices that were constructed by perfusing porcine hepatocyte suspensions mixed with cytodex-3 into polysulfon hollow-fibers. The BAL devices were prepared with 6 different cell densities. The mass of hepatocytes in each device was evaluated for (a) cell viability, (b) ability to degrade diazepam, (c) ability to synthesize urea, (d) incorporation of [3H]-leucine into protein, (e) glucose-6-phosphatase activity, (f) total RNA content, and (g) p53 gene expression. Hepatocyte viability was about 90% in each device. With increasing hepatocyte density, the diazepam concentration in the medium decreased from 9.26 +/- 0.96 mg/L at 1 x 10(5) cells/ml to a minimum of 5.25 +/- 1.02 mg/L at 5 x 10(6) cells/ml and thereafter remained at low levels. Urea production and [3H]-leucine incorporation into protein increased progressively until the cell density reached 5 x 10(6)/ml and thereafter remained at high levels. Glucose-6-phosphatase activity and total RNA content stayed at high levels until the cell density reached 5 x 10(6)/ml and then progressively decreased. p53 gene expression differed from the other parameters, since it increased only when the cell density reached 5 x 10(7)/ml. In conclusion, the density of 5 x 10(6) cells/ml is a critical inflection point for most of the functional parameters, although p53 gene expression is not elevated at this cell density. These findings suggest that 5 x 10(6) cells/ml is the optimal hepatocyte density in the hollow-fiber BAL device.     

体外培养猪骨髓间充质干细胞hHCN2基因的转染及表达

背景：通过超极化活化的阳离子电流调制心脏自律性成为该领域研究的焦点。 目的：将起搏基因质粒CMV-hHCN2-3xha-IRES-EGFP转染到猪骨髓间充质干细胞,检测其在骨髓间充质干细胞中核酸和蛋白水平是否表达。 方法：采用单纯直接贴壁法或密度梯度离心结合直接贴壁法分离、纯化、增殖获得骨髓间充质干细胞,脂质体2000转染质粒CMV-hHCN2-3xha-IRES-EGFP至骨髓间充质干细胞。 结果与结论：单纯直接贴壁法收集到的细胞增殖速度慢,而密度梯度离心结合直接贴壁法细胞增殖速度较快,原代细胞培养第3代后转染48 h荧光显微镜下可见骨髓间充质干细胞发出荧光,对照组无荧光。细胞转染率达15%-20%。RT-PCR检测及Western blot 印迹检测证明了hHCN2基因在骨髓间充质干细胞有表达。密度梯度离心结合直接贴壁法较单纯直接贴壁法培养骨髓间充质干细胞的培养效率更高。转染目的基因hHCN2的骨髓间充质干细胞蛋白有表达。     

In vitro study of monocyte viability during the initial adhesion to albumin- and fibrinogen-coated surfaces

Surface adherent monocytes and macrophages play a central role in the inflammatory response to biomaterials. In the present study the adhesion, viability and apoptotic changes in material surface adherent monocytes during the first hours of cell-surface interactions in vitro were studied, using tissue culture polystyrene surfaces coated with human albumin and fibrinogen. Human peripheral blood monocytes were enriched by a two-step gradient centrifugation and resuspended (1 x 10(6)/ml) in RPMI with 10% fetal bovine serum. The cells were added to polystyrene surfaces coated with human fibrinogen or albumin and incubated in 37 degrees C (5% CO2, 100% humidity) for 30 min, 1, 2, 3 and 24 h. The adherent cells were stained for early apoptotic changes (exposed phosphatidylserine) and cell death using Annexin-V-fluorescein and propidium iodide staining, respectively. A bi-phasic adhesion was observed on the fibrinogen coated surface, having the highest number of adherent cells after 30 min and 24 h, while the cell number was markedly reduced after 1-3 h. The number of adherent cells on albumin was relatively low after all short time incubations but had reached a high level after 24 h.The number of adherent dead cells was highest after I h on both albumin (approximately 30%) and fibrinogen (approximately 15%). In the 24 h cultures, the viability of adherent cells was high on both surfaces (95-100%). Viable cells staining positive for early apoptotic changes could only be clearly observed on the albumin coated surface, after 30 min of cell-material surface interaction. Cell death, including apoptotic death, thus seems to play an important role during the initial interactions between monocytes and a foreign surface.     

Feasibility of using human spleen cells to produce interferon

Spleen cells of subjects who died suddenly are capable of producing large amounts of interferon in response to induction with Newcastle disease virus (NDV) and Sendai virus (1-2.5 IU per 1000 cells). The optimal conditions for interferon production by these cells include using NDV, the H strain, as an inducer in a dose of 10 ID50/cell and fresh spleen cells stored no more than 24 hours at 4-6 degrees C in a concentration of 0.5-1.0 x 10(7)/ml, with the incubation time of 20-24 hours. It is recommended that spleen cells from subjects who died suddenly be used for human interferon production.     

Monoclonal antibody production in semi-continuous serum- and protein-free culture. Effect of glutamine concentration and culture conditions on cell growth and antibody secretion

We have recently shown that the semi-continuous cultivation of a mouse hybridoma line in spinner flasks, with a basal defined medium (BDM) devoid of serum and protein, increases the secretion of the immunoreactive monoclonal antibody (MAb) by a factor of ca. 2.4, compared to culture in flasks with serum-containing medium (Schneider, 1989). To further optimise MAb production, we have now investigated the composition of BDM and the mode of cultivation. Hybridoma cells were inoculated at 0.3 x 10(6) cells/ml in 200 ml of BDM containing 4, 6 or 8 mM glutamine; after 3-4 days (when the cell density reached greater than or equal to 10(6) cells/ml) 20, 40, 60 or 100% of the culture medium were replaced daily by fresh nutritive BDM with or without 33, 66 or 100% cell recycling. Daily, over a total period of 15-16 days, viable cells were counted and the concentration of the MAb, of glucose and glutamine (the main nutrients) and of lactate, alanine and ammonia (the main metabolites) were assayed. These experiments indicate that to provide optimal cell growth and MAb production: (i) the concentration of glutamine in the nutritive medium should be maintained at 8 mM, otherwise it falls on some days to 0 with a significant amount of cell death; at 25 mM, glucose concentration is not a limiting factor, whatever the culture conditions; (ii) with a semi-continuous mode of cultivation, a perfusion rate of 40%/day appears optimal; without cell recycling, a rate of 20% does not provide enough nutrients and/or does not remove enough metabolites, whereas a rate of 60% washes over the cells; with cell recycling, rates of 60 (moderately) or 100% (considerably) increase cellular metabolism without concurrent augmentation of MAb secretion; (iii) the recycling of the cells increases the mean cell densities and the rate of production of the MAb, as well as the rate of consumption of nutrients and of production of metabolites; recycling of 33-66% is optimal, since the total recycling progressively raises the number of dead cells and debris; (iv) there are maximal values for cell densities (ca. 2.5 X 10(6) cells/ml) and MAb production (ca. 26 micrograms/10(6) cells X day) as well as for nutrient consumption and metabolite production (except with a very high perfusion rate).(ABSTRACT TRUNCATED AT 400 WORDS)