The effect of chitosan and PVDF substrates on the behavior of embryonic rat cerebral cortical stem cells

In this study, the behavior of neural stem cells from embryonic rat cerebral cortex were compared on the chitosan and poly(vinylidene fluoride) (PVDF) substrates at single-cell and neurosphere level. It was found that chitosan and PVDF substrates inhibited the proliferation and differentiation of single neural stem cells. It seemed that single-cell cultures on both substrates show cells remained dormant. However, neurospheres could exhibit different or similar behavior on these two substrates, which is dependent on the presence or absence of serum. More cells migrated outside from the neurospheres and longer processes extended from differentiated cells on chitosan than on PVDF when neurospheres were cultured in the serum-free medium. On the contrary, when serum was added to the culture system, chitosan and PVDF could induce the neurosphere-forming cells into an extensive cellular substratum of protoplasmic cells upon which process-bearing cells spread. In addition, based on the immunocytochemical analysis, the percentages of differentiated cell phenotypes of neurospheres cultured on chitosan and PVDF substrates became similar in the presence of serum. Therefore, it is reasonable to suggest that biomaterials may stimulate or inhibit the proliferation and differentiation of neural stem cells according to the complex environmental conditions. The information presented here should be useful for the development of biomaterials to regulate the preservation, proliferation, and differentiation of neural stem cells.     

Proliferation and differentiation of neural stem cells on lysine-alanine sequential polymer substrates

The purpose of this study was to explore the phenotypic potential of embryonic rat cerebral cortical stem cells by inducing differentiation on lysine-alanine sequential (LAS) polymer substrates at neurosphere level. LAS polymer is a heterologous polymer of lysine and alanine and has been demonstrated to enhance axon growth of neurons in a serum-free medium in vitro. It was found that very few cells migrated outside of the neurospheres but extremely long processes extended from differentiated cells could form a network between remote neurospheres when cells were cultured on LAS substrates at a low density of 120 neurospheres/cm(2) in the serum-free medium. On the contrary, when the neurosphere density was increased to 360 neurospheres/cm(2), many neurosphere-forming cells migrated out from their original aggregate and exhibited short processes morphology. Furthermore, when serum was added to the culture system, the neurosphere-forming cells could be induced into an extensive cellular substratum of protoplasmic cells upon which process-bearing cells spread. Clearly, neurospheres could exhibit different behaviors on LAS substrates according to the complex environmental conditions. Here, we proposed that neurospheres would change their social communication and adopt different strategies to communicate with other neurospheres when they detected each other's presence. Therefore, the mediation of cell behavior on LAS substrates by communication between neurospheres should be taken into account.     

Behavior of embryonic rat cerebral cortical stem cells on the PVA and EVAL substrates

Cell behavior is determined by intrinsic programs and complex interactions among cells, medium components and substrates. Several previous reports have demonstrated the usefulness of extrinsic signals coming from soluble growth factors and cell-cell contact for regulating the proliferation and differentiation of neural stem cells. At present, the effects of substrate on neural stem cells are not known. In this study, the behavior of neural stem cells, isolated from embryonic rat cerebral cortex, was observed and compared on the polyvinyl alcohol (PVA) and poly (ethylene-co-vinyl alcohol) (EVAL) substrates in the presence of the mitogenic effect of basic fibroblast growth factor (bFGF) in the serum-free medium. It was found that PVA and EVAL exerted different influences on the fate of neural stem cells. The behavior of neural stem cells on the EVAL was independent of cell density at the single-cell level. Single neural stem cells seemed to remain dormant on the EVAL. Conversely, the development of cell clusters, termed neurospheres, was in a density-dependent manner on the EVAL. Neurospheres continuously proliferated under high-density culture condition, but differentiated into neurons and astrocytes under low-density culture condition. However, regardless of single cells or neurospheres, cultured cells could not survive on the PVA. Therefore, it is reasonable to assume that biomaterials may stimulate or inhibit the proliferation and differentiation of neural stem cells. These in vitro results are very encouraging since this information should be useful for the development of strategies for regulating the preservation, proliferation and differentiation of neural stem cells.     

The alteration of cell membrane charge after cultured on polymer membranes

In this work, cell electrophoresis, measuring the electrophoretic mobility of cells, was used to investigate the variation of surface charge property of cells after cultured on different polymer membranes. HepG2 cell line, derived from a well-differentiated, human hepatoma, was used as a model cell. The polymer biomaterials used in this study included polyvinyl alcohol (PVA), poly(ethylene-co-vinyl alcohol) (EVAL), and polyvinylidene fluoride (PVDF). For cells cultured in the presence of serum, cell mobility after being cultured on PVA substrates was considerably higher than that on EVAL or PVDF substrates. This effect was completely suppressed by cycloheximide (CHX) in the serum-free medium. Taken together, the cell surface charge property can be altered after cells cultured on different polymer substrates. The precise mechanism by which the variation of electrophoretic mobility of cultured cells is unknown, but it is reasonable to assume that the polymer substrates could influence the absorption of serum proteins on cell membrane surface to change cell electrophoretic mobility and, simultaneously, to regulate adhesion, growth and function of cultured cells.     

成年小鼠神经干细胞体外培养、鉴定及分化

目的:建立一种简便易行的从成年小鼠脑组织分离、培养和鉴定神经干细胞(neural stem cells,NSCs)的方法,为相关研究提供新的研究手段。方法:采用机械分离和酶消化结合方法分离成年昆明种小鼠的脑组织,用无血清培养基悬浮培养;倒置相差显微镜观察细胞形态;MTT法(四甲基偶氮唑盐微量酶反应比色法)观察NSCs的自我增殖能力;免疫荧光细胞化学技术检测NSCs标志物巢蛋白(Nestin)的表达;多聚赖氨酸铺板和撤除培养基中FGF和EGF的条件下,给予5%血清和1μm维甲酸诱导NSCs分化,免疫荧光细胞化学技术检测GFAP(标记胶质细胞),β-tubulin Ⅲ(标记神经元)蛋白的表达来测定NSCs的分化能力。结果:从成年小鼠脑组织分离的细胞,在无血清培养液中可形成神经球,并可在体外扩增和连续传代,免疫荧光细胞化学表明神经球Nestin阳性表达,在给予血清和维甲酸条件下神经球可表达GFAP和β-tubulin Ⅲ。结论:本研究成功建立了体外培养成年小鼠脑组织分离和培养NSCs的方法,培养的NSCs具有自我更新、增殖及多向分化潜能。此方法是一个稳定、简便易行的方法,可广泛用于神经干细胞相关的基础和应用研究。     

人胚脑神经干细胞的分离培养、克隆和分化

探讨从人胚脑分离培养的神经干细胞在增殖和分化方面的生物学特点。用无血清培养技术从 4月龄人胎中脑组织中分离培养出神经干细胞 ,用有限稀释法获得单细胞克隆球 ,消化后用含 Brd U的培养液培养 ,待形成神经干细胞球后 ,进行 Brd U和nestin免疫荧光检测。取第 4代神经干细胞球用含 10 % FBS的培养液诱导分化 ,3周后分别进行神经元、星形胶质细胞和少突胶质细胞特异性标记物 MAP-2、GFAP和 CNP免疫荧光检测。结果显示 ,单细胞悬液培养 2周后可形成神经干细胞球 ;神经球 Br-d U和 nestin免疫荧光检测均呈阳性 ;神经干细胞分化后呈 MAP-2、GFAP和 CNP阳性的三种类型细胞 ,但分化的神经元数量较少、胞体较小、突起较少。提示从人胚中脑组织中分离得到的神经干细胞具有增殖和自我更新能力 ,并具有分化为神经元、星形胶质细胞和少突胶质细胞的多分化潜能 ;与啮齿类动物相比 ,人神经干细胞增殖速度较慢 ,分化的神经元较少且稍欠成熟     

小鼠来源诱导多能干细胞定向分化为神经元的体外实验研究*

 目的： 探讨源于小鼠的诱导多能干细胞（induced pluripotent stem cells, iPSCs）体外定向分化为神经元的方法,为大量稳定地获得神经元及提供种子细胞治疗脊髓损伤奠定体外实验基础。方法: 源于小鼠的iPSCs在不同的诱导培养基中经悬浮、贴壁、再悬浮和再贴壁培养。免疫荧光检测iPSCs多能性标志物、神经干细胞及其分化细胞标志物的表达。RT-PCR检测神经元及胶质细胞基因表达并行神经元基因测序鉴定,流式细胞术检测iPSCs定向分化为神经干细胞及进一步分化为神经元的比例。结果: 源于小鼠的iPSCs表达干细胞多能性标志物Sox2、Oct4和SSEA1。悬浮培养可以形成类球形拟胚体;经诱导及机械分离后的细胞可形成神经球,神经球经诱导后可分化为神经元。免疫荧光显示iPSCs可诱导出表达nestin的神经球,贴壁培养的神经球可分化为分别表达微管相关蛋白2（MAP-2）、胶质细胞原纤维酸性蛋白（GFAP）及髓磷脂碱性蛋白(MBP)的神经元、星形胶质细胞和少突胶质细胞。RT-PCR及基因鉴定结果显示形成小鼠神经元;流式细胞术检测结果显示分化细胞中神经干细胞和神经元的比例分别为63.93%±1.47%和21.40%±1.70%。结论: 源于小鼠的诱导多能干细胞能够稳定地在体外定向分化为神经元,为脊髓损伤的治疗提供了一个可靠的细胞来源。     

梯度血清递减体外培养人脐带间充质干细胞

背景：人脐带间充质干细胞的扩增与培养条件密切相关,而含体积分数10%~20%胎牛血清的培养基可促进细胞生长。 目的：建立梯度血清递减扩增培养脐带间充质干细胞的培养技术。 方法：采用胶原酶Ⅱ消化分离获得脐带间充质干细胞悬液,并通过贴壁培养进行纯化,细胞贴壁后采用梯度血清递减方法,即第1代80%含血清培养基,20%无血清培养基;第2代50%含血清培养基,50%无血清培养基;第3代20%含血清培养基,80%无血清培养基;第4代100%无血清培养基。另一种传代中始终采用含体积分数10%胎牛血清的α-MEM完全培养液。用流式细胞仪检测细胞的表面标记,进行成骨诱导试验,同时与经典的含10%胎牛血清的α-MEM培养体系进行比较。 结果与结论：梯度血清递减培养法与经典α-MEM培养体系所获得的细胞在扩增能力、细胞形态、免疫表型等方面相似。细胞在两种培养体系中均能保持良好的分化潜能。但梯度血清浓度法培养间充质干细胞可使用更少量胎牛血清,提高临床应用安全性。     

适合人肌母细胞的无血清培养基

背景：肌母细胞体外培养大多使用添加胎牛血清培养基,存在很多不足,开发无血清培养基,更加稳定、安全、经济,有广泛的应用前景。 目的：初步探索适合人肌母细胞培养的无血清培养基。 方法：配制含胎牛血清培养基 (DMEM/F12 1∶1添加胰岛素样生长因子1、碱性成纤维细胞生长因子和体积分数20%胎牛血清),间充质干细胞无血清培养基组(无血清培养基、2%血清替代物、2 mmol/L L-谷氨酰胺,人脐带间充质干细胞,细胞纯度大于99%,UltraCULTURETM添加血清替代物,谷氨酰胺)。自制无血清培养基组(GibcoTM添加胰岛素样生长因子1,碱性成纤维细胞生长因子,谷氨酰胺)。3种培养基分别对人肌母细胞分别进行培养,观察肌母细胞的形态、免疫组织化学的鉴定,计算克隆的形成率,绘制细胞生长的曲线,MTT检测肌母细胞的活性,比较3种培养基培养肌母细胞增殖、分化的差异。 结果与结论：各组细胞形态上无明显差异;各组免疫组织化学鉴定肌母细胞纯度均达99%;含胎牛血清培养基组和自制无血清培养基组克隆形成率显著高于间充质干细胞无血清培养基组(P < 0.01),含胎牛血清培养基组克隆形成率显著高于自制无血清培养基组(P < 0.01);含胎牛血清培养基组与自制无血清培养基组细胞数远高于间充质干细胞无血清培养基组;自制无血清培养基组细胞活性显著高于含胎牛血清培养基组和间充质干细胞无血清培养基组(P < 0.01)。自制无血清培养基组可有效用于肌母细胞的培养,在促进肌母细胞早期贴壁、增殖上还需进一步优化。  中国组织工程研究杂志出版内容重点：组织构建;骨细胞;软骨细胞;细胞培养;成纤维细胞;血管内皮细胞;骨质疏松;组织工程      

Generation of Schwann Cell-Derived Multipotent Neurospheres Isolated from Intact Sciatic Nerve

Schwann cells (SCs) are the supporting cells of the peripheral nervous system and originate from the neural crest. They play a unique role in the regeneration of injured peripheral nerves and have themselves a highly unstable phenotype as demonstrated by their unexpectedly broad differentiation potential. Thus, SCs can be considered as dormant, multipotent neural crest-derived progenitors or stem cells. Upon injury they de-differentiate via cellular reprogramming, re-enter the cell cycle and participate in the regeneration of the nerve. Here we describe a protocol for efficient generation of neurospheres from intact adult rat and murine sciatic nerve without the need of experimental in vivo pre-degeneration of the nerve prior to Schwann cell isolation. After isolation and removal of the connective tissue, the nerves are initially plated on poly-D-lysine coated cell culture plates followed by migration of the cells up to 80?% confluence and a subsequent switch to serum-free medium leading to formation of multipotent neurospheres. In this context, migration of SCs from the isolated nerve, followed by serum-free cultivation of isolated SCs as neurospheres mimics the injury and reprograms fully differentiated SCs into a multipotent, neural crest-derived stem cell phenotype. This protocol allows reproducible generation of multipotent Schwann cell-derived neurospheres from sciatic nerve through cellular reprogramming by culture, potentially marking a starting point for future detailed investigations of the de-differentiation process.     

An optimal hormonally defined serum-free medium for the differentiation of a colic adenocarcinoma cell line

Summary The aim of this work was to design a serum-free medium which can promote both growth and differentiation of an adenocarcinoma cell line (HT29-D4). Undifferentiated HT29-D4 cells growing as multilayers in 10% FBS DME medium, were first subcultured in glucose-free medium containing decreasing concentrations of serum and then in a hormonally defined serum-free medium constituted essentially of glucose-deprived DME supplemented with galactose, selenous acid, hormones (hydrocortisone and triiodothyronine), growth factors (insulin and epidermal growth factor), transferrin, fibronectin and bovine serum albumin. HT29-D4 cells grew in monolayer and displayed a highly differentiated enterocytic phenotype at the ultrastructural level. The carcinoembryonic antigen was restricted within the apical membrane domain whereas HLA class 1 molecules and transferrin receptors remained within the basolateral membrane domain. These findings demonstrate that the HT29-D4 cells grown in the serum-free medium were highly differentiated.Abbreviations CEA Carcinoembryonic antigen - FBS Fetal bovine serum - LA Linoleic acid - OA Oleic acid - T3 Triiodothyronine - Gal-medium DME without glucose (Galactose 0.9 g/l) - Gluc-medium 10% FBS DME (Glucose 4.5 g/l)     

Differentiation of myoblasts in serum-free media: effects of modified media are cell line-specific

Myoblast cell lines are grown and differentiated readily in cell culture. Two cell lines typically used for investigating the growth and differentiation of muscle are the mouse cell line C2C12 and the rat cell line L6. The differentiation of these cells in vitro requires a switch from a serum-rich medium to a less rich medium after the cells have reached confluence. Since the components present in serum are not well characterized, the use of a better defined medium for these studies was investigated. C2C12 and L6 myoblasts were differentiated in both serum-containing and serum-free media. The differentiation state of these cultures was then tested both microscopically and biochemically. Cultures were checked for myotube formation, the activity of creatine phosphokinase and the presence of sarcomeric actin. In C2C12 cells, the extent of differentiation was greater in the serum-free than in the serum-containing system. In both media types, the C2C12 cells produced sarcomeric actin, showing the presence of sarcomere structure in the myotubes. In L6 cells, however, myotubes were readily formed in medium containing 2% horse serum, but not in the serum-free system. In addition, the ability of C2C12 cells to differentiate on substrates coated with extracellular matrix proteins was shown to be media-dependent. The presence of extracellular matrix proteins did not enable L6 cells to form myotubes when cultured in serum-free media. Primary cultures of chick myoblasts were able to differentiate in both media tested, with Dulbecco's modified Eagle medium containing horse serum being a more efficient medium for cell fusion. This study shows a divergence in muscle cell line responses in three cell lines, two of which are typically used as 'model systems' for understanding muscle growth and development.     

In vitro differentiated neural stem cells express functional glial glutamate transporters

The possibility to isolate stem cells from the adult central nervous system and to maintain and propagate these cells in vitro has raised a general interest with regards to their use in cell replacement therapy for degenerative brain diseases. Considering the critical role played by astrocytes in the control of glutamate homeostasis, we have characterised the expression of functional glutamate transporters in neural stem cells exposed to selected culture conditions favouring their differentiation into astrocytes. Commonly, neural stem cells proliferate in suspension as neurospheres in serum-free medium. The addition of serum or a supplement of growth factors (G5) to the culture medium was found to trigger cell adhesion on coated surfaces and to favour their differentiation. Indeed, after 7 days in these conditions, the vast majority of the cells adopted markedly distinct morphologies corresponding to protoplasmic (with serum) or fibrous (with G5 supplement) astrocytes and approximately 35–40% acquired the expression of the glial fibrillary acidic protein (GFAP). Immunocytochemical analysis also revealed that the treatments with serum or with the G5 supplement triggered the expression of the glial glutamate transporters GLT-1 (35 and 21%, respectively) and GLAST (29 and 69%, respectively). This effect was correlated with a robust increase in the Na⁺-dependent [³H]-D-aspartate uptake, which was partially inhibited by dihydrokainate, a selective blocker of GLT-1. Together, these results indicate that in vitro differentiation of cultured neural stem cells can give rise to distinct populations of astrocytes expressing functional glutamate transporters.     

神经前体细胞的增殖和分化及其对Parkinson病的治疗作用

本实验分离 1 1～ 1 5 d胎鼠的大脑皮层 ( CP)和中脑的神经前体细胞 ( MP) ,观察它们在体外的增殖和分化及其对帕金森病 ( PD)的治疗作用。结果发现 ,CP较 MP生长迅速 ,容易形成神经球 ,加入 N2 / B2 7有助于神经球的形成 ;有 /无血清分化后 ,CP和 MP都能发育成微管相关蛋白 -2 ( MAP-2 )阳性细胞 ,其中 MP倾向于发育成酪氨酸羟化酶 ( TH)阳性细胞。将 MP或 CP植入6 -OHDA损伤的大鼠纹状体后 ,MP发育成的 TH+神经元数量明显地较 CP移植组和对照组者多 ( P<0 .0 5 )且 MP移植后 4～ 8周旋转行为发生明显改善 ,与 CP移植组和对照组相比有显著性差异 ( P<0 .0 5 )。上述结果提示 ,虽然 CP在体外的增殖能力较MP强 ,但 MP更易于分化成 TH阳性神经元并改善 PD大鼠的旋转行为 ,此点对于神经前体细胞治疗 PD的应用极其重要。     

新生小鼠海马神经干细胞体外培养条件下的增殖与分化

背景：神经干细胞移植可用于中枢神经损伤的临床治疗。 目的：观察新生小鼠海马神经干细胞在体外培养条件下的增殖和分化。 方法：从新生昆明小鼠海马取材,采用机械分离法对原代细胞进行无血清培养,采用机械法复合酶消化法对原代细胞进行传代,以体积分数为10%胎牛血清诱导分化。免疫荧光行巢蛋白、β-微管蛋白Ⅲ和胶质纤维酸性蛋白染色,对培养的细胞进行鉴定。CCK-8法检测神经干细胞增殖能力。 结果与结论：从新生小鼠海马分离得到的细胞具有连续传代形成克隆球的能力,克隆球呈巢蛋白免疫反应阳性;加入胎牛血清可诱导分化为β-微管蛋白Ⅲ和胶质纤维酸性蛋白阳性细胞。提示实验成功建立了体外培养新生小鼠海马组织分离和培养神经干细胞的方法,培养的神经干细胞在体外培养条件下保持着自我增殖和分化的潜能。     

Comparative evaluation of cytotoxicity of cadmium in rat liver cells cultured in serum-containing medium and commercially available serum-free medium

Cadmium (Cd) is an industrial pollutant and carcinogenic metal. Most in vitro Cd toxicity studies have been carried out in various cell lines cultured in 10% fetal bovine serum (FBS) containing medium. In this report, we compared the toxic effect of Cd (0-300 microM) on cell growth, total RNA, total proteins, and antioxidant enzymes in rat normal liver cells cultured in medium with 10% FBS or commercially available serum-free medium for 4 or 8 hours. With Cd concentration at above 100 microM, the total levels of RNA, protein and cell growth decreased in serum-containing medium, while their levels increased in serum-free medium compared to the controls. The glutathione peroxidase and glutathione reductase levels were lower in serum-free medium than in serum-containing medium, indicating less oxidative stress in cells grown in serum-free medium. These results clearly suggest that Cd showed higher toxicity to liver cells grown in serum-containing medium in comparison to commercially available serum-free medium. It is speculated that albumin and other substances present in commercial serum-free medium chelated Cd and thereby protected these cells against Cd toxicity. Even under in vivo conditions, cadmium enters into various organs after passing through blood which contains serum. Based on these studies, it appears that media containing serum may be ideal for in vivo toxicity correlation studies with animal cells.     

Bombyx mori silk fibroin membranes as potential substrata for epithelial constructs used in the management of ocular surface disorders

Membranes were prepared from fibroin, a protein isolated from the domesticated silkworm (Bombyx mori) silk, and evaluated as a potential substratum for corneal limbal epithelial cells. These membranes (i.e., B. mori silk fibroin [BMSF] membranes) were cast from dialyzed solutions of fibroin protein (4% w/v) dispensed into 35-mm-diameter culture dishes and dried at room temperature (23-24 degrees C). The resulting material was transparent, easy to handle, and supported levels of human limbal epithelial (HLE) cell growth comparable to that observed on tissue culture plastic. Remarkably, these results were obtained utilizing a commercial serum-free medium (CnT-20) designed for the ex vivo expansion of corneal epithelial progenitor cells. The potential benefits of serum proteins on this culture system were examined through addition of fetal bovine serum (FBS) either to fibroin stocks prior to membrane casting or by supplementation of the CnT-20 medium. Membranes cast in the presence of FBS displayed increasing opacity and induced little change in HLE growth. Supplementation of CnT-20 medium with FBS deterred cell growth on all substrata, including tissue culture plastic control substrata. The remarkable properties of BMSF membranes demonstrated under serum-free conditions warrant investigation of this material as a substratum in the creation of tissue-engineered constructs for the restoration of diseased or damaged ocular surface.     

HEK 293 cell suspension culture using fibronectin-adsorbed polymer nanospheres in serum-free medium

Previously, we reported on suspension culture of anchorage-dependent animal cells using plain polymer nanospheres in serum-containing medium. For commercial cell culture, it is more advantageous to use serum-free medium than serum-containing medium. To culture anchorage-dependent animal cells using polymer nanospheres in serum-free medium, the nanospheres need to be coated with cell adhesion proteins. In this study, we utilized fibronectin-adsorbed polymer nanospheres for suspension culture of anchorage-dependent animal cells in serum-free medium. Fibronectin was adsorbed onto poly(lactic-co-glycolic acid) nanospheres (433 nm in average diameter) by immersing the nanospheres in fetal bovine serum. The nanospheres were used to culture human embryonic kidney (HEK) 293 cells in serum-free medium in stirred suspension bioreactors. Nanospheres attached between HEK 293 cells and promoted cell aggregate formation compared with culture without nanospheres. Most cells in the aggregates were viable over a 10-day culture period. Importantly, the use of poly(lactic-co-glycolic acid) nanospheres promoted the cell growth significantly, compared with culture without nanospheres (3.8- vs 1.8-fold growth). The nanosphere culture method developed in this study removes the time-consuming and costly process of adaptation of anchorage-dependent animal cells to suspension culture in serum-free medium. This culture method may be useful for the large-scale suspension culture of various types of anchorage-dependent animal cells in serum-free medium.     

嗅黏膜神经干细胞的体外培养和向酪氨酸羟化酶阳性神经元的分化

目的:建立体外培养和诱导嗅黏膜神经干细胞向酪氨酸羟化酶阳性神经元分化的方法,探讨该细胞的干性和分化特性。方法:首先用含10%胎牛血清的DMEM/F-12混合培养基培养成年大鼠嗅黏膜细胞,当细胞贴壁后将培养基更换为含表皮生长因子(epidermal growth factor,EGF)和碱性成纤维细胞生长因子(basic fibroblastgrowth factor,bFGF),不含血清的干细胞培养基,以促进干细胞增殖形成神经球。将神经球取出用干细胞培养基悬浮培养以纯化扩增神经干细胞。应用干细胞相关蛋白Nestin及CD133的抗体对神经干细胞进行免疫荧光染色,观察上述蛋白在细胞的表达。用Neurobasal培养基(含B27、NGF、ATRA及SHH)培养扩增后的神经干细胞,诱导其向神经元分化。用神经丝蛋白(neurofilament-200,NF-200)和酪氨酸羟化酶(tyrosine hydroxylase,TH)抗体对分化的细胞进行免疫荧光染色;用免疫印迹法检测上述细胞裂解样品内的相应标志蛋白的电泳条带。结果:嗅黏膜神经干细胞高表达Nestin及CD133两种神经干细胞标志蛋白;干细胞经诱导分化后其形态具有神经元特征,并且高表达NF和TH两种神经细胞标志蛋白。结论:贴壁/悬浮序贯培养方法可体外纯化扩增嗅黏膜神经干细胞,该细胞可分化为酪氨酸羟化酶阳性神经元。     

The proliferation and function of human mononuclear leukocytes and natural killer cells in serum-free medium

We recently developed a serum-free (SF) culture medium that supports the growth of several established lymphoid cell lines. In an effort to develop a standardized medium for assay of human natural killer (NK) cell activity, we compared the cytotoxic activity of peripheral blood mononuclear leukocytes (PBL) and purified large granular lymphocytes (LGL) cultured in SF medium containing interleukin 2 (IL-2) or medium containing 10% fetal bovine serum (FBS) plus IL-2. The results indicated that PBL had a 30% increase in cumulative net cell growth and had as high or higher cytotoxic activity after growth in SF medium than in medium containing FBS. Purified LGL had a 50% increase in cumulative net cell growth and persisted approximately 2 weeks longer in culture in medium containing FBS than in SF medium. However, the cytotoxic activity of cells grown in SF medium persisted during the initial 3 weeks of culture. Purified LGL that were maintained and were subcultured at cell densities of 10(6) cells or greater per milliliter of either SF or FBS-containing medium had equivalent levels of cytotoxicity over a 44-day period in either medium compared with cells subcultured at a density of 5 X 10(5) cells per milliliter of medium. NK cells produced a cytotoxic factor (NKCF) in SF medium, and its cytotoxic activity was blocked by 10% FBS. We conclude that the SF medium supplemented with IL-2 can be used as an alternative to FBS-containing medium with IL-2 for the growth of NK cells and is advantageous for the production of NKCF.