髓鞘结合糖蛋白抑制神经干细胞向神经元分化和轴突生长

目的： 观察来源于胚胎大鼠海马神经细胞的特征;观察髓鞘结合糖蛋白(MAG)对神经干细胞的增殖、分化及神经元轴突生长的影响。方法: 从胚胎鼠的海马提取细胞进行体外培养,应用免疫荧光染色法检测神经干细胞(NSCs)标志蛋白nestin和doublecortin的表达。应用BrdU掺入法检测不同剂量的MAG-Fc对NSCs增殖的影响。免疫荧光染色法观察各种亚型神经细胞的比例并比较神经元样细胞的轴突长度。结果: 来自SD大鼠16 d 胚胎海马的细胞明显表现出神经干细胞的特征。神经干细胞分化7 d 后,对照组新生成的β-tubulin Ⅲ阳性细胞的比例为18.17%±2.79%,其轴突长度为(136.27±33.66)μm。MAG-Fc (200 μg/L)处理后,β-tubulin Ⅲ阳性细胞比例和轴突长度分别显著减少为10.05%±3.42% (P<0.01)和(84.87±24.94)μm(P<0.01)。增殖实验表明,不同浓度的MAG-Fc对神经干细胞的BrdU整合比率无明显影响(P>0.05)。结论: MAG-Fc对神经干细胞向神经元样细胞的分化及其轴突的生长均有抑制作用,但对神经干细胞的增殖无明显影响。     

Sox2诱导小鼠胚胎成纤维细胞直接重编程为神经干细胞

目的:探讨Sox2诱导小鼠胚胎成纤维细胞(mouse embryonic fibroblasts,MEFs)直接重编程为神经干细胞的方法,为诱导神经干细胞(induced neural stem cells,i NSCs)作为种子细胞治疗脊髓损伤(spinal cord injury,SCI)奠定实验基础。方法:逆转录病毒感染Sox2转录因子的MEFs在神经干细胞培养基中贴壁培养10 d。随后,悬浮、贴壁反复循环培养3次。Real-time PCR检测神经干细胞标志基因和多潜能标志基因的表达。i NSCs在分化培养基中贴壁培养7~14 d,免疫荧光分别检测神经干细胞、神经元、星形胶质细胞和少突胶质细胞的标志物nestin、MAP2、GFAP和MBP的表达。将i NSCs显微注射至小鼠大脑皮质,7~14 d后免疫荧光检测神经细胞标志物nestin、MAP2、GFAP和MBP的表达。结果:Real-time PCR显示i NSCs的多种神经干细胞标志基因nestin、Blbp、Pax6和zbtb16表达较诱导前显著增高(P0.05),且i NSCs不表达多潜能相关基因Nanog、Oct4和zfp42。免疫荧光显示i NSCs高表达神经干细胞标志物nestin。免疫荧光同时表明i NSCs可在体内外存活并分化为神经元、星形胶质细胞和少突胶质细胞。结论:Sox2可以诱导MEFs直接重编程为神经干细胞。i NSCs具有自我更新的能力,且在体内外都具有三向分化潜能,可作为修复SCI合适的种子细胞。     

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     

促红细胞生成素促进体外鼠胚脑皮质神经干细胞增殖

目的检测体外培养SD大鼠胚脑皮质神经干细胞(neural stem cells,NSCs)增殖和分化的生物学特性,为NSCs研究提供适宜的细胞模型;探讨促红细胞生成素(erythropoietin,EPO)对NSCs增殖的影响,为NSCs的相关研究提供实验依据。方法本研究对孕14d(E14)SD大鼠取鼠胚脑皮质悬浮培养、贴壁诱导分化。采用光电镜观察,以nestin免疫荧光染色鉴定NSCs,微管相关蛋白2(microtubule associated protein2,MAP2)和神经胶质原纤维酸性蛋白(glia fibrillary acid protein,GFAP)检测NSCs分化。取第三代(P3)NSCs向悬浮培养基中添加不同剂量的EPO,通过四甲基偶氮唑蓝(MTT)检测法检测NSCs的增殖情况。结果分离E14dSD大鼠胚脑皮质,在添加B27、bFGF、EGF的无血清培养基中培养,可形成大量悬浮的神经球并可进行体外扩增传代,神经球内的细胞均呈Nestin阳性、BrdU阳性。在添加10%胎牛血清的培养基中,神经干细胞可自然分化为神经元和神经胶质细胞。与对照组对比,加入≥5U/mlEPO后MTT检测NSCsOD值明显增高。结论 SD大鼠胚脑皮质体外培养可得到大量增殖的神经干细胞并能分化为神经元和神经胶质细胞,EPO可促进体外NSCs的增殖。     

大鼠脊髓神经干细胞的鉴定及光镜和电镜观察

本研究应用无血清培养技术对分离的大鼠胚胎脊髓神经干细胞进行体外培养,在倒置显微镜和电镜下观察细胞形态,应用BrdU标记、免疫荧光染色检测细胞增殖、分化情况。免疫荧光显示nestin、MAP2、GFAP以及BrdU/nestin、BrdU/MAP2、Br-dU/GFAP均有阳性表达,说明从大鼠胚胎脊髓可成功分离出神经干细胞,它们分化后可以表达神经元、星形胶质细胞的特异性抗原。脊髓神经干细胞具有自我更新能力,能分化为神经元和星型胶质细胞。     

嗅鞘细胞对神经干细胞增殖与分化的影响

观察嗅鞘细胞(OECs)对神经干细胞(NSCs)增殖与分化的影响。取孕14d的SD胚鼠嗅球和腹侧中脑组织,分为OECs+NSCs共培养组和NSCs单独培养组进行培养。用p75免疫组化法,p75、BrdU/nestin、GFAP、NF(神经原纤维)和p75/nestin免疫荧光法分别鉴定OECs和NSCs并观察其增殖与分化。在培养7d时,绝大多数OECs呈梭形且发出2~3个突起,少量呈扁平椭圆形,两者均呈p75阳性。在7d时,单独培养的NSCs表现为典型的神经球悬浮生长,呈BrdU/nestin阳性;14d后偶见神经球贴壁分化,球中的少数细胞呈绿色荧光标记的NF阳性,大部分呈GFAP阳性。在5d时,OECs+NSCs共培养组形成神经球;10d时球体积不断增大,球心透亮度良好;12d后神经球的体积不再增大,开始贴附在OECs上生长,可见神经球向四周伸出突起并开始分化;14d时NSCs紧贴OECs生长并同OECs广泛交织在一起,可见NSCs和OECs分别呈nestin和p75阳性,NSCs中的大部分呈NF阳性,小部分为GFAP阳性。NSCs单独培养组和OECs+NSCs共培养组中NF阳性细胞率分别为47.2%和69.5%,前者明显少于后者(P<0.05)。以上研究结果提示OECs有促进NSCs增殖和诱导其分化的作用。     

神经干细胞在老年性痴呆模型鼠基底前脑内的成活和迁移

为探讨神经干细胞移植入老年性痴呆模型鼠基底前脑的成活和迁移情况,本研究利用无血清培养技术,加表皮生长因子(EGF)和碱性成纤维生长因子(FGF-2)刺激生长,在体外进行神经干细胞的克隆培养,用5-溴-2-脱氧尿苷(BrdU)标记,采用免疫组化和免疫荧光法研究神经干细胞的增殖特性和多向分化潜能,用免疫组化和免疫荧光双标技术观察神经干细胞移植后在老年性痴呆模型鼠基底前脑的成活和迁移。结果显示:克隆细胞球呈nestin和BrdU阳性反应。免疫荧光双标检测,贴壁的细胞为BrdU+GFAP阳性反应或者BrdU+NF阳性反应。移植后3周、4周,移植的针道附近以及整个基底前脑散在有许多BrdU+NF和BrdU+GFAP免疫荧光双标细胞。本研究结果提示,基底前脑神经干细胞能够分化为神经元和星形胶质细胞;基底前脑神经干细胞移植后能够在老年性痴呆模型鼠基底前脑内存活和迁移,可以与脑组织整合,并且能够分化成为神经元和星形胶质细胞。     

胎儿海马神经干细胞的体外培养及神经元前体细胞的纯化

目的　从人胎儿海马分离培养具有自我更新和多向分化能力的神经干细胞 ,并从中纯化神经元前体细胞。　方法　利用无血清培养从胚胎 4个月的胎儿海马区分离细胞 ,并在体外连续传代培养 ;采用免疫荧光细胞化学技术检测神经上皮干细胞蛋白 (nestin)的表达、经BrdU孵育后的BrdU表达 ;比较两种诱导分化方法所获得的神经元和胶质细胞的比例差异 ;利用单细胞克隆技术纯化神经元前体细胞。　结果　分离的细胞具有连续克隆能力 ,在体外培养了 16个月 ,传了 4 3代 ;细胞冻存、复苏后仍保持干细胞特性 ;培养的细胞呈Nestin阳性 ,在BrdU孵育后呈BrdU阳性 ,诱导分化后的细胞能够表达Tubulin、NeuN或GFAP ;利用无血清诱导所得到的分化细胞中神经元的比例约占 80 % ,而血清诱导的分化细胞中胶质细胞的比例则大于 90 %。利用单细胞克隆技术可从神经球中纯化的细胞表达Nestin ,并且全部分化成神经元。　结论　从胎儿海马区分离的细胞具有自我更新能力和多向分化潜能 ,属于神经干细胞 ,从中可纯化出神经元前体细胞     

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。     

脑皮质微血管内皮细胞刺激神经干细胞增殖并增强向神经元分化的潜能

目的体外观察脑皮质微血管内皮细胞(CMECs)对来自大鼠海马神经干细胞(NSCs)增殖和分化的影响响。方法采用Transwell建立神经干细胞与脑微血管内皮细胞共培养模型,通过相差显微镜形态学观察及共培养早期nestin和NF,及后期NF免疫组化检测鉴定,计算各阳性细胞数、总细胞数和阳性细胞率。结果在共培养第7天,共培养组NSCs的nestin阳性率为(64.04±9.40)%,对照组仅(9.41±4.80)%(P<0.01);NF阳性细胞率为(13.72±3.92)%,对照组仅(39.79±5.20)%(P<0.01);撤除CMECs后第4天,共培养组NSCs分化成神经元的比例为(55.42±4.75)%,对照组仅(27.18±2.62)%(P<0.01)。结论本结果提示CMECs能促进NSCs的自我更新,抑制其分化,并有增强其向神经元方向分化的潜能。     

Activation of canonical Wnt pathway promotes proliferation of retinal stem cells derived from adult mouse ciliary margin

Adult retinal stem cells represent a possible cell source for the treatment of retinal degeneration. However, only a small number of stem cells reside in the ciliary margin. The present study aimed to promote the proliferation of adult retinal stem cells via the Wnt signaling pathway. Ciliary margin cells from 8-week-old mice were dissociated and cultured to allow sphere colony formation. Wnt3a, a glycogen synthase kinase (GSK) 3 inhibitor, fibroblast growth factor (FGF) 2, and a FGF receptor inhibitor were then applied in the culture media. The primary spheres were dissociated to prepare either monolayer or secondary sphere cultures. Wnt3a increased the size of the primary spheres and the number of Ki-67-positive proliferating cells in monolayer culture. The Wnt3a-treated primary sphere cells were capable of self-renewal and gave rise to fourfold the number of secondary spheres compared with nontreated sphere cells. These cells also retained their multilineage potential to express several retinal markers under differentiating culture conditions. The Wnt3a-treated cells showed nuclear accumulation of beta-catenin, and a GSK3 inhibitor, SB216763, mimicked the mitogenic activity of Wnt3a. The proliferative effect of SB216763 was attenuated by an FGF receptor inhibitor but was enhanced by FGF2, with Ki-67-positive cells reaching over 70% of the total cells. Wnt3a and SB216763 promoted the proliferation of retinal stem cells, and this was partly dependent on FGF2 signaling. A combination of Wnt and FGF signaling may provide a therapeutic strategy for in vitro expansion or in vivo activation of adult retinal stem cells.     

Multipotent stem cells from adult olfactory mucosa.

Multipotent stem cells are thought to be responsible for the generation of new neurons in the adult brain. Neurogenesis also occurs in an accessible part of the nervous system, the olfactory mucosa. We show here that cells from human olfactory mucosa generate neurospheres that are multipotent in vitro and when transplanted into the chicken embryo. Cloned neurosphere cells show this multipotency. Multipotency was evident without prior culture in vitro: cells dissociated from adult rat olfactory mucosa generate leukocytes when transplanted into bone marrow-irradiated hosts, and cells dissociated from adult mouse olfactory epithelium generated numerous cell types when transplanted into the chicken embryo. It is unlikely that these results can be attributed to hematopoietic precursor contamination or cell fusion. These results demonstrate the existence of a multipotent stem-like cell in the olfactory mucosa useful for autologous transplantation therapies and for cellular studies of disease.     

成年大鼠侧脑室下区星形胶质细胞的分离培养及纯化研究

成年哺乳动物侧脑室下区星形胶质细胞(AST)的神经干细胞特性研究是当前神经科学领域的热点,为了进一步了解AST生物学特性,体外培养是探讨AST细胞学特性的有力手段,而怎样通过体外培养得到高纯度的成年AST是亟待解决的问题。本研究以2.5月的成年大鼠侧脑室下区为实验材料进行AST培养,并对传统的培养方法进行改良。首先在AST培养基中增加B27添加剂,结合成年AST体外生长特性,采用低浓度血清(2.5%～5%)和血清浓度调整法对培养的AST进行纯化。然后采用GFAP免疫细胞化学染色方法对培养至14d的细胞进行鉴定及纯度检测,采用流式细胞仪检测B27添加剂对AST细胞周期的影响。结果显示:B27添加剂能有效促进体外培养的成年AST的生长和增殖,采用此方法培养的成年AST纯度达90%以上;B27添加剂与低浓度血清的组合以及根据细胞特性及时调整血清浓度是一种有效的纯化成年AST方法。本方法的建立可望为AST的神经干细胞特性研究提供理想的细胞模型。     

Primary cultures of human livers and their albumin-producing capacity

Primary cultures of surgically obtained noncancerous portions of human liver tissues were made. Liver tissues were poorly dissociated with collagenase, but well dissociated with dispase. The yield and viability of cells were improved somewhat when dissociated with collagenase followed by dispase. The mean cell yield was 1.1 X 10(6) cells/g liver. The epithelial-like morphology of the dissociated liver cells was maintained for about one week, but thereafter degenerative alteration of cells was observed. In liver explant culture, an active outgrowth of cells was observed for more than one month. Albumin production in culture fluids from dissociated livers was detectable for about 2 weeks, but later became undetectable, while that from explant culture was detectable for at least one month. These data demonstrate that adult human hepatocytes can be isolated from noncancerous portions of livers with relatively high yield, and that albumin production of the dissociated cells is detectable for several days.     

bFGF和EGF对胚胎神经干细胞分化为神经元及神经胶质细胞的影响

目的：观察碱性成纤维生长因子（bFGF）和表皮生长因子（EGF）对体外培养胚胎神经管神经干细胞生长和分化的影响。方法：从孕12天大鼠胚胎神经管分离神经干细胞，进行原代培养，分为bFGF组、EGF组、bFGF＋EGF组及对照组：培养过程中观察干细胞的生长，培养2小时做nestin染色鉴定神经干细胞，培养第5天用免疫组化方法检测培养细胞神经元特异烯醇化酶（NSE）和胶质纤维酸性蛋白（GFAP）的表达，以观察神经干细胞分化为神经元及神经胶质细胞的状况。结果：取材细胞大部分为nestin免疫阳性细胞；各实验组均可促进培养细胞的生长和分 化。免疫组化中，EGF使神经干细胞增殖成团，增加GFAP的表达（P＜0．01）；bFGF能明显增加NSE及GFAP的表达（P＜0．01）；两种因子联合应用，神经元和神经胶质细胞均比对照组增多（P＜0．01）。结论：EGF和bFGF两类生长因子均能促进胚胎神经干细胞的生长，在分化方面，EGF倾向于诱导干细胞增并向着胶质细胞分化，bFGF则诱导干细胞分 成更多的神经元。     

Asymmetric cell kinetics genes: the key to expansion of adult stem cells in culture

A singular challenge in stem cell research today is the expansion and propagation of functional adult stem cells. Unlike embryonic stem cells, which are immortal in culture, adult stem cells are notorious for the difficulty encountered when attempts are made to expand them in culture. One overlooked reason for this difficulty may be the inherent asymmetric cell kinetics of stem cells in postnatal somatic tissues. Senescence is the expected fate of a culture whose growth depends on adult stem cells that divide with asymmetric cell kinetics. Therefore, the bioengineering of strategies to expand adult stem cells in culture requires knowledge of cellular mechanisms that control asymmetric cell kinetics. The properties of several genes recently implicated to function in a cellular pathway(s) that regulates asymmetric cell kinetics are discussed. Understanding the function of these genes in asymmetric cell kinetics mechanisms may be the key that unlocks the adult stem cell expansion problem.     

Neural stem cells directly differentiated from partially reprogrammed fibroblasts rapidly acquire gliogenic competency

Neural stem cells (NSCs) were directly induced from mouse fibroblasts using four reprogramming factors (Oct4, Sox2, Klf4, and cMyc) without the clonal isolation of induced pluripotent stem cells (iPSCs). These NSCs gave rise to both neurons and glial cells even at early passages, while early NSCs derived from clonal embryonic stem cells (ESCs)/iPSCs differentiated mainly into neurons. Epidermal growth factor-dependent neurosphere cultivation efficiently propagated these gliogenic NSCs and eliminated residual pluripotent cells that could form teratomas in vivo. We concluded that these directly induced NSCs were derived from partially reprogrammed cells, because dissociated ESCs/iPSCs did not form neurospheres in this culture condition. These NSCs differentiated into both neurons and glial cells in vivo after being transplanted intracranially into mouse striatum. NSCs could also be directly induced from adult human fibroblasts. The direct differentiation of partially reprogrammed cells may be useful for rapidly preparing NSCs with a strongly reduced propensity for tumorigenesis.     

Spontaneous neural differentiation of stem cells in culture of human olfactory epithelium

We studied differentiation of stem cells in dissociated cultures of olfactory epithelium. Staining with anti-nestin antibodies revealed stem cells in the primary monolayer culture of the olfactory epithelium from adult human. Proliferation of these cells during culturing in serum-containing medium in the presence of nerve growth factors FGF2 and NGF led to the formation of neurospheres freely floating in the medium or attached to the substrate. Further long-term culturing and cloning of dissociated cells from these neurospheres in media not containing nerve growth factors led to spontaneous neural differentiation of the olfactory epithelium stem cells. The cells with phenotypic signs of differentiated neurons were stained with antibodies against β-tubulin and neurospecific enolase. Differentiated neurons formed diffuse and spatially organized neuronal networks. We hypothesized that factors triggering neural differentiation of olfactory epithelium stem cells are produced by astrocytes present in these cultures. __________ Translated from Kletochnye Tehnologii v Biologii i Medicine, No. 4, pp. 183–188, October, 2007     

The potential of stem cells in adult tissues representative of the three germ layers

Mature adult tissues contain stem cells that express many genes normally associated with the early stage of embryonic development, when maintained in appropriate environments. Cells procured from adult tissues representative of the three germ layers (spinal cord, muscle, and lung), each exhibiting the potential to mature into cells representative of all three germ layers. Cells isolated from adult tissues of different germ layer origin were propagated as nonadherent clusters or spheres that were composed of heterogeneous populations of cells. When the clusters or spheres were dissociated, the cells had the ability to reform new, nonadherent spheres for several generations. When implanted in vivo, in association with biodegradable scaffolds, into immunodeficient mice, tissue containing cells characteristic of the three germ layers was generated. These findings suggest the existence of a population of stem cells in adult tissues that is quite different and distinct from embryonic stem cells that demonstrate a greater potency for differentiation across germ lines than previously believed. Such cells could potentially be as useful as embryonic stem cells in tissue engineering and regenerative medicine.     

大鼠脑组织细胞培养的形态学观察

为观察原代培养 SD大鼠大脑组织 ,包括神经干细胞在内的各种细胞的形态 ,取新生大鼠 ,无菌操作下取出整个大脑 ,制备成单细胞悬液 ,接种培养 ,免疫细胞化学鉴定各类细胞的同时用光镜和扫描电镜对不同阶段和种类的细胞进行形态学观察。结果显示 :在体外培养出神经元、胶质细胞和神经干细胞 ;神经细胞在体外的发育时程跟体内基本一致 ,神经干细胞在体外 2 0 d左右分化成熟 ,获取了神经细胞和干细胞体外培养的光镜和扫描电镜形态。结果提示 ,成体神经细胞体外分离、培养的条件关键点在于尽可能贴近自然 ,由此可保证细胞培养的质量 ,获得可靠的神经干细胞、神经元和胶质细胞。为各类神经细胞提供了形态学资料。