GDNF对神经干细胞增殖、分化的影响

神经干细胞(neural stem cells,NSCs)具有如下特点:(1)可以向神经组织分化或源自神经系统的一部分。(2)具备维持和更新的自主能力。(3)可通过细胞分裂增殖。以上特点决定了它的应用价值,被公认为治疗阿尔茨海默氏病,帕金森氏症,脊髓损伤,中风等神经退行性疾病的最佳方案。用干细胞治疗癌症,免疫相关性疾病,和其他疾病被认为是很有创新的新疗法,可能有一天会扩展到修复和补充大脑损伤。胶质细胞源性神经营养因子(glial Cell line一derived neurotrophic factor,GDNF)为TGF一β超家族的一员,具有很强神经保护作用,大量实验研究证实GDNF可促进帕金森病大鼠模型的中脑神经干细胞定向分化为多巴胺能神经元,同时大量实验发现其可促进神经干细胞增殖及分化,为神经干细胞的应用奠定了基础。     

小鼠造血干细胞增殖与分化性能的研究

本文选择Ｙ染色体特异的性别决定基因作为新的细胞遗传标志,采用ＰＣＲ技术研究了小鼠造血干细胞的增殖与分化性能。将雄鼠骨髓细胞输注给经致死剂量射线照射的雌性受体小鼠、ＰＣＲ测试结果表明,所有ＣＦＵ－Ｓ均为供体起源。供体来源的ＣＦＵ－Ｓ在其输入体内后,可通过增殖,分化形成各系造血细胞,但ＣＦＵ－Ｓ中的纤维母细胞和ＣＦＵ－Ｓ重建造血后受体小鼠骨髓中的纤维母细胞均为受体起源。由此可见,小鼠骨髓中的ＣＦＣ－Ｓ     

人类胚胎干细胞体外诱导分化为神经干细胞

人类胚胎干细胞是替代治疗充满希望的细胞来源. 描述了从人胚胎干细胞诱导分化出神经干细胞的方法. 将人胚胎干细胞系PKU1, PKU2在细菌培养皿中悬浮培养, 分化形成囊性拟胚体. 拟胚体接种至组织培养皿, 加入N2培养液和生长因子bFGF培养2周, 拟胚体贴壁、展开,中心出现灶状增生, 有突起的小细胞. 用机械方法取下此种细胞, 重新接种, 则细胞团悬浮生长,形成神经球. 培养10天后, 将神经球打散成单细胞接种, 该细胞贴壁生长旺盛. 免疫荧光检测显示为几乎100% 纯净的nestin阳性细胞. 将培养液中的生长因子撤除, 继续培养7~10天, 细胞分化为神经元, 该细胞呈现β-tubulin isotype_Ⅲ 阳性、GABA阳性、serotonin阳性、synaptophysin阳性. 在生长因子PDGF-AA诱导下, 细胞分化为星形胶质细胞, 其GFAP阳性; 或少突胶质细胞, 其O4阳性. 可见, 人类胚胎干细胞经上述方法培养可分化为典型神经干细胞, 表达神经干细胞特异的标志分子nestin、能自我更新、具有分化为神经系统三类主要细胞的能力.     

Wnt信号通路与神经干细胞

神经干细胞增殖、分化机制的研究为神经系统疾病治疗提供了新的途径,具有巨大的潜在应用价值和理论研究意义。业已发现,Wnt信号通路对神经干细胞的增殖发挥着决定性作用,但新近的研究却表明Wnt信号能够明显促进神经干细胞向神经元分化,这种不同的表现可能与神经干细胞的内在特点、周围环境及靶基因的不同有关。本文试从Wnt信号通路及其在调控神经干细胞的增殖、分化中的作用加以综述。     

磷脂酶D1信号对神经干细胞向神经分化的重要影响

磷脂酶D1(PLD1)在细胞生长、存活、分化、膜转运和细胞骨架组织等多种功能的调控中发挥重要作用。近年来研究发现,PLD1在神经干细胞（NSCs）向神经元的分化中也起关键作用。PLD1参与多种信号通路如Rho家族GTP酶和Ca²⁺信号通路的调节,影响轴突生长、突触发育及其可塑性。因此,PLD1作为神经系统中一种重要的信号分子引起了广泛的关注。本文综述了PLD1的结构、功能、作用机制及其在NSCs向神经分化中的调控作用,对深入研究NSCs的分化和神经元的再生有重要的指导意义。     

Notch信号通路对神经干细胞增殖分化的作用

神经干细胞作为一种具有自我更新能力和多向分化潜能的细胞,它的增殖和分化受到多种源于自身或外在、邻近或远程细胞信号通路的调控,各种细胞因子及胞间通讯在神经干细胞的增殖和分化中发挥着重要的作用。近年来的多种研究表明,Notch信号通路正是这样一种可以通过相邻细胞的配体与受体相互作用,从而传递信号,进一步发挥其生物学功能的重要信号通路。该通路参与了神经干细胞维持自我形态及向多种具有不同功能的神经细胞分化的过程．对于研究神经干细胞的增殖和分化具有巨大的意义。该文将就当前Notch信号通路对神经干细胞增殖分化影响的相关研究进行简要综述。     

适宜电刺激促进脂肪干细胞向神经方向分化

目的:研究不同强度电刺激对脂肪干细胞(adipose tissue-derived stem cells,ADSC)向神经元方向分化的作用。方法:在细胞电刺激室内对ADSCs进行电刺激(10Hz,1h),强度选用五个强度,分别为0 V/cm、0.5 V/cm、1.0 V/cm、3.0 V/cm、5.0 V/cm;电刺激后,对细胞进行流式凋亡检测及CCK-8活性检测,明确不同电刺激对ADSCs的影响;同时,应用免疫荧光染色、Western Blotting评估各组细胞神经特异性标志物microtubule-associated protein 2(MAP-2)与β-tubulin的表达情况。应用RT-PCR检测MAP-2、β-tubulin和neurofilaments 200(NF-200)的mRNA水平,评价不同强度电刺激对ADSCs其向神经方向分化的影响。结果:1V/cm的电刺激,未引起明显的细胞凋亡,同时促进了细胞增殖。此外,1V/cm电刺激后,细胞中的MAP-2和β-tubulin的免疫荧光染色强度及蛋白含量显著提高;MAP-2、β-tubulin和NF-200的mRNA及蛋白量显著提高。3V/cm及更高强度的电刺激可导致凋亡细胞数目显著增加。结论:强度为1V/cm的电刺激可促进脂肪干细胞的增殖,并促进其向神经方向分化,为神经损伤的治疗提供了新的可行方法。     

脑挫裂伤致miR-9升高促进神经干细胞分化

目的：探讨颅脑损伤后miR-9表达的变化和对神经干细胞分化和增值的影响,为颅脑损伤后神经功能修复治疗提出新的思路。方法：通过RT-PCR技术检测miR-9在挫裂伤脑组织中的表达情况;培养胚胎来源神经干细胞,并通过免疫荧光鉴定神经干细胞及其分化;转染miR-9后,通过MTT测定神经干细胞的增殖情况,和流式细胞仪检测分化神经元所占比例。结果：miR-9在挫裂伤脑组织中表达显著上升。对神经干细胞过表达miR-9可显著促进细胞增殖,并诱导分化成神经元。结论：脑挫裂伤时miR-9显著升高,并具有着促进神经干细胞增值和诱导分化的作用,可为伤后神经功能修复提供新的治疗方法。     

脑挫裂伤致miR-9 升高促进神经干细胞分化

目的:探讨颅脑损伤后miR-9表达的变化和对神经干细胞分化和增值的影响,为颅脑损伤后神经功能修复治疗提出新的思路。方法:通过RT-PCR技术检测miR-9在挫裂伤脑组织中的表达情况;培养胚胎来源神经干细胞,并通过免疫荧光鉴定神经干细胞及其分化;转染miR-9后,通过MTT测定神经干细胞的增殖情况,和流式细胞仪检测分化神经元所占比例。结果:miR-9在挫裂伤脑组织中表达显著上升。对神经干细胞过表达miR-9可显著促进细胞增殖,并诱导分化成神经元。结论:脑挫裂伤时miR-9显著升高,并具有着促进神经干细胞增值和诱导分化的作用,可为伤后神经功能修复提供新的治疗方法。     

大脑皮层神经干细胞定向分化为神经元过程中钙调蛋白的表达

目的研究大脑皮层神经干细胞定向分化为神经元过程中钙调蛋白的表达及意义.方法采用细胞培养、免疫细胞化学方法(SABC法)观察钙调蛋白在神经干细胞定向分化过程中不同时段的表达情况.采用计算机图像分析技术对不同时段分化神经元中钙调蛋白的平均积分光密度进行定量测定.结果在神经干细胞定向分化为神经元的过程中,钙调蛋白于细胞核及核周呈阳性表达,随分化神经元的生长细胞核阳性表达逐渐减弱而胞浆增强,同时可见阳性反应物伸入树突及轴突.结论新生大鼠大脑皮层神经干细胞定向分化为神经元过程中,钙调蛋白的表达对神经干细胞定向分化的神经元的生长和发育起着重要作用.     

Mesenchymal stem cells regulate the proliferation and differentiation of neural stem cells through Notch signaling

The effects of mesenchymal stem cells (MSCs) on proliferation and cell fate determination of neural stem cells (NSCs) have been investigated. NSCs were co-cultured with MSCs or NIH3T3 cells using an in vitro transwell system. After 4 days, immunofluorescence staining showed that the number of cells positive for the cell proliferation antigen, ki-67, in neurospheres in MSCs was greater than in NIH3T3 cells. In some experiments, the top-layers of MSCs and NIH3T3 cells were removed to induce NSCs differentiation. Seven days after initiating differentiation, the levels of the neuronal marker, NSE, were higher in NSCs in MSCs co-culture group, and those of glial fibrillary acidic protein (GFAP) were lower, compared with NIH3T3 cells co-culture group. These were confirmed by immunofluorescence. The role of the Notch signaling pathway analyzed with the specific inhibitor, DAPT, and by examining the expression of Notch-related genes using RT-PCR showed that after co-culturing with MSCs for 24 h, NSCs expressed much higher levels of ki-67, Notch1, and Hes1 than did NSCs co-cultured with NIH3T3 cells. Treatment with DAPT decreased ki-67, Notch1 and Hes1 expression in NCSs, and increased Mash1 expression. The data indicate that the interactions between MSCs and NSCs promote NSCs proliferation and are involved in specifying neuronal fate, mediated in part by Notch signaling.     

Proteomic analysis of neural differentiation of mouse embryonic stem cells

Mouse embryonic stem cells (mESCs) can differentiate into different types of cells, and serve as a good model system to study human embryonic stem cells (hESCs). We showed that mESCs differentiated into two types of neurons with different time courses. To determine the global protein expression changes after neural differentiation, we employed a proteomic strategy to analyze the differences between the proteomes of ES cells (E14) and neurons. Using 2-DE plus LC/MS/MS, we have generated proteome reference maps of E14 cells and derived dopaminergic neurons. Around 23 proteins with an increase or decrease in expression or phosphorylation after differentiation have been identified. We confirmed the downregulation of translationally controlled tumor protein (TCTP) and upregulation of alpha-tubulin by Western blotting. We also showed that TCTP was further downregulated in derived motor neurons than in dopaminergic neurons, and its expression level was independent of extracellular Ca(2+) concentration during neural differentiation. Potential roles of TCTP in modulating neural differentiation through binding to Ca(2+), tubulin and Na,K-ATPase, as well as the functional significance of regulation of other proteins such as actin-related protein 3 (Arp3) and Ran GTPase are discussed. This study demonstrates that proteomic tools are valuable in studying stem cell differentiation and elucidating the underlying molecular mechanisms.     

Chemical inhibition of sulfation accelerates neural differentiation of mouse embryonic stem cells and human induced pluripotent stem cells

Pluripotency of embryonic stem cells (ESCs) is maintained by the balancing of several signaling pathways, such as Wnt, BMP, and FGF, and differentiation of ESCs into a specific lineage is induced by the disruption of this balance. Sulfated glycans are considered to play important roles in lineage choice of ESC differentiation by regulating several signalings. We examined whether reduction of sulfation by treatment with the chemical inhibitor chlorate can affect differentiation of ESCs. Chlorate treatment inhibited mesodermal differentiation of mouse ESCs, and then induced ectodermal differentiation and accelerated further neural differentiation. This could be explained by the finding that several signaling pathways involved in the induction of mesodermal differentiation (Wnt, BMP, and FGF) or inhibition of neural differentiation (Wnt and BMP) were inhibited in chlorate-treated embryoid bodies, presumably due to reduced sulfation on heparan sulfate and chondroitin sulfate. Furthermore, neural differentiation of human induced pluripotent stem cells (hiPSCs) was also accelerated by chlorate treatment. We propose that chlorate could be used to induce efficient neural differentiation of hiPSCs instead of specific signaling inhibitors, such as Noggin.     

A novel method for culturing neural stem cells

The standard culture method for neural stem cells cannot prevent the attachment of neurospheres, which eventually result in differentiation. This study developed a new method for long-term neural stem cell cultivation. In the antiattachment group, neural stem cells were cultured in flasks coated with 1.5% agarose gel. As a control, cells were cultured in plastic flasks. The 5-bromine-deoxyuridine incorporation assay was used to determine the S-phase labeling index of both groups. The methyl thiazolyl tetrazolium (MTT) colorimetric assay was used to determine the total cell vitality. After a 3-mo culture, the spontaneous differentiation of stem cells was studied using immunocytochemistry for neuroepithelial stem cell protein. We found that neural stem cells grew rapidly in the antiattachment flasks. There was no statistically significant difference between the two groups in terms of the S-phase labeling index or MTT assay. When cultured for 3 mo in vitro, many more cells differentiated in the control than in the antiattachment group (32.05 vs. 0.64%, P < 0.01). Moreover, the neural stem cells in the antiattachment group remained multipotent. Therefore, flasks coated with agarose gel are suitable for long-term neural stem cell culture.     

Effects of sulforaphane on neural stem cell proliferation and differentiation

Sulforaphane (SFN) is a natural organosulfur compound with anti‐oxidant and anti‐inflammation properties. The objective of this study is to investigate the effect of SFN on the proliferation and differentiation of neural stem cells (NSC). NSCs were exposed to SFN at the concentrations ranging from 0.25 to 10 µM. Cell viability was evaluated with MTT assay and lactate dehydogenase (LDH) release assay. The proliferation of NSCs was evaluated with neurosphere formation assay and Ki‐67 staining. The level of Tuj‐1 was evaluated with immunostaining and Western blot to assess NSC neuronal differentiation. The expression of key proteins in the Wnt signaling pathway, including β‐catenin and cyclin D1, in response to SFN treatment or the Wnt inhibitor, DKK‐1, was determined by Western blotting. No significant cytotoxicity was seen for SFN on NSCs with SFN at concentrations of less than 10 µM. On the contrary, SFN of low concentrations stimulated cell proliferation and prominently increased neurosphere formation and NSC differentiation to neurons. SFN treatment upregulated Wnt signaling in the NSCs, whereas DKK‐1 attenuated the effects of SFN. SFN is a drug to promote NSC proliferation and neuronal differentiation when used at low concentrations. These protective effects are mediated by Wnt signaling pathway.     

Embryonic stem cells in non-human primates: An overview of neural differentiation potential

Non-human primate (NHP) embryonic stem (ES) cells show unlimited proliferative capacities and a great potential to generate multiple cell lineages. These properties make them an ideal resource both for investigating early developmental processes and for assessing their therapeutic potential in numerous models of degenerative diseases. They share the same markers and the same properties with human ES cells, and thus provide an invaluable transitional model that can be used to address the safety issues related to the clinical use of human ES cells. Here, we review the available information on the derivation and the specific features of monkey ES cells. We comment on the capacity of primate ES cells to differentiate into neural lineages and the current protocols to generate self-renewing neural stem cells. We also highlight the signalling pathways involved in the maintenance of these neural cell types. Finally, we discuss the potential of monkey ES cells for neuronal differentiation.     

Muscarinic acetylcholine receptors involved in the regulation of neural stem cell proliferation and differentiation in vitro

Neural stem cells (NSCs) are currently considered powerful candidates for cell therapy in neurodegenerative disorders such as Parkinson's disease. However, it is not known when and how NSCs begin to differentiate functionally. Recent reports suggest that classical neurotransmitters such as acetylcholine (Ach) are involved in the proliferation and differentiation of neural progenitor cells, suggesting that neurotransmitters play an important regulatory role in development of the central nervous system (CNS). We have shown by calcium imaging and immunochemistry that proliferation and differentiation are enhanced by M2 muscarinic Ach receptors (mAchR) expressed on the NSC surface and on their neural progeny. Moreover, atropine, an mAchR antagonist, blocks the enhancement and inhibits the subsequent differentiation of NSCs. Further understanding of this neural-nutrition role of Ach might elucidate fetal brain development, the brain's response to injury, and learning and memory.     

Culture and neural differentiation of rat bone marrow mesenchymal stem cells in vitro

Adult bone marrow mesenchymal stem cells (MSCs) can differentiate into several types of mesenchymal cells, including osteocytes, chondrocytes, and adipocytes, but can also differentiate into non-mesenchymal cells, such as neural cells, under appropriate experimental conditions. Until now, many protocols for inducing neuro-differentiation in MSCs in vitro have been reported. But due to the differences in MSCs' isolation and culture conditions, the results of previous studies lacked consistency and comparability. In this study, we induced differentiation into neural phenotype in the same MSCs population by three different treatments: beta-mercaptoethanol, serum-free medium and co-cultivation with fetal mouse brain astrocytes. In all of the three treatments, MSCs could express neural markers such as NeuN or GFAP, associating with remarkable morphological modifications. But these treatments led to neural phenotype in a non-identical manner. In serum-free medium, MSCs mainly differentiated into neuron-like cells, expressing neuronal marker NeuN, and BME can promote this process. Differently, after co-culturing with astrocytes, MSCs leaned to differentiate into GFAP(+) cells. These data confirmed that MSCs can exhibit plastic neuro-differentiational potential in vitro, depending on the protocols of inducement.     

神经营养因子与神经干细胞

生长因子在神经干细胞的增殖,分化和存活过程中有重要作用。神经营养因子是其中的一类,它包括神经生长因子（NGF）家族,胶质源性神经营养因子（GDNF）家族和其它神经营养因子。NGF家族包括NGF,BDNF,NT－3,NT－4／5和NT－6。这一家族可促进epidermic growth facter(EGF)反应 海马及前脑室管膜下区神经干细胞的存活和分化。GDNF家族包括GDNF,NTN,PSP和ART。GDNF家族促神经发育的作用主要在外周,它促进肠神经嵴前体细胞的存活和增殖,且对外周感觉神经的发育至关重要。其它生长因子如bFGF和EGF,它们能促进神经干细胞增殖和存活;CNTF和LIF等在神经干细胞的分化中也有重要作用。