三七总皂苷促进脑出血后侧脑室室管膜下神经干细胞的增殖和分化**☆

目的：三七总皂苷可促进去大脑皮质血管后成年大鼠前脑侧脑室室管膜下层神经干细胞Nestin、PCNA和bFGF的表达，以及促进离体胎鼠皮质神经干细胞增殖、分化作用。实验拟采用胶原酶诱导大鼠脑出血模型和免疫组织化学染色法观察三七总皂甙对脑出血大鼠侧脑室室管膜下神经干细胞增殖和分化的作用。 方法：实验于2002/2006年在北京中医药大学神经解剖学实验室完成。①实验材料：Wistar大鼠60只，雄性，清洁级，体质量220~250 g，由中国中医研究院实验动物中心提供，将大鼠随机分为正常组、模型组和给药组，20只/组，实验过程中对动物处置符合动物伦理学标准。三七总皂苷血栓通注射液由内蒙古康源药业提供，批准文号:22-5802-内卫药准字(1999) 1787号，规格:5 mL:175 mg。②实验方法：采用胶原酶诱导大鼠脑出血模型，给药组术后腹腔内注射三七总皂苷35 mg，1次/d，模型组术后腹腔注射生理盐水，1次/d，正常组不作任何处理。③实验评估：采用免疫组织化学染色法和图像分析技术检测增殖细胞核抗原（PCNA）、β－Ⅲ型微管蛋白（Tuj-1）、胶质原纤维酸性蛋白（GFAP）在室管膜下的表达。 结果：60只大鼠均进入结果分析。脑出血后模型组同侧侧脑室内、外侧壁及背外侧角室管膜下区有增殖细胞核抗原、β－Ⅲ型微管蛋白、胶质原纤维酸性蛋白阳性细胞，给予三七总皂苷干预后，室管膜下细胞增殖细胞核抗原、胶质原纤维酸性蛋白、β－Ⅲ型微管蛋白阳性细胞数目和反应强度较模型组明显增强，差异具有显著性意义（P < 0.05， P < 0.01）。 结论：三七总皂苷具有促进脑出血后侧脑室背外侧角室管膜下区神经干细胞增殖、分化，并向病灶迁移，促进损伤修复的作用。     

Controlling neural stem cell division within the adult subventricular zone: an APPealing job

For years, scientists investigating amyloid precursor protein (APP) have focused on its pathogenetic role in the brains of Alzheimer's disease patients. Now, a study by Caille et al. adds new sites of action and new physiological functions for APP. They show that there are binding sites for secreted N-terminal nonamyloidogenic APP (sAPP) on epidermal growth factor (EGF)-responsive neural stem cells in the subventricular zone of the adult brain, where sAPP acts as an EGF cofactor to stimulate proliferation of these cells. This result opens the hypothesis that changes in the levels of sAPP could influence activity of the neurogenic regions of the adult brain in normal and pathological conditions.     

大鼠胚胎神经干细胞的培养与鉴定

目的体外培养大鼠胚胎神经干细胞(NSCs),观察其生长、增殖特点。方法取孕15d的大鼠,采用机械分离法获取海马区细胞,以106个细胞/m l的密度接种到无血清NSCs培养基中培养,分离纯化至第5代。以10%胎牛血清(FBS)和2%多聚赖氨酸诱导分化,免疫细胞化学鉴定。结果取NSCs的细胞球及诱导分化后的细胞作免疫细胞化学染色鉴定,细胞分别呈小鼠抗巢蛋白(nestin)、小鼠抗微管蛋白(-βtubu lin)、豚鼠抗胶质纤维酸性蛋白(GFAP)及小鼠抗O4免疫化学反应阳性。结论大鼠胚胎脑海马区有NSCs存在,离体培养时能分裂增殖,并能被诱导分化。     

Hypoxia/ischemia depletes the rat perinatal subventricular zone of oligodendrocyte progenitors and neural stem cells

Cerebral hypoxia/ischemia of the newborn has a frequency of 4/1,000 births and remains a major cause of cerebral palsy, epilepsy, and mental retardation. Despite progress in understanding the pathogenesis of hypoxic-ischemic injury, the data are incomplete regarding the mechanisms leading to permanent brain injury. Here we tested the hypothesis that cerebral hypoxia/ischemia damages stem/progenitor cells in the subventricular zone (SVZ), resulting in a permanent depletion of oligodendrocytes. We used a widely accepted rat model and examined animals at recovery intervals ranging from 4 h to 3 weeks. Within hours after the hypoxic-ischemic insult 20% of the total cells were deleted from the SVZ. The residual damaged cells appeared necrotic. During 48 h of recovery deaths accumulated; however, these later deaths were predominantly apoptotic. Many apoptotic SVZ cells stained with a marker for immature oligodendrocytes. At 3 weeks survival, the SVZ was smaller and markedly less cellular, and it contained less than 1/4 the normal complement of neural stem cells. The corresponding subcortical white matter was dysmyelinated, relatively devoid of oligodendrocytes and enriched in astrocytes. We conclude that neural stem cells and oligodendrocyte progenitors in the SVZ are vulnerable to hypoxia/ischemia. Consequently, the developmental production of oligodendrocytes is compromised and regeneration of damaged white matter oligodendrocytes does not occur resulting in failed regeneration of CNS myelin in periventricular loci. The resulting dysgenesis of the brain that occurs subsequent to perinatal hypoxic/ischemic injury may contribute to the cognitive and motor dysfunction that results from asphyxia of the newborn.     

大鼠胚胎脑皮层神经干细胞的分离和培养

目的探讨分离、培养、纯化大鼠胚胎神经干细胞(neuralstem cell,NSCs)的最佳条件,以获得充足的神经干细胞来源,用于中枢神经系统疾病的治疗.方法分离孕13～15 d胎鼠大脑皮层,在无血清含神经生长因子N2培养液中培养,利用有限稀释法单克隆培养和改良法连续传代纯化并扩增NSCs,免疫组织化学法对NSCs及分化细胞进行鉴定.结果可以通过体外培养获得大量神经源性干细胞,在体外经多次传代后仍具有很强的增殖能力和多向分化潜能.结论NSCs的存活和分裂依赖于神经生长因子和N2添加剂的浓度,胚胎脑组织和神经球分离方法影响NSCs的形成速度和数量.掌握NSCs的体外纯化培养和鉴定手段可为进一步研究NSCs生物学特性及神经系统损伤的治疗提供新方法.     

Oligodendrogenesis from neural stem cells: Perspectives for remyelinating strategies

Mobilization of remyelinating cells spontaneously occurs in the adult brain. These cellular resources are specially active after demyelinating episodes in early phases of multiple sclerosis (MS). Indeed, oligodendrocyte precursor cells (OPCs) actively proliferate, migrate to and repopulate the lesioned areas. Ultimately, efficient remyelination is accomplished when new oligodendrocytes reinvest nude neuronal axons, restoring the normal properties of impulse conduction. As the disease progresses this fundamental process fails. Multiple causes seem to contribute to such transient decline, including the failure of OPCs to differentiate and enwrap the vulnerable neuronal axons. Regenerative medicine for MS has been mainly centered on the recruitment of endogenous self-repair mechanisms, or on transplantation approaches. The latter commonly involves grafting of neural precursor cells (NPCs) or neural stem cells (NSCs), with myelinogenic potential, in the injured areas. Both strategies require further understanding of the biology of oligodendrocyte differentiation and remyelination. Indeed, the success of transplantation largely depends on the pre-commitment of transplanted NPCs or NSCs into oligodendroglial cell type, while the endogenous differentiation of OPCs needs to be boosted in chronic stages of the disease. Thus, much effort has been focused on finding molecular targets that drive oligodendrocytes commitment and development. The present review explores several aspects of remyelination that must be considered in the design of a cell-based therapy for MS, and explores more deeply the challenge of fostering oligodendrogenesis. In this regard, we discuss herein a tool developed in our research group useful to search novel oligodendrogenic factors and to study oligodendrocyte differentiation in a time- and cost-saving manner.     

半乳凝素1对脑损伤大鼠室管膜下区内源性神经干细胞原位增殖及迁移的影响

背景：半乳凝素1表达于室管膜下区的星形胶质细胞中并诱导其分化，分化的星形胶质细胞可明显提高脑源性神经生长因子的产生。 目的：观察侧脑室注入半乳凝素1对脑缺血损伤大鼠内源性神经干细胞增殖、迁移的影响。 设计、时间及地点：细胞学体内观察实验，于2007-03/11在佳木斯大学神经科学研究所完成。 材料：纯种清洁级成年Wistar大鼠48只，随机分为模型组、药物组，24只/组。半乳凝素1为北京晶美生物工程公司产品。 方法：两组大鼠均采用线栓法制作局灶性大脑中动脉闭塞模型。造模后24 h，药物组经右侧侧脑室注入10 μL浓度为0.2 g/L的半乳凝素1，模型组注射等量生理盐水。分别于缺血再灌注后3，7，14，28 d处死大鼠，取脑组织制作石蜡切片，处死前1 d腹腔注射BrdU。 主要观察指标：免疫组织化学染色检测大脑室管膜下区BrdU和巢蛋白阳性细胞的表达。 结果：模型组缺血再灌注3 d后大脑室管膜下区BrdU、巢蛋白阳性细胞开始增加，7 d增殖达高峰，14 d后表达开始下降，28 d后下降至最低。药物组缺血再灌注3 d后大脑室管膜下区两种阳性细胞均明显增加；7 d 增殖达高峰，半定量分析BrdU、巢蛋白阳性细胞数分别是模型组的2倍和1.5倍，且BrdU阳性细胞向腹外侧迁移，巢蛋白阳性细胞胞体变大，突起增长，并有向外侧迁移进入脑实质的迹象；14 d后开始下降；28 d降至最低，但仍明显多于模型组（P < 0.05）。 结论：经侧脑室注入半乳凝素1在大鼠脑缺血后可激活内源性神经干细胞原位增殖，并存在由增殖区向外周脑实质迁移的趋势。     

Pharmacological study of a cholinergic mechanism within the rat posterior hypothalamic nucleus which mediates a hypertensive response

In unanesthetized freely moving rats, microinjection of a variety of cholinergic agonists into the posterior hypothalamic nucleus (PHN) consistently produced an elevation in mean arterial pressure (MAP). Experiments were undertaken to pharmacologically characterize this cholinergic mechanism. Microinjection of carbachol (0.1--100 nmol) into the PHN elicited reproducible and dose-related increase in MAP (17--47 mm Hg) and variable changes in heart rate. Similar responses, although longer in onset and duration, were produced by microinjection of the cholinesterase inhibitors, neostigmine, physostigmine and echothiophate. The pressor responses produced by neostigmine and physostigmine, but not by carbachol, were shown to be dependent upon intact stores of acetylcholine in the PHN. Blockade of postsynaptic muscarinic receptors by prior microinjection of atropine abolished the rise in MAP to subsequent injection of cholinergic agonists; however, similar pretreatment with the antinicotinic agent, mecamylamine, was without effect. The peripheral mechanism through which a rise in MAP was produced by cholinergic stimulation of PHN was the sympathetic nervous system since i.v. injection of an alpha-adrenergic blocking agent, phentolamine, attenuated the pressor response to intrahypothalamic injection of carbachol or neostigmine. Adrenal catecholamine release or vasopressin release were not important mechanisms in this regard. From this study we conclude that within the rat PHN there exists a muscarinic, cholinergic mechanism which, upon activation, mediates a rise in MAP through an increase in sympathetic tone.     

Effect of midazolam on the proliferation of neural stem cells isolated from rat hippocampus

In many recent studies,the inhibitory transmitter gamma-aminobutyric acid has been shown to modulate the proliferation,differentiation and survival of neural stem cells.Most general anesthetics are partial or allosteric gamma-aminobutyric acid A receptor agonists,suggesting that general anesthetics could alter the behavior of neural stem cells.The neuroprotective efficacy of general anesthetics has been recognized for decades,but their effects on the proliferation of neural stem cells have received little attention.This study investigated the potential effect of midazolam,an extensively used general anesthetic and allosteric gamma-aminobutyric acid A receptor agonist,on the proliferation of neural stem cells in vitro and preliminarily explored the underlying mechanism.The proliferation of neural stem cells was tested using both Cell Counting Kit 8 and bromodeoxyuridine incorporation experiments.Cell distribution analysis was performed to describe changes in the cell cycle distribution in response to midazolam.Calcium imaging was employed to explore the molecular signaling pathways activated by midazolam.Midazolam(30-90 μM) decreased the proliferation of neural stem cells in vitro.Pretreatment with the gamma-aminobutyric acid A receptor antagonist bicuculline or Na-K-2Cl cotransport inhibitor furosemide partially rescued this inhibition.In addition,midazolam triggered a calcium influx into neural stem cells.The suppressive effect of midazolam on the proliferation of neural stem cells can be partly attributed to the activation of gamma-aminobutyric acid A receptor.The calcium influx triggered by midazolam may be a trigger factor leading to further downstream events.     

From stem cells towards neural layers: a lesson from re-aggregated embryonic retinal cells

Cells from dissociated embryonic avian retinae have the capacity to re-aggregate in rotation culture and form cellular spheres reconstituting a complete arrangement of all retinal layers. This exquisite phenomenon is based upon in vitro proliferation of multipotent precursor stem cells and spatial organization of their differentiating descendants. The addition of soluble factors from cultured retinal pigmented epithelial (RPE) or radial glial cells is essential to revert inside-out spheres (rosetted retinal spheres) into correctly laminated outside-out spheres (stratified spheres). Such complete restoration of a laminated brain tissue by cell re-aggregation has been achieved only for the embryonic avian retina, but not the mammalian retina, nor for other brain parts. This review summarises the history of the re-aggregation approach, presents avian retinal re-aggregate models, and analyses roles of the RPE and Müller cells for successful retinal tissue regeneration. It is predicted that these results will become biomedically relevant, as stem cell biology will soon open ways to produce large amounts of human retinal precursors.     

Moderate fetal alcohol exposure impairs neurogenic capacity of murine neural stem cells isolated from the adult subventricular zone

Gestational alcohol exposure leads to a spectrum of neurological symptoms which range from severe mental retardation caused by high dose exposure, to subtle cognitive and neuropsychiatric symptoms caused by low-to-moderate doses. We and other investigators have demonstrated that exposure to moderate levels of alcohol throughout gestation leads to impaired neurogenesis in the adult hippocampus, although the mechanisms by which this occurs are not known. To begin to distinguish cell-intrinsic from microenvironmental contributions to impaired adult neurogenesis, we isolated neural stem progenitor cells (NSPCs) from the adult SVZ of mice exposed to moderate levels of alcohol throughout gestation. We found that NSPCs isolated from fetal alcohol exposed (FAE) mice displayed reduced neurosphere formation in culture, as assessed by a serial passage neurosphere assay, and reduced neuronal differentiation upon growth factor withdrawal. These studies suggest that gestational alcohol exposure leads to long-lasting NSPC-intrinsic dysregulation, which may underlie in vivo neurogenic deficits.     

星形胶质细胞条件培养液体外诱导胎鼠室管膜前下区神经干细胞向多巴胺能神经元的分化

背景：在神经干细胞移植治疗神经系统退行性变及修复神经系统功能损伤过程中,有效的神经干细胞体外增殖与多巴胺能神经元的定向诱导分化尤为关键。 目的：以星形胶质细胞条件培养液为诱导剂,观察胎鼠室管膜前下区神经干细胞体外向多巴胺能神经元的分化。 设计、时间及地点：细胞学体外对照观察,于2006-12/2007-08在解放军第三军医大学新桥医院实验中心完成。 材料：清洁级新生2 d龄KM小鼠15只,孕16 d Wistar大鼠40只,均由解放军第三军医大学实验动物中心提供。 方法：采用差速黏附法和振荡分离法纯化培养KM小鼠星形胶质细胞,收集传至第3代、培养5 d的星形胶质细胞条件培养液,-20 ℃冻存待用。体外分离Wistar胎鼠室管膜前下区神经干细胞,加入含B27和碱性成纤维细胞生长因子的DMEM/F12无血清培养基进行原代培养,传至第3代后按0.5×108 L-1密度接种,设立2组：对照组单纯加入含体积分数0.1为胎牛血清的DMEM/F12培养基予以自然分化,实验组加入已制备的星形胶质细胞条件培养液进行诱导分化。 主要观察指标：免疫细胞化学染色鉴定胎鼠室管膜前下区神经干细胞,流式细胞仪检测胎鼠室管膜前下区神经干细胞向多巴胺能神经元分化的阳性率。 结果：培养的神经球细胞表达巢蛋白,可分化为神经元特异性烯醇化酶、胶质纤维酸性蛋白阳性细胞。诱导分化7 d后,实验组可见酪氨酸羟化酶阳性细胞,胞体呈圆形或椭圆形,酪氨酸羟化酶位于胞质及突起中;对照组酪氨酸羟化酶阳性细胞在数量、细胞成熟形态上均未达到实验组水平。实验组酪氨酸羟化酶阳性细胞分化率明显高于对照组（t=35.296,P < 0.01）。 结论：在体外星形胶质细胞条件培养液可显著促进胎鼠室管膜前下区神经干细胞向多巴胺能神经元分化。     

中脑源性神经干细胞培养过程中pitx3以及凋亡基因的表达

目的 探讨胚胎大鼠腹侧中脑源性神经干细胞培养过程中pitx3、TH以及凋亡基因的表达.方法 分离E14.5 d胚胎大鼠腹侧中脑组织,用机械吹打方法形成细胞悬液培养,传代7 d、14 d、28 d后,用real-time PCR检测pitx3、Bax、Bcl-2的表达情况.结果 在培养的神经干细胞克隆中,pitx3、Bax基因7～21 d表达逐渐增加,而Bcl-2 基因表达逐渐下降.结论 胚胎大鼠腹侧中脑源性神经干细胞具有分化为中脑多巴胺能神经的潜能,但是随着培养时间的延长,调亡的细胞也在不断增加.     

Neural tissue-spheres: a microexplant culture method for propagation of precursor cells from the rat forebrain subventricular zone

By combining new and established protocols we have developed a procedure for isolation and propagation of neural precursor cells from the forebrain subventricular zone (SVZ) of newborn rats. Small tissue blocks of the SVZ were dissected and propagated en bloc as free-floating neural tissue-spheres (NTS) in EGF and FGF2 containing medium. The spheres were cut into quarters when passaged every 10-15th day, avoiding mechanical or enzymatic dissociation in order to minimize cellular trauma and preserve intercellular contacts. For analysis of regional differences within the forebrain SVZ, NTS were derived from three rostro-caudal levels of the lateral ventricles (anterior, intermediate and posterior) and propagated separately. Explants from all three levels produced proliferating NTS, but "anterior" NTS in general grew to smaller sizes than "intermediate" and "posterior" NTS. Posterior NTS moreover maintained their neurogenic potential throughout 77 days of propagation, while the ability of anterior NTS to generate neurons severely declined from day 40. The present procedure describes isolation and long-term expansion of forebrain SVZ tissue with potential preservation of the endogenous cellular content, thus allowing experimental studies of neural precursor cells and their niche.     

Nestin-positive cells in the spinal cord: a potential source of neural stem cells

Some literatures have reported neural precursor cells (NPCs) exist in spinal cord of adult mammal, however, the NPCs distribution feature in spinal cord of adult mice so far is not described in detail. In order to observe and compare the distribution feature of NPCs in various spinal cord regions of adult mice, to research a potential source of neural stem cells (NSCs), we obtained NPCs distribution feature by analyzing the distribution of the nestin-containing cells (NCCs) in spinal cord of adult nestin second-intron enhancer controlled LacZ reporter transgenic mice (pNes-Tg) with LacZ staining and positive cell quantification. The results showed that: NCCs were observed in various regions of spinal cord of adult mice, but amount of NCCs was different in distinct region, the rank order of NCCs amount in various spinal cord regions was dorsal horn region greater than central canal greater than the ventral and lateral horn. NCCs in dorsal horn region mainly distributed in substantia gelatinosa, NCCs in central canal mainly distributed in ependymal zone, on the contrary, NCCs in ventral, lateral horn, medullae, nucleus regions of spinal cord were comparatively less. The rank order of NCCs amount in various spinal cord segments was cervical segment greater than lumbar sacral segment greater than thoracic segment. There was no significantly difference between NCCs amount in the left and right sides, and within cervical 1–7, thoracic 1–12, lumbar 1–5, sacral segment of spinal cord in adult mice. These data collectively indicate that NPCs extensively distribute in various regions of spinal cord of adult mice, especially in substantia gelatinosa and ependymal zone. NPCs in cervical segment are abundant, NPCs in thoracic segment are the least while compared the different spinal cord segment, the NPCs in various regions of spinal cord of adult mice are a potential source of NSCs.     

Chemokines influence the migration and fate of neural precursor cells from the young adult and middle-aged rat subventricular zone

We have previously demonstrated a role for the chemokines MCP-1, MIP-1α and GRO-α in directing subventricular zone (SVZ)-derived neural precursor cell migration towards the site of cell death in the adult rodent brain. However the influence of chemokines such as MCP-1, MIP-1α and GRO-α on the differentiation of adult neural precursor cells has not previously been investigated. Further, as the majority of neurological disorders and injuries occur during ageing, it is important to investigate the effect of chemokines on adult neural precursor cell cultures obtained from the ageing brain. This study therefore examined the effect of MCP-1, MIP-1α and GRO-α on SVZ-derived neural precursor cell differentiation in vitro, and assessed whether precursor cells from the middle-aged rat brain (13 months old) follow the same migratory and differential profile as neural precursor cells obtained from the young adult rat brain (2 months old). We observed that each of the chemokines examined generated differing effects in regards to neuronal or glial differentiation. Further, both MIP-1α and GRO-α increased total cell number, suggesting an effect on precursor cell proliferation and/or survival. In agreement with cultures obtained from young adult brains, SVZ-derived neural precursor cells cultured from the middle-aged brain exhibited chemotactic migration in response to a concentration gradient. These results indicate that the chemokines MCP-1, MIP-1α and GRO-α can influence both the migration and fate choice of SVZ-derived neural precursor cells, as well as promoting cell viability. While a response to each of these chemokines is maintained in the middle-aged brain, a distinct age-related alteration in differential fate can be identified.     

Plasticity‐related gene 1 is important for survival of neurons derived from rat neural stem cells

Plasticity‐related gene 1 (Prg1) is a membrane‐associated lipid phosphate phosphatase. In this study, we first investigated the role of Prg1 in the survival of neurons derived from rat neural stem cells (NSCs) using small interfering RNA (siRNA). Prg1 knock‐down decreased the cell number. Interestingly, Prg1 knock‐down increased genomic DNA fragmentation, suggesting the possible induction of apoptosis. Exogenously expressed Prg1 rescued the cells from death and restored the loss of 3‐(4,5‐dimethylthiazol‐2‐yl)‐2,5‐diphenyltetrazolium bromide (MTT) activity induced with Prg1 siRNA. However, exogenously expressed mutated‐Prg1 (the 253rd amino acid, histidine253, had been changed to alanine) did not rescue the cell death or restore the MTT activity. Histidine253 of Prg1 has been reported to be important for lipid phosphate phosphatase activity. These results suggest that Prg1 is important for survival of neurons through its dephosphorylation activity. © 2013 Wiley Periodicals, Inc.