亚低温可促进脑出血大鼠内源性神经干细胞的增殖*

背景：亚低温对脑出血后脑组织保护作用的研究多集中在减轻脑水肿方面,对神经干细胞的增殖是否有促进作用研究很少。 目的：观察亚低温对脑出血大鼠血肿周围、侧脑室旁神经干细胞增殖的影响。 方法：采用自体血注入尾状核制作Wistar大鼠脑出血模型,亚低温组于制作模型后给予局部亚低温4 h,对照组给予常温处理。 结果与结论：脑出血后1,3,7,14 d,亚低温组Longa 5分制法评分低于对照组(P < 0.05)。免疫组织化学方法检测亚低温组各时间点血肿周边及侧脑室旁组织的BrdU阳性细胞数明显多于对照组(P < 0.05)。初步提示亚低温处理可以促进干细胞内源性增殖,对脑出血有保护作用。     

Transplantation of neural stem cells that overexpress SOD1 enhances amelioration of intracerebral hemorrhage in mice

Previous studies have shown that intraparenchymal transplantation of neural stem cells (NSCs) ameliorates neurologic deficits in animals with intracerebral hemorrhage (ICH). However, massive grafted cell death after transplantation, possibly caused by a hostile host brain environment, lessens the effectiveness of this approach. We focused on the effect of oxidative stress against grafted NSCs and hypothesized that conferring antioxidant properties to transplanted NSCs may overcome their death and enhance neuroprotection after ICH. Copper/zinc-superoxide dismutase (SOD1) is a specific antioxidant enzyme that counteracts superoxide anions. We investigated whether genetic manipulation to overexpress SOD1 enhances survival of grafted NSCs and accelerates amelioration of ICH. Neural stem cells that overexpress SOD1 were administered intracerebrally 3 days after ICH in a mouse model. Histologic and behavioral tests were examined after ICH. Copper/zinc-superoxide dismutase overexpression protected the grafted NSCs via a decrease in production of reactive oxygen species. This resulted in an increase in paracrine factors released by the NSCs, and an increase in surviving neurons in the striatum and a reduction in striatal atrophy. In addition, SOD1 overexpression showed progressive improvement in behavioral recovery. Our results suggest that enhanced antioxidative activity in NSCs improves efficacy of stem cell therapy for ICH.     

Fluoxetine promotes gliogenesis during neural differentiation in mouse embryonic stem cells

Selective serotonin reuptake inhibitors (SSRIs) are commonly prescribed for treatment of mood disorders and depression, even during pregnancy and lactation. SSRIs are thought to be much safer than tricyclic antidepressants, with a low risk of embryonic toxicity. Several recent studies, however, have reported that fetal exposure to SSRIs increases the risk of adverse effects during fetal and neonatal development. This is consistent with our previous finding that fluoxetine, a prototypical SSRI, profoundly affected the viability of cultured embryonic stem (ES) cells as well as their ability to differentiate into cardiomyocytes. Furthermore, we found that fluoxetine induced fluctuations in ectodermal marker gene expression during ES cell differentiation, which suggests that fluoxetine may affect neural development. In the present study, we investigated the effects of fluoxetine on the process of differentiation from ES cells into neural cells using the stromal cell‐derived inducing activity (SDIA) method. Fluoxetine treatment was found to enhance the expression of glial marker genes following neural differentiation, as observed by immunocytochemical analysis or quantitative RT‐PCR. The promoter activity of glial marker genes was also significantly enhanced when cells were treated with fluoxetine, as observed by luciferase reporter assay. The expression of neuronal markers during ES cell differentiation into neural cells, on the other hand, was inhibited by fluoxetine treatment. In addition, FACS analysis revealed an increased population of glial cells in the differentiating ES cells treated with fluoxetine. These results suggest that fluoxetine could facilitate the differentiation of mouse ES cells into glial cell lineage, which may affect fetal neural development. © 2010 Wiley‐Liss, Inc.     

Reactive astrogliosis induces astrocytic differentiation of adult neural stem/progenitor cells in vitro

Neural stem cells reside in defined areas of the adult mammalian brain, including the dentate gyrus of the hippocampus. Rat neural stem/progenitor cells (NSPCs) isolated from this region retain their multipotency in vitro and in vivo after grafting into the adult brain. Recent studies have shown that endogenous or grafted NSPCs are activated after an injury and migrate toward lesioned areas. In these areas, reactive astrocytes are present and secrete numerous molecules and growth factors; however, it is not currently known whether reactive astrocytes can influence the lineage selection of NSPCs. We investigated whether reactive astrocytes could affect the differentiation, proliferation, and survival of adult NSPCs by modelling astrogliosis in vitro, using mechanical lesion of primary astrocytes. Initially, it was found that conditioned medium from lesioned astrocytes induced astrocytic differentiation of NSPCs without affecting neuronal or oligodendrocytic differentiation. In addition, NSPCs in coculture with lesioned astrocytes also displayed increased astrocytic differentiation and some of these NSPC-derived astrocytes participated in glial scar formation in vitro. When proliferation and survival of NSPCs were analyzed, no differential effects were observed between lesioned and nonlesioned astrocytes. To investigate the molecular mechanisms of the astrocyte-inducing activity, the expression of two potent inducers of astroglial differentiation, ciliary neurotrophic factor and leukemia inhibitory factor, was analyzed by Western blot and shown to be up-regulated in conditioned medium from lesioned astrocytes. These results demonstrate that lesioned astrocytes can induce astroglial differentiation of NSPCs and provide a mechanism for astroglial differentiation of these cells following brain injury.     

星形胶质细胞源性因子对神经干细胞分化的实验研究

目的探讨星形胶质细胞源性因子对神经干细胞分化的影响。方法分离和培养新生大鼠脑组织的神经干细胞;采用差速贴壁法和振荡法分离纯化星形胶质细胞,用免疫细胞化学染色法,胶质纤维酸性蛋白(GFAP)标记星形胶质细胞,进行细胞的纯度鉴定;将星形胶质细胞和神经干细胞在互不接触的情况下进行共培养,免疫荧光法观察神经干细胞分化后神经元特异性烯醇化酶(NSE)、GFAP和酪氨酸羟化酶(TH)的表达。结果纯化的星形胶质细胞GFAP抗体标记阳性,细胞纯度达98%;星形胶质细胞与神经干细胞共培养时,神经干细胞贴壁分化加快,NSE阳性细胞及TH阳性细胞明显多于对照组(P<0·05)。结论星形胶质细胞源性因子可快速诱导神经干细胞向神经元细胞、包括多巴胺神经元细胞分化,提示星形胶质细胞支持神经元发生。     

嗅鞘细胞诱导神经干细胞分化后神经元电生理特性的研究

目的探索大鼠嗅鞘细胞对神经干细胞(NSC)分化的影响,以及分化后神经元电生理特性。方法取新生鼠大脑皮质,原代培养大鼠NSC。NSC分为实验组和对照组,实验组将无血清培养的NSC中加入嗅鞘细胞条件培养液,对照组单纯无血清培养NSC。光镜下观察细胞分化情况,免疫组化法分别检测巢蛋白(nestin)、神经生长因子受体(NGFRp75)、神经丝蛋白(NF200)和胶质纤维酸性蛋白(GFAP)的表达,膜片钳检测神经元电生理特性。结果实验组嗅鞘细胞主要诱导NSC分化为神经元,少量分化为胶质细胞。对照组NSC逐渐萎缩,最终死亡。分化后的神经元记录到快速激活、快速失活能被河豚毒素特异阻断的钠电流,以及慢激活、慢失活能被四乙铵特异阻断的延迟整流性钾电流。结论嗅鞘细胞能诱导NSC分化成神经元,分化后的神经元具有活跃的电生理特性。     

大鼠脑出血后内源性神经干细胞激活和增殖的实验研究

目的 观察大鼠脑出血模型内源性神经干细胞(NSCs)的激活、增殖情况及其对神经行为学表现的影响.方法 将72只SD大鼠按单双号分为脑出血组和假手术组.每组36只.脑出血组利用立体定向技术,将一定量的Ⅳ型胶原酶用微量进样器分别精确注入大鼠内囊诱导脑出血模型.假手术组注射等量体积的PBS.分别于术后1、7、14、21、28和35 d观察大鼠的神经功能表现.所有大鼠处死前1 d腹腔内注射5.溴脱氧尿嘧啶(BrdU),免疫组织化学方法动态检测大鼠脑内巢蛋白(nestin)和BrdU的表达.结果 假手术组大鼠脑内未见nestin和BrdU的表达.脑出血组血肿周围基底节和脑室下区可见nestin和BrdU的表达.脑出血后7 d后开始明显增加.14 d达高峰,21 d开始下降.28d恢复正常.脑出血后l～35d大鼠神经功能无明显恢复,与内源性NSCs的增殖程度无明显相关.结论 脑出血可导致内源性NSCs的激活和诱导其增殖:然而这种状态下NSCs的增殖能力和内源性NSCs对脑出血后神经功能缺损的修复均有限.     

In vitro culture and differentiation of rat embryonic midbrain-derived neural stem cells

BACKGROUND: Midbrain-derived neural stem cells (mNSCs) can differentiate into functional mature dopamincrgic neurons. The mNSCs are considered the ideal choice for cell therapy of Parkinson's disease. OBJECTIVE: To isolate rat embryonic mNSCs and to observe the differentiation characteristics of mNSCs induced by cell growth-promoting factors. DESIGN, TIME AND SETTING: An in vitro cell culture study based on the molecular biology of nerve cells was carried out at the Institute of Clinical Medicine, China-Japan Friendship Hospital (China) from March to November 2007. MATERIALS: Sprague Dawley rats at embryonic day 14 were used in this study. Nestin antibody, β-Ⅲ tubulin antibody, glial fibrillary acidic protein (GFAP) antibody and cyclic nucleotide 3'-phosphohydrolase (CNPase) antibody were provided by Abeam; DMEM/F12 medium and N2 supplement were provided by Invitrogen; epidermal growth factor (EGF) and fibroblast growth factor-2 (FGF2) were provided by R＆D Systems. METHODS: The ventral mesencephalon was dissected from embryonic day 14 rat embryos. By trypsin digestion and mechanical separation, the brain tissue was triturated into a fine single-cell suspension. The cells were cultured in 5 mL serum-free medium containing DMEM/Fl2, 1% N2 supplement, 20 ng/mL EGF and FGF2. The mNSCs at the third generation were coated with 10 μg/mL polylysine and induced to differentiate in the DMEM/Fl2 supplemented with 1% fetal bovine serum and 1% N2. MAIN OUTCOME MEASURES: The neural spheres of the third passage were identified by nestin immunofluorescence; at the same time, the cells were induced to differentiate, and the types of differentiated cell were identified by immunofluorescence for βⅢ tubulin, GFAP and CNPase. RESULTS: Seven days after primary culture, a great many neurospheres could be obtained by successive pasage. Immunofluorescence assays showed that the neurospheres were nestin positive, and after differentiation, the cells expressed GFAP, CNPase and β -Ⅲ-tubulin. CONCLUSION: Embryonic day 14 rat mNSCs can differentiate into neuron-like cells and glial cells following induction by EGF, FGF2 and N2 additive.     

In vitro culture and differentiation of rat embryonic midbrain-derived neural stem cells*☆

BACKGROUND： Midbrain-derived neural stem cells （mNSCs） can differentiate into functional mature dopaminergic neurons. The mNSCs are considered the ideal choice for cell therapy of Parkinson＇s disease. OBJECTIVE： To isolate rat embryonic mNSCs and to observe the differentiation characteristics of mNSCs induced by cell growth-promoting factors. DESIGN, TIME AND SETTING： An in vitro cell culture study based on the molecular biology of nerve cells was carried out at the Institute of Clinical Medicine, China-Japan Friendship Hospital （China） from March to November 2007. MATERIALS： Sprague Dawley rats at embryonic day 14 were used in this study. Nestin antibody, β-Ⅲ tubulin antibody, glial fibrillary acidic protein （GFAP） antibody and cyclic nucleotide 3＇-phosphohydrolase （CNPase） antibody were provided by Abcam; DMEM/F12 medium and N2 supplement were provided by Invitrogen; epidermal growth factor （EGF） and fibroblast growth factor-2 （FGF2） were provided by R＆D Systems. METHODS： The ventral mesencephalon was dissected from embryonic day 14 rat embryos. By trypsin digestion and mechanical separation, the brain tissue was triturated into a fine single-cell suspension. The cells were cultured in 5 mL serum-free medium containing DMEM/FI 2, 1% N： supplement, 20 ng/mL EGF and FGF2. The mNSCs at the third generation were coated with 10ug/mL polylysine and induced to differentiate in the DMEM/F12 supplemented with 1% fetal bovine serum and 1% N2. MAIN OUTCOME MEASURES： The neural spheres of the third passage were identified by nestin immunofluorescence; at the same time, the cells were induced to differentiate, and the types of differentiated cell were identified by immunofluorescence for β Ⅲ tubulin, GFAP and CNPase. RESULTS： Seven days after primary culture, a great many neurospheres could be obtained by successive pasage. Immunofluorescence assays showed that the neurospheres were nestin positive, and after differentiation, the cells expressed GFAP, CNPase and β -Ⅲ-tu     

神经干细胞分化与bHLH转录调控因子

近年来,许多bHLH转录调控因子被克隆。研究揭示,bHLH转录调控因子参与了中枢神经系统神经干细胞的分化。根据bHLH转录调控因子在神经分化过程中的作用,它们可分为决定因子和分化因子。此外,有负调控因子调控bHLH蛋白参与神经干细胞分化。     

Dnmt3a regulates both proliferation and differentiation of mouse neural stem cells

DNA methylation is known to regulate cell differentiation and neuronal function in vivo. Here we examined whether deficiency of a de novo DNA methyltransferase, Dnmt3a, affects in vitro differentiation of mouse embryonic stem cells (mESCs) to neuronal and glial cell lineages. Early‐passage neural stem cells (NSCs) derived from Dnmt3a‐deficient ESCs exhibited a moderate phenotype in precocious glial differentiation compared with wild‐type counterparts. However, successive passaging to passage 6 (P6), when wild‐type NSCs become gliogenic, revealed a robust phenotype of precocious astrocyte and oligodendrocyte differentiation in Dnmt3a^?/? NSCs, consistent with our previous findings in the more severely hypomethylated Dnmt1^?/? NSCs. Mass spectrometric analysis revealed that total levels of methylcytosine in Dnmt3a^?/? NSCs at P6 were globally hypomethylated. Moreover, the Dnmt3a^?/? NSC proliferation rate was significantly increased compared with control from P6 onward. Thus, our work revealed a novel role for Dnmt3a in regulating both the timing of neural cell differentiation and the cell proliferation in the paradigm of mESC‐derived‐NSCs. © 2012 Wiley Periodicals, Inc.     

Association between p75 neurotrophin receptor gene expression and cell apoptosis in tissues surrounding hematomas in rat models of intracerebral hemorrhage

Animal models of intracerebral hemorrhage were established by injection of autologous blood into the caudate nucleus in rats. Cell apoptosis was measured by flow cytometry and immunohistochemical staining of the p75 neurotrophin receptor. p75 neurotrophin receptor protein was detected by immunohistochemistry. p75 neurotrophin receptor mRNA was examined by quantitative real-time polymerase chain reactions. At 24 hours after modeling, cellular apoptosis occured around hematoma with upregulation of p75 neurotrophin receptor protein and mRNA was observed, which directly correlated to apoptosis. This observation indicated that p75 neurotrophin receptor upregulation was associated with cell apoptosis around hematomas after intracerebral hemorrhage.     

Neural cell injury microenvironment induces neural differentiation of human umbilical cord mesenchymal stem cells

This study aimed to investigate the neural differentiation of human umbilical cord mesenchymal stem cells (hUCMSCs) under the induction of injured neural cells. After in vitro isolation and culture, passage 5 hUCMSCs were used for experimentation. hUCMSCs were co-cultured with normal or Aβ_1-40-injured PC12 cells, PC12 cell supernatant or PC12 cell lysate in a Transwell co-culture system. Western blot analysis and flow cytometry results showed that choline acetyltransferase and microtubule-associated protein 2, a specific marker for neural cells, were expressed in hUCMSCs under various culture conditions, and highest expression was observed in the hUCMSCs co-cultured with injured PC12 cells. Choline acetyltransferase and microtubule-associated protein 2 were not expressed in hUCMSCs cultured alone (no treatment). Cell Counting Kit-8 assay results showed that hUCMSCs under co-culture conditions promoted the proliferation of injured PC12 cells. These findings suggest that the microenvironment during neural tissue injury can effectively induce neural cell differentiation of hUCMSCs. These differentiated hUCMSCs likely accelerate the repair of injured neural cells.     

Immunodeficiency reduces neural stem/progenitor cell apoptosis and enhances neurogenesis in the cerebral cortex after stroke

Acute inflammation in the poststroke period exacerbates neuronal damage and stimulates reparative mechanisms, including neurogenesis. However, only a small fraction of neural stem/progenitor cells survives. In this report, by using a highly reproducible model of cortical infarction in SCID mice, we examined the effects of immunodeficiency on reduction of brain injury, survival of neural stem/progenitor cells, and functional recovery. Subsequently, the contribution of T lymphocytes to neurogenesis was evaluated in mice depleted for each subset of T lymphocyte. SCID mice revealed the reduced apoptosis and enhanced proliferation of neural stem/progenitor cells induced by cerebral cortex after stroke compared with the immunocompetent wild‐type mice. Removal of T lymphocytes, especially the CD4⁺ T‐cell population, enhanced generation of neural stem/progenitor cells, followed by accelerated functional recovery. In contrast, removal of CD25⁺ T cells, a cell population including regulatory T lymphocytes, impaired functional recovery through, at least in part, suppression of neurogenesis. Our findings demonstrate a key role of T lymphocytes in regulation of poststroke neurogenesis and indicate a potential novel strategy for cell therapy in repair of the central nervous system. © 2010 Wiley‐Liss, Inc.     

脑脊液中细胞源性囊泡对间充质干细胞向神经前体细胞分化的影响

目的探讨脑脊液微囊泡在间充质干细胞(MSCs)向神经干细胞分化中的作用。方法从人脑脊液中分离微囊泡,从小鼠骨髓中分离原代MSCs。将MSCs传代后在神经分化诱导培养基和脑脊液微囊泡作用下神经分化诱导。细胞形态学观察细胞突起数目和长度,western blot检测细胞神经特异性蛋白表达水平变化。结果单纯神经诱导液组单位面积内细胞突起长度为(2.2±0.4)mm,突起数量为(94±12)个;神经诱导液加脑脊液微囊泡诱导的细胞中细胞突起更长(5.7±1.2)mm,数目也更多(178.2±32)个,差异具有统计学意义(P0.01)。微囊泡组细胞中NSE、Nestin和MAP-2表达水平高于单纯神经诱导液组细胞,差异具有统计学意义(P0.01)。结论脑脊液微囊泡可有效促进MSCs向神经干细胞分化,有望为干细胞移植治疗神经功能缺损提供了一个新的思路。     

Overexpression of Wnt3a facilitates the proliferation and neural differentiation of neural stem cells in vitro and after transplantation into an injured rat retina

Neural stem cell‐based therapy is a promising option for repair after injury. However, poor stem cell proliferation and insufficient differentiation of the stem cells into neurons are still difficult problems. The present study investigated whether transplantation of neural stem cells (NSCs) genetically modified to express Wnt3a is a promising approach to overcome these difficulties. We explored the possibility that Wnt3a might contribute to the therapeutic effect of NSC transplantation in retinal repair. The relative promotion of proliferation and neural differentiation by modified NSCs was investigated in a rat model of optic nerve crush. A recombinant lentivirus (Lenti‐Wnt3a) was engineered to express Wnt3a. NSCs infected with control lentivirus (Lenti‐GFP) or Lenti‐Wnt3a were transplanted into the subretinal space immediately after the optic nerve crush. The proliferation and neural differentiation activity of the NSCs were assessed in vitro and in vivo. Overexpression of Wnt3a in NSCs induced activation of Wnt signaling, promoted proliferation, and directed the differentiation of the NSCs into neurons both in vitro and in vivo. Our study suggests that Wnt3a can potentiate the therapeutic benefits of NSC‐based therapy in the injured retina. © 2013 Wiley Periodicals, Inc.     

Spatio-temporal dynamics, differentiation and viability of human neural stem cells after implantation into neonatal rat brain

Neural stem cells (NSCs) have attracted major research interest due to their potential use in cell replacement therapy. In patients, human cells are the preferred choice, one source of human NSCs being the brain of fetuses. The aims of the present study were to explore the long‐term differentiation, mobility and viability of NSCs derived from the human fetal striatum in response to intracerebral implantation. To investigate long‐term spatio‐temporal and functional dynamics of grafts in vivo by magnetic resonance imaging, these cells were labeled with superparamagnetic iron oxide (SPIO) nanoparticles prior to implantation. SPIO‐labeling of human NSCs left the quantitative profile of the proliferation, cell composition and differentiation capacity of the cells in vitro unaltered. Also after transplantation, the phenotypes after long‐term cell differentiation were not significantly different from naïve cells. Upon transplantation, we detected a hypointensity corresponding to the striatal graft location in all animals and persisting for at least 4 months. The hypointense signal appeared visually similar both in location and in volume over time. However, quantitative volumetric analysis showed that the detectable, apparent graft volume decreased significantly from 3 to 16 weeks. Finally, the human NSCs were not proliferating after implantation, indicating lack of tumor formation. These cells are thus a promising candidate for translationally relevant investigations for stem cell‐based regenerative therapies.