神经干细胞抗帕金森病的实验治疗学进展

神经干细胞(neural stem cells,NSCs)具有高度的自我更新能力、多向分化潜能(包括神经元、星型胶质细胞和少突胶质细胞)和迁移能力.主要来源于哺乳动物胚胎期的大部分脑区以及成体脑组织的两个区域:海马齿状回的颗粒下层和侧脑室的室管膜下区.目前,应用NSCs治疗帕金森病(Parkinson's diseas...     

Vanadium compounds enhance adult neurogenesis after brain ischemia

Generation of neural precursors persists throughout life in the forebrain subventricular zone (SVZ) and dentate gyrus (DG) subgranular zone (SGZ) in rodent and human brains. In addition, newborn granule cells in the hippocampal DG are important for learning and memory formation. Brain injuries such as seizures or trauma could trigger endogenous programs for adult neurogenesis. Although brain ischemia also increases proliferation of neural progenitor cells in SVZ and SGZ, most neural progenitor cells are dead within 2 weeks after brain ischemia. In addition, there is no therapeutic agent to promote neurogenesis in the adult brain following brain injury. Here we found that intraperitoneal administrations of vanadium compounds, a stimulator of phosphatidylinositol 3-kinase (PI3K)/Akt and extracellular signal regulated kinase (ERK) pathways markedly enhances brain ischemia-induced neurogenesis. Thus, vanadium compounds are potential therapeutic agent to enhance ischemia-induced neurogenesis through PI3K/Akt and ERK activation.     

Neural stem cells: the basic biology and prospects for brain repair]

Neural stem cells (NSCs) are multipotential progenitor cells that have self-renewal activities. A single NSC is capable of generating various kinds of cells within the CNS, including neurons, astrocytes, and oligodendrocytes. Because of these characteristics, there is an increasing interest in NSCs and neural progenitor cells from the aspects of both basic developmental biology and therapeutic applications for damaged brain. By understanding the nature of NSCs present in the CNS, extracellular factors and signal transduction cascades involved in the differentiation and maintenance of NSCs, population dynamics and localization of NSCs in embryonic and adult brains, prospective identification and isolation of NSCs, and induction of NSCs into particular neuronal phenotypes, it would be possible to develop a feasible strategy to manipulate cells in situ to treat damaged brain.     

Adult neural stem cell therapy: expansion in vitro, tracking in vivo and clinical transplantation

Neural stem cells (NSCs) are present not only in the developing nervous systems, but also in the adult human central nervous system (CNS). It is long thought that the subventricular zone of the lateral ventricles and the dentate gyrus of the hippocampus are the main sources of human adult NSCs, which are considered to be a reservoir of new neural cells. Recently adult NSCs with potential neural capacity have been isolated from white matter and inferior prefrontal subcortex in the human brain. Rapid advances in the stem cell biology have raised appealing possibilities of replacing damaged or lost neural cells by transplantation of in vitro-expanded stem cells and/or their neuronal progeny. However, sources of stem cells, large scale expansion, control of the differentiations, and tracking in vivo represent formidable challenges. In this paper we review the characteristics of the adult human NSCs, their potentiality in terms of proliferation and differentiation capabilities, as well as their large scale expansion for clinical needs. This review focuses on the major advances in brain stem cell-based therapy from the clinical perspective, and summarizes our work in clinical phase I-II trials with autologuous transplantation of adult NSCs for patients with open brain trauma. It also describes multiple approaches to monitor adult human NSCs labeled superparamagnetic nanoparticles after transplantation and explores the intriguing possibility of stem cell transplantation.     

Neurogenic drugs and compounds to treat CNS diseases and disorders

Neurological diseases and related conditions affect an estimated 1 billion of individuals worldwide [1]. There is still no cure for neurological diseases and disorders, barely a few treatments more or less efficient. This mandates the design and development of novel paradigms and strategies, to discover and develop new treatments and cures for these diseases. Neurogenesis occurs in the adult brain of mammals primarily in two regions, the dentate gyrus (DG) of the hippocampus and the subventricular zone, in various species including in humans. Neural progenitor and stem cells have been isolated, propagated and characterized in vitro from the adult brain of mammals, including humans. The confirmation that neurogenesis occurs in the adult brain and neural stem cells (NSCs) reside in the adult central nervous system (CNS) of mammals, opens new avenues and opportunities for treating neurological diseases and injuries [2].     

Epigallocatechin-3-gallate rescues LPS-impaired adult hippocampal neurogenesis through suppressing the TLR4-NF-κB signaling pathway in mice

Adult hippocampal dentate granule neurons are generated from neural stem cells (NSCs) in the mammalian brain, and the fate specification of adult NSCs is precisely controlled by the local niches and environment, such as the subventricular zone (SVZ), dentate gyrus (DG), and Toll-like receptors (TLRs). Epigallocatechin-3-gallate (EGCG) is the main polyphenolic flavonoid in green tea that has neuroprotective activities, but there is no clear understanding of the role of EGCG in adult neurogenesis in the DG after neuroinflammation. Here, we investigate the effect and the mechanism of EGCG on adult neurogenesis impaired by lipopolysaccharides (LPS). LPS-induced neuroinflammation inhibited adult neurogenesis by suppressing the proliferation and differentiation of neural stem cells in the DG, which was indicated by the decreased number of Bromodeoxyuridine (BrdU)-, Doublecortin (DCX)- and Neuronal Nuclei (NeuN)-positive cells. In addition, microglia were recruited with activatingTLR4-NF-κB signaling in the adult hippocampus by LPS injection. Treating LPS-injured mice with EGCG restored the proliferation and differentiation of NSCs in the DG, which were decreased by LPS, and EGCG treatment also ameliorated the apoptosis of NSCs. Moreover, pro-inflammatory cytokine production induced by LPS was attenuated by EGCG treatment through modulating the TLR4-NF-κB pathway. These results illustrate that EGCG has a beneficial effect on impaired adult neurogenesis caused by LPSinduced neuroinflammation, and it may be applicable as a therapeutic agent against neurodegenerative disorders caused by inflammation.     

Untangling the functional potential of PSA-NCAM-expressing cells in CNS development and brain repair strategies

Central nervous system (CNS) neural stem cells (NSCs), which are mostly defined by their ability to self-renew and to generate the three main cell lineages of the CNS, were isolated from discrete regions of the adult mammalian CNS including the subventricular zone (SVZ) of the lateral ventricle and the dentate gyrus in the hippocampus. At early stages of CNS cell fate determination, NSCs give rise to progenitors that express the polysialylated form of the neural cell adhesion molecule (PSA-NCAM). PSA-NCAM(+) cells persist in adult brain regions where neuronal plasticity and sustained formation of new neurons occur. PSA-NCAM has been shown to be involved in the regulation of CNS myelination as well as in changes of cell morphology that are necessary for motility, axonal guidance, synapse formation, and functional plasticity in the CNS. Although being preferentially committed to a restricted either glial or neuronal fate, cultured PSA-NCAM(plus) progenitors do preserve a relative degree of multipotentiality. Considering that PSA-NCAM(+) cells can be neatly used for brain repair purposes, there is much interest for studying signaling factors regulating their development. With this regard, it is noteworthy that neurotransmitters, which belong to the micro-environment of neural cells in vivo, regulate morphogenetic events preceding synaptogenesis such as cell proliferation, migration, differentiation and death. Consistently, several ionotropic but also G-protein-coupled neurotransmitter receptors were found to be expressed in CNS embryonic and postnatal progenitors. In the present review, we outlined the ins and outs of PSA-NCAM(plus) cells addressing to what extent our understanding of extrinsic and in particular neurotransmitter-mediated signaling in these CNS precursor cells might represent a new leading track to develop alternative strategies to stimulate brain repair.     

α7 Nicotinic receptor agonist reactivates neurogenesis in adult brain

Reactivation of neurogenesis by endogenous Neural Stem/Progenitor Cells (NS/PC) in the adult brain or spinal cord holds the key for treatment of CNS injuries as well as neurodegenerative disorders, which are major healthcare issues for the world's aging population. Recent studies show that targeting the α7 nicotinic acetylcholine receptors (α7nAChR) with a specific TC-7020 agonist inhibits proliferation and stimulates neuronal differentiation of NS/PC in subventricular zone (SVZ) in the adult mouse brain. TC-7020-induced neuronogenesis is observed in different brain regions, including: (1) βIII Tubulin-expressing cortical neurons, (2) calretinin expressing hippocampal neurons and (3) cells in substantia nigra (SN) expressing predopaminergic Nurr1+phenotype. Reactivation of developmental integrative nuclear FGFR1 signaling (INFS), via gene transfection reinstates neurogenesis in the adult brain by promoting neuronal differentiation of brain NS/PC. TC-7020 neuronogenic effect is associated with a robust accumulation of endogenous FGFR1 in the nuclei of differentiating cells. Furthermore, direct in vitro stimulation of neural stem/progenitor cells with α7nAChR agonist activates INFS and neuronal-like differentiation and activation of neuronal genes. The α7nAChR upregulation of early neuronal βIII-Tubulin gene involves neurogenic FGFR1-Nur signaling and direct FGFR1 interaction with the gene promoter. The reactivation of developmental INFS and neurogenesis in adult brain by the α7nAChR agonist may offer new strategy to treat brain injuries, neurodegenerative and neurodevelopmental diseases.     

De-routing neuronal precursors in the adult brain to sites of injury: Role of the vasculature

Neurogenesis in the adult brain occurs predominantly in the two regions, the subventricular zone (SVZ) bordering the lateral ventricle and subgranular zone (SGZ) of the hippocampus. The neuronal precursors are produced in the specialized microenvironment called neurovasculature niche. Recent evidences indicate that in addition to neurogenesis promoting environment, vasculature also serves as a substrate for migration for these newly generated cells. Importantly, under some pathological condition, including stroke, neurogenesis is enhanced in the adult brain. Newly generated neuronal precursors migrate to the sites of injury along the blood vessels and try to integrate to the damaged brain circuitry. This self-healing capacity of the adult brain is, however, insufficient to produce a noticeable amelioration in the affected neuronal network since only a tiny proportion of cells succeed to integrate and survive. Here we review the mechanisms of neuronal recruitment into the post-stroke regions with particular attention to the guidance of neuronal precursors along the blood vessels. We also outline some of the molecular factors that have been used or have a potential to be employed to improve the cell recruitment into the sites of injury.     

丹酚酸B对脑缺血再灌注大鼠神经细胞损伤和神经发生的影响

本文旨在观察丹酚酸B对脑缺血再灌注大鼠神经发生和神经细胞损伤的影响，探讨丹酚酸B促进机体功能恢复的作用环节。研究采用大鼠局灶性脑缺血再灌注模型，治疗给药，用BrdU法观察海马齿状回颗粒下层(sub-granular zone，SGZ)和侧脑室下层(sub-ventricular zone，SVZ)神经发生的变化；尼氏体染色观察神经细胞损伤；平衡杆法观察肢体功能恢复。结果显示，缺血后再灌注7 d，模型组SGZ和SVZ的BrdU细胞明显多于假手术组(P<0.05)，丹酚酸B(10 mg·kg^-1)显著增加SGZ和SVZ的BrdU细胞数目(P<0.01 vs模型组)；缺血再灌注14 d，模型动物缺血侧海马CA1区和皮层神经细胞明显减少，丹酚酸B(10 mg·kg^-1)明显改善神经细胞损伤(P<0.01 vs模型组)；同时，丹酚酸B(10 mg·kg^-1)明显促进缺血动物肢体功能恢复。以上结果表明，丹酚酸B能够增加脑缺血大鼠SVZ和SGZ的BrdU细胞数目，改善缺血区神经细胞损伤，促进肢体功能恢复，提示促进神经发生是丹酚酸B改善脑功能的重要环节。     

Effect of cytokine treatment on the neurogenesis process in the brain of soman-poisoned mice

We previously described that enhanced proliferation of neural progenitors occurred in the subgranular zone (SGZ) of the dentate gyrus and in the subventricular zone (SVZ) of the mouse brain following soman poisoning. Then, a discrete number of these cells seemed to migrate and engraft into the main damaged brain regions (hippocampus; septum and amygdala) and subsequently differentiate into neurons. In the present study, the effect of a cytokine treatment on the neurogenesis process was evaluated. For this purpose, subcutaneous injection of a cocktail of 40 microg/kg epidermal growth factor (EGF) and basic fibroblast growth factor (bFGF) was administered daily to soman-poisoned mice (110 microg/kg soman and 5.0 mg/kg methyl nitrate atropine), from post-soman days 1 to 8. To label replicating neural progenitors, 200 mg/kg bromodeoxyuridine (BrdU) was injected twice a day between post-soman days 6 and 8. Mice were sacrificed on post-soman day 9 or 34. On post-soman day 9, the cytokine treatment had no effect on the proliferation of neural progenitors in the SVZ and SGZ, as assessed by BrdU immunochemistry. However, this treatment seemed to promote the migration of neural precursor cells from the proliferative areas towards damaged brain regions. Indeed, in the CA1 hippocampal layer of soman-poisoned mice, on post-soman day 34, the cytokine treatment increased the number of healthy pyramidal neurons stained by hemalun-eosin dye. The cytokine treatment also augmented the number of BrdU-labeled cells in the CA1 hippocampal layer and amygdala. Interestingly, the administration of cytokines resulted in the differentiation of BrdU-positive cells into new neurons in the CA1 hippocampal layer, whereas astrocytic differentiation was preferentially observed in the amygdala.     

Adult neural stem cells for the treatment of neuroinflammation

Background: The application is in the field of stem cells and their therapeutic application for the treatment of inflammation. Objective: It aims at characterizing the potential of adult-derived neural progenitor and stem cells for the treatment of inflammation of the central nervous system (CNS). Methods: Neural progenitor and stem cells were isolated and expanded from the subventricular zone (SVZ) of adult mice (aNSCs). They were administered intravenously in an animal model of multiple sclerosis (MS). Results: Mice transplanted either at the disease onset or at the onset of the first relapse show clinical signs of improvements. Adult NSCs exert their therapeutical activity by reducing neuroinflammation. Conclusion: The application claims the use of aNSCs and multipotent somatic stem cells for the treatment of inflammation, associated with neurological diseases, disorders and injuries particularly, and for inducing tolerance to the immune central and/or peripheral system     

Endogenous and exogenous CNS derived stem/progenitor cell approaches for neurotrauma

Neural stem/progenitor cells capable of generating new neurons and glia, reside in specific areas of the adult mammalian central nervous system (CNS), including the ependymal region of the spinal cord and the subventricular zone (SVZ), hippocampus, and dentate gyrus of the brain. Much is known about the neurogenic regions in the CNS, and their response to various stimuli including injury, neurotrophins (NFs), morphogens, and environmental factors like learning, stress, and aging. This work has shaped our current views about the CNS's potential to recover lost tissue and function post-traumatically and the therapies to support the intrinsic regenerative capacity of the brain or spinal cord. Recently, intensive research has explored the potential of harvesting, culturing, and transplanting neural stem/progenitors as a therapeutic intervention for spinal cord injury (SCI) and traumatic brain injury (TBI). Another strategy has focused on maximizing the potential of this endogenous population of cells by stimulating their recruitment, proliferation, migration, and differentiation in vivo following traumatic lesions to the CNS. The promise of such experimental treatments has prompted tissue and biomaterial engineers to implant synthetic three-dimensional biodegradable scaffolds seeded with neural stem/progenitors into CNS lesions. Although there is no definitive answer about the ideal cell type for transplantation, strong evidence supports the use of region specific neural stem/progenitors. The technical and logistic considerations for transplanting neural stem/progenitors are extensive and crucial to optimizing and maintaining cell survival both before and after transplantation, as well as for tracking the fate of transplanted cells. These issues have been systematically addressed in many animal models, that has improved our understanding and approach to clinical therapeutic paradigms.     

Soman poisoning increases neural progenitor proliferation and induces long-term glial activation in mouse brain

To date, only short-term glial reaction has been extensively studied following soman or other warfare neurotoxicant poisoning. In a context of cell therapy by neural progenitor engraftment to repair brain damage, the long-term effect of soman on glial reaction and neural progenitor division was analyzed in the present study. The effect of soman poisoning was estimated in mouse brains at various times ranging from 1 to 90 days post-poisoning. Using immunochemistry and dye staining techniques (hemalun-eosin staining), the number of degenerating neurons, the number of dividing neural progenitors, and microglial, astroglial or oligodendroglial cell activation were studied. Soman poisoning led to rapid and massive (post-soman day 1) death of mature neurons as assessed by hemalun-eosin staining. Following this acute poisoning phase, a weak toxicity effect on mature neurons was still observed for a period of 1 month after poisoning. A massive short-termed microgliosis peaked on day 3 post-poisoning. Delayed astrogliosis was observed from 3 to 90 days after soman poisoning, contributing to glial scar formation. On the other hand, oligodendroglial cells or their precursors were practically unaffected by soman poisoning. Interestingly, neural progenitors located in the subgranular zone of the dentate gyrus (SGZ) or in the subventricular zone (SVZ) of the brain survived soman poisoning. Furthermore, soman poisoning significantly increased neural progenitor proliferation in both SGZ and SVZ brain areas on post-soman day 3 or day 8, respectively. This increased proliferation rate was detected up to 1 month after poisoning.     

Neural stem cells and neurodegeneration

Neurodegenerative diseases, such as Parkinson's disease, are characterized by a continuous loss of specific populations of neurons. Possible regenerative interventions include transplanting developing neural tissue or neural stem cells into the host brain, and inducing proliferation of endogenous stem cells by pharmacological manipulations. Neural stem cells (NSC), with the capacity to self-renew and produce the major cell types of the brain, exist in the developing and adult central nervous system (CNS). These cells can be grown in vitro while retaining the potential to differentiate into nervous tissue. This review focuses on regenerative therapy in neurodegenerative diseases using NSC.     

不同细胞因子体外诱导神经干细胞向神经细胞分化的研究

目的观察碱性纤维母细胞生长因子、白血病抑制因子、脑源性神经营养因子及不同组合对成年SD大鼠脑神经干细胞在体外分化为神经细胞的作用。方法用含碱性纤维母细胞生长因子（bFGF）、B27的无血清细胞培养技术体外培养成年SD大鼠脑神经干细胞,单细胞克隆后行Nestin免疫细胞化学染色;根据培养液中所加营养因子的不同将单细胞克隆传代细胞分为5组培养：bFGF、LIF、BDNF、bFGF＋LIF、bFGF＋BDNF组,此5组细胞培养1周,进行NSE免疫细胞化学染色,计数阳性细胞比例后进行统计学分析。结果单细胞克隆培养后克隆球细胞表达Nestin;与bFGF组、LIF组、BDNF组相比,bFGF＋BDNF组和bFGF＋LIF组神经干细胞分化为神经细胞的比例较高（P〈0．01）,其中bFGF＋BDNF组神经细胞的比例最高。结论在bFGF培养条件下,BDNF促进成年SD大鼠脑神经干细胞向神经细胞分化的能力高于LIF。     

Activin A secreted by human mesenchymal stem cells induces neuronal development and neurite outgrowth in an in vitro model of Alzheimer’s disease: neurogenesis induced by MSCs via activin A

Alzheimer’s disease (AD) is characterized by progressive loss of memory in addition to cortical atrophy. Cortical atrophy in AD brains begins in the parietal and temporal lobes, which are near the subventricular zone (SVZ). The aim of this study was to activate the neurogenesis in the SVZ of AD brains by human mesenchymal stem cells (hMSCs). Neural stem cells (NSCs) were isolated from SVZ of 4-month-old 5XFAD mice. Co-culture of hMSCs with SVZ-derived NSCs from 5XFAD mice induced neuronal development and neurite outgrowth. To examine the inducing factor of neurogenesis, human cytokine array was performed with co-cultured media, and revealed elevated release of activin A from hMSCs. Also, we confirmed that the mRNA levels of activin A and activin receptor in the SVZ of 5XFAD mice were significantly lower than normal mice. Treatment of human recombinant activin A in SVZ-derived NSCs from 5XFAD mice induced neuronal development and neurite outgrowth. These data suggest that use of hMSCs and activin A to recover neurogenesis in future studies of cortical regeneration to treat AD.     

Novel strategies for discovering inhibitors of Dengue and Zika fever

Neurogenesis occurs in discrete regions of the adult brain, particularly the hippocampus. It is enhanced in the hippocampus of animal models and patients with neurological diseases and disorders, such as Alzheimer's disease (AD) and epilepsy. Adult hippocampal neurogenesis is modulated by drugs used for treating AD and depression, particularly galantamine, memantine and fluoxetine. This reveals that adult neurogenesis and newly generated neuronal cells of the adult hippocampus are involved in neurological diseases and disorders and that adult neurogenesis and neural stem cells (NSCs) of the adult hippocampus are the target of drugs used for treating AD and depression. Hence, adult neurogenesis and NSCs open new opportunities for our understanding of the pathology of the nervous system and new avenues to discover and develop novel drugs for treating neurogical diseases and disorders; drugs that would target specifically the NSCs of the neurogenic regions in the adult brain, or neurogenic drugs, and that would reverse or compensate deficits and impairments associated with neurological diseases and disorders, particularly those associated with the hippocampus. Adult NSCs represent a model to discover and develop novel drugs for treating neurological diseases and disorders. These drugs may also have potential for regenerative medicine and the treatment of brain tumors.     

Expression of the ubiquitin ligase HRD1 in neural stem/progenitor cells of the adult mouse brain

Neural stem/progenitor cells (NSCs) reside in the subventricular zone (SVZ) and subgranular zone of the hippocampal dentate gyrus in adult mammals. The ubiquitin ligase HRD1 is associated with degradation of amyloid precursor protein and believed to be specifically expressed in neurons and not in astrocytes. We investigated expression of HRD1 using immunohistochemistry and found colocalization of HRD1 with the NSC marker protein nestin and glial fibrillary acidic protein in the NSCs of the SVZ (the SVZ astrocytes) but not in the hippocampus. In the hippocampal dentate gyrus, HRD1 is localized in the nucleus of nestin-positive cells.     

Neural stem cells: a pharmacological tool for brain diseases?

Stem cells are believed to provide a tool by which new cells and tissues can be made and by which damaged ones can be replaced or repaired. Over the past few years, the existence of a subset of stem cells has been documented in the fetal brain, therefore named neural stem cells (NSCs). To this regard, the more recent demonstration that similar cells are present in the adult mammalian brain and retain the capability to produce new neurons, has undermined the dogma that neurons are only generated during the fetal life and has stimulated investigations into the regulation and role of adult neurogenesis. Here, we will review the recent advancements on the biology of brain stem cells and discuss the mechanisms and drugs regulating adult neurogenesis, aiming at better estimating the possible future applications of NSCs for brain repair.