内源性神经干细胞的应用及其基础研究

目前对于神经系统损伤所致的神经元丢失尚无有效的治疗方法,然而研究表明成年哺乳动物的内源性神经干细胞能产生新的神经元,这些神经干细胞迁移至损伤区域,分化为成熟神经元,填补和部分修复脑组织。近年来研究者们对内源性神经干细胞治疗潜在价值的探讨日益增多,尤其是有关缺血性脑损伤、帕金森病、阿尔兹海默病、创伤性脑外伤的治疗进展。本文就内源性神经干细胞的治疗潜在价值基础研究进展做一综述。     

神经干细胞在神经系统疾病中的研究应用进展

随着神经干细胞理论的提出,为神经系统疾病的治疗带来了很大的希望。神经干细胞(NSCs)是指自我更新、且具有分化为神经元、星形胶质细胞、少突胶质细胞等多向分化潜能的细胞。当中枢神经系统受到损伤或退行性变时,内源性神经干细胞开始启动神经修复,但受到数量及微环境的影响,作用非常有限。近年,人们采用各种体外培养方法,可以获得一定数量的外源性神经干细胞,在神经干细胞移植治疗各种神经系统疾病,包括缺血性脑卒中、帕金森病、阿尔茨海默病和脊髓损伤等方面做了很多动物及临床前研究。本文综述神经干细胞移植在神经系统疾病治疗中的应用。     

诱导多能干细胞在帕金森病治疗中的应用进展

帕金森病（Parkinson's disease, PD）是由于黑质中多巴胺能神经元（dopaminergic neurons, DAns）的病变导致多巴胺含量降低而引起的一种神经退行性疾病,其发病机制尚不明确,而且临床缺乏有效的早期诊断和治疗手段。诱导多能干细胞（induced pluripotent stem cells, iPSCs）的出现为神经系统疾病特别是神经退行性疾病的治疗带来了希望。基于iPSCs的细胞模型可以广泛开展PD发病机制的研究,同时以iPSCs来源的DAns、神经干细胞（neural stem cells, NSCs）等的细胞移植治疗,更是未来PD治疗最有希望的手段。从基于iPSCs的不同基因突变类型的细胞模型与不同分化程度的细胞移植治疗两个方面介绍诱导多能干细胞在PD研究中的进展,旨在分析诱导多能干细胞在帕金森病方面的应用及不足。     

神经干细胞的研究现状及运用前景

近年来的研究表明胚胎期和成年期动物的神经组织及人脑中可以分离出神经干细胞.神经干细胞能不断增殖并且具有分化成神经元、星型胶质细胞和少突胶质细胞的能力.神经干细胞的这种特性为中枢神经系统退行性病变和损伤的治疗打下了基础.对神经干细胞的分布、生物学特性、鉴定、增殖与分化及其治疗中枢神经系统疾病中的应用前景进行了综述.     

干细胞与神经退行性疾病

神经退行性疾病是一类以神经元退行性病变或凋亡, 从而导致个体行为异常乃至死亡为主要特征的疾病. 随着社会逐渐步入老龄化, 神经退行性疾病的发病率不断攀升, 而大多这类疾病诊断困难, 目前尚无有效的治疗措施. 干细胞研究的迅速发展, 为这类疾病的治疗提供了新的途径和可能. 目前多种干细胞在神经退行性疾病动物模型上的尝试已取得进展. 本文综述了胚胎干细胞、间充质干细胞、神经干细胞等在神经退行性疾病如帕金森氏病、阿尔茨海默氏病、亨廷顿病、肌萎缩性侧索坏死等的治疗中的应用和进展.     

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。     

人胚胎干细胞向神经上皮祖细胞的诱导分化

人胚胎干细胞具有自我更新和多向分化潜能,是研究早期胚胎发育和细胞替代治疗的重要细胞来源.采用一种与小鼠成纤维细胞共培养的方法进行人胚胎干细胞的神经诱导,可产生高纯度的神经上皮祖细胞,其神经上皮特异性基因的表达有一定的时空性;诱导生成的神经上皮祖细胞具有增殖潜能并可分化为神经元和星型胶质细胞,是潜在的神经干细胞.人胚胎干细胞来源的神经上皮祖细胞为研究神经发育和神经诱导提供了新材料,也为神经系统疾病的细胞替代治疗提供了新的细胞来源.     

成年鼠脑中神经干细胞的纯化

神经干细胞具有自我复制和多向分化的潜能 ,它可分化为成熟神经元和神经胶质细胞 ,人们希望利用神经干细胞的分化潜能治疗帕金森病等神经系统疾病 ,但首先必须分离纯化这些细胞。以往 ,人们从发育外周神经系统中纯化神经干细胞 ,而脑中干细胞纯化率从未超过 5 %。最近 ,ＲｏｄｎｅｙＬ .Ｒｉｅｔｚｅ等以 80 %的纯化率分离成年鼠脑干细胞并检测这些细胞的特性。他们发现 ,其中一种可在室管膜和脑室下腔区域找到的干细胞活性很强 ,在 ｑｕｅｒｋｏｐｆ变异鼠 (一种嗅觉神经元缺陷的鼠 )中 ,这种细胞选择性缺失 ,提示它可能是离体主要的功能性…     

帕金森病整合医学治疗方法的探讨

本文对中老年常见的神经变性疾病帕金森病国内外发展概况、发病原因、发病机制进行了简要概述。对于帕金森病的临床治疗,本文提出整合医学治疗方法的理念,这种治疗包括常规一般临床药物治疗、肠道正常菌群和微生态制剂的微生态疗法的治疗、中医药单方和复方制剂的治疗,以及手术治疗(神经核毁损术,脑深部电刺激术)、干细胞治疗、基因编辑治疗等。整合当前最先进的理论和临床实践,提出了综合治疗帕金森病的方案。     

神经干细胞迁移浅识

神经干细胞的迁移是近年来神经科学领域研究的热点之一.神经干细胞的增殖、迁移、分化和网络重建的特性为研究中枢神经系统退行性疾病及损伤后功能的恢复奠定了基础,其中神经干细胞的迁移发挥了重要作用.目前已经有大量研究探索神经干细胞的迁移,本文将分别从神经干细胞的迁移现象、神经干细胞迁移的影响因素及其应用意义等方面做一综述.     

诱导型多能干细胞iPSc研究现状及其移植治疗帕金森综合症应用前景

诱导多能干细胞(i PS细胞)在小鼠和人上的成功获取,使干细胞领域的研究进入了一个崭新的时代。干细胞研究是再生医学的重要组成部分,研究干细胞的最终目的是应用干细胞治疗疾病,其在疾病模型建立、药物筛选、细胞移植等方面具有极大的应用潜力。i PSCs是由体细胞诱导分化而成的"多能细胞",具备和胚胎干细胞类似的功能,既解决了ESCs的伦理障碍,又为ESCs的获得提供了一条全新的途径,具有重要的理论和应用价值。i PS细胞不仅打破了道德理论的束缚,而且在再生医学、组织工程和药物发现及评价等方面具有积极的价值。神经系统遗传性疾病发病率居各系统遗传病之首,但其发病的分子机制仍不完全清楚,运用体细胞重编程技术建立的疾病特异性诱导多能干细胞模型将有助于揭示神经系统遗传性疾病的发病机理。近几年i PS细胞最新研究成果表明,利用疾病患者i PS细胞模型已逐渐应用于帕金森氏病、老年性痴呆症、脊髓侧索硬化症、脊髓肌肉萎缩症及舞蹈症等5种常见神经性退行性疾病发病机理的研究。本文主要对i PSc的发展历程,避免病毒基因干扰诱导i PS细胞进行的优化,以及干细胞尤其是i PS细胞移植治疗帕金森病等神经系统疾病的现状及应用前景进行系统阐述与论证。     

Functional integration of grafted neural stem cell-derived dopaminergic neurons monitored by optogenetics in an in vitro Parkinson model

Intrastriatal grafts of stem cell-derived dopamine (DA) neurons induce behavioral recovery in animal models of Parkinson''s disease (PD), but how they functionally integrate in host neural circuitries is poorly understood. Here, Wnt5a-overexpressing neural stem cells derived from embryonic ventral mesencephalon of tyrosine hydroxylase-GFP transgenic mice were expanded as neurospheres and transplanted into organotypic cultures of wild type mouse striatum. Differentiated GFP-labeled DA neurons in the grafts exhibited mature neuronal properties, including spontaneous firing of action potentials, presence of post-synaptic currents, and functional expression of DA D₂ autoreceptors. These properties resembled those recorded from identical cells in acute slices of intrastriatal grafts in the 6-hydroxy-DA-induced mouse PD model and from DA neurons in intact substantia nigra. Optogenetic activation or inhibition of grafted cells and host neurons using channelrhodopsin-2 (ChR2) and halorhodopsin (NpHR), respectively, revealed complex, bi-directional synaptic interactions between grafted cells and host neurons and extensive synaptic connectivity within the graft. Our data demonstrate for the first time using optogenetics that ectopically grafted stem cell-derived DA neurons become functionally integrated in the DA-denervated striatum. Further optogenetic dissection of the synaptic wiring between grafted and host neurons will be crucial to clarify the cellular and synaptic mechanisms underlying behavioral recovery as well as adverse effects following stem cell-based DA cell replacement strategies in PD.     

Effects of stem cell therapy on protein profile of parkinsonian rats using an18O‐labeling quantitative proteomic approach

The application of neural stem cell (NSC) research to neurodegenerative diseases has led to promising clinical trials. Currently, NSC therapy is most promising for Parkinson's disease (PD). We conducted behavioral tests and immunoassays for the profiling of a PD model in rats to assess the therapeutic effects of NSC treatments. Further, using a multiple sample comparison workflow, combined with ¹⁸O‐labeled proteome mixtures, we compared the differentially expressed proteins from control, PD, and NSC‐treated PD rats. The results were analyzed bioinformatically and verified by Western blot. Based on our initial findings, we believe that the proteomic approach is a valuable tool in evaluating the therapeutic effects of NSC transplantation on neurodegenerative disorders.     

Stem cells as promising therapeutic options for neurological disorders

Due to the limitations of pharmacological and other current therapeutic strategies, stem cell therapies have emerged as promising options for treating many incurable neurologic diseases. A variety of stem cells including pluripotent stem cells (i.e., embryonic stem cells and induced pluripotent stem cells) and multipotent adult stem cells (i.e., fetal brain tissue, neural stem cells, and mesenchymal stem cells from various sources) have been explored as therapeutic options for treating many neurologic diseases, and it is becoming obvious that each type of stem cell has pros and cons as a source for cell therapy. Wise selection of stem cells with regard to the nature and status of neurologic dysfunctions is required to achieve optimal therapeutic efficacy. To this aim, the stem cell‐mediated therapeutic efforts on four major neurological diseases, Parkinson's disease, Huntington's disease, amyotrophic lateral sclerosis, and stroke, will be introduced, and current problems and future directions will be discussed. J. Cell. Biochem. 114: 743–753, 2013. © 2012 Wiley Periodicals, Inc.     

Human ES and iPS cells as cell sources for the treatment of Parkinson's disease: Current state and problems

Cell therapy using human embryonic stem cells (hESCs) is a promising therapeutic option for Parkinson's disease (PD), an incurable neurodegenerative disease. A prerequisite for clinical application of hESCs for PD is an efficient and strict differentiation of hESCs into midbrain dopamine (mDA) neuron‐like cells, which would be directly translated into high effectiveness of the therapy with minimum risk of undesirable side effects. Due to fruitful efforts from many laboratories, a variety of strategies for improving efficiency of dopaminergic differentiation from hESCs have been developed, mostly by optimizing culture conditions, genetic modification, and modulating intracellular signaling pathways. The rapid advances in the fields of dopaminergic differentiation of hESCs, prevention of tumor formation, and establishment of safe human induced pluripotent stem cells (hiPSCs) would open the door to highly effective, tumor‐free, and immune rejection‐free cell therapy for PD in the near future. J. Cell. Biochem. 109: 292–301, 2010. © 2009 Wiley‐Liss, Inc.     

Treatment of Parkinson's disease using cell transplantation

The clinical trials with intrastriatal transplantation of human fetal mesencephalic tissue, rich in dopaminergic neurons, in Parkinson''s disease (PD) patients show that cell replacement can work and in some cases induce major, long-lasting improvement. However, owing to poor tissue availability, this approach can only be applied in very few patients, and standardization is difficult, leading to wide variation in functional outcome. Stem cells and reprogrammed cells could potentially be used to produce dopaminergic neurons for transplantation. Importantly, dopaminergic neurons of the correct substantia nigra phenotype can now be generated from human embryonic stem cells in large numbers and standardized preparations, and will soon be ready for application in patients. Also, human induced pluripotent stem cell-derived dopaminergic neurons are being considered for clinical translation. Available data justify moving forward in a responsible way with these dopaminergic neurons, which should be tested, using optimal patient selection, cell preparation and transplantation procedures, in controlled clinical studies.     

Can cellular models revolutionize drug discovery in Parkinson's disease?

The study of mechanisms that underlie Parkinson's disease (PD), as well as translational drug development, has been hindered by the lack of appropriate models. Both cell culture systems and animal models have limitations, and to date none faithfully recapitulate all of the clinical and pathological phenotypes of the disease. In this review we examine the various cell culture model systems of PD, with a focus on different stem cell models that can be used for investigating disease mechanisms as well as drug discovery for PD. We conclude with a discussion of recent discoveries in the field of stem cell biology that have led to the ability to reprogram somatic cells to a pluripotent state via the use of a combination of genetic factors; these reprogrammed cells are termed “induced pluripotent stem cells” (iPSCs). This groundbreaking technique allows for the derivation of patient-specific cell lines from individuals with sporadic forms of PD and also those with known disease-causing mutations. Such cell lines have the potential to serve as a human cellular model of neurodegeneration and PD when differentiated into dopaminergic neurons. The hope is that these iPSC-derived dopaminergic neurons can be used to replicate the key molecular aspects of neural degeneration associated with PD. If so, this approach could lead to transformative new tools for the study of disease mechanisms. In addition, such cell lines can be potentially used for high-throughput drug screening. While not the focus of this review, ultimately it is envisioned that techniques for reprogramming of somatic cells may be optimized to a point sufficient to provide potential new avenues for stem cell-based restorative therapies.     

Stem cell‐based therapy for Huntington's disease

Huntington's disease (HD) is a late‐onset neurodegenerative disease characterized by a progressive loss of medium spiny neurons in the basal ganglia. The development of stem cell‐based therapies for HD aims to replace lost neurons and/or to prevent cell death. This review will discuss pre‐clinical studies which have utilized stem or progenitor cells for transplantation therapy using HD animal models. In several studies, neural stem and progenitor cells used as allotransplants and xenografts have been shown to be capable of surviving transplantation and differentiating into mature GABAergic neurons, resulting in behavioral improvements. Beneficial effects have also been reported for transplantation of stem cells derived from non‐neural tissue, for example, mesenchymal‐ and adipose‐derived stem cells, which have mainly been attributed to their secretion of growth and neurotrophic factors. Finally, we review studies using stem cells genetically engineered to over‐express defined neurotrophic factors. While these studies prove the potential of stem cells for transplantation therapy in HD, it also becomes clear that technical and ethical issues regarding the availability of stem cells must be solved before human trials can be conducted. J. Cell. Biochem. 114: 754–763, 2013. © 2012 Wiley Periodicals, Inc.     

From bench to bed: the potential of stem cells for the treatment of Parkinson’s disease

Parkinson’s disease (PD) is the most common movement disorder. The neuropathology is characterized by the loss of dopamine neurons in the substantia nigra pars compacta. Transplants of fetal/embryonic midbrain tissue have exhibited some beneficial clinical effects in open-label trials. Neural grafting has, however, not become a standard treatment for several reasons. First, the supply of donor cells is limited, and therefore, surgery is accompanied by difficult logistics. Second, the extent of beneficial effects has varied in a partly unpredictable manner. Third, some patients have exhibited graft-related side effects in the form of involuntary movements. Fourth, in two major double-blind placebo-controlled trials, there was no effect of the transplants on the primary endpoints. Nevertheless, neural transplantation continues to receive a great deal of interest, and now, attention is shifting to the idea of using stem cells as starting donor material. In the context of stem cell therapy for PD, stem cells can be divided into three categories: neural stem cells, embryonic stem cells, and other tissue-specific types of stem cells, e.g., bone marrow stem cells. Each type of stem cell is associated with advantages and disadvantages. In this article, we review recent advances of stem cell research of direct relevance to clinical application in PD and highlight the pros and cons of the different sources of cells. We draw special attention to some key problems that face the translation of stem cell technology into the clinical arena.