大鼠胚胎干细胞的研究进展

胚胎干细胞是来源于早期胚胎内细胞团或着床后胚原始生殖细胞的一类未分化的全能性（多能性）干细胞，具有无限增殖和全向分化的能力。ES细胞能够自我更新和多向分化的生物学特性具有重要的医学价值，在基因治疗、组织工程学、药学研究等许多领域都具有广泛的应用前景。至今为止人类已建立了数百个小鼠的ES细胞系。但相对大鼠而言．由于其ES细胞在体外培养时较易发生分化，故建系较难。Iannaccone等从大鼠PVG近交系大鼠的囊胚分离克隆了大鼠ES细胞系-RESC-01。本文主要综述了目前分离、培养大鼠胚胎干细胞的技术进展，我实验小组在预实验中得到的结果及面临的问题，讨论其在临床工作中的应用前景。     

bFGF在人胚胎干细胞中自我更新的研究进展

人胚胎干细胞具有自我更新和多向分化的独特生物学特性。维持人和小鼠胚胎干细胞增殖的生长因子不同,白血病抑制因子（LIF）不能维持人胚胎干细胞的生长。目前已经确定了数种维持人胚胎干细胞（hESCs）自我更新的生长因子,其中碱性成纤维细胞生长因子（bFGF）信号系统是人胚胎干细胞自我更新中最重要的调节因素之一。将从bFGF及其受体在人胚胎干细胞中的表达和作用的最新进展进行综述。     

肿瘤干细胞分离方法的研究进展（文献综述）

干细胞是一类具有无限或者永生的自我更新能力的细胞,多向分化潜能和自我更新是干细胞的两个基本特征。干细胞从维持多能性到分化的分子机制的逐渐揭密,当今严重威胁生命的顽疾就会迎刃而解。对肿瘤的研究发现,恶性肿瘤细胞的生长、分化等特性与干细胞特点惊人的相似,     

外环境在体外培养干细胞分化技术中的应用

干细胞是未分化的前体细胞,既能自我更新,又能朝各种细胞系分化。依据它们的来源不同,大致可以分为两类,一种来源于胚胎干细胞,包括来自于胚泡期内细胞群的胚胎干细胞(ES)以及来自于胎期的生殖嵴的干细胞(EG),还有一种有争议的干细胞是来白于睾丸肿瘤细胞的胚胎性癌细胞(EC),它     

胚胎干细胞与神经干细胞的神经分化

胚胎干细胞 (ES细胞 )是从哺乳类动物囊胚的内细胞群或原始生殖细胞分离经体外培养获得的具有发育全能性的细胞 ,能广泛地分化为各种组织细胞并能参与包括生殖系的嵌合体形成。已经证明维甲酸(RA)能诱导 ES细胞分化产生具有神经元和胶质细胞特性的细胞 ,大约 40 %～ 6 0 %的细胞显示神经元表型 ,其余许多细胞显示为星形胶质细胞。神经干细胞是指中枢神经系统中具有自我更新能力和多种分化潜能的特殊细胞群。它们不仅存在于发育的哺乳动物神经系统中 ,而且还存在于成年哺乳动物神经系统内 ,其中 ,位于侧脑室附近的室管膜下区和海马是目前…     

miRNA与干细胞的生物学行为

背景：以往对干细胞的研究主要集中在基因方面,但目前越来越多的证据表明,miRNA在干细胞的自我更新和分化过程中发挥着重要的调控作用。 目的：介绍miRNA的形成及其对干细胞自我更新和多向分化的影响。 方法：以“microRNA,stem cell”为检索词,应用计算机检索Elsevier数据库2000-01/2010-05文章;以“miRNA,干细胞”为检索词检索中国期刊全文数据库2000-01/2010-05文章。 结果与结论：不同组织不同细胞存在自身特异的miRNA表达谱及序列特征,这可以作为某些组织或细胞的特异性分子标志。在细胞的不同发育阶段,miRNA组成不同,决定细胞的分化方向以及分化时相,是细胞“定时”、“定向”分化的“开关”。在各种干细胞中均存在特异性的miRNA,并且在干细胞的不同分化阶段亦有特异性miRNA表达,它们是保持干细胞自我更新和多向分化特性的关键分子之一。miRNA作为一种新的调控基因表达的小分子RNA,为干细胞的研究提供了一种新的途径。     

转录因子Oct-4、Nanog与胚胎干细胞的自我更新

胚胎干细胞自我更新分子机制是胚胎干细胞研究的前沿及热点课题。除外源性信号如LIF、BMP、Wnt能维持胚胎干细胞的未分化状态外,转录因子Oct-4和Nanog特异性表达于全能胚胎干细胞,并与其它转录因子如Sox2一起构成调控网络,共同调控与胚胎干细胞多能性相关的一系列重要分子,是保持胚胎干细胞自我更新和多潜能性的关键分子。     

人类胚胎干细胞特异表达新基因HPESCRG1的克隆和特性分析

目的克隆一个人类胚胎干细胞特异表达的新基因并对其特性进行分析。方法从一个在人类胚胎干细胞(embryonicstem,ES)中特异表达的表达序列标签CF948547出发,应用生物信息学方法和分子生物学技术克隆一个新基因,采用逆转录-聚合酶链反应分析新基因的表达谱,并应用增强型绿色荧光蛋白真核表达系统分析新基因的亚细胞定位。结果成功克隆了一个新基因HPESCRG1,GenBank登录号为AY283672。该基因cDNA长1395bp,包含9个外显子和8个内含子,开放阅读框为250～1146bp,定位在3q13.13,预测编码297个氨基酸,预计分子量为33784,等电点为9.35。其编码蛋白有一个SAP功能域,该蛋白定位在细胞核内。该基因仅在人类ES细胞中表达,而在其分化细胞不表达,在人胚胎成纤维细胞、人间充质干细胞、成人和流产胚胎的多种正常组织中不表达。结论HPESCRG1基因是一个人类ES细胞中表达特异性新基因,很可能与人类ES细胞的自我更新和维持其未分化状态密切相关。     

干细胞分化抗原及标记物研究进展

干细胞是一类具有自我更新和分化潜能的细胞,现在已经有一些分化抗原或膜分子作为干细胞的标记物,以用于鉴定和分离干细胞,但至今尚未找到特异的干细胞标记物。干细胞的鉴定还需依赖多个指标综合分析,同时需致力研究和寻找干细胞的特异标记。     

白血病干细胞的细胞和分子生物学特性及治疗对策

从以下5个方面阐述白血病干细胞的细胞和分子生物学特性及治疗对策:(1)白血病干细胞的概念和检测方法;(2)白血病干细胞的细胞生物学特征;(3)白血病干细胞的可能来源和生成机制;(4)白血病干细胞自我更新能力的分子调控和靶向治疗策略;(5)白血病干细胞在白血病发生过程中的地位。     

Molecular Mechanisms Controlling the Cell Cycle in Embryonic Stem Cells

Embryonic stem (ES) cells are originated from the inner cell mass of a blastocyst stage embryo. They can proliferate indefinitely, maintain an undifferentiated state (self-renewal), and differentiate into any cell type (pluripotency). ES cells have an unusual cell cycle structure, consists mainly of S phase cells, a short G1 phase and absence of G1/S checkpoint. Cell division and cell cycle progression are controlled by mechanisms ensuring the accurate transmission of genetic information from generation to generation. Therefore, control of cell cycle is a complicated process, involving several signaling pathways. Although great progress has been made on the molecular mechanisms involved in the regulation of ES cell cycle, many regulatory mechanisms remain unknown. This review summarizes the current knowledge about the molecular mechanisms regulating the cell cycle of ES cells and describes the relationship existing between cell cycle progression and the self-renewal.     

Role of Cripto-1 in Stem Cell Maintenance and Malignant Progression

Cripto-1 is critical for early embryonic development and, together with its ligand Nodal, has been found to be associated with the undifferentiated status of mouse and human embryonic stem cells. Like other embryonic genes, Cripto-1 performs important roles in the formation and progression of several types of human tumors, stimulating cell proliferation, migration, epithelial to mesenchymal transition, and tumor angiogenesis. Several studies have demonstrated that cell fate regulation during embryonic development and cell transformation during oncogenesis share common signaling pathways, suggesting that uncontrolled activation of embryonic signaling pathways might drive cell transformation and tumor progression in adult tissues. Here we review our current understanding of how Cripto-1 controls stem cell biology and how it integrates with other major embryonic signaling pathways. Because many cancers are thought to derive from a subpopulation of cancer stem-like cells, which may re-express embryonic genes, Cripto-1 signaling may drive tumor growth through the generation or expansion of tumor initiating cells bearing stem-like characteristics. Therefore, the Cripto-1/Nodal signaling may represent an attractive target for treatment in cancer, leading to the elimination of undifferentiated stem-like tumor initiating cells.Embryonic development involves coordinated processes of proliferation of progenitor stem cells that carry the potential of self-renewal and subsequent differentiation into distinct cell lineages.¹ After fertilization, totipotent stem cells of the blastocyst give rise to all tissues. With subsequent cell divisions, stem cells retain their self-renewal capacity, but they become more restricted in their differentiation potential, becoming progenitor cells (adult or somatic stem cells) that give rise to differentiated somatic cells in specific tissues.¹Therefore, two fundamental properties characterize stem cells: self-renewal, the ability to maintain their identity through a long period of time, and multipotency, the ability to generate all differentiated cell types of a specific tissue. A stem cell that asymmetrically divides can generate a new stem cell and a committed daughter cell. In the adult, a pool of stem cells resides within specific microenvironments or niches in adult tissues and functions as an internal repair system, dividing to replenish specialized cells and also maintaining the normal turnover of regenerative organs, such as blood, skin, or intestinal epithelium.² Stem cells, therefore, are of interest for their potential use in regenerative medicine.Recent progress has identified potential molecular signatures of embryonic stem (ES) cells that delineate pathways that are used by somatic stem cells in the maintenance of self-renewal and in cell fate decisions.³ Among these markers of stemness, Cripto-1 represents an important component of a critical core pathway that is used by ES cells. In this review we highlight the role of Cripto-1 in stem cell self-renewal and differentiation with particular emphasis on the cross talk with other ES cell genes. Finally, re-expression of Cripto-1 in human cancers and its contribution to malignant progression is discussed.     

Oct4 dependence of chromatin structure within the extended Nanog locus in ES cells

Embryonic stem (ES) cells offer insight into early developmental fate decisions, and their controlled differentiation may yield vast regenerative potential. The molecular determinants supporting ES cell self-renewal are incompletely understood. The homeodomain proteins Nanog and Oct4 are essential for mouse ES cell self-renewal. Using a high-throughput approach, we discovered DNaseI hypersensitive sites and potential regulatory elements along a 160-kb region of the genome that includes GDF3, Dppa3, and Nanog. We analyzed gene expression, chromatin occupancy, and higher-order chromatin structure throughout this gene locus and found that expression of the reprogramming factor Oct4 is required to maintain its integrity.     

Notch signaling is inactive but inducible in human embryonic stem cells

The NOTCH signaling pathway performs a wide range of critical functions in a number of different cell types during development and differentiation. The role of NOTCH signals in human embryonic stem cells (hESCs) has not been tested. We measured the activity of canonical NOTCH signaling in undifferentiated embryonic stem (ES) cells and tested the requirement for NOTCH activity in hESC self-renewal or differentiation by growing hESCs in the presence of gamma-secretase inhibitors. Our results suggest that NOTCH signaling is not required for the propagation of undifferentiated human ES cells but instead is required for the maintenance of the differentiating cell types that accumulate in human ES cell cultures. Our studies suggest that NOTCH signaling is not required in human embryonic differentiation until the formation of extraembryonic, germ layer, or tissue-specific stem cells and progenitors.     

Self-renewal of embryonic stem cells through culture on nanopattern polydimethylsiloxane substrate

Embryonic stem (ES) cells can undergo continual proliferation and differentiation into cells of all somatic cell lineages in vitro; they are an unlimited cell source for regenerative medicine. However, techniques for maintaining undifferentiated ES cells are often inefficient and result in heterogeneous cell populations. Here, we determined effects of nanopattern polydimethylsiloxane (PDMS) as a culture substrate in promoting the self-renewal of mouse ES (mES) cells, compared to commercial plastic culture dishes. After many passages, mES cells efficiently maintained their undifferentiated state on nanopattern PDMS, but randomly differentiated on commercial plastic culture dishes, as indicated by partially altered morphologies and decreases in alkaline phosphatase activity and stage-specific expression of embryonic antigen-1. Under nanopattern PDMS conditions, we found increased activities of STAT3 and Akt, important proteins involved in maintaining the self-renewal of mES cells. The substrate-cell interactions also enhanced leukemia inhibitory factor (LIF)-downstream signaling and inhibited spontaneous differentiation, concomitant with reduced focal adhesion kinase (FAK) signaling. This reduction in FAK signaling was shown to be important for promoting mES cell self-renewal. Thus, our data demonstrates that nanopattern PDMS contributes to maintaining the self-renewal of mES cells and may be applicable in the large-scale production of homogeneously undifferentiated mES cells.