诱导多能干细胞在肝脏疾病中的研究进展

干细胞,特别是诱导多能干细胞(iPS细胞)可分化为有功能的肝细胞,同时避开了胚胎干细胞的伦理问题,为终末期肝病的替代治疗提供了新的种子细胞.文章对iPS细胞在肝脏疾病研究中的实验方法、研究结果以及临床应用前景予以阐述,为iPS细胞在肝病治疗方面的实验和临床应用提供借鉴.     

诱导性多能干细胞的来源 优化及应用

<正>诱导性多能干细胞(induced pluripotent stem cells,iPS cells)可来源于人和动物细胞,可通过导入特定的几个转录因子转染直接诱导胎儿、新生儿和成年动物体细胞,使其重编程为iPS细胞。这相对于胚胎干细胞(embryonic stem cells,ES cells)的来源更方便、更丰富[1]。iPS细胞的产生克服了使用传统方法的伦理问题,iPS细胞具有和胚胎干细胞类似的功     

维持干细胞多能性关键基因被发现

健康报讯 日前，我国科学家首次发现并明确证实了决定小鼠干细胞多能性的关键基因决定簇。这是继我国科学家在国际上首次证明iPS细胞具有全能性后，在国际竞争最激烈的领域——干细胞多能性维持机制研究方面获得的又一重大突破。     

美日首次用iPS细胞培育出功能性人类肝脏

据英国《卫报》和《自然》杂志网站2013年7月4日报道,日本横滨市立大学与美国西奈山医学院科学家合作,利用人类诱导多能干细胞(iPS细胞)构建出微小"肝芽",然后移植到小鼠体内,结果这些肝芽成功生长成微型人类肝脏,并像健康器官一样具有正常的肝功能。研究人员表示,这是首次报告从iPS细胞培育出功能性人类器官,虽然还只是初步成果,但却有望给再生医学领域带来革新性的疗法,减少对于捐赠器官的依赖。     

诱导性多能干细胞形成过程中转录因子的研究进展

诱导性多能干细胞(iPS)是以反转录病毒为载体将胚胎特异性转录因子导入体细胞,使其诱导分化为具有胚胎干细胞(ESCs)特性的细胞。这种多能干细胞在细胞形态、增殖速率、致瘤性、基因表达以及形成嵌合小鼠的能力上与ESCs有许多相似之处,将来可能成为ESCs在临床应用中的替代。现对iPS细胞相关的几种转录因子及其在重编程过程中的作用,以及转导基因的选择予以综述。     

诱导多能干细胞技术及应用前景

诱导多能干细胞( induced pluripotent stem cells,iPS)自2006年问世,已成为当今干细胞乃至生命科学领域研究的热点。本文就诱导多能干细胞的研究技术进展、应用前景以及存在的问题作一综述。     

胚胎干细胞与促再生药物研究

具有体外诱导干细胞定向分化的药样小分子,在再生医学领域可望有以下潜在用途:利用其固有的促组织再生作用,到达靶组织后促进成体干细胞定向分化;通过体外诱导,获得足够量的均一前体细胞用于细胞移植治疗用;细胞移植的同时给药,促进被移植的前体细胞在体内进一步定向分化,达到提高疗效,降低致瘤性的目的。近年来,由于诱导多能干(induced pluripotentstem,iPS)细胞的问世,同样具有多能性的人类胚胎干(embryonic stem,ES)细胞研究可为iPS的命运提供借鉴,因而再次受到高度关注。人类ES细胞定向分化体系在药物筛选应用中有独到之处,可在药物研发早期获得人类细胞易感的有效性与安全性资料。研究促再生的药样小分子可通过体外初级筛选和次级筛选,进一步在合适的动物模型进行研究。再生医学微环境学将推动细胞移植和促再生药研究的进程。     

诱导多能干细胞研究进展

用外源性表达的转录因子Oct3/4、Sox2、c-Myc和Klf4通过对成体细胞的重新编程来产生诱导多能干细胞(iPS cells).iPS细胞的出现不仅为成体细胞重编程机制的研究提供了新的方法,而且为某些疾病发生发展的机制研究与特异的细胞治疗,特别是再生医学研究带来希望.     

诱导性多能干细胞(iPS细胞)研究现状

iPS细胞全称为诱导性多能干细胞,是由体细胞诱导而成的干细胞,具有和胚胎干细胞类似的发育多潜能性。2006年7月,日本科学家首次宣布发现了将小鼠皮肤细胞转化为多能干     

诱导多功能干细胞分化为脊髓神经元的代表性标志物的鉴定

近期引起广泛关注的诱导多功能干细胞(induced pluripotent stem cells,iPS)的成功开发为神经再生提供了一条新的思路.由病毒或非病毒的方法传输重要的转录因子对体细胞进行重编程而产生的iPS细胞,除了拥有胚胎干细胞所具有的各种分化潜能外,它还绕开了人类胚胎干细胞研究所带来的伦理问题,为再生医学和组织移植提供充足的细胞来源.然而多能性的干细胞注射至体内并不能自动分化为各种成体细胞,因此移植多能性干细胞的关键一步就是需要在体外优化分化条件使之达到最恰当、最适宜移植的程度,这样才能够在移植后迁移至神经受损部位,达到在结构和功能上的修复或替代.本篇综述以细胞治疗神经损伤中的脊髓损伤(spinal cord injury,SCI)疾病模型为出发点,以iPS细胞向脊髓神经元分化为方向,综述探讨鉴定与区别脊髓中的神经元的各类特定标志物.该篇文章的重要研究意义在于一方面利用这些特定的标志物可以区分从多能干细胞分化为各类神经细胞的混合细胞鉴定筛选出分化为神经元细胞的比例,从而找出最优分化条件;而在另一方面利用这些标志蛋白在体内鉴定已经移植的神经细胞前体如何可以进一步分化为神经元细胞,从而可以进一步探讨移植的不同神经细胞在再生修复中的作用与机制.     

Generation of Transgene-free Induced Pluripotent Stem Cells with Non-viral Methods

Induced pluripotent stem(iPS) cells were originally generated from mouse fibroblasts by enforced expression of Yamanaka factors(Oct3/4,Sox2,Klf4,and c-Myc).The technique was quickly reproduced with human fibroblasts or mesenchymal stem cells.Although having been showed therapeutic potential in animal models of sickle cell anemia and Parkinson’s disease,iPS cells generated by viral methods do not suit all the clinical applications.Various non-viral methods have appeared in recent years for application of iPS cells in cell transplantation therapy.These methods mainly include DNA vector-based approaches,transfection of mRNA,and transduction of reprogramming proteins.This review summarized these non-viral methods and compare the advantages,disadvantages,efficiency,and safety of these methods.     

Therapeutic potential of motor neurons differentiated from embryonic stem cells and induced pluripotent stem cells

Degeneration of motor neurons (MN) caused by disease or injury leads to paralysis and is fatal in some conditions. To date, there are no effective treatments for MN disorders; therefore, cell therapy is a promising strategy to replace lost MN. Embryonic stem (ES) cells isolated from the inner cell mass of mammalian blastocysts self-renew and are pluripotent because they differentiate into cell types of the three germinal layers. Reprogramming of adult cells to a state similar to ES cells, termed induced pluripotent stem (iPS) cells, has been recently reported. It is well established that pluripotent cell types can give rise to specialized phenotypes, including neurons. Mouse, monkey and human MN can be differentiated from ES and iPS cells using procedures generally involving embryoid bodies formation and stimulation with retinoic acid and Sonic hedgehog. Differentiated MN express characteristic molecular markers such as Islet1, HB9 and Choline acetyltransferase, exhibit electrophysiological maturity and are able to form synaptic contacts similar to neuromuscular junctions in vitro. Furthermore, transplanted MN promote functional recovery in animal models of neurodegenerative diseases and MN injury. The potential clinical applications of stem cell-derived MN was enhanced after iPS cell derivation, which makes possible the generation of patient-specific pluripotent cells for autologous cell replacement therapies and may be used for drug development and disease modeling. This review summarizes MN differentiation protocols from ES and iPS cells in regard to neuronal differentiation efficiency, expression of MN markers and functional properties in vitro, as well as their therapeutic effects after grafting.     

Induced pluripotent stem cells

Induced pluripotent stem (iPS) cells are a recent development which has brought a promise of great therapeutic values. The previous technique of somatic cell nuclear transfer (SCNT) has been ineffective in humans. Recent discoveries show that human fibroblasts can be reprogrammed by a transient over expression of a small number of genes; they can undergo induced pluripotency. iPS were first produced in 2006. By 2008, work was underway to remove the potential oncogenes from their structure. In 2009, protein iPS (piPS) cells were discovered. Surface markers and reporter genes play an important role in stem cell research. Clinical applications include generation of self renewing stem cells, tissue replacement and many more. Stem cell therapy has the ability to dramatically change the treatment of human diseases.

     

利用细胞因子和丁酸钠将小鼠诱导多能干细胞高效诱导为有功能的肝细胞

Background  Hepatocyte transplantation has been proposed as an alternative to whole-organ transplantation to support many forms of hepatic insufficiency. Unfortunately, the lack of donor livers makes it difficult to obtain enough viable human hepatocytes for hepatocyte-based therapies. Therefore, it is urgent to find new ways to provide ample hepatocytes. Induced pluripotent stem (iPS) cells, a breakthrough in stem cell research, may terminate these hinders for cell transplantation. For the promise of iPS cells to be realized in liver diseases, it is necessary to determine if and how efficient they can be differentiated into functional hepatocytes.      

Methods  In this study, we directly compared the hepatic-differentiation capacity of mouse iPS cells and embryonic stem (ES) cells with three different induction approaches: conditions via embryonic body (EB) formation plus cytokines, conditions by combination of dimethyl sulfoxide and sodium butyrate and chemically defined, serum free monolayer conditions. Among these three induction conditions, more homogenous populations can be promoted under chemically defined, serum free conditions. The cells generated under these conditions exhibited hepatic functions in vitro, including glycogen storage, indocynine green (ICG) uptake and release as well as urea secretion. Although efficient hepatocytes differentiation from mouse iPS cells were observed, mouse iPS cells showed relatively lower hepatic induction efficiency compared with mouse ES cells.

Results  Mouse iPS cells would be efficiently differentiated into functional hepatocytes in vitro, which may be helpful in facilitating the development of hepatocytes for transplantation and for research on drug discovery.

Conclusion We demonstrate that mouse iPS cells retain full potential for fetal liver development and describe procedures that facilitates the efficient generation of highly differentiated human hepatocyte-like cells from iPS cells in vitro.

     

诱导性多潜能干细胞的研究进展与应用

分化成熟的体细胞可在体外被重编程为诱导性多潜能干细胞,后者具有与胚胎干细胞相似的自我更新能力和发育多潜能性,同时避免了免疫排斥和伦理问题.患者特异性的诱导性多潜能干细胞将成为再生医学、药物筛选和毒理测试的理想工具.     

人类3D大脑类器官研究进展

人类3D大脑类器官为研究人脑发育和神经系统疾病提供了新的模型。体外培育的人类3D大脑类器官主要是由人多能干细胞（human pluripotent stem cell,hPSC）,包括人胚胎干细胞（embryonic stem cell,ESC）和诱导多能干细胞（induced pluripotent stem cell,iPSC）分化而来。iPSC重编程技术与3D大脑类器官技术相结合,可以获得来自患者的iPSC并分化成包括神经元及大脑类器官在内的几乎任何人体细胞或组织,是动物实验向临床试验转化的桥梁。本文回顾了从多能干细胞技术到3D大脑类器官诞生并发展的历程,介绍了以3D大脑类器官为工具构建脑发育和神经系统疾病的研究模型,讨论了大脑类器官在其他方面的应用和相关技术的研究进展,并分析了3D大脑类器官的局限性及其未来可能的发展方向。     

干细胞与转化医学研究进展浅析

干细胞与医学转化是近阶段比较热门的学科。由于干细胞的多种分化潜能和高度的自我更新能力,已经成为修复生命有机体功能细胞的种子细胞,而且在再生医学和组织工程中愈发引起人们的广泛重视。干细胞在临床转换应用的实验研究结果给许多种疾病带来了希望,它克服了临床常规治疗的局限性。目前,干细胞的临床研究处于一个快速的发展阶段,世界各国均高度重视。我国政府对干细胞研究也高度重视,加大了科研的投入,加强了规范化管理,制定了相关政策。如果在干细胞治疗的领域采用转化医学的模式,将科研与临床密切的联系结合,重视在大型实验动物如猪,狗,猴的人类疾病的动物模型的干细胞治疗应用研究,将会促进干细胞临床转化的速度。     

人胚胎多能干细胞研究中的几个问题

目前在人胚胎多能干细胞的研究中存在材料来源不足、培养体系复杂和自发性分化的问题.这3个基本问题限制了人胚胎多能干细胞的基础和临床应用研究.要建立新的胚胎多能干细胞系应利用细胞核移植和细胞质重新编程功能建立新的途径,并探讨其中的机制和可能的关键因子;干细胞培养时主要进行简化培养体系和抑制细胞分化的研究;对干细胞分化进行临床应用研究时,主要将多种方法联合应用来诱导和筛选目的细胞并对其形态和功能进行评价.