转导特定基因重编程体细胞为多能干细胞

通过转导特定基因将体细胞重编程可获得诱导性多能干细胞,这种建系方法标志着干细胞实验技术的重大突破。本文综述该细胞建立、鉴定及最新进展。     

体细胞重编程为诱导多能干细胞

诱导多功能性干细胞(induced pluripotent stem cells,iPS细胞)是通过导入特定的转录因子(如Oct3/4、Sox2、c-Myc和Klf4等)将体细胞诱导重编程为多能性干细胞,其功能与胚胎干细胞相似.iPS细胞的建立,在生命科学领域引起了新的轰动.目前,iPS细胞的研究领域在转录因子的优化、iPS细胞的筛选、载体的运用、体细胞种类的选择和iPS细胞的应用等方面取得突破进展,但仍然存在致癌性、效率低等一系列急需解决的问题.     

DNA甲基化与肿瘤

表观遗传指不涉及DNA序列改变的,可随细胞分裂而遗传的基因组修饰作用;DNA甲基化是其中研究最多的基因表达调节机制.异常DNA甲基化可致肿瘤发生,它亦是肿瘤基因诊断和治疗的靶点.文章介绍DNA甲基化基本概念、作用效果及其可能机制;并讨论异常DNA甲基化与肿瘤的关联,包括肿瘤中DNA异常甲基化原因、异常甲基化致瘤机制及基...     

巴马小型猪胎儿成纤维细胞重编程为诱导多能性细胞的研究

目的探讨巴马小型猪胎儿成纤维细胞重编程为诱导多能性细胞的方法。方法应用经典的逆转录病毒介导方法,将Oct4,Sox2,c-Myc和Klf4四种人源性转录因子转导入巴马小型猪的胎儿成纤维细胞中,建立形态和特征类似猪上胚层细胞来源的猪多能性细胞(pig induced pluripotent cells,piPCs)。免疫荧光化学方法检测多能性细胞标记物,RT-PCR检测了该细胞体外三胚层相关基因表达水平。结果巴马小型猪胎儿成纤维细胞重编程的piPCs细胞呈AKP染色阳性,体外长期传代都保持正常的染色体核型,猪上胚层多潜能性细胞标记分子Oct4,Sox2,Nanog,Tra-1-60,Tra-1-81和SSEA-4呈阳性表达,并且表达小鼠胚胎干细胞(ES)多潜能性细胞标记分子SSEA-1,体外诱导分化后具有三胚层特异基因的表达,但是体内分化能力存在缺陷。结论巴马小型猪胎儿成纤维细胞重编程成功诱导成多能性细胞。     

重编程细胞的命运

背景：体细胞重新编程技术也称细胞重组技术,使已经完成分化的体细胞回到原始的全能性或多能性状态,并可以重新分化成与原来不一样的细胞。通过重编程技术可以获得患者特异性诱导多能干细胞和疾病特异性诱导多能干细胞,显著减少了免疫排斥反应。 目的：探讨关于直接重编程到特定系的方法,总结参与重编程的分子机制。 方法：以“重编程”为中文检索词,“reprogramming”为英文检索词,应用计算机检索维普(VIP)期刊全文数据库、万方全文数据库、中国知网全文数据库、PubMed 数据库、Springer 数据库1958 年1 月至2015年4月有关细胞重编程技术的文献,排除与研究目的无关及重复性研究,保留40篇文献进一步分析。 结果与结论：当前重编程的步骤效率很低,在特定群只有相对少量的细胞能进行重编程,重编程的完整性和程度也有待证实。直接重编程成体、定系的细胞从一种细胞到另一种细胞一直是发育生物学很难达到的目标。最近的研究证明分化的细胞强制表达特异转录因子能促进细胞分化。这些发现使再生医学领域有了重大进展,可以提供替代细胞治疗各种再生紊乱。目前,基本的分子机制需要进一步阐明,在直接重编程被应用于临床之前还有许多问题需要解决。 中国组织工程研究杂志出版内容重点：干细胞;骨髓干细胞;造血干细胞;脂肪干细胞;肿瘤干细胞;胚胎干细胞;脐带脐血干细胞;干细胞诱导;干细胞分化;组织工程     

血液细胞重编程为诱导性多能干细胞的研究进展

诱导性多能干细胞（iPSCs)技术能够将已分化的体细胞反转为多能细胞,因其不存在伦理、排斥等问题,在再生医学领域具有广阔的应用前景。尽管已经建立了来源于多种体细胞的诱导性多能干细胞,但是能实际应用于临床、取材便利、诱导安全的供体来源仍然具有局限性。我们从血液细胞作为供体细胞进行重编程的特点、优势及应用等方面进行了综述。     

羊水细胞重编程为iPS细胞

据Wolfrum K 2010年10月29日[PLoS ONE,2010,5(10):e13703]报道,柏林Max Planck分子遗传学研究所的研究人员成功地将羊水细胞转化为诱导多能干细胞(iPS细胞)。这些由羊水衍生的iPS细胞几乎与胚胎干细胞没有区别。然而,它们却能记住     

结直肠癌与DNA甲基化的相关研究进展

结直肠癌已成为影响人类健康的最常见恶性肿瘤之一。近几年来对肿瘤的发病机制的研究热点已不仅仅是传统对核基因组的研究,除DNA的遗传学变化之外更多对基因功能的调节方式也被人们所了解研究,DNA的甲基化便是其中研究最为透彻的一种表观遗传学调节DNA功能的方式。当肿瘤细胞mtDNA的分子病理学研究越来越多的时候,人们的目光又投向了这些分子变化与肿瘤细胞线粒体功能的相关性。本文综述了现有研究中对肿瘤DNA甲基化所获得成果,及在结直肠癌的相关进展。     

哺乳动物卵母细胞的DNA甲基化和组蛋白修饰

哺乳动物卵母细胞发育过程中呈现出独特的表观遗传修饰模式。包括DNA甲基化和组蛋白修饰等在内的表观遗传修饰的建立,是一个复杂但高度有序的过程,对哺乳动物卵母细胞成熟和早期胚胎发育至关重要。因此,探究并揭示卵母细胞表观遗传特征建立的机制,对深入理解哺乳动物生殖发育机理和相关疾病的发生发展具有重要意义。本文以小鼠和人类为典型代表,阐述了哺乳动物卵母细胞发育过程中DNA甲基化以及组蛋白甲基化、乙酰化、泛素化、磷酸化和乳酸化的分布模式和动态变化特征,总结并探讨了这些表观遗传修饰之间潜在的关联及影响其发挥生物学功能的多种调控因素。     

DNA methylation analysis as novel tool for quality control in regenerative medicine

Cell-based regenerative medicine, including tissue engineering, is a novel approach to reconstituting tissues that do not spontaneously heal, such as damaged cartilage, and to curing diseases caused by malfunctioning cells. Typically, manufacturing processes to generate cartilage for replacement therapies involve isolation and expansion of cells from cartilage biopsies. A challenge in the field is potential contamination by other cell types (e.g., fibroblast-like cells), which can overgrow the desired cells during culturing and may ultimately compromise clinical efficacy. No standard analytical system has been absolutely effective in ensuring the identity of these cell-based products. Therefore, we tested deoxyribonucleic acid methylation analysis as a quality assessment tool, applying it to Genzyme's Carticel product, a chondrocyte implant that the Food and Drug Administration has approved. We identified 7 potent discriminators by assaying candidate genomic regions derived from methylation discovery approaches and literature searches regarding a functional role of genes in chondrocyte biology. Using a support vector machine, we trained an optimal cell type classifier that was absolutely effective in discriminating chondrocytes from synovial membrane derived cells, the major potential contaminant of chondrocyte cultures. The abundant marker availability and high quality of this assay format also suggest it as a potential quality control test for other cell types grown or manipulated in vitro.     

Pancreatic development and stem cell-based regenerative medicine

After the gut endoderm is formed, subsequent permissive induction signals from the notochord allows the pancreas to emerge and growout from a specific site of the embryonic gut epithelium. The first pancreas-specific gene, pdx1, is expressed around this stage. Interaction between pancreatic epithelium and the surrounding mesenchyme allows the pancreas bud to further grow and differentiate to form ductal, exocrine or endocrine lineages. Several lines of evidence from gene knockout mice and cell lineage studies suggest that a common pancreas stem cell first gives rise to exocrine and endocrine progenitor cells. The endocrine progenitor then give rise to four different endocrine cells: alpha, beta, delta, and PP cells, although it is not known how and when these cells arise. We have focused our studies on the understanding of endodermal induction and organogenesis of the pancreas. We specifically aimed at the isolation of pancreatic stem cells and the development of functional pancreatic endocrine beta cells in culture. For this aim, we used ES cells as a model system. Here, I review the literature on the development and regeneration of the pancreas. Some recent results on growing pancreatic cells from ES (embryonic stem) cells.     

牙髓干细胞在再生医学中的应用研究与进展

BACKGROUND:Dental pulp stem cells are characterized by multi-lineage differentiation and proliferation abilities and are easy to obtain, so they are becoming an issue of concern in regenerative medicine. OBJECTIVE:To provide clues and direction for further study by analyzing progress of domestic and overseas research on dental pulp stem cells, and summarizing their application in regenerative medicine. METHODS:The “dental pulp stem cell, regenerative medicine, tissue engineering” in Chinese and English served as the search terms to search articles related to dental pulp stem cells and regenerative medicine, published from 2000 to 2015 in Medline, PubMed, CNKI, Wanfang and Cqvip databases. Totally 46 articles were selected for overview.  RESULTS AND CONCLUSION:Dental pulp stem cells, which hold the capacity of self-renewal and multi-lineage differentiation, are relatively easy to obtain, and exhibit a great potential in regenerative medicine. The research of dental pulp stem cells in repairing bone defects has entered the clinical trial phase, but the research of cell differentiation into other tissues is still in basic trial phase and needs further development.     

Anti-HLA antibodies in regenerative medicine stem cell therapy

Research on stem cell therapies for regenerative medicine is progressing rapidly. Although the use of autologous stem cells is a tempting choice, there are several instances in which they are either defective or not available in due time. Allogenic stem cells derived from healthy donors presents a promising alternative. Whether autologous or allogenic, recent advances have proven that stem cells are not as immune privileged as they were thought. Therefore understanding the interactions of these cells with the recipient immune system is paramount to their clinical application. Transplantation of stem cells induces humoral as well as cellular immune response. This review focuses on the humoral response elicited by stem cells upon their administration and consequences on the survival and maintenance of the graft. Current transplantation identifies pre- and post-transplantation anti-HLA antibodies as immune rejection and cell signaling effectors. These two mechanisms are likely to operate similarly in the context of SC therapeutics. Ultimately this knowledge will help to propose novel strategies to mitigate the allogenic barriers. Immunogenetics selection of the donor cell and immunomonitoring are key factors to allow the implementation of regenerative stem cell in the clinics.     

Liver regenerative medicine: advances and challenges

Liver transplantation is the standard care for many end-stage liver diseases. However, donor organs are scarce and some people succumb to liver failure before a donor is found. Liver regenerative medicine is a special interdisciplinary field of medicine focused on the development of new therapies incorporating stem cells, gene therapy and engineered tissues in order to repair or replace the damaged organ. In this review we consider the emerging progress achieved in the hepatic regenerative medicine within the last decade. The review starts with the characterization of liver organogenesis, fetal and adult stem/progenitor cells. Then, applications of primary hepatocytes, embryonic and adult (mesenchymal, hematopoietic and induced pluripotent) stem cells in cell therapy of liver diseases are considered. Current advances and challenges in producing mature hepatocytes from stem/progenitor cells are discussed. A section about hepatic tissue engineering includes consideration of synthetic and natural biomaterials in engineering scaffolds, strategies and achievements in the development of 3D bioactive matrices and 3D hepatocyte cultures, liver microengineering, generating bioartificial liver and prospects for fabrication of the bioengineered liver.     

Stem cell sources for regenerative medicine: the immunological point of view

Stem cell transplantation consists in the introduction of stem cells or derived products in a diseased organism. Because of the differentiation properties of stem cells, the goal is to replace damaged cells or tissues. Numbers of stem cell were identified and isolated from embryos, fetuses, or adult organs, harboring different properties, and thus providing multiple strategies of regenerative medicine for different diseases. More recently, the artificial induction of stemness properties in adult somatic cells has proposed a new way to generate stem cells. One important concern of stem cell therapy is the possible risk that transplanted stem cells could be rejected by the recipient's immune system. Depending on their source, stem cell transplantation is associated with diverse immunological situations. If some sources allow autologous transplantation, others cannot bypass an allogeneic context between the donor and the recipient. This review summarizes all of the stem cell sources for regenerative medicine and the immunological questions associated to their use. Regarding the emerging strategies compatible with autologous transplantation, this article points notably the complexity of the choice between the immunological safety and the specific advantages of allogeneic stem cells.     

Dynamic DNA methylation reprogramming: active demethylation and immediate remethylation in the male pronucleus of bovine zygotes.

DNA methylation reprogramming (DMR) is believed to be a key process by which mammalian zygotes gain nuclear totipotency through erasing epigenetic modifications acquired during gametogenesis. Nonetheless, DMR patterns do not seem to be conserved among mammals. To identify uniform rules underlying mammalian DMRs, we explored DMRs of diverse mammalian zygotes. Of the zygotes studied, of particular interest was the bovine zygote; the paternal DNA methylation first decreased and was then rapidly restored almost to the maternal methylation level even before the two-cell stage. The 5-azadeoxycytidine treatment led to complete demethylation of the male pronucleus. The unusually dramatic changes in DNA methylation levels indicate that the bovine male pronucleus undergoes active demethylation, which is followed by de novo methylation. Our results show that, in bovine, the compound processes of active DNA demethylation and de novo DNA methylation, along with de novo H3-K9 trimethylation also, take place altogether within this very narrow window of pronucleus development.