实验动物干细胞的研究及应用

干细胞(Stem cell)指具有自我更新、高度繁殖能力和具分化潜能的细胞。按分化潜能不同分为:全能干细胞、多能干细胞和定向干细胞。全能干细胞包括胚胎干细胞(ES细胞)和胚胎生殖细胞。由于干细胞的发现和突出的研究成果,国际上将此作为重大的科技进展[1]。自Evans等从延迟着床胚     

绵羊胚胎干细胞的分离与增殖培养

研究了囊胚(胚龄、处理方法)、传代方法(机械法和酶法)及培养液对绵羊类胚胎干细胞生长的影响,建立了绵羊类胚胎干细胞的分离培养体系.结果表明,实验获得的体外受精胚用于类胚胎干细胞的分离,具有较好的增殖及传代能力;囊胚的质量和胚龄影响绵羊类胚胎干细胞的贴壁及增殖;机械切割(半胚法)处理囊胚,可获得跟免疫法相近的内细胞团贴壁率(半胚法46%,免疫法53.6%);添加了一定浓度的胎牛血清、细胞生长因子、胰岛素及维生素C的DMEM高糖培养液可一定程度地促进类胚胎干细胞的增殖,适于绵羊类胚胎干细胞的培养.     

昆明鼠胚胎干细胞的分离培养与鉴定

目的：从昆明系小鼠的早期胚胎分离和培养胚胎干细胞(ES细胞)．方法：收集小鼠3．5d胚龄的囊胚，将其培养在小鼠胚胎成纤维细胞饲养层上，5—6d后取隆起生长的内细胞团块分离后再培养，观察集落的生长情况并通过碱性磷酸酶染色、原位杂交、细胞核型分析等对细胞集落进行鉴定．结果：KS细胞集落性生长，符合小鼠胚胎干细胞的一系列特性．结论：昆明系小鼠囊胚在胚胎成纤维细胞饲养层上可以发育成ES细胞，并能进行传代培养．     

胚胎干细胞的研究进展

胚胎干细胞（embryonic stem cell,ES细胞）是来源于囊胚内细胞团的一种多能细胞,具有分化的多向性和长期增殖能力,已经广泛用于生命科学的许多领域,它在医学方面的应用也成为医学领域的研究热点。本文综述了胚胎干细胞在诱导分化为神经细胞、造血干细胞、内皮细胞等方面的研究进展及在临床应用前景。     

胚胎大鼠室下带神经干细胞分离、培养与鉴定

自从1992年Reynolds和Weiss首先报道在成年小鼠纹状体中分离培养出能在体外不断增殖、具有多种分化潜能的细胞群以来,神经干细胞(neural stem cells,NSCs)诱人的应用前景激发了许多科学家的兴趣．近来的研究进一步证实,胚胎和成年哺乳动物的神经组织和人脑中可以分离出神经干细胞,在体外培养时可被生长因子诱导而增殖,并具有分化成神经元和胶质细胞的潜能．本研究采用无血清培养技术,从孕14d胚胎大鼠前脑室下带(SVZ)中成功分离培养出神经干细胞,经增殖获得大量的克隆球团,用nes-     

利用四倍体胚胎补偿法克隆ES猪技术

胚胎干细胞（ES）是从附植前胚胎内细胞团（ICM）或胎儿原始生殖细胞（PGCS）分离而来的经过体外长期培养、具有多方向分化潜能和种系嵌合能力的全能性或多能性细胞,通常我们又把从原始生殖细胞分离而来的胚胎干细胞称谓胚胎生殖细胞（EG）。由于胚胎干细胞具有特殊生物学特性,     

小鼠孤雌生殖胚胎干细胞的分离及分化潜能研究

用免疫外科法从小鼠孤雌生殖胚胎分离胚胎干细胞,并研究了其在体内、体外的分化潜能．结果发现:从小鼠孤雌生殖的胚胎中可分离出胚胎干细胞(pES),可以传代培养25代,能表达很强的碱性磷酸酶,核型稳定呈40XX．培养至第18代的pES在体内可诱导肿瘤形成,并可分化为三个胚层的组织细胞．免疫组化结果显示:神经细胞特异性烯醇化酶（NSE）、肌肉特异性肌动蛋白?-actin均呈阳性,表明分离培养的pES在体内可至少分化为来自外胚层和中胚层的组织细胞．传至第20～24代的pES细胞,经体外定向诱导分化,可定向分化为节律性收缩的心肌细胞及神经细胞．免疫组化检测显示节律性收缩的心肌细胞表达?-actin,而神经细胞表达NSE．结果表明:利用免疫外科法可从孤雌生殖的小鼠胚胎建立pES,这些pES在体内、体外都具有分化为多种类型细胞的潜能．     

大鼠胎脑神经干细胞的分离和培养

胚龄14．5～16．5d(E14．5～16．5)的大鼠胎脑组织获得大鼠胎脑神经干细胞(rat fetal neural stem cells，rFNSCs)，培养于含有碱性成纤维细胞生长因子(basic fibroblast growth factor，bFGF)和表皮生长因子(epidermal growth factor，EGF)的无血清培养液DMEM／F12中，用^3[H]胸苷掺入试验检测EGF和bFGF对大鼠胚胎神经干细胞分裂和增殖的影响．BrdU结合反应和nestin免疫组化检测显示培养细胞在早期时代约90％以上具有分裂增殖能力并显示nestln阳性，而且这些细胞在培养过程中可以分化神经元、星形胶质细胞和少突胶质细胞，证明分离培养的是神经干细胞，可用于移植、定向分化和基因转移的研究．     

胚胎干细胞的体外扩增

探讨了胚胎干细胞在体外大量扩增的方法。将胚胎干细胞复苏后，选择合适的培养基(含高糖和谷氨酰胺的DMEM，加入ψ=20％胎牛血清，10^5U/L青链霉素双抗，0．1mmol／L L—谷氨酰胺，10^3IU／L白血病抑制因子，0．1mmol／L β-巯基乙醇)进行培养。此外，使用早代胚胎于细胞；培养时使用不涂明胶的一次性培养瓶；掌握好消化、复苏和冻存时机并及时换液；按照严格步骤进行培养、传代、冻仔。对扩增后的ES细胞进行染色体和全能性检测。结果表明，在较短时问内(5d)可将胚胎干细胞扩增16倍以上。扩增后的ES细胞较好地保持了胚胎干细胞的全能性和核型。可见使用合适的培养基，按照严格步骤操作，短期内完全可以大量扩增胚胎干细胞。     

全反式维甲酸对小鼠胚胎不同阶段神经干细胞诱导作用研究

目的:探讨全反式维甲酸对小鼠胚胎不同阶段神经干细胞(NSCs)的诱导分化情况.方法:分离孕12.5d及15.5d的胚胎小鼠脑皮质.取第3代NSCs,用含1μmol·L-1的全反式维甲酸在体外诱导小鼠胚胎不同阶段的NSCs.诱导5d后,通过神经元微管相关蛋白2(MAP2)免疫荧光染色和Westernblots检测NSCs分化为神经元的比例.结果:与对照组相比,全反式维甲酸可明显提高神经元分化的比例.E12.5干细胞和E15.5胚胎干细胞分化为神经元的比例分别为30%±1.47%和16.21%±1.36%.结论全反式维甲酸具有显著的促神经干细胞分化成神经元的效应,并对胚胎不同阶段神经干细胞的诱导作用有所不同.     

Inhibition of pluripotential embryonic stem cell differentiation by purified polypeptides

Murine embryonic stem (ES) cells are pluripotent cell lines established directly from the early embryo which can contribute differentiated progeny to all adult tissues, including the germ-cell lineage, after re-incorporation into the normal embryo. They provide both a cellular vector for the generation of transgenic animals and a useful system for the identification of polypeptide factors controlling differentiation processes in early development. In particular, medium conditioned by Buffalo rat liver cells contains a polypeptide factor, ES cell differentiation inhibitory activity (DIA), which specifically suppresses the spontaneous differentiation of ES cells in vitro, thereby permitting their growth as homogeneous stem cell populations in the absence of heterologous feeder cells. ES cell pluripotentiality, including the ability to give rise to functional gametes, is preserved after prolonged culture in Buffalo rat liver media as a source of DIA. Here, we report that purified DIA is related in structure and function to the recently identified hematopoietic regulatory factors human interleukin for DA cells and leukaemia inhibitory factor. DIA and human interleukin DA/leukaemia inhibitory factor have thus been identified as related multifunctional regulatory factors with distinct biological activities in both early embryonic and hematopoietic stem cell systems.     

Embryonic and extraembryonic stem cell lines derived from single mouse blastomeres

The most basic objection to human embryonic stem (ES) cell research is rooted in the fact that ES cell derivation deprives embryos of any further potential to develop into a complete human being. ES cell lines are conventionally isolated from the inner cell mass of blastocysts and, in a few instances, from cleavage stage embryos. So far, there have been no reports in the literature of stem cell lines derived using an approach that does not require embryo destruction. Here we report an alternative method of establishing ES cell lines-using a technique of single-cell embryo biopsy similar to that used in pre-implantation genetic diagnosis of genetic defects-that does not interfere with the developmental potential of embryos. Five putative ES and seven trophoblast stem (TS) cell lines were produced from single blastomeres, which maintained normal karyotype and markers of pluripotency or TS cells for up to more than 50 passages. The ES cells differentiated into derivatives of all three germ layers in vitro and in teratomas, and showed germ line transmission. Single-blastomere-biopsied embryos developed to term without a reduction in their developmental capacity. The ability to generate human ES cells without the destruction of ex utero embryos would reduce or eliminate the ethical concerns of many.     

造血干细胞的研究进展

干细胞是一类具有自我更新、高度增殖和多向分化潜能的原始细胞．造血干细胞在胚胎时期的发生、发育过程已得到进一步阐明．造血干细胞的移植已成功的应用于治疗多种血液系统和相关系统疾病．作者对造血干细胞的来源、细胞表面标志和其临床应用前景进行了综述．     

Derivation of embryonic germ cells and male gametes from embryonic stem cells

Egg and sperm cells (gametes) of the mouse are derived from a founder population of primordial germ cells that are set aside early in embryogenesis. Primordial germ cells arise from the proximal epiblast, a region of the early mouse embryo that also contributes to the first blood lineages of the embryonic yolk sac. Embryonic stem cells differentiate in vitro into cystic structures called embryoid bodies consisting of tissue lineages typical of the early mouse embryo. Because embryoid bodies sustain blood development, we reasoned that they might also support primordial germ cell formation. Here we isolate primordial germ cells from embryoid bodies, and derive continuously growing lines of embryonic germ cells. Embryonic germ cells show erasure of the methylation markers (imprints) of the Igf2r and H19 genes, a property characteristic of the germ lineage. We show that embryoid bodies support maturation of the primordial germ cells into haploid male gametes, which when injected into oocytes restore the somatic diploid chromosome complement and develop into blastocysts. Our ability to derive germ cells from embryonic stem cells provides an accessible in vitro model system for studies of germline epigenetic modification and mammalian gametogenesis.     

Human embryonic stem cell lines derived from single blastomeres

The derivation of human embryonic stem (hES) cells currently requires the destruction of ex utero embryos. A previous study in mice indicates that it might be possible to generate embryonic stem (ES) cells using a single-cell biopsy similar to that used in preimplantation genetic diagnosis (PGD), which does not interfere with the embryo's developmental potential. By growing the single blastomere overnight, the resulting cells could be used for both genetic testing and stem cell derivation without affecting the clinical outcome of the procedure. Here we report a series of ten separate experiments demonstrating that hES cells can be derived from single blastomeres. In this proof-of-principle study, multiple biopsies were taken from each embryo using micromanipulation techniques and none of the biopsied embryos were allowed to develop in culture. Nineteen ES-cell-like outgrowths and two stable hES cell lines were obtained. The latter hES cell lines maintained undifferentiated proliferation for more than eight months, and showed normal karyotype and expression of markers of pluripotency, including Oct-4, SSEA-3, SSEA-4, TRA-1-60, TRA-1-81, nanog and alkaline phosphatase. These cells retained the potential to form derivatives of all three embryonic germ layers both in vitro and in teratomas. The ability to create new stem cell lines and therapies without destroying embryos would address the ethical concerns of many, and allow the generation of matched tissue for children and siblings born from transferred PGD embryos.     

用于“治疗性克隆”人胚胎干细胞研究面临的问题与可能的解决办法

利用培育的干细胞(SC)来实现组织再生和器官修复对于许多重大疾病如糖尿病、心脏疾病、老年性痴呆(AD)、帕金森病(PD)、神经损伤等的治疗具有重要意义,同时也是新药研发的重要工具.使用体细胞核转移技术(SCNT)克隆人类早期胚胎和提取干细胞,即所谓的"治疗性克隆"(Therapeutic cloning)技术,是目前进行干细胞个性化治疗的重要手段,具有广泛的临床应用前景.通过这种方法获得人胚胎干细胞的研究尚处于基础阶段,仍面临着许多有待解决的科学问题和技术挑战.在此主要就用于"治疗性克隆"人胚胎干细胞的研究进展做了简要综述,着重探讨了在该研究领域面临的主要困难,特别是在获得人成熟卵细胞方面,并提出了可能的解决办法.     

Derivation of androgenetic embryonic stem cells from m-carboxycinnamic acid bishydroxamide (CBHA) treated androgenetic embryos

The androgenetic embyronic stem (aES) cells are useful models in studying the effects of imprinted genes on pluripotency maintaining and embryo development. The expression patterns of imprinted genes are significantly different between uniparental derived aES cells and zygote-derived embryonic stem (ES) cells, therefore, the imprinting related cell pluripotency needs further exploitation. Several approaches have been applied in generation of androgenetic embryos and derivation of aES cell lines. Here, we describe a method to generate androgenetic embryos by injecting two mature sperms into one enucleated oocyte. Then these androgenetic embryos were treated with a histone deacetylase inhibitor: m-carboxycinnamic acid bishydroxamide (CBHA). Further, aES cell lines were successfully derived from these treated androgenetic embryos at blastocyst stage. The CBHA could improve not only the quality of androgenetic embryos, but also the efficiencies of aES (CaES) cells derivation and chimeric mice generation. The imprinted gene expression pattern in the CBHA treated embryo-derived aES (CaES) cells was also highly similar to that of zygote-derived ES cells.     

Properties and applications of embryonic stem cells

Mouse embryonic stem (ES) cells are pluripotent cells derived from the early embryo and can be propagated stably in undifferentiated state in vitro. They retain the ability to differentiate into all cell types found in the embryonic and adult body in vivo, and can be induced to differentiate into many cell types under appropriate culture conditions in vitro. Using these properties, people have set up various differentiated systems of many cell types and tissues in vitro. Through analysis of these systems, one can identify novel bioactive factors and reveal mechanisms of cell differentiation and organogenesis. ES cell-derived differentiated cells can also be applied to cell transplantation therapy. In addition, we summarized the features and potential applications of human ES cells.     

Monoclonal mice generated by nuclear transfer from mature B and T donor cells

Cloning from somatic cells is inefficient, with most clones dying during gestation. Cloning from embryonic stem (ES) cells is much more effective, suggesting that the nucleus of an embryonic cell is easier to reprogram. It is thus possible that most surviving clones are, in fact, derived from the nuclei of rare somatic stem cells present in adult tissues, rather than from the nuclei of differentiated cells, as has been assumed. Here we report the generation of monoclonal mice by nuclear transfer from mature lymphocytes. In a modified two-step cloning procedure, we established ES cells from cloned blastocysts and injected them into tetraploid blastocysts to generate mice. In this approach, the embryo is derived from the ES cells and the extra-embryonic tissues from the tetraploid host. Animals cloned from a B-cell nucleus were viable and carried fully rearranged immunoglobulin alleles in all tissues. Similarly, a mouse cloned from a T-cell nucleus carried rearranged T-cell-receptor genes in all tissues. This is an unequivocal demonstration that a terminally differentiated cell can be reprogrammed to produce an adult cloned animal.