人类的克隆

韩国科学家成功地克隆了30个人类胚胎，并从中提取出干细胞，这是克隆技术适于人类的第一个证据。研究人员计划由此衍生出胚胎干细胞系，以帮助研究者认识复杂的疾病，     

干细胞的魔力:再造生物组织

 干细胞具有再生各种生物组织器官的潜能,在医学界被称为“万用细胞”。近几年来,干细胞领域重要的进展是培养人体的类器官,目前已经培养出人类大脑、心脏等多种器官。胚胎干细胞由于能被诱导分化为机体几乎所有的细胞类型而在治疗疾病方面有着极其诱人的前景。但是,之前科学家却一直未能在实验室中使胚胎干细胞独自发育成具有复杂的三维结构的组织。近期,这一领域取得了突破--英国剑桥大学的研究人员采用两种干细胞成功培育出与正常胚胎非常相似的小鼠胚胎。     

走向智能自主的无人机控制技术

 干细胞具有再生各种生物组织器官的潜能，在医学界被称为“万用细胞”。近几年来，干细胞领域重要的进展是培养人体的类器官，目前已经培养出人类大脑、心脏等多种器官。胚胎干细胞由于能被诱导分化为机体几乎所有的细胞类型而在治疗疾病方面有着极其诱人的前景。但是，之前科学家却一直未能在实验室中使胚胎干细胞独自发育成具有复杂的三维结构的组织。近期，这一领域取得了突破--英国剑桥大学的研究人员采用两种干细胞成功培育出与正常胚胎非常相似的小鼠胚胎。     

胚胎干细胞及其在人类疾病治疗中的应用

胚胎干细胞是一类多能性干细胞,近年来已成为生命科学研究领域的热点之一．尤其在人类疾病治疗方面有着诱人的应用前景．本文主要介绍了胚胎干细胞在几种疑难疾病治疗上的应用及其前景,胚胎干细胞与异种器官移植。以及目前存在的一些问题．     

哺乳动物异种间体细胞核移植技术进展

自1997年绵羊体细胞核移植成功后,克隆技术发展迅速,克隆技术与胚胎干细胞的结合,产生了治疗性克隆的理念.文中对克隆技术的研究进展、方法和意义作了综述,并重点对哺乳类动物异种间核移植的方法技术和伦理学进行讨论.     

干细胞研究国际发展态势分析

干细胞以其自我更新和多向分化的能力得到了国际社会的普遍关注,为干细胞疗法的临床应用带来了希望.该文结合文献计量方法,对干细胞以及诱导多能干细胞、胚胎干细胞和间充质干细胞等3个干细胞研究重点领域的科研现状进行了分析,总结了这些领域的发展趋势和重点研究方向,并根据分析结果,对我国干细胞领域采取的措施、今后发展的方向提出了建...     

事件

克隆“多莉”羊的英国科学家跳槽新加坡成功克隆“多莉”羊的一名科学家辞掉在英国的工作,加入新加坡一家研究人类胚胎干细胞的公司。世界第一只克隆的哺乳动物“多莉”羊,是苏格兰一组科学家的集体研究成果,现在这组科学家中的科尔曼博士将跳槽新加坡的 ES 细胞国际公司,从事利用人类胚胎干细胞克隆技术治疗糖尿病的研究。科尔曼说,新加坡在     

美国 科学家造出干细胞 彻底摆脱伦理束缚

近日，来自美国哈佛大学的生物科学家首次对外宣布，他们在试验环境下，成功找到了一种将成人皮肤细胞组织和人体胚胎干细胞融合，人工制造人类干细胞组织的全新方法。参与该项研究的科学家表示，这种转换生成干细胞的新技术，将使得科研人员在不必破坏人类胚胎的前提下，能够有针对性地高效制造各种极具科研价值的人类干细胞组织，它很可能会成为近年来基因科学研究领域内一项重大技术突破。科学家同时预计，由此在生命科学界将有望彻底摆脱伦理道德和社会法律的束缚，真正迎来该学科领域快速发展的全新时代。     

国外有关克隆技术的法制规定

自 1 997年克隆羊多莉诞生后 ,引起各国政府对克隆技术在人体和科学研究中所出现的问题的重视。近年体细胞克隆技术、核移植技术和胚胎干细胞培育技术已日趋成熟 ,一方面通过动物实验可以解决生命科学上的未知问题 ,尤其是人们期待其在再生医学和再生医疗上发挥作用 ;另一方面各国政府和科研人员也感觉到 ,在克隆动物实验研究和克隆技术应用于人类的实验研究方面其界限尚不清楚。在这种情况下 ,世界各国相继制定了各种法律法规 ,对此项研究进行规制。在 1 997年 5月世界卫生组织 (WHO)的会议上制定了“关于克隆技术的决议” ,明确指出不允…     

医疗

中国新型基因药物成为肠癌克星近日,来自美国哈佛大学的生物科学家首次对外宣布,他们在试验环境下,成功找到了一种将成人皮肤细胞组织和人体胚胎干细胞融合,人工制造人类干细胞组织的全新方法。参与该项研究的科学家表示,这种转换生成干细胞的新技术,将使得科研人员在不必破坏人类胚胎的前提下,能够有针对性地高效制造各种极具科研价值的人类干细胞组织,它很可能会成为近年来基因科学研究领域内一项重大技术突破。科学家同时预计,由此在生命科学界将有望彻底摆脱伦理道德和社会法律的束缚,真正迎来该学科领域快速发展的全新时代。结肠癌是困…     

Developmental reprogramming after chromosome transfer into mitotic mouse zygotes

Until now, animal cloning and the production of embryonic stem cell lines by somatic cell nuclear transfer have relied on introducing nuclei into meiotic oocytes. In contrast, attempts at somatic cell nuclear transfer into fertilized interphase zygotes have failed. As a result, it has generally been assumed that unfertilized human oocytes will be required for the generation of tailored human embryonic stem cell lines from patients by somatic cell nuclear transfer. Here we report, however, that, unlike interphase zygotes, mouse zygotes temporarily arrested in mitosis can support somatic cell reprogramming, the production of embryonic stem cell lines and the full-term development of cloned animals. Thus, human zygotes and perhaps human embryonic blastomeres may be useful supplements to human oocytes for the creation of patient-derived human embryonic stem 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.     

Embryonic stem cell as nuclear donor could promote in vitro development of the heterogeneous reconstructed embryo

The nucleus of a somatic cell could be dedifferentiated and reprogrammed in an enucleated heterogeneous oocyte. Some reconstructed oocytes could develop into blastocysts in vitro, and a few could develop into term normally after transferred into foster mothers, but most of cloning embryos fail to develop to term. In order to evaluate the efficacy of embryonic stem cell as nucleus donor in interspecific animal cloning, we reconstructed enucleated rabbit oocytes with nuclei from mouse ES cells, and analyzed the developmental ability of reconstructed embryos in vitro. Two kinds of fibroblast cells were used as donor control, one derived from ear skin of an adult Kunming albino mouse, and the other derived from a mouse fetus. Three types of cells were transferred into perivitelline space under zona pellucida of rabbit oocytes respectively. The reconstructed oocytes were fused and activated by electric pulses, and cultured in vitro. The developmental rate of reconstructed oocytes derived from embryonic stem cells was 16.1%, which was significantly higher than that of both the adult mouse fibroblast cells (0%-3.1%, P < 0.05) and fetus mouse fibroblast cells (2.1%-3.7%, P < 0.05). Chromosome analysis confirmed that blastocyst cells were derived from ES donor cell. These observations show that reprogramming is easier in interspecific embryos reconstructed with ES cells than that reconstructed with somatic cells, and that ES cells have the higher ability to direct the reconstructed embryos development normally than fibroblast cells.     

Cloned goats (Gapra hircus) from foetal fibroblast cell lines

Mammalian cloning has been one of the most active research topics in the world. Cloning within vitro culured foetal fibroblast cells, in comparison with embryonic cells, can be used not only to theoretically study the embryonic or cellular development and differentiation in mammals, but also to utilize the unlimited fibroblast cells to produce large numbers of clonings. The preliminary results are as follows: (i) The division and development of the cloned embryos with embryonic donor cells and goat foetal fibroblast donor cells were 55%, 77% and 35%, 31%, respectively. There is no significant statistical difference between them, (ii) These studies result in the birth of two cloned goats derived from two 30-day foetal fibroblast cell lines, which are the first cloned mammals from somatic cells in China. This project has established a technological data base for the furture research on adult mammalian somatic cloning and nucleocytoplasmic interactions in animal development, and a novel technique for the cloning of animals with a high-level expression of transgene(s).     

Nuclear reprogramming and pluripotency

The cloning of mammals from differentiated donor cells has refuted the old dogma that development is an irreversible process. It has demonstrated that the oocyte can reprogramme an adult nucleus into an embryonic state that can direct development of a new organism. The prospect of deriving patient-specific embryonic stem cells by nuclear transfer underscores the potential use of this technology in regenerative medicine. The future challenge will be to study alternatives to nuclear transfer in order to recapitulate reprogramming in a Petri dish without the use of oocytes.     

成纤维细胞和ES细胞在小鼠和兔去核卵母细胞内发育

以昆明白小鼠成纤维细胞和胚胎干（ES）细胞作为供核细胞,以昆明白小鼠和日本大耳白兔的MⅡ期去核卵母细胞作为受体,采用核移植方法,构楚了克隆胚胎．在同种克隆中,以ES细胞为供核细胞的克隆胚胎卵裂率明显低于以成纤维细胞为供核细胞的克隆胚胎卵裂率（24．4％相对于56．9％,P〈0．05）,1．8％的ES细胞克隆胚胎发育到囊胚阶段,而成纤维细胞克隆胚胎没能发育到囊胚阶段;在异种克隆中,以ES细胞为供核细胞的克隆胚胎卵裂率（89．6％）和囊胚发育率（18．8％）明显高于以成纤维细胞为供核细胞的克隆胚胎卵裂率（54．2％）和囊胚发育率（4．2％）．     

Comparative pluripotency analysis of mouse embryonic stem cells derived from wild-type and infertile hermaphrodite somatic cell nuclear transfer blastocysts

Therapeutic cloning, whereby embryonic stem cells （ESCs） are derived from patient-specific cloned blastocysts via somatic cell nuclear transfer （SCNT）, holds great promise for treating many human diseases using regenerative medicine. Teratoma formation and germline transmission have been used to confirm the pluripotency of mouse stem cells, but human embryonic stem cells （hESCs） have not been proven to be fully pluripotent owing to the ethical impossibility of testing for germ line transmis- sion, which would be the strongest evidence for full pluripotency. Therefore, formation of differentiated cells from the three somatic germ layers within a teratoma is taken as the best indicator of pluripotency in hESC lines. The possibility that these lines lack full multi- or pluripotency has not yet been evaluated. In this study, we established 16 mouse ESC lines, including 3 genetically defective nuclear transfer- ESC （ntESC） lines derived from SCNT blastocysts of infertile hermaphrodite F1 mice and 13 ntESC lines derived from SCNT blastocysts of normal F1 mice. We found that the defective ntESCs expressed all in vitro markers of pluripotency and could form teratomas that included derivatives from all three germ layers, but could not be transmitted via the germ line, in contrast with normal ntESCs. Our results in- dicate that teratoma formation assays with hESCs might be an insufficient standard to assess full pluripotency, although they do define multipotency to some degree. More rigorous standards are required to assess the safety of hESCs for therapeutic cloning.     

Preliminary study on human fibroblasts as feeder layer for human embryonic stem cells culture in vitro

To avoid the direct contact with mouse cells and possible heterogeneous pathogen in future application ,we need to replace mouse embryonic fibroblasts with human fibroblasts as the feeder layer to maintain human embryonic stem cells growth in the undifferentiated state,We Success-fully use human fibroblasts derved from aborted fetus and adult prepuces as feeder layer to maintain human embryonic stem cells growth ,During the passage and growth on this feeder layer,the human embryonic stem cells can keep their undifferentiated state.     

Potential of stem-cell-based therapies for heart disease

The use of stem cells to generate replacement cells for damaged heart muscle, valves, vessels and conduction cells holds great potential. Recent identification of multipotent progenitor cells in the heart and improved understanding of developmental processes relevant to pluripotent embryonic stem cells may facilitate the generation of specific types of cell that can be used to treat human heart disease. Secreted factors from circulating progenitor cells that localize to sites of damage may also be useful for tissue protection or neovascularization. The exciting discoveries in basic science will require rigorous testing in animal models to determine those most worthy of future clinical trials.