Ethical guidance on human embryonic and fetal tissue transplantation: A European overview

This article presents an overview ofregulations, guidelines and societal debates ineight member states of the EC about a)embryonic and fetal tissue transplantation(EFTT), and b) the use of human embryonic stemcells (hES cells) for research into celltherapy, including `therapeutic' cloning. Thereappears to be a broad acceptance of EFTT inthese countries. In most countries guidance hasbeen developed. There is a `strong' consensusabout some of the central conditions for `goodclinical practice' regarding EFTT.International differences concern, amongstothers, some of the informed consent issuesinvolved, and the questions whether anintermediary organisation is necessary, whetherthe methods of abortion may be influenced bythe possible use of EFT, and whether EFTTshould only be used for the experimentaltreatment of rare disorders. The potential useof hES cells for research into cell therapy hasgiven a new impetus to the debate about (human)embryo research. The therapeutic prospects withregard to the retrieval and research use of hEScells appear to function as a catalyst for theintroduction of less restrictive regulationsconcerning research with spare embryos, atleast in some European countries. It remains tobe seen whether the prospect of treatingpatients suffering from serious disorders withtransplants produced by therapeutic cloningwill decrease the societal and moral resistanceto allowing the generation of embryos for`instrumental' use.     

Forschen mit humanen embryonalen Stammzellen in Deutschland

From July 2002 to May 2008, 36 applications for the import and use of human embryonic stem cells (hES) were reviewed by the German Central Ethics Committee for Stem Cell Research (ZES). A flood of applications anticipated by opponents to human embryonic stem cell research has not occurred since the enactment of the German Stem Cell Act in 2002. On the contrary, German hES cell research is below international average in terms of project numbers. The current restrictions for using hES cells in Germany might be causative for the opinion that this type of research is not considered to be very promising. This could hold true especially for research aiming at clinical applications. Consequently, potential research goals of premium importance, especially those of potential clinical relevance, could be seriously jeopardized.     

Derivation of human embryonic stem cell lines, towards clinical quality

Human embryonic stem (hES) cells offer an excellent source of cells for transplantation in the treatment of severe diseases. To be clinically safe, the lines have to be derived using strict quality criteria and good manufacturing practice. Animal proteins are immunogenic and may contain microbes, and they should not be used in establishing or propagating hES cells. Derivation systems have been improved towards clinical quality by establishing all 25 hES cell lines using human skin fibroblasts as feeder cells instead of mouse fibroblasts. A further 21 cell lines have been established using synthetic serum instead of fetal calf serum in the medium. In the five latest derivations, the inner cell mass was isolated mechanically instead of by immunosurgery (animal antibodies). Feeder-free derivation would be optimal, but it is not yet considered safe. Clinical-quality lines can be derived by establishing the skin fibroblast feeders in the good manufacturing practice laboratory with human serum in the medium, and by establishing the hES cells on such feeders. In this process, a serum replacement that contains only human protein can be used, the inner cell mass has to be isolated mechanically, and the colonies have to be split mechanically for passaging. Somatic cell nuclear transfer would help to overcome rejection of transplanted cells.     

Humane embryonale Stammzellen

The remarkable capability of human embryonic stem cells (hES cells) to differentiate into all somatic cell types and tissues opens promising perspectives for the development of novel therapeutic approaches for neurological disorders. This article provides an overview on the current state of research in this field. We present strategies and results on the generation of selected neural subtypes (dopaminergic neurons, retinal progenitors, motoneurons, oligodendrocytes) and discuss problems and risks associated with a potential clinical application of this novel cell source.     

Therapeutic cloning: far from application at this stage]

Therapeutic cloning has become possible since the discovery that nuclei from somatic cells of adult animal tissue can successfully be used for cloning and the fact that human embryonic stem cell lines have been established from preimplantation embryos. When nuclei from healthy tissue of a patient are transplanted into enucleated oocytes, these oocytes can be artificially activated so that embryos develop from which embryonic stem cells of the donor can be derived. These embryonic stem cells can be cultured as permanent lines in unlimited numbers and remain pluripotent, i.e. they can be induced to differentiate into the required cell type by adding one or more specific factors. These cells can then be transplanted back into the patient suffering from either a lack or dysfunction of these cells. This approach prevents the rejection of the transplanted cells by the patient's immunological system. As this type of cloning has a very low efficiency, a large number of unfertilized donor oocytes is required. It is questionable whether enough donors are or will be available for this purpose. The cultured cells must satisfy certain conditions before they can be used for transplantation. They must be checked for chromosomal abnormalities, and a complete differentiation of the embryonic stem cells into the cells types needed by the patient is necessary as after the transplantation, undifferentiated stem cells will form teratomas. Furthermore, it is difficult to ensure that the cells end up in the right place and to ensure that they fully integrate into the existing tissue to form functional connections. Due to this array of technical problems the question remains as to whether therapeutic cloning will become feasible in the near future.     

What justifies the United States ban on federal funding for nonreproductive cloning?

This paper explores how current United States policies for funding nonreproductive cloning are justified and argues against that justification. I show that a common conceptual framework underlies the national prohibition on the use of public funds for cloning research, which I call the simple argument. This argument rests on two premises: that research harming human embryos is unethical and that embryos produced via fertilization are identical to those produced via cloning. In response to the simple argument, I challenge the latter premise. I demonstrate there are important ontological differences between human embryos (produced via fertilization) and clone embryos (produced via cloning). After considering the implications my argument has for the morality of publicly funding cloning for potential therapeutic purposes and potential responses to my position, I conclude that such funding is not only ethically permissible, but also humane national policy.     

Shifting paradigms? Reflections on regenerative medicine,embryonic stem cells and pharmaceuticals

Will human embryonic stem (hES) cells lead to a revolutionary new regenerative medicine? We begin to answer this question by drawing on interviews with scientists and clinicians from leading labs and clinics in the UK and the USA, exploring their views on the bench‐bedside interface in the fields of hES cells, neuroscience and diabetes. We employ Bourdieu's concepts of field, habitus and capital in order to understand stem cell science and cell transplantation. We also build on research on the sociology of expectations, and explore expectations of pharmaceutical approaches in hES research through our concept of ‘expectational capital’. In the process we discuss emerging expectations within stem cell research, most especially the ‘disease in a dish’ approach, where hES cells will be used as tools for unravelling the mechanisms of disease to enable the development of new drugs. We argue that experts’ persuasive promises advance their interests in the uncertain stem cell field, and explore how this performative strategy might stabilise the emerging ‘disease in a dish’ model of translational research.     

Cloning: applications in humans. II. Ethical considerations

Reproductive cloning in adults/children evokes unfavourable reactions. Direct objections are that cloning is unnatural, that it affects human dignity and violates the individual's right to genetic uniqueness. Consequential objections concern unjustified health risks for the progeny, unjustified psychosocial risks for the clone child and the risk of cloning for eugenetic purposes. There is consensus that reproductive cloning of existing persons is unjustifiable as yet because of the health risks for the offspring. Reproductive cloning of embryos is possible by means of nucleus transplantation and of embryo splitting. The ethical analysis of reproductive cloning of embryos depends on the purposes and applications. At least some of the moral objections against cloning of adults/children are not or not completely applicable to reproductive cloning of embryos. Conditions to be put to reproductive cloning of embryos are efficacy, safety and, at least for the time being, avoidance of asynchrony in transferring identical embryos. The ethical aspects of its application in the context of genetical reproductive techniques must be evaluated separately. Therapeutic cloning may be acceptable if alternatives are lacking.     

The derivation and potential use of human embryonic stem cells

Human embryonic stem cells lines can be derived from human blastocysts at high efficiency (>50%) by immunosurgical isolation of the inner cell mass and culture on embryonic fibroblast cell lines. These cells will spontaneously differentiate into all the primary embryonic lineages in vitro and in vivo, but they are unable to form an integrated embryo or body plan by themselves or when combined with trophectoderm cells. They may be directed into a number of specific cell types and this enrichment process requires specific growth factors, cell-surface molecules, matrix molecules and secreted products of other cell types. Embryonic stem (ES) cells are immortal and represent a major potential for cell therapies for regenerative medicine. Their use in transplantation may depend on the formation of a large bank of suitable human leucocyte antigen (HLA) types or the genetic erasure of their HLA expression. Successful transplantation may also require induction of tolerance in recipients and ongoing immune suppression. Although it is possible to customize ES cells by therapeutic cloning or cytoplasmic transfer, it would appear unlikely that these strategies will be used extensively for producing ES cells compatible for transplantation. Embryonic stem cell research may deliver a new pathway for regenerative medicine.     

Stem cell research in Germany: Ethics of healing vs. human dignity

On 25 April 2002, the German Parliament has passed a strict new law referring to stem cell research. This law took effect on July 1, 2002. The so-called embryonic Stem Cell Act (Stammzellgesetz — StZG) permits the import of embryonic stem (ES) cells isolated from surplus IvF-embryos for research reasons. The production itself of ES cells from human blastocysts has been prohibited by the German Embryo Protection Act of 1990, with the exception of the use of ES cells which exist already. The debate on the legitimate use of ES cells escalated, after the main German research funding agency, the Deutsche Forschungsgemeinschaft (DFG), unexpectedly published new guidelines recommending are stricted use of human ES cells for research. Meanwhile, the debate has ethically dividedsociety, political parties, government and church members into a group supporting and a group rejecting ES cell research. The arguments in favour of such a research can be summarized as arguments derived from a new ethics ofhealing calling for a therapeutic imperative, whereas the arguments against can be summarized as arguments violating the fundamental principle of human dignity as they imply the destruction of human embryos. This article willtry to present and evaluate various ethical arguments founded on the latest biological and medical data on the potential use of stem cell technologies. It will finally come to the conclusion that ES cell research is opposed to human dignity, since the procedures of isolating ES cells require the destruction and instrumentalization of human embryos. Human embryos are human beings at a very early stage of their development, fully possessing the ability of completing their development. At this very early stage, human embryos are extremely dependent and fragile, and thus vulnerable corporealities. Vulnerability and human dignity demand the protection of the embryo's corporeal integrity. Hence, this essay will try to propagate research with adult stem(AS) cells, a procedure which does not require the destruction of human embryos; with regard to the necessary plasticity, it should be emphasized that AS cells very much resemble ES cells.This revised version was published online in October 2005 with corrections to the Cover Date.     

Cellular therapy--the possible future of regenerative medicine

Stem cells are a unique cell population capable of self-renewal and differentiation into different cell lines. There are two main types of stem cells: embryonic stem cells (pluripotent) and somatic/adult stem cells (multipotent cells differentiated into the specific types of the tissue they originate from). Scientists are now interested in finding the sources of cells that can be used for therapeutic cloning as a method of saving human life and a new trend in regenerative medicine. Reproductive cloning, which aims at creating genetically identical human beings, is prohibited and is subject to national legislation in each country. Mesenchymal stem cells, with their capability to elude detection by the host's immune system and their relative ease of expansion in culture, are a very promising source of stem cells for regenerative medicine. This is the vast potential of cellular therapy for treating damaged and degenerating tissues.     

A European discussion about stem cells for therapeutic use

Stem cells as a source material for growing cellular transplants to repair dysfunctional organs appear to be a new challenge for medical science. Though stem cells are also present in foetal and adult organs, embryonic stem cells from the pre-implantation embryo in particular have the potency to proliferate easily in vitro and the capacity to differentiate into all the body's organ-specific cells. Therefore, these are the ideal cells for developing new cell transplantation therapies for diseases such as Parkinson's disease, diabetes mellitus and heart failure. The use of spare in vitro fertilization (IVF) embryos or pre-implantation embryos specially created to harvest human embryonic stem cells is, however, controversial and an ethical problem. In a European discussion platform organised by the European Commission Research Directorate-General, the status quo of the progress was presented and subsequently commented upon and discussed in terms of medical-ethical, social, industrial and patient interests. The expectations of this new medical technology were high, but clinical trials seem only acceptable once the in vitro differentiation of stem cells can be adequately controlled and once it is known how in vitro prepared stem cells behave after implantation. The ethical justification of the use of in vitro pre-implantation embryos remains controversial. The prevailing view is that the interests of severely ill patients for whom no adequate therapy exists, surmounts the interest of protection of a human in vitro pre-implantation embryo, regardless of whether it was the result of IVF or of transplantation of a somatic cell nucleus of the patient in an enucleated donor egg cell (therapeutic cloning).     

人胚胎干细胞建系研究中的伦理管理

目的：建立国人胚胎干细胞系递交国际干细胞库,并在此基础上建立既符合中国国情又得到国际认可的相关伦理管理体系。方法：在比尔盖茨基金会的资助下,与北京大学生命科学院再生生物学实验室合作,募集胚胎建立人胚胎干细胞系,在此过程中探讨可行的符合国际伦理原则的相关伦理管理机制。结果：成功建立了国人胚胎干细胞系及相关伦理管理体系。结论：进行干细胞研究时应充分重视伦理问题,国际干细胞伦理管理与中国相关伦理原则是可以有机结合的。     

人胚胎干细胞建系研究中的伦理管理

目的：建立国人胚胎干细胞系递交国际干细胞库,并在此基础上建立既符合中国国情又得到国际认可的相关伦理管理体系。方法：在比尔盖茨基金会的资助下,与北京大学生命科学院再生生物学实验室合作,募集胚胎建立人胚胎干细胞系,在此过程中探讨可行的符合国际伦理原则的相关伦理管理机制。结果：成功建立了国人胚胎干细胞系及相关伦理管理体系。结论：进行干细胞研究时应充分重视伦理问题,国际干细胞伦理管理与中国相关伦理原则是可以有机结合的。     

Therapeutic cloning and the constitution--a Canadian perspective

Recent developments in the field of therapeutic cloning have been welcomed by many in the medical community as important breakthroughs that may help provide a better understanding of a variety of human diseases. Nevertheless, research in this field appears to have struck a sensitive nerve in society. A large amount of social debate has been generated regarding the validity of therapeutic cloning, and there are many seeking legislation to have the practice restricted. It is unclear, however, whether such restrictions can be legally justified. Analysing cloning in such a social and legal context raises a number of questions. What scientific procedures are behind therapeutic cloning? What is the legal status of the cultured or unimplanted embryo? Can cloning be considered an aspect of reproductive liberty as protected by the constitution? What medical advances might therapeutic cloning further? What social benefits and harms might arise from its promotion or restriction? Such questions, and the broader debate surrounding human therapeutic cloning, are addressed in this paper in three parts. Part 1 presents an overview of the basic biological principles behind cloning and the science behind the therapeutic cloning of specific cells and tissues. Part 2 analyses ss. 7, 2, 15(1) and 1 of the Canadian Charter of Rights and Freedoms and how they may be implicated by legal incursions into the field of human cloning. Several Charter-based arguments, both for and against the practice, are presented. Finally, Part 3 assesses some recent scientific developments in cloning technology, and how they affect the debate over the constitutionality of human therapeutic cloning.     

转染人内皮抑素对卵巢癌细胞A2780体内外生长的影响

目的:探讨人内皮抑素(hum an endostatin,hES)对人卵巢癌细胞株A2780体内、外生长的影响及其可能机制。方法:高保真PCR从含有人内皮抑素基因的人肝脏组织中扩增出人内皮抑素编码区克隆入pcDNA3.1载体中,构建pcDNA3.1-ES重组质粒;将此重组质粒转染人卵巢癌细胞A2780中,观察A2780细胞生长。建立人卵巢癌裸鼠模型,随机将其分为两组:hES转染细胞组(A组,10只),对照组(B组,10只)。1月后,测量瘤体积、计算抑瘤率;标本行HE染色分析组织学形态;同时用W estern b lot检测hES、凋亡抑制蛋白bc l-2的表达;流式细胞仪检测转染对裸鼠移植瘤细胞凋亡率的影响。结果:hES转染A2780细胞后,细胞生长速率减慢。转染hES的裸鼠肿瘤生长较对照组明显减慢(P<0.001),抑瘤率为74%;HE染色及W estern b lot提示:转染后(A组)的组织学形态与转染前(B组)有显著差异;A组hES蛋白水平明显高于B组,而bc l-2蛋白水平明显低于B组;流式结果显示转染使肿瘤细胞的凋亡显著增加(P<0.05)。结论:转染hES体内、外均可抑制卵巢癌A2780细胞的生长,其机制与其促进了凋亡有关。     

The Commercialization of Human Stem Cells: Ethical and Policy Issues

The first stage of the human embryonic stem(ES) cell research debate revolved aroundfundamental questions, such as whether theresearch should be done at all, what types ofresearch may be done, who should do theresearch, and how the research should befunded. Now that some of these questions arebeing answered, we are beginning to see thenext stage of the debate: the battle forproperty rights relating to human ES cells. The reason why property rights will be a keyissue in this debate is simple and easy tounderstand: it costs a great deal of money todo this research, to develop new products, andto implement therapies; and private companies,researchers, and health professionals requirereturns on investments and reimbursements forgoods and services. This paper considersarguments for and against property rightsrelating to ES cells defends the followingpoints: (1) It should be legal to buy and sellES cells and products. (2) It should be legalto patent ES cells, products, and relatedtechnologies. (3) It should not be legal tobuy, sell, or patent human embryos. (4) Patentson ES cells, products, and related technologiesshould not be excessively broad. (5) Patents onES cells, products, and related technologiesshould be granted only when applicants statedefinite, plausible uses for their inventions. (6) There should be a research exemption in EScell patenting to allow academic scientists toconduct research in regenerative medicine. (7)It may be appropriate to take steps to preventcompanies from using patents in ES cells,products, and related technologies only toblock competitors. (8) As the field ofregenerative medicine continues to develop,societies should revisit issues relating toproperty rights on a continuing basis in orderto develop policies and develop regulations tomaximize the social, medical, economic, andscientific benefits of ES cell research andproduct development.     

Banking on it: public policy and the ethics of stem cell research and development

If the therapeutic potential of stem cell-based therapies is ever realized, demand for stem cells and derivative tissues will be tremendous and will create new challenges for health care systems, especially publicly funded health care systems. We propose a framework for the ethical analysis of stem cell research and development that considers the welfare of communities, tissue recipients, and cell sources in relation to a range of stem cell production and distribution options. Ethical desiderata include: equitable access, maximized potential therapeutic benefit across demographic and disease groups, and reasonable cost. Other ethical priorities include the minimization of stem cell line and tissue wastage, risk of immune rejection, risk of transmitting diseases, the use of human embryos, and risk to those contributing source cells. We array plausible sources of stem cells and distribution strategies to characterize 12 potential models for producing and distributing cells and tissues in the future. We describe "personalized", "matched", and "universalized" models, and compare the ethical acceptability of these models. Popular and scientific discourses about stem cells typically emphasize personalized or matched stem cell distribution models. We show that universalized models may ultimately best serve the interest of taxpayers, communities and patients who hold high stakes in the therapeutic success of stem cell science. They are therefore highly worthy of scientific pursuit. This conclusion is provisional and the framework must be reapplied as scientific knowledge, technological capacity and ethical mores evolve.     

Telomere length regulation during cloning, embryogenesis and ageing

Telomeres are nucleoprotein complexes at the end of eukaryotic chromosomes with an essential role in chromosome capping. Owing to the end-replication problem of DNA polymerase, telomeres shorten during each cell division. When telomeres become critically short, they loose their capping function, which in turn induces a DNA damage-like response. This mechanism inhibits cell proliferation at the senescence stage and there is evidence that it limits the regenerative capacity of tissues and organs during chronic diseases and ageing. The holoenzyme telomerase synthesises telomeric DNA de novo, but, in humans, it is active only during embryogenesis, in immature germ cells and in a subset of stem/progenitor cells during postnatal life. Telomere length can be maintained or increased by telomerase, a process that appears to be regulated by a variety of telomere-binding proteins that control telomerase recruitment and activity at the telomeres. During embryogenesis, telomerase is strongly activated at the morula/blastocyst transition. At this transition, telomeres are significantly elongated in murine and bovine embryos. Early embryonic telomere elongation is telomerase dependent and leads to a rejuvenation of telomeres in cloned bovine embryos. Understanding of the molecular mechanisms underlying this early embryonic telomere elongation programme is of great interest for medical research in the fields of regeneration, cell therapies and therapeutic cloning.     

Health charities, unethical research and organizational integrity

Organizations, particularly Catholic hospitals, schools and social service agencies, should re-examine their relationships to health and medical charities promoting unethical research such as human embryonic stem cell research and therapeutic cloning. Part 6 of the Ethical and Religious Directives provides a helpful framework for ethical analysis and action.