Differentiation of embryonic and adult stem cells into insulin producing cells

Replacement of insulin producing cells represents an almost ideal treatment for patients with diabetes mellitus type 1. Transplantation of pancreatic islets of Langerhans is successful in experienced centers. The wider application of this therapy, however, is limited by the lack of donor organs. Insulin producing cells generated from stem cells represent an attractive alternative. Stem cells with the potential to differentiate into insulin producing cells include embryonic stem cells (ESC) as well as adult stem cells from various tissues including the pancreas, liver, bone marrow and adipose tissue. The use of human ESC is hampered by ethical concerns but research with human ESC may help us to decipher important steps in the differentiation process in vitro since almost all information available on pancreas development are based on animal studies. The present review summarizes the current knowledge on the development of insulin producing cells from embryonic and adult stem cells with special emphasis on pancreatic, hepatic and human mesenchymal stem cells.     

Attempts towards derivation and establishment of bovine embryonic stem cell-like cultures

Current knowledge on the biology of mammalian embryonic stem cells (ESC) is stunningly sparse in light of their potential value in studies of development, functional genomics, generation of transgenic animals and human medicine. Despite many efforts to derive ESC from other mammalian species, ESC that retain their capacity for germ line transmission have only been verified in the mouse. However, the criterion of germ line transmission may not need to be fulfilled for exploitation of other abilities of these cells. Promising results with human ESC-like cells and adult stem cells have nourished great expectations for their potential use in regenerative medicine. However, such an application is far from reality and substantial research is required to elucidate aspects of the basic biology of pluripotent cells, as well as safety issues associated with the use of such cells in therapy. In this context, methods for the derivation, propagation and differentiation of ESC-like cultures from domestic animals would be highly desirable as biologically relevant models. Here, we review previously published efforts to establish bovine ESC-like cells and describe a procedure used in attempts to derive similar cells from bovine Day 12 embryos.     

Stem cell sources for cardiac regeneration

Cell-based cardiac repair has the ambitious aim to replace the malfunctioning cardiac muscle developed after myocardial infarction, with new contractile cardiomyocytes and vessels. Different stem cell populations have been intensively studied in the last decade as a potential source of new cardiomyocytes to ameliorate the injured myocardium, compensate for the loss of ventricular mass and contractility and eventually restore cardiac function. An array of cell types has been explored in this respect, including skeletal muscle, bone marrow derived stem cells, embryonic stem cells (ESC) and more recently cardiac progenitor cells. The best-studied cell types are mouse and human ESC cells, which have undisputedly been demonstrated to differentiate into cardiomyocyte and vascular lineages and have been of great help to understand the differentiation process of pluripotent cells. However, due to their immunogenicity, risk of tumor development and the ethical challenge arising from their embryonic origin, they do not provide a suitable cell source for a regenerative therapy approach. A better option, overcoming ethical and allogenicity problems, seems to be provided by bone marrow derived cells and by the recently identified cardiac precursors. This report will overview current knowledge on these different cell types and their application in cardiac regeneration and address issues like implementation of delivery methods, including tissue engineering approaches that need to be developed alongside.     

Ethical boundary-work in the embryonic stem cell laboratory

Most accounts of the ethics of stem cell research are de- contextualised reviews of the ethical and legal literature. In this chapter we present a socially embedded account of some of the ethical implications of stem cell research, from the perspectives of scientists directly involved in this area. Based on an ethnography of two leading embryonic stem cell laboratories in the UK, our data form part of the findings from a larger project mapping the scientific, medical, social and ethical dimensions of innovative stem cell treatment, focusing on the areas of liver cell and pancreatic islet cell transplantation. We explore three key issues: what individual scientists themselves view as ethical sources of human embryos and stem cells; their perceptions of human embryos and stem cells; and how scientists perceive regulatory frameworks in stem cell research. We argue that these dimensions of laboratory practice are all examples of 'ethical boundary-work', which is becoming an integral part of the routine practice and performance of biomedical science. Our work adds to the relatively few sociological studies that explore ethics in clinical settings and to an even smaller body of work that explores scientists' views on the ethical issues relating to their research.     

干细胞研究进展及相关伦理学问题思考

始于上世纪末,迄今仍方兴未艾的干细胞研究,由于其特殊的细胞分化,组织再生,甚至可能的器官再造特性,引起了又一次生物医学革命,被视为20世纪末最重要的生物医学成就。但同时由于胚胎干细胞涉及的人类胚胎生命及组织、器官的再生成等伦理学问题,干细胞研究从问世的第一天起,就在生物医学家、哲学家、法学家、政治家间引起广泛的争论。文章简要复习了近年来干细胞研究成果及干细胞研究引起的相关伦理学争论,并就干细胞研究引发的伦理学问题及对未来医疗发展的影响提出作者的观点。     

Ethics, politics, and human embryo stem cell research.

Three reports on ethical aspects of research involving human embryonic stem cells were issued in the final months of 1999. Two were from governmental agencies or commissions: the National Institutes of Health and the National Bioethics Advisory Commission. The third report was issued by the American Association for the Advancement of Science and the Institute for Civil Society. All three reports endorse the use of federal funds for embryonic stem cell research, but other differences distinguish these reports. This article describes the differences and provides an ethical analysis of the main arguments.     

Our cells/ourselves: creating human embryos for stem cell research.

In September 1999, the National Bioethics Advisory Commission (NBAC) submitted its report, "Ethical issues in human stem cell research." The report recommends federal funding for stem cell research involving human embryos remaining after infertility treatment. It also suggests that at some later time, it may be appropriate for there to be federal funding for this same research using embryos expressly created for research purposes. This essay compares this recommendation to a similar recommendation reached 5 years earlier by the Human Embryo Research Panel of the National Institutes of Health. The NBAC recommendation is found to be much better packaged relative to the (contentious) goal of securing federal funding for this type of research. The merits of this goal are not discussed here. Instead, disappointment is expressed with the absence of any serious discussion of the ethical issues raised by the future possibility of stem cell research using research embryos. The report's silence on this question is significant given its promise to promote public debate on the profound ethical issues regarding human stem cell research.     

Seminal plasma enhances and accelerates progesterone-induced decidualisation of human endometrial stromal cells

In preparation for embryo implantation, endometrial stromal cells (ESC) undergo differentiation, termed decidualisation. Enhancing endometrial decidualisation may overcome reduced endometrial receptivity, a major limiting factor in natural and assisted reproduction. To determine whether seminal plasma (SP) influences decidualisation, primary human ESC were treated with progesterone (P4, 50 ng mL(-1)) in the presence or absence of dialysed SP (0.5%) for 24 h or for up to 27 days to investigate immediate early effects or the effects of prolonged exposure, respectively. Combined SP and P4 treatment induced ESC morphological differentiation. Relative to control, P4 alone, and SP alone combined treatment with SP and P4 for 27 days significantly upregulated mRNA levels of the decidua-specific markers prolactin (PRL) and insulin-like growth factor binding protein 1 (IGFBP1). Consistently, PRL protein secretion was significantly increased over the course of 27 days combined SP and P4 treatment relative to control, P4 alone and SP alone. Likewise, IGFBP1 secretion was significantly greater relative to control and P4 alone over the course of 27 days. Thus, SP enhances and accelerates P4-mediated decidualisation of human ESC and may enhance endometrial receptivity.     

瘦素对子宫内膜间质细胞分泌白细胞介素的影响

目的:观察瘦素对体外培养人子宫内膜间质细胞(ESC)分泌白细胞介素-6(IL-6)和白细胞介素-8(IL-8)的影响,探讨瘦素对女性生殖生理的调节作用。方法:采用ELISA方法测定加入不同浓度瘦素时ESC分泌IL-6和IL-8的含量。结果:在ESC细胞上清液中瘦素能刺激IL-6、IL-8的产生,不同浓度瘦素刺激IL-6、IL-8分泌量不同,各组间比较有显著性差异(P<0·05,P<0·01)。结论:瘦素是细胞因子在子宫内膜产生的一种附加调节剂,通过调节局部细胞因子而调节生殖生理过程。     

Beta-lactam resistance and Enterobacteriaceae, United States

Extended-spectrum cephalosporins (ESC) are an important drug class for treating severe Salmonella infections. We screened the human collection from the National Antimicrobial Resistance Monitoring System 2000 for ESC resistance mechanisms. Of non-Typhi Salmonella tested, 3.2% (44/1,378) contained blaCMY genes. Novel findings included blaCMY-positive Escherichia coli O157:H7 and a blaSHV-positive Salmonella isolate. CMY-positive isolates showed a ceftriaxone MIC > or =2 microg/mL.     

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.     

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).     

Fresh or frozen? Classifying ‘spare’ embryos for donation to human embryonic stem cell research

United Kingdom (UK) funding to build human embryonic stem cell (hESC) derivation labs within assisted conception units (ACU) was intended to facilitate the ‘In-vitro fertilisation (IVF)-stem cell interface’, including the flow of fresh ‘spare’ embryos to stem cell labs. However, in the three sites reported on here, which received this funding, most of the embryos used for hESC research came from long term cryopreservation storage and/or outside clinics. In this paper we explore some of the clinical, technical, social and ethical factors that might help to explain this situation. We report from our qualitative study of the ethical frameworks for approaching women/couples for donation of embryos to stem cell research. Members of staff took part in 44 interviews and six ethics discussion groups held at our study sites between February 2008 and October 2009. We focus here on their articulations of social and ethical, as well as scientific, dimensions in the contingent classification of ‘spare’ embryos, entailing uncertainty, fluidity and naturalisation in classifying work. Social and ethical factors include acknowledging and responding to uncertainty in classifying embryos; retaining ‘fluidity’ in the grading system to give embryos ‘every chance’; tensions between standardisation and variation in enacting a ‘fair’ grading system; enhancement of patient choice and control, and prevention of regret; and incorporation of patients’ values in construction of ethically acceptable embryo ‘spareness’ (‘frozen’ embryos, and embryos determined through preimplantation genetic diagnosis (PGD) to be genetically ‘affected’). We argue that the success of the ‘built moral environment’ of ACU with adjoining stem cell laboratories building projects intended to facilitate the ‘IVF-stem cell interface’ may depend not only on architecture, but also on the part such social and ethical factors play in configuration of embryos as particular kinds of moral work objects.     

The ethical challenge of stem cell research.

This article analyzes the ethical issues raised by embryonic stem cell research and recent recommendations by the National Bioethics Advisory Commission (NBAC) regarding federal support for this research. The authors identify the key ethical issue as the moral significance that should be granted to early embryos and discuss arguments supporting the diverse answers to that question and the implications each view has on the formulation of rules and policies for stem cell research. The authors conclude that several of NBAC's recommendations regarding the derivation of stem cells from embryos for research are ethically justifiable and sound public policy.     

Comparison of neurosphere cells with cumulus cells after fusion with embryonic stem cells: reprogramming potential

Embryonic stem cells (ESCs) are the pluripotent cells that also have the capacity to induce the genomic reprogramming of differentiated somatic cells. The progressively restricted genomic potential of somatic cells observed during embryonic development can be reverted to a pluripotent state by the formation of cell hybrids with ESCs. To assess the reprogramming potential of ESCs, we investigated the reprogramming of one of two different somatic cell populations, neurosphere cells (NSCs) and cumulus cells (CCs), after fusion with ESCs. Specifically, hybrid cells were produced by cell fusion of E14 ESCs with either NSCs or CCs containing the neo/lacZ and Oct4-GFP transgenes. The first reprogramming event, observed by the presence of Oct4-GFP in the hybrid cells, could be identified on Day 2, at approximately 45 h after fusion in both ESC-NSC and ESC-CC hybrids. In addition, the two ESC-somatic cell hybrids exhibit a similar reprogramming rate and share characteristics with the E14 ESC line: (1) expression of pluripotent markers (Oct4, Rex-1 and nanog); (2) inactivation of differentiated tissue-specific gene expression; and (3) the capacity to differentiate into all three germ layers. Taken together, our results suggest that the ESC-somatic cell hybrids have fully acquired ESC characteristics and that somatic cells of different tissue origin have the same potential to be reprogrammed after fusion with ESCs.     

The importance of the use of stem cells for public health

Stem cells were elected 'Breakthrough of the Year' by Science(1) magazine in 1999, having shown that stem cells from adult tissues retained the ability to differentiate into other tissue types. During the previous year, the first human embryo stem cell lines were established. Since then, the number of scientific papers on stem cells has been increasing exponentially, establishing new paradigms that are rapidly challenged by subsequent experiments. This paper reviews the stem cell research field, divided into two groups: embryo and adult stem cells. While the differentiation potential of the former is well characterized in mice and humans, their use in cell therapy and research has been hampered by histocompatibility, safety and ethical issues. In contrast, adult stem cells do not present these problems. However, the extent of their plasticity is still under investigation. Nevertheless, numerous clinical trials in humans are under way, mainly with stem cells derived from bone marrow. This paper discusses discuss the importance of working with both classes of human stem cells in order to fulfill the promise of stem cell therapies.     

胚胎干细胞及诱导多能干细胞在胚胎毒性研究中的应用

药物对于生殖细胞或者早期胚胎的影响将会引起不孕或者种植前胚胎的发育异常,进而引起胚胎毒性或者是后代的畸形,因此药物的临床应用需要有可靠的实验数据证明其对胚胎的影响,而胚胎干细胞(embryonic stem cell,ESC)由于其无限增殖及多向分化的潜能而作为研究药物胚胎毒性的细胞模型得到广泛应用,以ESC为基础的胚胎干细胞实验(embryonic stem cell test,EST)是获得国际认可的胚胎毒性评价的体外替代方法,但是该实验方法的快速性和准确性存在一定的局限性,目前该细胞模型的研究主要集中于快速性和准确性的优化。新兴的诱导多能干细胞(induced pluripotent stem cells,i PSC),由于具有与ESC相似的增殖和分化特性,目前也被逐步应用于药物胚胎毒性的研究。     

Ethical decision making in international nursing research

Researchers in international settings must continually examine cross-cultural ethical issues to ensure that their work is ethically sound. In this article, the authors discuss the process of ethical decision making in international nursing research. They draw on research in Ghana during 1999 involving HIV seropositive women to document this process. Referring to this experience, they argue that international research involving human beings must meet two related but distinct ethical tests: It must meet international ethical standards for the protection of human participants but, at the same time, acknowledge the ethical standards related to the institutional setting and cultural environment in which the research takes place.     

诱导多潜能性干细胞的研究现状与临床应用前景

胚胎干细胞可作为细胞替代治疗中很好的供体细胞来源。但由于伦理学的原因,限制了胚胎干细胞在细胞替代治疗中的应用前景,而诱导多潜能性干细胞(induced pluripotent stem cell,iPS细胞)的出现则提供了一种替代胚胎干细胞的多潜能性细胞。因为iPS细胞的建立不需要卵细胞,也不破坏发育中的胚胎,所以iPS细胞不涉及伦理学问题。而且iPS细胞的建立相对简单,重复性好。因此,iPS细胞在细胞替代治疗和再生医学中有着广泛的应用前景。本文将回顾iPS细胞技术发展的历史,介绍现有的建立iPS细胞的不同方法和评估iPS细胞质量的手段,展望iPS细胞在细胞替代治疗上有待解决的问题和应用前景。