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.     

Synthesis and biological evaluation of a novel human stem/progenitor cells proliferation activator: 4-(4-(5-mercapto-1,3,4-oxadiazol-2-yl)phenyl) thiosemicarbazide (Stemazole)

Stem/progenitor cells are crucial for cell-based therapy and regenerative medicine, and their application in clinical and basic research requires a large supply of cells. To identify effective stem/progenitor cell proliferation activators, we synthesised a series of new 4-(4-(5-mercapto-1,3,4-oxadiazol-2-yl)phenyl) thiosemicarbazide (named Stemazole) derivatives. Preliminary evaluation of the structure-activity relationship (SAR) and the biological activities of the compounds were determined with a luminescent cell viability assay. The identified leading compound, Stemazole, exhibited remarkable proliferation-promoting activity in human hippocampal stem/progenitor cells (HSCs) in a time-dependent and concentration-dependent manner. The proliferation-promoting activity of Stemazole was further confirmed against a panel of human stem/progenitor cells derived from each of the three blastoderm layers. In conclusion, Stemazole is a novel activator of stem cells proliferation.     

From bench to bedside? Biomedical scientists' expectations of stem cell science as a future therapy for diabetes

The movement of scientific research from the bench to the bedside is becoming an increasingly important aspect of modern 'biomedical societies'. There is, however, currently a dearth of social science research on the interaction between the laboratory and the clinic. The recent upsurge in global funding for stem cell research is largely premised on the promise of translating scientific understanding of stem cells into regenerative medicine. In this paper, we report on the views of biomedical scientists based in the United Kingdom who are involved in human embryonic stem cell research in the field of diabetes. We explore their views on the prospects and problems of translational research in the field of stem cell science. We discuss two main themes: institutional influences on interactions between scientists and clinicians, and stem cell science itself as the major barrier to therapies. We frame our discussion within the emerging literature of the sociology of expectations.     

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.     

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.     

Somatische Stammzellen des zentralen Nervensystems

During neural development, the nervous system is created from stem cells that have the potential to proliferate, to reproduce (self-renew) themselves, and to differentiate into the appropriate neuronal and glial phenotypes. Although the adult brain has traditionally been thought of as a structure with very limited regenerative capacity, these neural stem cells have recently been shown to exist in the adult central nervous system (CNS) as well. In vitro and following transplantation, neural stem cells obtained from the fetal and adult brain are able to generate neurons, astrocytes, and oligodendrocytes, the three major CNS cell types. Therefore, neural stem cells are potential sources for specialized neural cells needed to treat a variety of neurological disorder. The present review describes how somatic stem cells of the central nervous system can be cultivated in vitro and to which extend stem cell transplantation is effective in animal models for neurological diseases. Finally, a perspective is given on the potential clinical use of human neural stem cells for the treatment of neurological diseases.     

Stem cells in the amniotic fluid: the new chance of regenerative medicine

Amniotic fluid has been used in prenatal diagnosis for more than decades. It yields a simple and reliable screening and diagnostic tool for a variety of congenital malformations and genetic diseases such as chromosomal aberrations, neural tube defects or storage diseases. Nowadays the widening knowledge provides evidence that amniotic fluid is not only a screening and diagnostic tool, but it may be also the source of the effective therapy of several congenital and adult disorders. A subset of cells, the so-called stem cells were found in the amniotic fluid as well as the placenta, and they proved to be capable of maintaining prolonged undifferentiated proliferation. Stem cells are able to differentiate into multiple tissue types, originating from the three germ layers. In the near future stem cells isolated from amniotic fluid or placenta and stored by cryopreservation may play a significant role in regenerative medicine. Congenital malformations as well as certain diseases in adults might be treated by tissues coming from progenitor cells of amniotic fluid stem cell origin. This study gives a summary of the main characteristics of amniotic fluid stem cells and it also presents important examples of their possible clinical application.     

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.     

Therapeutic cloning in debate]

Human embryos can be conceived by cell nuclear transfer in order to isolate human embryonic stem cells (hES cells) for research into autologous cell therapy (therapeutic cloning). However, this technique broaches the major ethical problem concerning the instrumental use of human preimplantation embryos. From the viewpoint of subsidiarity, it is argued that various potential alternatives for therapeutic cloning should first be investigated further. The question as to whether therapeutic cloning should be allowed only becomes apparent when research with surplus embryos obtained in the course of in-vitro fertilization suggests that usable transplants can be obtained in vitro from hES cells, and when the potential alternatives for therapeutic cloning are either less promising or need more time for development than is currently expected.     

Vitamin A/Retinol and Maintenance of Pluripotency of Stem Cells

Retinol, the alcohol form of vitamin A is a key dietary component that plays a critical role in vertebrate development, cell differentiation, reproduction, vision and immune system. Natural and synthetic analogs of retinol, called retinoids, have generally been associated with the cell differentiation via retinoic acid which is the most potent metabolite of retinol. However, a direct function of retinol has not been fully investigated. New evidence has now emerged that retinol supports the self-renewal of stem cells including embryonic stem cells (ESCs), germ line stem cells (GSCs) and cancer stem cells (CSCs) by activating the endogenous machinery for self-renewal by a retinoic acid independent mechanism. The studies have also revealed that stem cells do not contain enzymes that are responsible for metabolizing retinol into retinoic acid. This new function of retinol may have important implications for stem cell biology which can be exploited for quantitative production of pure population of pluripotent stem cells for regenerative medicine as well as clinical applications for cancer therapeutics.     

Le tissu adipeux : un donneur de cellules souches ?

Several laboratories have shown that the cells from the stroma-vascular fraction of the human adipose tissue express, depending on cell culture conditions, biochemical markers of multiple cell lineages including adipogenic, osteogenic, chondrogenic, myogenic, endothelial, neuronal and epithelial cell lineage. Furthermore, various in vivo approaches revealed the ability of the cells derived from the stroma-vacsular fraction of adipose tissue to repair ischemic or damaged tissues. Altogether these data strongly suggest that the stroma-vascular fraction of the human adipose tissue contains cells that exhibit properties like stem/progenitor cells. However, the exact nature of the cells, their potentiality to lead to differentiated cells in vivo as well as the mechanisms involved in their repair capability remain to be characterized to consider their use in regenerative and reparative medicine.     

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.     

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.     

高效诱导iPS的方法模型

Kazutoshi Takahashi和Shinya Yamanaka首次发现,来自“正常”体细胞的诱导多能干细胞（induced pluripotent stem cell,iPS细胞）利用所定义的一些因子可以再生,但所转染的细胞,仅百分之几变成多能细胞,而且整个过程非常慢。     

母乳干细胞研究进展

近年来,人母乳干细胞(hBSCs)的提出使得对母乳细胞成分及优点的认识比以往更加多样化.其具有的非侵入性的细胞来源方式、多项分化潜能、自我更新能力等特点,在细胞替代疗法、再生医疗中具有重要意义.这将提供一个新的途径来描述母乳在生命早期的重要性,以及解释母乳如何对婴幼儿和成人远期健康产生积极的影响.本文将从母乳干细胞来源...     

间充质干细胞治疗宫腔粘连的研究进展

宫腔粘连本质上是损伤或感染等因素导致子宫内膜受损并发生内膜纤维化.宫腔粘连的发病机制包括上皮-间质转化、过度的炎症反应、血管生成障碍、低雌激素状态及子宫内膜干细胞缺失.现有的临床治疗如宫腔镜下粘连分离术、激素治疗、物理屏障植入等,均不能有效改善中重度宫腔粘连患者情况及预防粘连复发.近年研究发现,间充质干细胞在修复组织及...     

生物技术与医学模式变革:迈向再生医学时代

基因工程、细胞工程、组织工程和整体动物工程等新的生物技术使医学模式发生变革,从以化学药物加手术刀为主要治疗手段的传统医学模式,迈向以基因治疗、细胞移植或生物人工组织器官移植为主要的治疗手段的"再生医学"模式。使用基因工程技术生产各种重组蛋白药物或疫苗越来越广泛地应用于临床。人类基因组计划(HGP)将在2003年完成全部高质量的基因组序列,HGP所开发的资源将对未来的20年的医学领域药物开发、疾病诊断、疾病易感性预测、个体化疾病预防及治疗方案设计等方面都产生巨大的影响。基因治疗从简单的单基因形式走向一整套基因的替代的复杂形式。DNA微阵列和蛋白组微阵列等科学研究技术将应用于临床诊断。核移植技术正在用于培养通用干细胞,用于移植以治疗艾滋病、糖尿病和帕金森氏病等难治性疾病。通过干细胞移植可以再生受损的组织器官。在体外构建可供移植的生物人工组织器官以取代丧失功能的组织器官,这正是组织工程的目标。再生医学存在不少科学技术困难和伦理问题。新的生物技术不仅给我们带来希望,而且还带我们带来不可预测危险。     

At the Dawn of a New Discovery: The Potential of Breast Milk Stem Cells

Breast milk contains bioactive molecules that provide a multitude of immunologic, developmental and nutritional benefits to the infant. Less attention has been placed on the cellular nature of breast milk, which contains thousands to millions of maternal cells in every milliliter that the infant ingests. What are the properties and roles of these cells? Most studies have examined breast milk cells from an immunologic perspective, focusing specifically on the leukocytes, mainly in the early postpartum period. In the past decade, research has taken a multidimensional approach to investigating the cells of human milk. Technologic advances in single cell analysis and imaging have aided this work, which has resulted in the breakthrough discovery of stem cells in breast milk with multilineage potential that are transferred to the offspring during breastfeeding. This has generated numerous implications for both infant and maternal health and regenerative medicine. This review summarizes the latest knowledge on breast milk stem cells, and discusses their known in vitro and in vivo attributes as well as potential functions and applications.