A new therapeutic strategy could break the stalemate in the war on cancer by targeting not all cancerous cells but the small fraction that lie at the root of cancers. Lucie Laplane offers a comprehensive analysis of cancer stem cell theory, based on an original interdisciplinary approach that combines biology, biomedical history, and philosophy.

While the clinical promise of much stem cell research remains largely theoretical, patients are nonetheless pursuing unproven stem cell therapies in jurisdictions around the world—a phenomenon referred to as “stem cell tourism.” These treatments are generally advertised on a direct-to-consumer basis via the Internet. Research shows portrayals of stem cell medicine on such websites are overly optimistic and the claims made are unsubstantiated by published evidence. However, anecdotal evidence suggests that parents are (...) pursing these “treatments” for their children, despite potential physical and financial risk. Physicians are in a unique position as they can be expected to be involved in, or privy to, such decisions. In this paper, we consider what duties physicians may have toward minor patients whose parents/guardians wish to engage in stem cell tourism on their behalf. We use the Canadian perspective to address the broadly relevant issues raised by this trend. (shrink)

Hematopoietic stem cell transplantation is a widely accepted practice in the United Kingdom (UK). The relatively liberal UK law permits donation both within families and from strangers, and even allows the creation of “saviour siblings” who are brought into being with the specific intent of having them donate stem cells to save other members of their family. This chapter describes the regulation of HSCT in the UK and highlights some ethical issues related to discrimination against some categories (...) of potential donors, the accuracy of the information provided to potential donors, and the controversy concerning saviour siblings. (shrink)

Skeletal muscle stem cells or satellite cells are responsible for muscle regeneration in the adult. Although satellite cells are highly resistant to stress, and display greater capacity to repair molecular damage than the committed progeny, their regenerative potential declines with age. During ageing, satellite cells switch to a state of permanent cell cycle arrest or senescence which prevents their activation. A recent study reveals that the senescence of satellite cell relies on defective autophagy, the quality control mechanism (...) that degrades damaged proteins and organelles. Molecular damage is generated by oxidative stress that also promotes epigenetic changes that activate the expression of master genes, in a double‐hit mechanism that ensures senescence. Importantly, genetic, and pharmacological correction of defective autophagy reverses satellite cell senescence and restores muscle regeneration in geriatric mice, with perspectives of modulating age‐related functional decline of muscle. This study provides new clues to understand stem cell and organismal ageing. (shrink)

This paper examines a case of failed interdisciplinary collaboration, between experimental stem cell research and theoretical systems biology. Recently, two groups of theoretical biologists have proposed dynamical systems models as a basis for understanding stem cells and their distinctive capacities. Experimental stem cell biologists, whose work focuses on manipulation of concrete cells, tissues and organisms, have largely ignored these proposals. I argue that ‘failure to communicate’ in this case is rooted in divergent views of explanation: (...) the theoretically-inclined modelers are committed to a version of the covering-law view, while experimental stem cell biologists aim at mechanistic explanations. I propose a way to reconcile these two explanatory approaches to cell development, and discuss the significance of this result for interdisciplinary collaboration in systems biology and beyond. (shrink)

Stem cell research has entered the public consciousness through the media. Proponents and opponents of all such research, or of human embryonic stem cell research specifically, engage in heated exchanges in the modern public forum where stakeholders negotiate, the agora. One common claim that emerges from the fray is that a particular type of stem cell research should be pursued as the most promising path toward the reduction of suffering and untimely death for all (...) of humanity. Upon evaluation, experimental data regarding the potential role of stem cells in regenerative therapies for three conditions—spinal cord injury, type 1 diabetes, and cardiovascular disease—tell distinct, complex, and inconclusive stories. Further analyses in this article incorporate realistic considerations of a broad range of relevant factors--limited funding for biomedical research, media motives, the discordance hypothesis of evolutionary medicine, the relationship between religion and science, medical care in developing nations, and culture wars over abortion. Holistic investigation inspired by the current agora conversation supports the need to drastically change interactions regarding stem cell research so that its potential to benefit humanity may be more fully realized. (shrink)

Stem cell tourism is a small but growing part of the thriving global medical tourism marketplace. Much stem cell research remains at the experimental stage, with clinical trials still uncommon. However, there are over 700 clinics estimated to be operating in mostly developing countries – from Costa Rica and Argentina to China, India and Russia – that have lured many patients, mostly from industrialized countries, driven by desperation and hope, which in turn continue to fuel the (...) growth of such tourism.While much research has focused on such dimensions as the promotions that allow such businesses to make their services known, media coverage, some patient research, and regulatory conditions for developing country clinics, little attention has been paid to the non-affected members of the general population, the future potential users of such services. This empirical study based on five focus group discussions with a diverse group of healthy adults in a Canadian city, explored participant views of patients who use stem cell tourism services, the likelihood they would avail themselves of such services if they were to suffer similar illnesses, and the conditions under which they might do so, and the impact that admonitions and advice from international expert bodies might have on their decisions. Our findings suggest that these healthy adults are sympathetic to the drivers of hope and desperation, and, despite cautions about research limitations, may seek such treatments themselves under similar conditions. These findings are discussed in the context of the policy and ethical issues raised by this form of medical tourism. (shrink)

Stem cell research is the product of cumulative, integrated effort between and within laboratories and disciplines. The many collaborative steps that lead to that special “Eureka moment”, when something that has been a puzzle perhaps for years suddenly become clear, is among the greatest pleasures of a scientific career. In this essay, the serendipitous pathway from first acquaintance with pluripotent stem cells to advanced cardiovascular models that emerged from studying development and disease will be described. Perhaps inspiration (...) for later generations of stem cell researchers simply to follow whatever they find interesting. (shrink)

Hematopoiesis unfolds within the bone marrow niche where hematopoietic stem cells (HSCs) play a central role in continually replenishing blood cells. The hypoxic bone marrow environment imparts peculiar metabolic characteristics to hematopoietic processes. Here, we discuss the internal metabolism of HSCs and describe external influences exerted on HSC metabolism by the bone marrow niche environment. Importantly, we suggest that the metabolic environment and metabolic cues are intertwined with HSC cell fate, and are crucial for hematopoietic processes. Metabolic dysregulation (...) within the bone marrow niche during acute stress, inflammation, and chronic inflammatory conditions can lead to reduced HSC vitality. Additionally, we raise questions regarding metabolic stresses imposed on HSCs during implementation of stem cell protocols such as allo‐SCT and gene therapy, and the potential ramifications. Enhancing our comprehension of metabolic influences on HSCs will expand our understanding of pathophysiology in the bone marrow and improve the application of stem cell therapies. (shrink)

Understanding aging and how it affects an organism's lifespan is a fundamental problem in biology. A hallmark of aging is stem cell senescence, the decline of functionality, and number of somatic stem cells, resulting in an impaired regenerative capacity and reduced tissue function. In addition, aging is characterized by profound remodeling of the immune system and a quantitative decline of adequate immune responses, a phenomenon referred to as immune‐senescence. Yet, what is causing stem cell and (...) immune‐senescence? This review discusses experimental studies of potentially immortal Hydra which have made contributions to answering this question. Hydra transcription factor FoxO has been shown to modulate both stem cell proliferation and innate immunity, lending strong support to a role of FoxO as critical rate‐of‐aging regulator from Hydra to human. Constructing a model of how FoxO responds to diverse environmental factors provides a framework for how stem cell factors might contribute to aging. (shrink)

: Successful stem cell therapies might change the natural contours of human life. If that happened, it would unsettle our ethical commitments and encourage us to see the entire natural world merely as material to be manipulated.

BackgroundIn 2004, patient advocate groups were major players in helping pass and implement significant public policy and funding initiatives in stem cells and regenerative medicine. In the following years, advocates were also actively engaged in Washington DC, encouraging policy makers to broaden embryonic stem cell research funding, which was ultimately passed after President Barack Obama came into office. Many advocates did this because they were told stem cell research would lead to cures. After waiting more (...) than 10 years, many of these same patients are now approaching clinics around the world offering experimental stem cell-based interventions instead of waiting for scientists in the US to complete clinical trials. How did the same groups who were once the strongest supporters of stem cell research become stem cell tourists? And how can scientists, clinicians, and regulators work to bring stem cell patients back home to the US and into the clinical trial process?DiscussionIn this paper, we argue that the continued marketing and use of experimental stem cell-based interventions is problematic and unsustainable. Central problems include the lack of patient protection, US liability standards, regulation of clinical sites, and clinician licensing. These interventions have insufficient evidence of safety and efficacy; patients may be wasting money and time, and they may be forgoing other opportunities for an intervention that has not been shown to be safe and effective. Current practices do not contribute to scientific progress because the data from the procedures are unsuitable for follow-up research to measure outcomes. In addition, there is no assurance for patients that they are receiving the interventions promised or of what dosage they are receiving. Furthermore, there is inconsistent or non-existent follow-up care. Public policy should be developed to correct the current situation.ConclusionThe current landscape of stem cell tourism should prompt a re-evaluation of current approaches to study cell-based interventions with respect to the design, initiation, and conduct of US clinical trials. Stakeholders, including scientists, clinicians, regulators and patient advocates, need to work together to find a compromise to keep patients in the US and within the clinical trial process. Using HIV/AIDS and breast cancer advocate cases as examples, we identify key priorities and goals for this policy effort. (shrink)

This paper explores the notions of hope and how individual patient autonomy can trump carefully reasoned ethical concerns and policies intended to regulate stem cell transplants. We argue that the same limits of knowledge that inform arguments to restrain and regulate unproven treatments might also undermine our ability to comprehensively dismiss or condemn them. Incautiously or indiscriminately reasoned policies and attitudes may drive critical information and data underground, impel patients away from working with clinical researchers, and tread needlessly (...) on hope, the essential motivator of patients, advocates and researchers alike. We offer recommendations to clinicians and health care providers to help balance the discourse with individuals seeking treatment while guarding against fraud, misconception, and patient harm. (shrink)

Cellular mechanisms whereby quiescent stem cells sense tissue injury and transition to an activated state are largely unknown. Quiescent skeletal muscle stem cells (MuSCs, also called satellite cells) have elaborate, heterogeneous projections that rapidly retract in response to muscle injury. They may therefore act as direct sensors of their niche environment. Retraction is driven by a Rac‐to‐Rho GTPase activity switch that promotes downstream MuSC activation events. These and other observations lead to several hypotheses: (1) projections are morphologically dynamic (...) at quiescence, providing a surveillance function for muscle damage; (2) quiescent projection dynamics are regulated by the relative balance of Rac and Rho activities promoted by niche‐derived cues; (3) projections, particularly their associated filopodia, sense tissue damage via changes to the biomechanical properties of the niche and/or detection of signaling cues released by damaged myofibers; and (4) the dynamic nature of projections results in a population of MuSCs with heterogeneous functional properties. These concepts may extend to other types of quiescent stem cells, as well as prove useful in translational research settings. (shrink)

If stem cell-based therapies are developed, we will likely confront a difficult problem of justice: for biological reasons alone, the new therapies might benefit only a limited range of patients. In fact, they might benefit primarily white Americans, thereby exacerbating long-standing differences in health and health care.

The research on stem cell-based therapies has greatly expanded in recent years. Our text attempts to seek those religious and ethical challenges that stem cell therapy and research bring into debate. Our thesis is that bioethics can defend its principle without a religious background. We will develop our argumentation on three major points: firstly, a comparison between secular ethics and religious views will clarify why stem cell therapy and research are important from a scientific (...) point of view, addressing the very center of the human being; in our view, being based on secular society, bioethics can answer the challenges of stem cell therapy and research; secondly, following Hans Jonas' perspective on experimenting on humans, we seek to understand the philosophical guidance that sciences dealing with stem cell need; thirdly, we will map the ethical guidelines for clinical translational research that have been adopted by the International Society for Stem Cell Research. . (shrink)

The closely related debates concerning abortion, the protection of the embryo and stem cell science have captured the legislative agenda in Mexico in recent years. This paper examines some contemporary debates related to stem cell science and the legal and political action that has followed in the wake of the latest Supreme Court judgment on abortion, which debates are directly linked to the degrees of protection of the embryo stipulated in the Mexican Constitution. While some Mexican (...) states have opted to take no further action, others, where conservative political forces are in the majority, have been very active in seeking to ensure that their constitutions are amended to protect human life from conception onwards. This intense legislative activity has not, however, been repeated at the federal level, where there is currently no overarching national regulatory framework governing stem cell research. Although major efforts have been made by the conservative block within the Senate to bring forward legislative proposals for the prohibition of human embryonic stem cell research, and despite the public expression by the federal government of its commitment to encourage inward investment and innovation in the area of biotechnology, stem cell science has, so far, remained unregulated. The legislative challenge is to resist the pressure that has been injected by religious leaders and to act in accordance with the values and principles adopted by the community in the Mexican Constitution. In the final analysis, Mexico faces particular difficulties in accommodating conservative political forces on one hand, while recognising on the other its need, as an emerging economy, to promote a progressive approach to innovation in biotechnology. (shrink)

This paper explores the notions of hope and how individual patient autonomy can trump carefully reasoned ethical concerns and policies intended to regulate stem cell transplants. We argue that the same limits of knowledge that inform arguments to restrain and regulate unproven treatments might also undermine our ability to comprehensively dismiss or condemn them. Incautiously or indiscriminately reasoned policies and attitudes may drive critical information and data underground, impel patients away from working with clinical researchers, and tread needlessly (...) on hope, the essential motivator of patients, advocates and researchers alike. We offer recommendations to clinicians and health care providers to help balance the discourse with individuals seeking treatment while guarding against fraud, misconception, and patient harm. (shrink)

Examining stem cell biology from a philosophy of science perspective, this book clarifies the field's central concept, the stem cell, as well as its aims, methods, models, explanations and evidential challenges. The first chapters discuss what stem cells are, how experiments identify them, and why these two issues cannot be completely separated. The basic concepts, methods and structure of the field are set out, as well as key limitations and challenges. The second part of the (...) book shows how rigorous explanations emerge from stem cell experiments, and compares these to other kinds of scientific explanation. Model organisms, the role of genes, and the significance of collaboration are also discussed. The last part of the book considers relations to systems biology and clinical medicine, arguing that both the mathematical models of the former, and ethical principles of the latter, are necessary for stem cell biology to deliver on its promises. (shrink)

The pursuit of unproven stem cell-based interventions is an emerging issue that raises various concerns. Physicians play different roles in this market, many of which engage their legal, ethical and professional obligations. In Canada, physicians are members of a self-regulated profession and their professional regulatory bodies are responsible for regulating the practice of medicine and protecting the public interest. They also provide policy guidance to their members and discipline members for unprofessional conduct.

We review recent progress in the stem cell biology of the respiratory system, and discuss its scientific and translational ramifications. Several studies have defined novel stem cells in postnatal lung and airways and implicated their roles in tissue homeostasis and repair. In addition, significant advances in the generation of respiratory epithelium from pluripotent stem cells (PSCs) now provide a novel and powerful platform for understanding lung development, modeling pulmonary diseases, and implementing drug screening. Finally, breakthroughs have (...) been made in the generation of decellularized lung matrices that can serve as a scaffold for repopulation with respiratory cells derived from either postnatal or PSCs. These studies are a critical step forward towards the still distant goal of stem cell‐based regenerative medicine for diseases of lung and airways. (shrink)

The paper looks in detail at patients that were treated at one of the most discussed companies operating in the field of untried stem cell treatments, Beike Biotech of Shenzhen, China. Our data show that patients who had been treated at Beike Biotech view themselves as proactively pursuing treatment choices that are not available in their home countries. These patients typically come from a broad variety of countries: China, the United Kingdom, the United States, South Africa and Australia. (...) Among the patients we interviewed there seemed to be both an awareness of the general risks involved in such experimental treatments and a readiness to accept those risks weighed against the possible benefits. We interpret this evidence as possibly reflecting the emergence of risk-taking patients as ‘consumers’ of medical options as well as the drive of patients to seek treatment options in the global arena, rather than being hindered by the ethical and regulatory constraints of their home countries. Further, we found that these patients tend to operate in more or less stable networks and groups in which they interact and cooperate closely and develop opinions and assessments of available treatment options for their ailments. These patients also perform a multiple role as patients, research subjects, and research funders because they are required to pay their way into treatment and research activities. This new social dynamics of patienthood has important implications for the ethical governance of stem cell treatments. (shrink)

The stem cell story is not a simple story but a complex narrative: one that requires careful analysis in order to identify major themes and plots. This paper offers an analysis of the ethics of the clinical application of stem cells and argues that even quite risky therapies can be ethical. These arguments cannot be used to justify all aspects of contemporary stem cell science, including human embryonic stem cell science, which remains theoretical (...) and speculative. It is argued that the homogenisation of stem cell science obscures the distinction between clinical application and experimental laboratory science in a morally problematic way. (shrink)

Much of the current research in regenerative medicine concentrates on stem-cell therapy that exploits the regenerative capacities of stem cells when injected into different types of human tissues. Although new therapeutic paths have been opened up by induced pluripotent cells and human mesenchymal cells, the rate of success is still low and mainly due to the difficulties of managing cell proliferation and differentiation, giving rise to non-controlled stem cell differentiation that ultimately leads to cancer. (...) Despite being still far from becoming a reality, these studies highlight the role of physical and biological constraints (e.g., cues and morphogenetic fields) placed by tissue microenvironment on stem cell fate. This asks for a clarification of the coupling of stem cells and microenvironmental factors in regenerative medicine. We argue that extracellular matrix and stem cells have a causal reciprocal and asymmetric relationship in that the 3D organization and composition of the extracellular matrix establish a spatial, temporal, and mechanical control over the fate of stem cells, which enable them to interact and control (as well as be controlled by) the cellular components and soluble factors of microenvironment. Such an account clarifies the notions of stemness and stem cell regeneration consistently with that of microenvironment. (shrink)

The recent success in generating live offspring from embryonic stem cell –derived gametes in mice sparked visions of growing tailor-made sperm for men faced with infertility. However, although this development will almost certainly lead to new insights into the processes underlying spermatogenesis and thus in the possible causes of male infertility, it is less certain if deriving sperm from ES cells, which are in turn derived from a sterile man, can make someone a genetic parent. As the gap (...) between newly envisioned reproductive technologies and natural reproduction widens, the question thus needs to be asked if these possible therapies still lead to genetic parenthood. (shrink)

What is a stem cell? The answer is seemingly obvious: a cell that is also a stem, or point of origin, for something else. Upon closer examination, however, this combination of ideas leads directly to fundamental questions about biological development. A cell is a basic category of living thing; a fundamental 'unit of life.' A stem is a site of growth; an active source that supports or gives rise to something else. Both concepts are (...) deeply rooted in biological thought, with rich and complex histories. The idea of a stem cell unites them, but the union is neither simple nor straightforward. This book traces the origins of the stem cell concept, its use in stem cell research today, and implications of the idea for stem cell experiments, their concrete results, and hoped-for clinical advances. (shrink)

This book explores the ethical and governance concerns of stem cell technology, taking a comparative approach between countries of differing socio-economic status. The book provides a typology of different stem cell types and discusses key ethical issues surrounding the use of human stem cells in research. Topics covered include the moral status of human embryos, various religious perspectives, and the challenges posed by unproven stem cell interventions. The book also examines the existing governance (...) frameworks in the UK, Singapore, and Malaysia, identifying the laws, guidelines, and advisory bodies established to address the identified ethical issues. Applicable lessons on establishing robust regulatory frameworks, fostering public trust, and ensuring responsible research practices are outlined. By providing a comparative analysis of the interplay between ethics, governance, and the socio-economic contexts of these three commonwealth countries, this book will interest health law, research ethics and bioethics scholars. (shrink)

There are many kinds of clinical trials. The regulatory framework within which most drug development takes place appears to be the one that is to be applied to the development of novel stem cell-based clinical trials. In the standard drug development model, appropriate pre-clinical research is conducted, and investigators or research sponsors submit an investigational new drug application to the Food and Drug Administration.If approved, typical clinical trials start with Phase I, which is usually a trial to determine (...) the maximum tolerable dose of a drug. Phase I trials are often referred to as “safety studies” because the primary goal of Phase I research is to determine if an intervention is safe. (shrink)

Stem cells and the emerging field of regenerative medicine are at the frontiers of modern medicine. These areas of scientific inquiry suggest that in the future, damaged tissue and organs might be repaired through personalized cell therapy as easily as the body repairs itself, revolutionizing the treatment of numerous diseases. Yet the use of stem cells is fraught with ethical and public policy dilemmas that challenge scientists, clinicians, the public health community, and people of good will everywhere. (...) How shall we deal with these amazing biomedical advances, and how can we talk about potential breakthroughs with both moral and scientific intelligence? This book provides an innovative look at these vexing issues through a series of innovative Socratic dialogues that elucidate key scientific and ethical points in an approachable manner. Addressing the cultural and value issues underlying stem cell research while also educating readers about stem cells' biological function and medical applications, _Stem Cell Dialogues_ features fictional characters engaging in compelling inquiry and debate. Participants investigate the scientific, political, and socioethical dimensions of stem cell science using actual language, analysis, and arguments taken from scientific, philosophical, and popular literature. Each dialogue centers on a specific, recognizable topic, such as the policies implemented by the George W. Bush administration restricting the use of embryonic stem cells; the potential role of stem cells in personalized medicine; the ethics of cloning; and the sale of eggs and embryos. Additionally, speakers debate the use of stem cells to treat paralysis, diabetes, stroke effects, macular degeneration, and cancer. Educational, entertaining, and rigorously researched, _Stem Cell Dialogues_ should be included in any effort to help the public understand the science, ethics, and policy concerns of this promising field. (shrink)

In 1998, researchers established the first human embryonic stem cell line. Their scientific triumph triggered an ethics and policy argument that persists today. Bioethicists, religious leaders, government officials, patient advocates, and scientists continue to debate whether this research poses a promise, a threat, or a mixed ethical picture for society.Scientists are understandably excited about the knowledge that could come from studying human embryonic stem cells. Most of them believe these cells offer a precious opportunity to learn more (...) about why diseases develop and how they might be prevented or attacked. In their quest to gain support for stem cell research, scientists and others have claimed that the research could generate cures and treatment for everything from heart disease to cancer. (shrink)

This article examines the assertion that human embryonic stem cells patents are immoral because they violate human dignity. After analyzing the concept of human dignity and its role in bioethics debates, this article argues that patents on human embryos or totipotent embryonic stem cells violate human dignity, but that patents on pluripotent or multipotent stem cells do not. Since patents on pluripotent or multipotent stem cells may still threaten human dignity by encouraging people to treat embryos (...) as property, patent agencies should carefully monitor and control these patents to ensure that patents are not inadvertently awarded on embryos or totipotent stem cells. (shrink)

Week-old embryos are considered the richest source of stem cells usable in medical treatments. Because the embryos are destroyed when the stem cells are removed, the debate over the embryo's legal, moral, political, and scientific status has exploded. In this debate, Sheldon Krimsky's Stem Cell Dialogues: A Philosophical and Scientific Inquiry into Medical Frontiers is the single best book. Evenhanded, eminently readable, up to date, educational, scientifically precise, powerfully researched, and very entertaining, Krimsky's slim volume is (...) one that no scientist, policy-maker, ethicist, or intelligent reader should miss. (shrink)

A basic component of moral objections to embryonic stem cell research is the claim that human embryos have the same moral status as typical adult human beings. There is no reason to accept this claim, however, unless adult humans once existed as embryos—that is, unless the developmental history of adult humans contains embryos to which the adults are numerically identical. The purpose of this paper is to argue that there are no such identities, and hence that no adult (...) human being ever existed as an embryo. (shrink)

The possibility of obtaining stem cells from human embryos has given rise to an intensive legal and ethical debate. In this paper, attention is paid to the normative disparity and ambiguity in Europe. An argument for the need for a minimal legal harmonization is made; and a prudent and flexible way to reach this successfully is suggested. Establishing a common legal framework seems to be the only way to guarantee true competitiveness for the European scientific community.

Restrictions on research on therapeutic cloning are questionable as they inhibit the development of a technique which holds promise for succesful application of pluripotent stem cells in clinical treatment of severe diseases. It is argued in this article that the ethical concerns are less problematic using therapeutic cloning compared with using fertilised eggs as the source for stem cells. The moral status of an enucleated egg cell transplanted with a somatic cell nucleus is found to be (...) more clearly not equivalent to that of a human being. Based on ethical considerations alone, research into therapeutic cloning should be encouraged in order to develop therapeutic applications of stem cells. (shrink)

Dyskeratosis congenita is a rare skin and bone marrow failure syndrome caused by defective telomere maintenance in stem cells. The major X‐linked form of the disease is due to mutations in a nucleolar protein, dyskerin, that is part of small nucleolar ribonucleoprotein particles that are involved in processing ribosomal RNA. It is also found in the telomerase complex, pointing to an unexpected link between these two processes. An autosomal dominant form is due to mutations in the RNA component of (...) telomerase (hTR). Patients with this form of the disease are more severely affected in later generations that carry the mutations, possibly due to the inheritance of shortened telomeres, disguising the inherited nature of the disease in some cases classified as aplastic anemia. Because of the importance of telomerase in tumour formation and aging, study of this disease may provide important clues about these fundamental processes. BioEssays 25:126–133, 2003. © 2003 Wiley Periodicals, Inc. (shrink)

Recent advances in stem cell research suggest that in the future it may be possible to create eggs and sperm from human stem cells through a process that we term in vitro gametogenesis (IVG). IVG would allow treatment of some currently untreatable forms of infertility. It may also allow same-sex couples to have genetically-related children. For example, cells taken from one man could potentially be used to create an egg, which could then be fertilised using naturally produced (...) sperm from another man to create a genetically-related child with half of its DNA from each of the men. In this chapter, we consider whether this technology could justifiably be denied to same-sex couples if it were made available as a fertility treatment to different-sex couples. We argue that it could not. (shrink)

Stem cell-derived embryo models (SCEMs) are model embryos used in scientific research to gain a better understanding of early embryonic development. The way humans develop from a single-cell zygote to a complex multicellular organism remains poorly understood. However, research looking at embryo development is difficult because of restrictions on the use of human embryos in research. Stem cell embryo models could reduce the need for human embryos, allowing us to both understand early development and improve (...) assisted reproductive technologies. There have been several rapid advances in creating SCEMs in recent years. These advances potentially provide a new avenue to study early human development. The benefits of SCEMs are predicated on the claim that they are different from embryos and should, therefore, be exempt from existing regulations that apply to embryos (such as the 14-day rule). SCEMs are proposed as offering a model that can capture the inner workings of the embryo but lack its moral sensitivities. However, the ethical basis for making this distinction has not been clearly explained. In this current controversy, we focus on the ethical justification for treating SCEMs differently to embryos, based on considerations of moral status. (shrink)

New molecular markers for epidermal stem cells have enabled their isolation both in vitro and from the epidermis lying between hair follicles. Micro‐dissection experiments have localised a second population of stem cells within hair follicles. Epidermal stem cells have a patterned distribution in vivo. The patterning can be reconstituted in vitro, showing that it is generated by interactions between keratinocytes and that the differentiation of epidermal stem cells is regulated by signals from other keratinocytes. Recent evidence (...) from transgenic mice suggests that stem cell behaviour in the gut may be regulated by similar cell‐cell interactions in vivo. Candidate genes for mediating these interactions are the homologues of Drosophila cell fate patterning genes such as Notch and Wingless and the Cadherin family of cell‐cell adhesion molecules. The roles of stem cells and of mutations of the Patched gene in epithelial carcinogenesis are discussed. (shrink)

Persons with serious and disabling medical conditions have traveled abroad in search of stem cell treatments in recent years. However, weak or nonexistent oversight systems in some countries provide insufficient patient protections against unproven stem cell treatments, raising concerns about exposure to harm and exploitation. The present article, the first of two, describes and analyzes stem cell tourism in Russia and India and addresses several scientific/medical, ethical, and policy issues raised by the provision of (...) unproven stem cell-based treatments within them. The distinction between treatment based on proven clinical research and "innovative treatment" is addressed and the authors conclude that the innovations at issue constitute neither. Regulatory measures need to be developed or strengthened in accord with internationally accepted standards in such countries to protect those seeking stem cell treatments. (shrink)

Egg or sperm? The mechanism of sexual fate decision in germ cells has been a long‐standing issue in biology. A recent analysis identified foxl3 as a gene that determines the sexual fate decision of germ cells in the teleost fish, medaka. foxl3/Foxl3 acts in female germline stem cells to repress commitment into male fate (spermatogenesis), indicating that the presence of mitotic germ cells in the female is critical for continuous sexual fate decision of germ cells in medaka gonads. Interestingly, (...) foxl3 is found in most vertebrate genomes except for mammals. This provides the interesting possibility that the sexual fate of germ cells in mammals is determined in a different way compared to foxl3‐possessing vertebrates. Considering the fact that germline stem cells are the cells where foxl3 begins to express and sexual fate decision initiates and mammalian ovary does not have typical germline stem cells, the mechanism in mammals may have been co‐evolved with germline stem cell loss in mammalian ovary. (shrink)

This chapter brings a philosophical perspective to the concept of stem cell. Three general questions both clarify the concept of stem cell and emphasize its ambiguities: (1) How should we define stem cells? (2) What makes them different from non-stem cells? (3) What is their ontology? (i.e. what kind of property is “stemness”?) Following this last question, the Chapter distinguishes four conceptions of stem cells and highlights their respective consequences for the cancer (...) class='Hi'>stem cell theory. Determining what kind of property stemness is, in what context, is an urgent question, at least for therapeutic strategies against cancers. I hope that this chapter also illustrates how philosophy can be useful to biology. -/- The Chapter starts by clarifying the notions of self-renewal and differentiation. This leads to the question “can we (and if so, how) distinguish stem cells from non-stem cells through these two properties?”. From that will follow an interrogation on whether stem cells belong to a natural kind. On this issue, biologists and philosophers have framed the following alternative: either the concept of stem cell refers to entities (the cells that belong to the stem cell natural kind) or it refers to a transient and reversible cell state. I will argue that four conceptions of stemness should be distinguished rather than two. Finally, I will develop the case of the cancer stem cell (CSC) theory in order to show why it is crucial to answer the ontological question: some therapies might or might not be efficient depending on what stemness is. (shrink)

Ontologies of living things are increasingly grounded on the concepts and practices of current life science. Biological development is a process, undergone by living things, which begins with a single cell and (in an important class of cases) ends with formation of a multicellular organism. The process of development is thus prima facie central for ideas about biological individuality and organismality. However, recent accounts of these concepts do not engage developmental biology. This paper aims to fill the gap, proposing (...) the lineage view of stem cells as an ontological framework for conceptualizing organismal development. This account is grounded on experimental practices of stem cell research, with emphasis on new techniques for generating biological organization in vitro. On the lineage view, a stem cell is the starting point of a cell lineage with a specific organismal source, time-interval of existence, and ‘tree topology’ of branch-points linking the stem to developmental termini. The concept of ‘enkapsis’ accommodates the cell-organism relation within the lineage view; this hierarchical notion is further explicated by considering the methods and results of stem cell experiments. Results of this examination include a (partial) characterization of stem cells’ developmental versatility, and the context-dependence of developmental processes involving stem cells. (shrink)

In this paper the permissibility of stem cell research on early human embryos is defended. It is argued that, in order to have moral status, an individual must have an interest in its own wellbeing. Sentience is a prerequisite for having an interest in avoiding pain, and personhood is a prerequisite for having an interest in the continuation of one's own existence. Early human embryos are not sentient and therefore they are not recipients of direct moral consideration. Early (...) human embryos do not satisfy the requirements for personhood, but there are arguments to the effect that they should be treated as persons nonetheless. These are the arguments from potentiality, symbolic value and the principle of human dignity. These arguments are challenged in this paper and it is claimed that they offer us no good reason to believe that early human embryos should be treated as persons. (shrink)

Stem cell biology is driven by experiment. Its major achievements are striking experimental productions: "immortal" human cell lines from spare embryos (Thomson et al. 1998); embryo-like cells from "reprogrammed" adult skin cells (Takahashi and Yamanaka 2006); muscle, blood and nerve tissue generated from stem cells in culture (Lanza et al. 2009, and references therein). Well-confirmed theories are not so prominent, though stem cell biologists do propose and test hypotheses at a profligate rate. 1 This (...) paper aims to characterize the role of experiment in stem cell biology, so as to answer the following question: how do experiments contribute to our knowledge of stem cells and related phenomena? The .. (shrink)

Mesenchymal stem cells (MSCs) are present in fat tissues throughout the body, yet little is known regarding their biological role within epidural fat. We hypothesize that debridement of epidural fat and/or subsequent loss of MSCs within this tissue, disrupts homeostasis in the vertebral environment resulting in increased inflammation, fibrosis, and decreased neovascularization leading to poorer functional outcomes post‐injury/operatively. Clinically, epidural fat is commonly considered a space‐filling tissue with limited functionality and therefore typically discarded during surgery. However, the presence of (...) MSCs within epidural fat suggests that itis more biologically active than historically believed and may contribute to the regulation of homeostasis and regeneration in the dural environment. While the current literature supports our hypothesis, it will require additional experimentation to determine if epidural fat is an endogenous driver of repair and regeneration and if so, this tissue should be minimally perturbed from its original location in the spinal canal. Also see the video abstract here https://youtu.be/MIol_IWK1os. (shrink)

The collection and storage of human tissue samples has been present in medicine for centuries, however, biobanking has recently become a dedicated activity. The technological developments that have allowed the isolation, storage and long term viability of human cells ex vivo, and to obtain relevant scientific information, including genetic information, open tremendous possibilities for advancing biomedical research. At the same time, these possibilities have raised complex ethical issues regarding tissue donors, researchers using samples and society awareness of biobanking as a (...) whole. This article aims to review the operation of stem cell biobanks, related ethical issues and the legal framework in Spain. Special consideration will be given to the new but revolutionary appearance of induced pluripotent stem cells. Most of the topics discussed here will be in the framework of banking adult derived stem cells, which do not entail in themselves any significant ethical dilemma. (shrink)

Embryonic stem cells are derived from the preimplantation embryo and can differentiate into virtually any other cell type, which is governed by lineage specific transcriptions factors binding to cis regulatory elements to mediate changes in gene expression. The reliance on transcriptional regulation to maintain pluripotency makes ESCs a valuable model to study the role of distal CREs such as enhancers in modulating gene expression to affect cell fate decisions. This review will highlight recent advance on transcriptional enhancers, (...) focusing on studies performed in ESCs. In addition, we argue that the Nanog locus, which encodes for an ESC-critical TF, is particularly informative because it contains multiple co-regulated genes and enhancers in close proximity to one another. The unique landscape at Nanog permits the study of ongoing questions including whether multiple enhancers function additively versus synergistically, determinants of gene specificity, and cell-to-cell variability in gene expression. Nanog encodes a transcription factor required to maintain ESC pluripotency. The Nanog locus is an ideal model to study enhancers because it contains multiple highly potent super-enhancers within a small region. Nanog and three super-enhancers are in close physical proximity but only two SEs are required for Nanog expression. (shrink)

Discussions about the use and derivation of pluripotent human embryonic stem cells are a stumbling block in developing public policy on stem cell research. On the one hand there is a broad consensus on the benefits of these cells for science and biomedicine; on the other hand there is the controversial issue of killing human embryos. I will focus on the compromise position that accepts research on spare embryos, but not on research embryos ('discarded-created-distinction', from now on (...) d-c-d). I will point out that this viewpoint is hard to maintain. The main focus is that the 'revealed beliefs' of its defenders are inconsistent with their 'professed beliefs', more specifically with their main argument, i.e. the potentiality argument. I will point out that (1) the defenders of d-c-d actually grant a relative moral status to the human embryo, (2) this moral status is dependent on internal and external criteria of potentiality, (3) potentiality seen as a variable value that also depends on external criteria cannot justify d-c-d, and (4) an approach to human embryonic stem cell-research that would also allow the use of research embryos is more compatible with the feelings, attitudes and values of those who currently defend d-c-d and, therefore, could lead to a broader consensus and to actions that alleviate individual human suffering. (shrink)

Robust ex vivo expansion of umbilical cord blood (UCB) derived hematopoietic stem and progenitor cells (HSPCs) should enable the widespread use of UCB as a source of cells to treat hematologic and immune diseases. Novel approaches for HSPC expansion have recently been developed, setting the stage for the production of blood stem cell derived products that fulfill our current best known criteria of clinical relevance. Translating these technologies into clinical use requires bioengineering strategies to overcome challenges of (...) scale‐up, reproducibility, and product quality assurance. Clinical‐scale implementation should also define criteria and targets for cost‐effective cell manufacturing. As production strategies become more effective, new opportunities in the therapeutic use of ex vivo expanded hematopoietic cell products will emerge. Herein we examine key technological milestones that need to be met in order to move ex vivo expanded HSPC therapies from the bench‐top to the bedside in a robust and reliable manner. (shrink)