The prelude to successful human somatic gene therapy, i.e. the efficient transfer and expression of a variety of human genes into target cells, has already been accomplished in several systems. Safe methods have been devised to do this using non‐viral and viral vectors. Potentially therapeutic genes have been transferred into many accessible cell types, including hematopoietic cells, hepatocytes and cancer cells, in several different approaches to ex vivo gene therapy. Successful in vivo gene (...) therapy requires improvements in tissuetargeting and new vector design, which are already being sought. Gene‐transfer protocols have been approved for human use in inherited diseases, cancer and acquired disorders. Althouth the results of these trials to date have been somewhat disappointing, human somatic cell gene therapy promises to be an effective addition to the arsenal of approaches to the therapy of many human diseases in the 21st century if not sooner. (shrink)

The case of Andrew Gobea, the first child to receive experimental gene therapy for SCID, and a reflection on the associated ethical implications of gene therapy research.

The article investigates the validity of two different versions of the slippery slope argument construed in relation to human gene therapy: the empirical and the conceptual argument. The empirical version holds that our accepting somatic cell therapy will eventually cause our accepting eugenic medical goals. The conceptual version holds that we are logically committed to accepting such goals once we have accepted somatic cell therapy. It is argued that neither the empirical nor (...) the conceptual version of the argument can provide a conclusive moral reason for banning somatic cell therapy. According to a third interpretation, referred to as the arbitrary result argument, the many apparent similarities between somatic cell therapy and eugenic-based human genetic engineering drive us to make principled choices concerning what differences and similarities between the two practices should be regarded as morally (ir)relevant. Decisions of this kind are likely to have unpredictable moral consequences. Thus formulated, the slippery slope argument has much plausibility. One objects to somatic cell therapy not so much because of what is at the bottom of the slope on which it lies, but because it is on a slope of which one does not know what is at the bottom. While the arbitrary result argument does not provide a conclusive reason for prohibiting human gene therapy, it reminds of a very important thing: when making bioethical decisions, we should be as specific and as consistent as possible about our basic moral and medical concepts. (shrink)

Despite widespread agreement that it would be ethical to use somatic cell gene therapy to correct serious diseases, there is still uneasiness on the part of the public about this procedure. The basis for this concern lies less with the procedure's clinical risks than with fear that genetic engineering could lead to changes in human nature. Legitimate concerns about the potential for misuse of gene transfer technology justify drawing a moral line that includes corrective germline (...) therapy but excludes enhancement interventions in both somatic and germline contexts. Keywords: somatic cell, germ line, genetic diseases, genetic engineering, humanness, enhancement, eugenics CiteULike Connotea Del.icio.us What's this? (shrink)

To discern the ethical issues involved incurrent gene therapy research, to explore theproblems inherent in possible future genetherapies, and to encourage debate within thescientific community about ethical questionsrelevant to both, we surveyed American Societyof Human Genetics scientists who engage inhuman genetics research. This study of theopinions of U.S. scientific experts about theethical issues discussed in the literature ongene therapy contributes systematic data on theattitudes of those working in the field as wellas elaborative comments. Our survey finds thatrespondents (...) are highly supportive of thepotential use of somatic cell gene therapy tocure serious diseases in adults and children aswell as prospective offspring. A clearmajority, however, believe that using suchgenetic techniques for enhancement purposes isunacceptable. Delineating the line betweendisease/disorder and improvement/enhancementposes a problem not easily resolved and oneconducive to the growth of slippery-slopeapprehensions. The majority of respondents alsoadvocate germ-line therapy, in theory at least,and under similar restrictions, but theyrecognize the roadblock that the existence ofunanticipated negative consequences currentlypresents. Another complex matter involvestrying to determine appropriate reasons forchoosing target diseases for research, forwhich the dichotomy between rare single-geneand common multifactorial diseases reveals anongoing dilemma. (shrink)

Any suggestion of altering the genetic makeup of human beings through gene therapy is quite likely to provoke a response involving some reference to a 'slippery slope'. In this article the author examines the topography of two different types of slippery slope argument, the logical slippery slope and the rhetorical slippery slope argument. The logical form of the argument suggests that if we permit somatic cell gene therapy then we are committed to accepting germ (...) line gene therapy in the future because there is no logically sustainable distinction between them. The rhetorical form posits that allowing somatic cell therapy now will be taking the first step on a slippery slope which will ultimately lead to the type of genocide perpetrated by the Nazis. The author tests the validity of these lines of argument against the facts of human gene therapy and concludes that because of their dependence on probabilities that cannot be empirically proven they should be largely disregarded in the much more important debate on moral line-drawing in gene therapy. (shrink)

types of application of genetic engineering for the insertion of genes into humans. The scientific requirements and the ethical issues associated with each type are discussed. Somatic cell gene therapy is technically the simplest and ethically the least controversial. The first clinical trials will probably be undertaken within the next year. Germ line gene therapy will require major advances in our present knowledge and it raises ethical issues that are now being debated. In order (...) to provide guidelines for determining when germ line gene therapy would be ethical, the author presents three criteria which should be satisfied prior to the time that a clinical protocol is attempted in humans. Enhancement genetic engineering presents significant, and troubling, ethical concerns. Except where this type of therapy can be justified on the grounds of preventive medicine, enhancement engineering should not be performed. The fourth type, eugenic genetic engineering, is impossible at present and will probably remain so for the foreseeable future, despite the widespread media attention it has received. Keywords: genetic engineering, somatic cells, germ cells, enhancement, eugenics, humanhood CiteULike Connotea Del.icio.us What's this? (shrink)

Somatic cell gene therapy has yielded promising results. If germ cell gene therapy can be developed, the promise is even greater: hundreds of genetic diseases might be virtually eliminated. But some claim the procedure is morally unacceptable. We thoroughly and sympathetically examine several possible reasons for this claim but find them inadequate. There is no moral reason, then, not to develop and employ germ-line gene therapy. Taking the offensive, we argue next (...) that medicine has a prima facie moral obligation to do so. (shrink)

In lieu of an abstract, here is a brief excerpt of the content:Human Gene TherapyMary Carrington Coutts (bio)On September 14, 1990, researchers at the U.S. National Institutes of Health (NIH) performed the first approved gene therapy procedure on a four-year-old girl named Ashanti DeSilva. Born with a rare genetic disease, severe combined immune deficiency (SCID), Ashanti lacked a healthy immune system and was extremely vulnerable to infection. Children with SCID usually develop overwhelming infections and rarely survive to (...) adulthood; even a common childhood illness like chicken pox is life-threatening. Ashanti led a cloistered existence, avoiding contact with people outside her family, remaining in the sterile environment of her home, and battling frequent illnesses with massive amounts of antibiotics.In Ashanti's gene therapy procedure, her own white blood cells were genetically modified and then infused back into her bloodstream. Laboratory tests show that the therapy has strengthened Ashanti's immune system. She no longer has recurrent colds, has been allowed to attend school, and has been immunized against whooping cough. This gene therapy procedure is not a cure, however. The genetically-treated white blood cells only survive for a few months and must then be replaced, but Ashanti's future is much brighter because of the new therapy (VI, Thompson [The First] 1993).Although this simplified description of Ashanti's gene therapy procedure sounds like a happy ending, it is little more than an optimistic chapter in a long story. The road to the first approved gene therapy procedure was rocky and fraught with controversy. The biology of human gene therapy is very complex, and there are still many techniques that need to be developed and diseases that need to be understood more fully before gene therapy is well established. The public policy debate surrounding the possible use of genetically engineered material in human subjects is equally complex. Major participants in the debate come from the fields of biology, government, law, medicine, philosophy, politics, and religion, each bringing different views to the discussion.In studying the ethics of gene therapy, one should draw a distinction between [End Page 63] therapy on somatic (non-reproductive) cells and germ (reproductive) cells. Only the germ cells carry the genes that will be passed on to the next generation. Reactions to gene therapy have varied widely. Some commentators on gene therapy object to any form of genetic manipulation, no matter how well-intentioned (VI, Rifkin 1983). Another reaction is to allow the use of somatic-cell therapy, but not to approve the use of germ-line therapy, which could have unforeseeable effects on future generations. A different stance is that, with proper regulation and safeguards, germ-line gene therapy is a logical extension of the progress made to date and that it is an ethically acceptable procedure.TechniquesTo date, 43 research protocols have been approved for somatic-cell gene therapy in the United States. The techniques employed in each protocol vary, but in general a virus is used as a "vector" to insert the desired gene into the DNA of the patient's cells, in order to compensate for a defective gene. For Ashanti's gene therapy, this technique involved obtaining white blood cells and introducing properly functioning genes into as many of the cells as possible. The normal genes were delivered through the use of a specially-engineered virus.Although similar techniques are used in germ-line gene therapy, the procedure is more difficult. There are two basic ways to perform germ-line gene therapy: (1) to treat a preimplantation embryo that carries a serious genetic defect before its implantation in the mother, which necessitates the use of in vitro fertilization techniques; or (2) to treat the germ cells (sperm or egg cells) of afflicted adults so that the genetic defects would not be passed on to their offspring, which requires the technical expertise to delete the defective gene and insert a properly functioning replacement. Because of the complexity of the procedures involved and the attendant ethical controversy, germ-line therapy is not currently performed.Candidate Diseases for Gene TherapyAt present, gene therapy is likely to be most successful in treating diseases that are caused by single-gene defects and has been approved for treating diseases such... (shrink)

Recombinant DNA technology will soon allow physicians an opportunity to carry out both somatic cell- and Germ-Line gene therapy. While somatic cell gene therapy raises no new ethical problems, gene therapy of gametes, fertilized eggs or early embryos does raise several novel concerns. The first issue discussed here relates to making a distinction between negative and positive eugenics; the second issue deals with the evolutionary consequences of lost genetic diversity. In (...) distinguishing between positive and negative eugenics, the concept of malady is applied as a definitional criterion for identifying genetic disorders that could qualify for Germ-Line therapy. Because gene replacement techniques are currently unavailable for humans, and because even if they were possible the number of people involved would be quite small, the loss of diversity concern seems moot. Finally, we dissuss the issue of iatrogenic disorders associated with gene therapy and discuss several ‘real world considerations.’. (shrink)

As the potential for the first human trials of somatic cell gene therapy nears, two ethical issues are examined: (1) problems of moral choice for members of institutional review boards who consider the first protocols, for parents, and for the clinical researchers, and the special protections that may be required for the infants and children to be involved, and (2) ethical objections to somatic cell therapy made by those concerned about a putative inevitable (...) progression of genetic knowledge from therapy to mass genetic engineering in human reproduction. The author's viewpoint is that a consensus exists on the required moral approach to somatic cell therapy, but that no moral approach yet exists for experiments beyond this level, especially in the germline cells of human beings. Keywords: gene therapy, somatic cells, germ cells, institutional review boards, genetic engineering CiteULike Connotea Del.icio.us What's this? (shrink)

Gene therapies to treat sickle cell disease are in development and are expected to have high costs. The large eligible population size — by far, the largest for a gene therapy — poses daunting budget challenges and threatens to exacerbate health disparities for Black patients, who make up the vast majority of American sickle cell patients.

Testing embryonic cells for genetic abnormalities gives us the capacity to predict whether and to what extent people will exist with disease and disability. Moreover, the freezing of embryos for long periods of time enables us to alter the length of a normal human lifespan. After highlighting the shortcomings of somatic‐cell gene therapy and germ‐line genetic alteration, I argue that the testing and selective termination of genetically defective embryos is the only medically and morally defensible way (...) to prevent the existence of people with severe disability, pain and suffering that make their lives not worth living for them on the whole. In addition, I consider the possible harmful effects on children born from frozen embryos after the deaths of their biological parents, or when their parents are at an advanced age. I also explore whether embryos have moral status and whether the prospects for disease‐preventing genetic alteration can justify long‐term cryopreservation of embryos. (shrink)

The Streptococcus pyogenes CRISPR‐Cas system has gained widespread application as a genome editing and gene regulation tool as simultaneous cellular delivery of the Cas9 protein and guide RNAs enables recognition of specific DNA sequences. The recent discovery that Cas9 can also bind and cleave RNA in an RNA‐programmable manner indicates the potential utility of this system as a universal nucleic acid‐recognition technology. RNA‐targeted Cas9 (RCas9) could allow identification and manipulation of RNA substrates in live cells, empowering the study of (...) cellular gene expression, and could ultimately spawn patient‐ and disease‐specific diagnostic and therapeutic tools. Here we describe the development of RCas9 and compare it to previous methods for RNA targeting, including engineered RNA‐binding proteins and other types of CRISPR‐Cas systems. We discuss potential uses ranging from live imaging of transcriptional dynamics to patient‐specific therapies and applications in synthetic biology. (shrink)

Herpes simplex virus (HSV)‐derived vectors are currently being developed for the introduction of foreign DNA into neurons. HSV vectors can facilitate a range of molecular studies on postmitotic neurons and may ultimately be used for somatic cell gene therapy for certain neurologic diseases. In this article, the salient features of the pathogenesis and molecular biology of HSV relevant to its use as a vector are described, along with an overview of the methods used to derive these (...) vectors. The accomplishments which have been made to date using the HSV vector system are discussed, with emphasis on the issues of this technology which remain to be addressed. HSV has the potential to be a most useful tool for neuronal cell transgenesis and it is likely that important neurobiological questions will be answered using this vector system. (shrink)

An understanding of the factors behind the evolution of multicellularity is one of today’s frontiers in evolutionary biology. This is because multicellular organisms are made of one subset of cells with the capacity to transmit genes to the next generation and another subset responsible for maintaining the functionality of the organism, but incapable of transmitting genes to the next generation. The question arises: why do somatic cells sacrifice their lives for the sake of germline cells? How is germ/soma separation (...) maintained? One conventional answer refers to inclusive fitness theory, according to which somatic cells sacrifice themselves altruistically, because in so doing they enhance the transmission of their genes by virtue of their genetic relatedness to germline cells. In the present article we will argue that this explanation ignores the key role of policing mechanisms in maintaining the germ/soma divide. Based on the pervasiveness of the latter, we argue that the role of altruistic mechanisms in the evolution of multicellularity is limited and that our understanding of this evolution must be enriched through the consideration of coercion mechanisms. (shrink)

Duchenne's muscular dystrophy (DMD), which affects 1/3500 live male births, involves a progressive degeneration of skeletal and cardiac muscle, leading to early death. The protein dystrophin is lacking in DMD and present, but defective, in the allelic, less severe, Becker muscular dystrophy and is also missing in the mdx mouse. Experiments on the mdx mouse have suggested two possible therapies for these myopathies. Implantation of normal muscle precursor cells (mpc) into mdx skeletal muscle leads to the conversion of dystrophin‐negative fibres (...) to ‐positive, with consequent improvement in muscle histology. Direct injectidn of dystrophin cDNA into skeletal or cardiac muscle also gives rise to dystrophin‐positive fibres. Although both appear promising, there are a number of questions to be answered and refinements to be made before either technique could be considered possible as treatments for myopathies in man. (shrink)

Reprogramming of somatic cells to a pluripotent state holds huge potentials for regenerative medicine. However, a debate over which method is better, somatic cell nuclear transfer (SCNT) or induced pluripotent stem (iPS) cells, still persists. Both approaches have the potential to generate patient‐specific pluripotent stem cells for replacement therapy. Yet, although SCNT has been successfully applied in various vertebrates, no human pluripotent stem cells have been generated by SCNT due to technical, legal and ethical difficulties. On (...) the other hand, human iPS cell lines have been reported from both healthy and diseased individuals. A recent study reported the generation of triploid human pluripotent stem cells by transferring somatic nuclei into oocytes, a variant form of SCNT. In this essay, we discuss this progress and the potentials of these two reprogramming approaches for regenerative medicine. (shrink)

It may be unethical to deny children with cystic fibrosis access to ethically approved clinical trials from which they might benefitDespite advances in nutritional management, aggressive antibiotic usage, and physiotherapy, cystic fibrosis remains a life limiting illness with high morbidity that imposes considerable burdens on children and families.1 Although survival to 40 years is predicted for children born in 1990s, the median age of death in 2003 was 24.2 years .The pathophysiological features of CF are produced by a defective (...) class='Hi'>gene on chromosome 7, resulting in the defective production of a protein that regulates cellular ion transport. Defective ion transport is thought to lead to increased mucus viscosity , with poor airway clearance, recurrent bacterial infection, lung damage, and death.Gene therapy , the insertion of a normally functioning gene into deficient host cells using a suitable vector, is a potential treatment or cure for diseases produced by single gene defects—for example, CF. Gene therapy does, however, have potential or actual risks, leading many to suggest that evidence of efficacy in adults should be demonstrated before trials are conducted in children. Many serious diseases in adults such as CF have their onset in childhood. If early treatment provides greater hopes of benefit, children may be more appropriate targets for GT in CF than adults. It may be unethical to deny them access to properly constructed, ethically approved clinical trials from which they might benefit.Since research in children should be scientifically valid, in the child’s best interests, and the subject of valid consent, this article will consider these parameters in relation to trials of GT in children with CF. Because of the importance of consumer participation in the design of research we present the results of a questionnaire about GT trials delivered …. (shrink)

Gene therapy and gene editing are revolutionising the treatment of genetic diseases, most notably haematological disorders. This paper evaluates the use of both techniques in hereditary blood disorders. Many studies have been conducted in this field, especially with gene therapy, with very promising results in diseases such as haemophilia, certain haemoglobinopathies and Fanconi anaemia. The application of these techniques in clinical practice and the foreseeable development of these approaches in the coming years suggest that it (...) might be useful to evaluate the results achieved thus far. It is also essential to reflect on the possible bioethical concerns raised by the use of both techniques, especially in terms of safety issues for patients, potential side effects, treatment duration, accessibility and cost of treatment, and the heritability of genetic changes produced if germline cells are used. (shrink)

This chapter contains sections titled: Promise and Disappointment Ethical Issues Resource Allocation References.

In 1956, I decided to apply my experience in microbial genetics to developing analogous systems for human cell lines, including the selection of mutants with either a loss or gain of a biochemical function. For instance, mutants resistant to azahypoxanthine showed a loss of the HPRT enzyme (hypoxanthine phosphoribosyl transferase), whereas gain of the same enzyme was accomplished by blocking de novo purine biosynthesis with aminopterin, while supplying hypoxanthine and thymine (HAT selection). Using HAT selection, we: (i) genetically transformed (...) HPRT− mutant cells to HPRT+ wild type by using DNA extracted from HPRT+ cells, and (ii) selected HPRT+ hybrid cells by fusing HPRT− D98/AH2 cells with skin cells. These approaches, which we dubbed in 1962 as a [first step toward gene therapy], contributed to the later development of (i) cell fusion techniques, (ii) the development of monoclonal antibodies, (iii) routine transformation of mammalian cells with cloned genes, and (iv) methods for creating transgenic organisms. (shrink)

It may be possible, one day, to use gene therapy to treat diseases whose genetic defects have been discerned. Because many genes responsible for inherited eye disorders within the retina have been identified, diseases of the eye are prime candidates for this form of therapy. The eye also has the advantage of being highly accessible with altered immunological properties, important considerations for easy delivery of virus and avoidance of systemic immune responses. Currently, adenovirus, adeno‐associated virus and lentivirus (...) have been used to successfully transfer genetic material to retinal pigment epithelium and photoreceptor cells. By harnessing therapeutic genes to these viruses, researchers have been able to demonstrate rescue in rodent models of retinitis pigmentosa, providing evidence that this form of therapy can be effective in delaying photoreceptor cell death. Future challenges include confirming therapeutic effects in animal models with eyes more anatomically similar to those of humans and demonstrating long‐term rescue with minimal toxicity. BioEssays 23:662–668, 2001. © 2001 John Wiley & Sons, Inc. (shrink)

The field of regenerative medicine has considerable therapeutic promise that is proving difficult to realize. As a result, governments have supported the establishment of intermediary agencies to “accelerate” innovation. This article examines in detail one such agency, the United Kingdom’s Cell and Gene Therapy Catapult. We describe CGTC’s role as an accelerator agency and its value narrative, which combines both “health and wealth.” Drawing on the notion of sociotechnical imaginaries, we unpack the tensions within this narrative and (...) its instantiation as the CGTC cell therapy infrastructure is built and engages with other agencies, some of which have different priorities and roles to play within the RM field. (shrink)

Hereditary retinal degeneration due to mutations in visual genes may be amenable to therapeutic interventions that modulate, either positively or negatively, the amount of protein product. Some of the proteins involved in phototransduction are rapidly moved by a lightdependent mechanism between the inner segment and the outer segment in rod photoreceptor cells, and this phenomenon is important in phototransduction.

In this paper, we apply the perspective of intra-organismal ecology by investigating a family of ecological models suitable to describe a gene therapy to a particular metabolic disorder, the adenosine deaminase deficiency (ADA-SCID). The gene therapy is modeled as the prospective ecological invasion of an organ (here, bone marrow) by genetically modified stem cells, which then operate niche construction in the cellular environment by releasing an enzyme they synthesize. We show that depending on the chosen order (...) (a choice that cannot be made on \textit{a priori} assumptions), different kinds of dynamics are expected, possibly leading to different therapeutic strategies. This drives us to discuss several features of the extension of ecology to intra-organismal ecology. (shrink)

BackgroundHIV cure research involving cell and gene therapy has intensified in recent years. There is a growing need to identify ethical standards and safeguards to ensure cell and gene therapy (CGT) HIV cure research remains valued and acceptable to as many stakeholders as possible as it advances on a global scale.MethodsTo elicit preliminary ethical and practical considerations to guide CGT HIV cure research, we implemented a qualitative, in-depth interview study with three key stakeholder groups (...) in the United States: (1) biomedical HIV cure researchers, (2) bioethicists, and (3) community stakeholders. Interviews permitted evaluation of informants’ perspectives on how CGT HIV cure research should ethically occur, and were transcribed verbatim. We applied conventional content analysis focused on inductive reasoning to analyze the rich qualitative data and derive key ethical and practical considerations related to CGT towards an HIV cure.ResultsWe interviewed 13 biomedical researchers, 5 community members, and 1 bioethicist. Informants generated considerations related to: perceived benefits of CGT towards an HIV cure, perceived risks, considerations necessary to ensure an acceptable benefit/risk balance, CGT strategies considered unacceptable, additional ethical considerations, and considerations for first-in-human CGT HIV cure trials. Informants also proposed important safeguards to developing CGT approaches towards an HIV cure, such as the importance of mitigating off-target effects, mitigating risks associated with long-term duration of CGT interventions, and mitigating risks of immune overreactions.ConclusionOur study identified preliminary considerations for CGT-based HIV cure across three key stakeholder groups. Respondents identified an ideal cure strategy as one which would durably control HIV infection, protect the individual from re-acquisition, and eliminate transmission to others. Known and unknown risks should be anticipated and perceived as learning opportunities to preserve and honor the altruism of participants. Preclinical studies should support these considerations and be transparently reviewed by regulatory experts and peers prior to first-in-human studies. To protect the public trust in CGT HIV cure research, ethical and practical considerations should be periodically revisited and updated as the science continues to evolve. Additional ethics studies are required to expand stakeholder participation to include traditionally marginalized groups and clinical care providers. (shrink)

Many Christian scholars, if not all of them, consider Genesis to be foundational texts of the Bible and the spring for all the other doctrines of the Scripture. Therefore, I'm considering the attempt to search and find arguments for cell therapy ethical issues in the fundamental text of Genesis as a challenging and educative task. Moreover, this could be the first step in analyzing the relationships between Christian religions and bioethics, in terms of finding reasonable decisions for ethical (...) challenges, raised by the current biomedical research. As for many other dilemmas of humanity, we have to recall the text of Genesis for analyzing the goodness or evilness of our actions in translational medicine, even though that is not the only way to get a reasonable ethical decision. My contribution is an essay that is trying to correlate the Genesis lessons with the needed arguments in deciding what could be good and what could be evil in the stem cell research, according to the religious convictions. The biggest challenges of biomedical research for Christian religions were due to the human cloning issue, made possible by the somatic cell nuclear transfer, but those challenges update the older debates on birth control pill, technologically assisted reproduction, or gene therapy. Issues related to in vitro fertilization, gene enhancement and gene therapy, human cell cloning, embryonic stem cell using, and chimera cell obtaining for research are being considered and related to the putative arguments extracted from the book of Genesis, describing the origins. As a matter of fact, I may conclude that the single way to reach a reasonable ethical decision in our society is to intersect ethics, science and theology and to engage large debates involving scientists, theologians, civil society representatives, ethicists (experts in applied ethics) and moral philosophers, having the two latest professionals as referees. (shrink)

Despite the progress achieved over the last decade after the birth of the first cloned mammal, the efficiency of reproductive cloning remains invariably low. However, research aiming at the use of nuclear transfer for the production of patient‐tailored stem cells for cell/tissue therapy is progressing rapidly. Yet, reproductive cloning has many potential implications for animal breeding, transgenic research and the conservation of endangered species. In this article we suggest that the changes in the epi‐/genotype observed in cloned embryos (...) arise from unbalanced nuclear reprogramming between parental chromosomes. It is probable that the oocyte reprogramming machinery, devised for resident chromosomes, cannot target the paternal alleles of somatic cells. We, therefore, suggest that a reasonable approach to balance this asymmetry in nuclear reprogramming might involve the transient expression in donor cells of chromatin remodelling proteins, which are physiologically expressed during spermatogenesis, in order to induce a male‐specific chromatin organisation in the somatic cells before nuclear transfer. BioEssays 30:66–74, 2008. © 2007 Wiley Periodicals, Inc. (shrink)

Gene therapy is the modification of the human genetic code to prevent disease or cure illness. This technology is in its infancy and remains confined to experimental clinical trials. Once the present barriers are overcome, gene therapy will confront humanity with a host of ethical challenges. Therapies targeted to the genes of germ-line cells will introduce permanent changes to the human gene pool. Furthermore, nonmedical gene modifications have the potential to introduce a new form (...) of eugenics into our society by which some members attempt to become inherently superior to others and humanity is re-engineered to man-made specifications. National Catholic Bioethics Quarterly 10.1 (Spring 2010): 45–50. (shrink)

Although the ability to perform gene therapy in human germ-line cells is still hypothetical, the rate of progress in molecular and cell biology suggests that it will only be a matter of time before reliable clinical techniques will be within reach. Three sets of arguments are commonly advanced against developing those techniques, respectively pointing to the clinical risks, social dangers and better alternatives. In this paper we analyze those arguments from the perspective of the client-centered ethos that (...) traditionally governs practice in medical genetics. This perspective clarifies the merits of these arguments for geneticists, and suggests useful new directions for the professional discussion of germ-line gene therapy. It suggests, for example, that the much discussed prospect of germ-line therapy in human pre-embryos may always be more problematic for medical genetics than adult germ-line interventions, even though the latter faces greater technical difficulties. (shrink)

For focal neurodegenerative diseases or brain tumors, localized delivery of protein or genetic vectors may be sufficient to alleviate symptoms, halt disease progression, or even cure the disease. One may circumvent the limitation imposed by the blood-brain barrier by transplantation of genetically altered cell grafts or focal inoculation of virus or protein. However, permanent gene replacement therapy for diseases affecting the entire brain will require global delivery of genetic vectors. The neurotoxicity of currently available viral vectors and (...) the transient nature of transgene expression invivomust be overcome before their use in human gene therapy becomes clinically applicable. (shrink)

Emerging evidence suggests that microRNA (miRNA)‐mediated post‐transcriptional gene regulation plays an essential role in modulating embryonic stem (ES) cell pluripotency maintenance, differentiation, and reprogramming of somatic cells to an ES cell‐like state. Investigations from ES cell‐enriched miRNAs, such as mouse miR‐290 cluster and human miR‐302 cluster, and ES cell‐depleted miRNAs such as let‐7 family miRNAs, revealed a common theme that miRNAs target diverse cellular processes including cell cycle regulators, signaling pathway effectors, transcription factors, (...) and epigenetic modifiers and shape their protein output. The combinatorial effects downstream of miRNA action allow miRNAs to modulate cell‐fate decisions effectively. Furthermore, the transcription and biogenesis of miRNAs are also tightly regulated. Thus, elucidating the interplay between miRNAs and other modes of gene regulation will shed new light on the biology of pluripotent stem cells and somatic cell reprogramming. (shrink)

There are an increasing number of cell therapy approaches being studied and employed world‐wide. An emerging area in this field is the use of human pluripotent stem cell (hPSC) products for the treatment of injuries/diseases that cannot be effectively managed through current approaches. However, as with any cell therapy, vast numbers of functional and safe cells are required. Bioreactors provide an attractive avenue to generate clinically relevant cell numbers with decreased labour and decreased batch (...) to batch variation. Yet, current methods of performing quality control are not readily scalable to the cell densities produced during bioreactor scale‐up. One potential solution is the application of inducible/controllable suicide genes that can trigger cell death in unwanted cell types. These types of approaches have been demonstrated to increase the quality and safety of the resultant cell products. In this review, we will provide background on these approaches and how they could be used together with bioreactor technology to create effective bioprocesses for the generation of high quality and safe hPSCs for use in regenerative medicine approaches. (shrink)

Gene therapy has emerged from the idea of inserting a wild‐type copy of a gene in order to restore the proper expression and function of a damaged gene. Initial efforts have focused on finding the proper vector and delivery method to introduce a corrected gene to the affected tissue or cell type. Even though these first attempts are clearly promising, seveal problems remain unsolved. A major problem is the influence of chromatin structure on transgene (...) expression. To overcome chromatin‐dependent repressive transgenic states, researchers have begun to use chromatin regulatory elements to drive transgene expression. Insulators or chromatin boundaries are able to protect a transgene against chromatin position effects at their genomic integration sites, and they are able to maintain transgene expression for long periods of time. Therefore, these elements may be very useful tools in gene therapy applications for ensuring high‐level and stable expression of transgenes. BioEssays 26:796–807, 2004. © 2004 Wiley Periodicals, Inc. (shrink)

Mos, a protein kinase, is specifically expressed and functions during meiotic maturation (or G2/M progression) of vertebrate oocytes. When expressed ectopically, however, it can also readily induce oncogenic transformation (or uncontrolled G1/S transitions) in somatic cells. In both of these cell types, Mos activates mitogen‐activated protein kinase (MAPK), which seems largely to mediate its different functions in both oocyte maturation and cellular transformation. In oocyte maturation, the Mos‐MAPK pathway probably serves to activate and stabilize M‐phase promoting factor (MPF) (...) (possibly by inhibiting some negative regulator(s) of this factor), while in cellular transformation, it seems to stabilize and activate the nuclear oncoprotein c‐Fos as well as to induce transcription of its gene. Thus, the different functions of Mos in oocytes and somatic cells may arise chiefly from its different MAPK‐mediated targets in the respective cell types. This review discusses the cellular basis that may enable Mos to act differently in oocytes and somatic cells. (shrink)

The majority of higher plants (including almost all important crops) demonstrate strict uniparental maternal inheritance of plasmagenes in the process of conventional sexual crossing; it is therefore impossible to generate heterozygosity for these genes with standard crossing procedures. However, recent experiments have shown that hybrid plants can be produced by somatic cell fusion and that these contain the cytoplasmic genes of both parents. The phenotypic and genetic properties of these hybrid plants are described here.

Recent political developments and disclosures of serious adverse events in human gene therapy (HGT) with the death of 18‐year old Jesse Gelsinger in the USA have shown that the clinical application of HGT raises some severe ethical issues. These have either been neglected or not yet been discussed to a satisfactory extent. In this paper, we will address this deficiency and develop strategies for a safer application of HGT. Such a study must first look closely at the science (...) of HGT itself. We will evaluate the latest preclinical research, especially data on the viruses that are used as vectors and on modes of administration of vectors. We will put forward new arguments concerning the toxicity assessment of so‐called ‘gene drugs‘, the tissue and cell type specificity of the vectors, and the duration and on‐set of gene expression. Secondly, we will look at procedural aspects of applied research ethics on the way to clinical application of HGT. There, informed consent (IC) and the patient‐researcher relationship are of utmost concern. Furthermore, we will explore the problem of expertise in risk assessment and will show how current regulations foster conflicts of interests that create dilemma situations even for those researchers who act in the best interest of the patients. We will conclude the article with a set of questions for ethicists who have to decide about the quality of HGT protocols. This may contribute to the safety of patients participating in HGT trials and to achieving the aim of efficient application of HGT. (shrink)

The cases for and against somatic gene therapy, germ-line gene therapy and gene therapy for enhancement are assessed. It is argued that none of these kinds of therapy is inherently wrong, and that an adequate assessment should consist in weighing risks and benefits. On this basis, it is argued that somatic therapy is a promising new kind of treatment that we should welcome; that we have technologies available that make germ-line (...) therapy superfluous, unless we want to engage in enhancement engineering; and that although we should be extremely cautious if we were to engage in enhancement engineering, we cannot categorically rule out that there might be cases in which this kind of therapy should be applied, e.g. if it was the only way of saving millions of lives. (shrink)

The concept of human gene therapy came on the heels of fundamental discoveries on the nature and working of the gene. However, realistic prospects to correct the underlying cause of recessive genetic disorders through the transfer of wild‐type alleles of defective genes had to wait for the arrival of recombinant DNA technology. These techniques permitted the isolation and insertion of genes into the first recombinant delivery systems. The realization that viruses are natural gene carriers provided inspiration (...) for gene therapy and, as engineered vectors, viruses became prominent gene delivery vehicles. Nonetheless, when put in the context of human and non‐human primate studies, all vectors fell short of success regardless of their viral or non‐viral origin. Recognition of issues such as inefficient gene transfer and short‐lived or scant expression in the relevant cell type(s) prompted researchers to refine and develop several gene delivery systems, in particular those based on retroviruses, adeno‐associated viruses and adenoviruses. Concomitantly, available technology was deployed to tackle disorders that require few genetically corrected cells to attain therapy. BioEssays 27: 506–517, 2005. © 2005 Wiley periodicals, Inc. (shrink)

Recombinant adeno‐associated viruses (rAAVs) are promising vectors for the delivery of various genetic constructs into eukaryotic cells. rAAVs have a number of properties that make it possible to successfully use them both in vitro and in vivo. Purification and concentration of rAAV vectors are critical for achieving high viral titer, stability, efficiency, and purity. This review systematically analyses all available purification approaches. The purification methods described in this work differ substantially from each other in mechanisms, efficiency, labor time, and cost. (...) Researchers have to choose a purification algorithm depending on the purpose of their work. We strive to simplify the choice of the necessary and sufficient technique based on the experimental needs and available resources of the laboratory. (shrink)