Hum. Reprod. Advance Access originally published online on September 2, 2006
Human Reproduction 2006 21(11):2749-2755; doi:10.1093/humrep/del233
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OPINION |
An ethical analysis of alternative methods to obtain pluripotent stem cells without destroying embryos
1 Centre for Environmental Philosophy and Bioethics, Ghent University, Ghent and 2 Research Centre Reproduction and Genetics, Vrije Universiteit Brussel, Brussels, Belgium
3 To whom correspondence should be addressed at: Blandijnberg 2, 9000 Ghent, Belgium. E-mail: heidi.mertes{at}ugent.be
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Abstract |
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 Top Abstract IntroductionThe alternative ways of...Balancing pros and cons...Solutions to the moral...Separation principle'Embryo-free' alternativesConclusionReferences |
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Although few ethical concerns exist regarding the use of adult stem cells, the field of embryonic stem cell research is fraught with moral qualms. Several alternative sources of pluripotent stem cells have recently been presented that try to sidestep the destruction of human embryos. The goal of these new proposals is to avoid embryo destruction, the main objection to embryonic stem cell research and thus introduce a type of stem cell research that would gain widespread approval and support. This article suggests that most embryo-saving alternatives fail to reach this goal given the concessions they require with regard to the speed of progress, technical complexity, safety and security of applications, degree of dependence on limited resources and extent of the field of application. The second part of the article identifies and analyses the two main strategies that alternative sources of pluripotent stem cells are based on and points out their shortcomings.
Key words: altered nuclear transfer/embryo research/ethics/stem cells/utilitarianism
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Introduction |
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TopAbstractIntroductionThe alternative ways of...Balancing pros and cons...Solutions to the moral...Separation principle'Embryo-free' alternativesConclusionReferences |
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Technologies based on both adult stem cells and embryonic stem cells hold a great promise for future medical research and treatments. Although few ethical concerns exist regarding the use of adult stem cells, the field of embryonic stem cell research is fraught with moral qualms. The position that one holds in the embryonic stem cell debate mainly depends on the status that one accords to the human embryo. In the ethics literature, three important positions are distinguished. The first position holds that the moral status of an embryo is absolute at all stages and equals the status of a person, leading to the conclusion that the destruction of embryos is immoral (Doerflinger, 1999
). According to the second position, the moral status of an embryo increases gradually as it develops, and thus, embryo research requires careful ethical consideration but is not immoral per se (Holm, 2003). Finally, it can be argued that an embryo holds no inherent moral status, and therefore not conducting embryo research given the possible benefits would be immoral (McCullough and Chervenak, 1994). The position defended in this article adopts the second, gradualistic position that requires a balancing of the early embryo’s status and the benefits to which embryonic stem cell research may lead.
During the previous year, several possible alternative sources of pluripotent stem cells have been presented that try to sidestep the destruction of human embryos and thus settle the ‘stem cell debate’. Some of these proposals were discussed by the President’s Council on Bioethics in their report (2005b) ‘Alternative Sources of Human Pluripotent Stem Cells’. We believe that the alternatives’ fixation on avoiding embryo destruction for research downplays the importance of the benefits of embryonic stem cell research. People who hold a gradualist view of the embryo’s moral status will have to balance the future positive consequences of research and therapy against the respect due to the embryo at an early stage. Given the huge possible benefits, both in terms of increased understanding of fundamental biological processes and in terms of therapy development, an ethical preference will in many cases remain for methods that obtain stem cells through embryo destruction over embryo-saving alternatives.
When this is ignored, there is a real danger that research involving alternative sources of pluripotent stem cells will receive disproportionate support for political reasons (Kass, 2005; Ready, 2005). When money is funnelled in the direction of ‘embryo-saving’ alternatives (the recent bills HR3144 and HR2574 in the US Congress do exactly that) at the expense of methods considered most promising at the moment, the advent of stem cell therapies may be significantly delayed.
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The alternative ways of obtaining pluripotent stem cells |
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The alternative sources of human pluripotent stem cells discussed in this article were presented by the President’s Council on Bioethics as follows.
Dead embryos
Landry and Zucker (2004) have suggested that instead of using good quality surplus IVF embryos, it would be more acceptable to use only those embryos that show irreversible cleavage arrest. After thawing, a certain number of embryos will no longer grow, divide and differentiate. Because cell division is a basic property of early embryos, Landry and Zucker call those embryos ‘organismically dead’ or just ‘dead’, even though they might still contain some healthy blastomeres out of which it may be possible to derive embryonic stem cells. They compare this approach to the removal of vital organs from human cadavers for medical or research purposes, a practice that is widely accepted.
Blastomere extraction
A second approach to obtaining pluripotent stem cells without destroying an embryo is blastomere extraction (Philipkoski, 2004; Weiss, 2005). In this procedure, one or two cells would be taken from a very early embryo, which is a common procedure used in PGD. These blastomeres would then be used to generate stem cells, while the embryo could still be implanted in a woman’s uterus.
Biological artefacts
This option contemplates obtaining stem cells from parthenotes or similar entities that are artificially created. Hurlbut (2004) wants to engineer a somatic cell nucleus lacking one or two genes that are crucial for embryogenesis. Subsequently, this nucleus would be transferred to an enucleated oocyte and would become a ‘cellular system’ that could never result in a human being and should thus be regarded as tissue rather than as an embryo, out of which pluripotent stem cells could be derived. This method has been labelled ‘altered nuclear transfer’ (ANT). Because the missing genes might have a negative impact on the quality of the derived stem cells, Hurlbut suggests reinserting them after cells have been extracted from the artefact.
Somatic cell dedifferentiation
Somatic cells are specialized to perform certain functions within the body, and thus only use a part of the genetic information they contain. However, the unused information does not disappear from the cell but is merely silenced. If this information could be reactivated, a somatic cell would return to its embryonic state without being part of an actual embryo, thus successfully circumventing the ethical issues involved in embryo destruction.
The report concluded that at least three of the proposed routes (all but blastomere extraction) deserve further exploration.
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Balancing pros and cons of alternative sources of pluripotent stem cells |
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Besides its importance for fundamental research, stem cell research is eventually aimed at the alleviation of suffering. What sets stem cell research apart from other medical research areas is the scope of its possibilities. It offers hope for several serious and often life-threatening illnesses and injuries that we are faced with, promising treatments for degenerative and autoimmune diseases and for injuries caused by damaged or lost tissue. The number of diseases treatable and their severity require not only that cures are developed but also that they are developed as fast as possible and that funds are allocated primarily for projects that have a high chance of redeeming the stem cell promise. Therefore, a fair balancing of possible sources of pluripotent stem cells cannot focus exclusively on the protection of the embryo but also needs to take factors affecting beneficence into account. Beneficence incorporates several criteria such as speed of progress, technical complexity, safety and security of applications, practical attainability and extent of the field of application (Pennings and Van Steirteghem, 2004
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Speed of progress
A first important factor is the speed of progress. If there are several ways to develop possibly life-saving treatments, a prima facie preference ought to be given to the fastest option.
This is a major drawback for Hurlbut’s (2004) proposal to produce an embryo-like entity through ANT, which is criticized by several scientists for requiring too many time-consuming experiments that would only delay the field and that could be put to better use in other areas of stem cell research (Melton et al., 2004; Russo, 2005). First, a suitable gene or set of genes would have to be identified that is crucial enough to impair the entity’s development when it is deleted, but whose deletion would not irreversibly damage the resulting stem cells. Second, the genetically engineered cell has to be therapeutically cloned, which is likely to be more difficult than cloning a ‘normal’ cell. Finally, a method has to be developed to reactivate the concerning gene(s). As the President’s Council’s report remarks, this procedure is so time consuming that it will not attract scientists’ interest, and ‘[m]any scientists, we suspect, would be reluctant to attempt such challenging feats with no rational purpose other than to satisfy the ethical objections of others’ (President’s Council on Bioethics, 2005b).
Technical complexity
The complexity of an approach will inevitably influence future applications. Extra technical difficulties call for extra research efforts, require financial resources and slow down the field. Additionally, more layers of complexity lower success rates and heighten the risk of delivering stem cells of suboptimal quality, which is especially worrisome in the advent of clinical trials.
This criterion clearly disfavours pluripotent stem cells obtained by ANT. ANT clearly poses a lot more technical difficulties than the derivation of stem cells from spare IVF embryos or embryos created by somatic cell nuclear transfer (SCNT) and thus has a much lower chance to succeed in delivering high-quality stem cells.
The Landry–Zucker proposal to use healthy blastomeres of dead embryos is also yet to prove that it can overcome the technical hurdles it is faced with. Stem cells have been derived from morula-stage embryos (Strelchenko et al., 2004) and recently from individual blastomeres (Chung et al., 2005). Nevertheless, it will be a trying task to make the technique work with possibly poor-quality blastomeres extracted from dead embryos. Finally, the resulting stem cells might be less suited for therapeutic use given the high chances of chromosomal imbalance.
Safety and security of applications
Eventually, stem cells are meant to be used not only in biomedical research but more importantly in therapies. Some sources of pluripotent stem cells may be very valuable for basic research but could be dangerous if used in patients. The main concern for any therapy using human tissue is immune rejection and graft-versus-host disease. That is why research efforts remain focused on autologous transplants and techniques like therapeutic cloning and reprogramming.
Another concern is the chance of negative side effects due to manipulations of genetic material. By removing and reinserting genes, as Hurlbut suggests, the genetic material of the resulting stem cells may be damaged, rendering them unpredictable. Consequently, their clinical use could endanger patients. In another example, recent successes in reprogramming skin cells by fusing them with embryonic stem cells leave scientists wondering whether the genome of the original somatic cell might be ‘contaminated’ by the embryonic stem cell’s DNA (Vogel, 2005). Similarly, it is unknown whether parthenogenetic stem cells without paternally imprinted genes will behave the same as stem cells that carry both gametic imprints.
Degree of dependence on limited resources
The practical attainability of certain alternatives depends on the previously discussed technical easiness but also on the availability of the necessary components. This poses a problem for sources of pluripotent stem cells that rely on a supply of human oocytes: SCNT, parthenogenesis, ANT and oocyte-assisted reprogramming (OAR). Harvesting human oocyte cells is an elaborate process, which involves certain risks for the donor. Moreover, only an average of 10–12 oocytes can be retrieved per donation, making them very scarcely available for research. For any large-scale applications of these techniques, alternative sources of oocytes will probably be needed. One possibility is using immature oocytes retrieved during infertility treatments (Heindryckx et al., 2005), tubal ligation or other surgical procedures. Also, there is hope that the successful derivation of oocytes from mouse embryonic stem cells (Hübner et al., 2003) may be extended to human cells.
Extent of the field of application
Different methods of deriving stem cells may address different subcategories of the enormous field of application and/or serve different segments of patients. When comparing new alternatives and the methods of embryonic research they seek to replace, it is important that their fields of application are similar. Just as adult stem cells and embryonic stem cells have different scopes of possibilities, stem cells from surplus IVF embryos and stem cells from therapeutically cloned embryos are not interchangeable. Even though both can be used in biomedical research, safe stem cell therapies will require stem cells with a reduced complexity of surface proteins, such as parthenogenetic stem cells, or ultimately stem cells carrying the same DNA as the patient to avoid immune rejection. Thus, although Landry–Zucker proposal of using dead IVF embryos can be considered as a valid alternative for the use of healthy surplus embryos, it cannot replace therapeutic cloning and should therefore not be portrayed as an alternative that makes all other embryonic research superfluous.
However, although from a therapeutic perspective SCNT is at present the preferred way to obtain usable stem cells, the scope of its applications may be limited on a practical level. Therapeutic cloning is a very expensive and complex procedure to obtain stem cells to cure one person. This feature blocks the application on a larger scale and causes concerns regarding justice. Given the cost, most probably only rich people will be able to afford it (McLaren, 2001).
This list of criteria is not all-encompassing, but it shows that different ways of obtaining pluripotent stem cells cause different ethical concerns. Including these concerns in the comparison of the current and alternative approaches of obtaining stem cells leads us to the conclusion that embryo-free options are not a priori morally preferable and that embryonic research is not automatically reprehensible (De Wert and Mummery, 2003). Both must be judged within the wider framework of their promise to alleviate suffering and of their potential to do so in a faster, better and safer way than their alternatives.
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Solutions to the moral problems |
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Essentially two strategies can be identified that are used by the proponents of alternative sources of pluripotent stem cells to dodge the moral challenges of embryonic stem cell research. The first strategy is based on the—contentious—view that the researcher is committing a moral wrong when he or she destroys embryos. One therefore tries to separate the derivation of embryonic stem cells from the ‘wrongful act’ of destroying embryos. The second strategy is to turn to embryo-free alternatives, either by transforming a somatic cell directly into a stem cell or by using artefacts that resemble embryos enough to allow for the derivation of pluripotent stem cells, but that ‘lack the essential attributes and capacities of a human embryo’ (President’s Council on Bioethics, 2005b
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Separation principle |
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Some people believe that although the use of embryonic tissue in itself is not immoral, purposely creating and destroying embryos for research is immoral. The current legislation in the US concerning federal funding of embryonic stem cell research is based on this distinction. To make embryonic stem cell research ethically acceptable in such a framework, a complete separation has to be established between the decision to create (and destroy) an embryo on the one hand and to use the embryonic tissue on the other hand. This idea finds its origin in the debate concerning the use of fetal tissue after abortion (Berghmans et al., 2002
). By severing the link between the ‘wrongful act’ and the subsequent use of the material that is obtained, the ‘complicity before and after the fact’ of those who use the cells or tissues for research or therapy is eliminated (Boer, 1999). The ‘separation principle’ states that a person is not morally responsible for some wrong if his or her actions can be separated from the wrongful act (ESHRE Taskforce on Ethics and Law, 2002).
An important distinction based on this principle is the distinction between surplus embryos and research embryos. In the case of therapeutic cloning, the decision to create and destroy embryos is made by the stem cell researcher, who therefore carries the full responsibility for the embryo’s destruction. When surplus embryos are used, however, the decision to destroy the embryo has already been made by the couple undergoing a fertility treatment. The researcher’s use of the embryonic tissue merely changes the method of destruction but has no impact on the embryo’s final fate. This became known as the ‘doomed embryo’ rule or the ‘nothing is lost’ argument (Zoloth, 2002; Pennings and Van Steirteghem, 2004).
Dead embryos
Landry and Zucker apply the separation principle when they suggest deriving stem cells from early IVF embryos that have died in the process of cryopreservation. This proposal not only separates the decision to discard certain IVF embryos from their use in stem cell derivation but also withdraws from any interference that may hasten the destruction of embryos bound to be disposed of. Even though this approach clears the stem cell researcher from any responsibility in the destruction of embryos, it leads to an ethically questionable practice. As noted by Rowley during the discussion of this proposal in the President’s Council, ‘this is a strange way of solving an ethical dilemma, that you let something that is useful die and then try strenuously to rescue cells from a dead embryo’ (President’s Council on Bioethics, 2005a). Moreover, it can be questioned if it is even possible to derive high-quality stem cells from a single blastomere of an embryo more than 24 h after spontaneous cleavage arrest, which is usually due to chromosomal abnormalities.
On the whole, this approach is not an embryo-saving strategy and prevents using the most valuable embryos for a good cause. In addition, it introduces the notion of a ‘dead’ embryo that scientists may not agree upon. In this proposal, the benefits of honouring the separation principle obviously fall short of the disadvantages that it incurs.
Blastomere extraction
The successful derivation of embryonic stem cells from morula-stage embryos (Strelchenko et al., 2004) and single mouse blastomeres (Chung et al., 2005) provides hope for the technical possibilities of this proposal. However, the biopsy may affect the successful implantation of the embryo (Vandervorst et al., 2000) and has a detrimental effect on the survival rate of cleavage-stage embryos after cryopreservation (Jericho et al., 2003). Although the available evidence indicates that the children born after PGD are not harmed by the procedure (Sermon, 2002), long-term follow-up is needed to corroborate this finding.
One way of avoiding possible risks is to limit the procedure to embryos that are left over after a fertility treatment and will never be implanted. This, however, results in an absurd situation, in which embryos would be thawed, biopsied and refrozen, only to be discarded later. Given the fact that blastomere biopsy is a complicated and an expensive technique, that there are no data on the quality of the stem cells that might be produced this way and that again, in the end this can hardly be called an embryo-saving strategy, it is clear that even though the researcher might not be an accomplice in the destruction of any embryo, this procedure remains ethically challenging.
The inconsistencies in both alternatives mentioned above result from a very strict interpretation of the researcher’s complicity; supporters of these proposals are not concerned about the death of supernumerary embryos resulting from IVF. The only thing they want to avoid at all costs is that embryos (of whatever kind) are destroyed for the creation of stem cell lines. But why would complicity only start at this point? Several embryos will be harmed by cryopreservation. Anyone making use of embryos resulting from a procedure in which embryos are destroyed can be considered morally responsible for their death. A truly embryo-saving strategy would be to design an IVF procedure in which only the number of embryos is created that could be replaced immediately and in which all embryos are replaced as stipulated in the Italian law. However, this policy is widely criticized for encouraging multiple pregnancies and for increasing the need of multiple ovarian stimulation cycles, thus unnecessarily increasing the risks involved for the woman.
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‘Embryo-free’ alternatives |
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The second strategy to overcome the moral objections against the use of embryos for stem cell research is to bypass the embryo altogether. Two methods can be distinguished here: somatic cell dedifferentiation and the use of biological artefacts.
Somatic cell dedifferentiation
Direct reprogramming of an adult somatic cell to return to the state of a pluripotent stem cell would be ideal. No embryo would have to be created to obtain stem cells, and thus none would have to be destroyed. More importantly, dedifferentiated cells would contain the same genetic information as the donor, hence reducing the risk of an immune reaction or graft-versus-host disease in clinical applications. By bypassing the SCNT, the procedure become simpler and better suited for large-scale applications.
Even though much remains unknown about the processes underlying dedifferentiation, human somatic cell nuclei have been reprogrammed indirectly by fusing them with an embryonic stem cell (Cowan et al., 2005). This method, however, is facing the technical challenge of removing the original embryonic stem cell’s chromosomes from the hybrid cell. Recently, Grompe and George (2005) have suggested developing a technique they call OAR to dodge these problems. This proposal would circumvent the creation of any embryo-like entity by using a somatic cell nucleus altered to express transcription factors characteristic of embryonic stem cells, which is then reprogrammed by transplantation into an enucleated oocyte. The resulting cell would display the molecular characteristics and developmental behaviour of a pluripotent stem cell rather than a totipotent embryo. For the time being, the reliability of this procedure has not been established, but nevertheless, reprogramming is widely considered the most promising route for future research.
Biological artefacts
The second solution is mainly represented by Hurlbut’s idea of altering the SCNT procedure to produce an embryo-like artefact that, although incapable of completing embryogenesis, could be a source of pluripotent stem cells. This artefact would be similar to a parthenote, that equally resembles an embryo in the first phase of its development, but results in disorganized (though differentiated) tissue with no chances of a live birth in mammals, unless profound genetic engineering is employed (Kono et al., 2004). However, even though these entities lack the potential to become human beings, the question for many remains whether they are fundamentally different from a human embryo or whether they are just some kind of defective embryo.
Hurlbut’s reasoning goes as follows: the entity created by ANT is not an embryo, therefore it cannot have any moral status and therefore its destruction for stem cell research is unproblematic. This reasoning prompts two questions: Which entities are embryos? and On which basis should moral status be accorded to them?
Which entities are embryos?
Statements have been made that as long as we cannot define an embryo, ‘finding a technical end-run around moral objections to creating embryonic stem cells is likely to flop’ (Russo, 2005). Unfortunately, as our knowledge about embryogenesis increases and new techniques are developed to create all kinds of entities using human gametes or cells, doubts about the defining characteristics of the embryo abound (Pennings and de Wert, 2005).
First, there is no clear distinction between non-viable embryos and non-embryonic entities mimicking embryogenesis. Hurlbut has made ardent attempts to convince the public that ANT does not merely create a non-viable entity, but a ‘biological entity that [...] lacks the attributes and capacities of a human embryo [...] a system that is not an organism, but is biologically (and morally) more akin to the partial organic potential of a tissue or cell culture’ (Hurlbut, 2004). If Hurlbut is right in his assessment that this ‘ANTity’ (Devolder, 2006) is not an embryo, consistency requires that parthenotes and aneuploid or improperly imprinted entities resulting from fertilization are not embryos either, because they equally lack the potential of developing into a human organism ‘by design and from [their] beginning’, even though they ‘may still proceed along partial trajectories of organic growth without being actual organisms’ (Hurlbut, 2004). This may not represent a great shift in how a parthenote is regarded, but it does collide with the intuitive classification of aneuploid entities as embryos. One might wonder if Hurlbut’s proposal leaves any room for the existence of non-viable embryos at all. At the same time, however, he stresses that ANT creates entities that are fundamentally different from non-viable embryos, which only adds to the confusion.
Second, it is unclear to what extent external factors can influence the difference between an embryo and a mere entity. Any definition of an embryo will need to incorporate the idea that it is a potential person. However, this potential can be interpreted very widely or very narrowly. A narrow interpretation would be that an entity only has the potential to become a human being if it can do so without any outside intervention. In this scenario, many entities are excluded from being embryos, including IVF embryos, because nobody was ever born in a Petri dish. If a somewhat wider interpretation is adopted to include embryos that can become human beings provided they are placed in a favourable environment, IVF embryos will be considered embryos, but human SCNT embryos might not, because the chances of these embryos developing to term if transferred are presumably close to non-existent. On the other extreme, one could say that any entity that can be manipulated into becoming a human being is an embryo, regardless of the extent of technical interference. In this case, parthenotes should be considered embryos (Kono et al., 2004). Even skin cells can be regarded as embryos, because they can become a human if only their nucleus is transferred to an enucleated oocyte. The right amount of technical interference that can be allowed without repudiating our common sense understanding of what an embryo is must lie somewhere in between these two extremes, but any interpretation of what it means to have the potential to become a human being is likely to be judged by some as too wide and by others as too narrow.
Even though it may be impossible to find a definition of the embryo that everyone can agree on, this does not imply that the stem cell debate is bound to persist. The problem for Hurlbut and colleagues is that they attribute full moral status, similar to a person’s, to every embryo, regardless of its characteristics. However, if different kinds of embryos demand different levels of respect, then the ethical debate may not be decided on the level of a definition (Dondorp and de Wert, 2005). The crucial query then becomes what characteristics endow an entity with moral status.
On which basis should moral status be accorded to entities that are embryos?
The main argument for according moral status to an embryo, apart from any status attributed by the intentional parents, is the potentiality argument. Because an embryo has the potential to become a human organism, and because we accord a supreme moral status to human life, many are convinced that some of that status has to be accorded to the embryo as well. Some religious groups advocate that this status even equals the moral status of a person, rendering any kind of utilitarian balancing unwarranted. However, the counterintuitive nature of this assessment is obvious in real-life situations: ‘If there was a young child inside an infertility clinic that had caught on fire and a shelf full of embryos in a freezer, which ought to [be] saved first? If the embryos were to be destroyed, that would be unfortunate. If the child were to be killed that would be a tragedy beyond belief.’ (Caplan, 2005).
On the other end of the spectrum it is argued that because embryos do not display any of the characteristics of a person, they are not entitled to any moral consideration other than that resulting from the intentional parents’ hope of the embryo becoming their child.
An intermediate position is most common however, holding that an embryo does not require the same respect as a person, but is entitled to some degree of protection, which increases as the embryo grows (Pennings and de Wert, 2003). This intermediate position is reflected in the widespread acceptance of embryo research for the development of infertility treatments and for the studying of congenital diseases on one hand and the widespread disapproval of using embryos for trivial purposes, such as the development of cosmetics, on the other. When it comes to embryonic stem cell research, some argue that it is far more promising and important than research into infertility, especially considering the scope of its possible applications, and should thus be permitted. Others argue that in the case of stem cell research, alternative strategies exist that are not present for research into infertility or congenital diseases, leaving embryonic stem cell research ‘unnecessary’ and therefore impermissible. The principle of necessity however fails to incorporate important factors that were discussed earlier, such as speed of progress, quality of resulting treatments, extent of the field of application, safety and security (Pennings and Van Steirteghem, 2004).
When deciding on the permissibility of a certain type of embryo research against the backdrop of an intermediate position, at least three factors need to be taken into consideration. First, embryos have a symbolic value in our society as they represent nascent human life and therefore command to be treated with respect and not to be used for trivial purposes (Robertson, 1999). Because stem cell research is all but trivial, this first factor is not persuasive when it comes to ruling out embryonic stem cell research. Second, certain embryos may be valuable for prospective parents, as they intend to have them implanted and hope they will become their child(ren). This category of embryos, being part of a ‘parental project’, holds a status that is significant enough to rule out their use in stem cell research. Non-destructive procedures (unless they are performed to the benefit of the embryo) would be unethical because they may harm a future person, and destructive procedures would be unethical because they would harm the intentional parents. The third and final factor to be considered is whether the embryo is viable and thus has the potential to become a person (Buckle, 1988). This factor depends both on intrinsic properties of the embryo (euploidy, normal imprinting, etc.) and, especially in the case of in vitro embryos, on the intentions of the prospective parents. It is hard to argue how an embryo that will never become a person can be morally harmed. Damaging an embryo that is intended to become a person in the future, however, collides with the anticipated rights of this future person. Keeping this in mind, we have compelling reasons to prevent embryos that will be implanted from being used in stem cell research, and to encourage the use of spare embryos, even though both types of embryos are identical on a biological level. Likewise, a parthenote or the artefact created by ANT does not deserve the same protection as a viable embryo.
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Conclusion |
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Although some possible alternative sources of pluripotent stem cells, such as reprogramming, offer promising routes for the future of stem cell research, many may be unable to solve the ethical problems of people adopting a gradualist vision of the embryo’s status. This is due to the numerous compromises that are necessary to bypass embryo destruction but that have a negative effect on the overall benefits of stem cell research. Depending on the status that one accords to the embryo, these compromises may nullify the ethical preference for embryo-free alternatives over methods involving the destruction of embryos.
Generally, two strategies are used to dodge ethical challenges in embryonic research: applying the separation principle and turning to biological artefacts. The first strategy tries to clear the stem cell researcher from any responsibility for the embryo’s destruction but fails to make a compelling case. The second strategy attempts to exclude the use of embryos entirely. However, it has proven to be a hard task to define the very entity that constitutes an embryo.
The presentation of embryonic stem cell research as unethical and of embryo-free stem cell research as ethical is therefore too simplistic, and in the case of many proposed alternatives, unrealistic and misleading.
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References |
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