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About this article Cite this article Ethics of therapeutic cloning. Copy to clipboard. Creating embryos merely as a means - for whatever laudable purpose - fails grant them any sort of respect.
Only if we have truly subverted our Christian faith to a faith in medical progress and all its rituals and promises can we find a way to respect what we destroy as some kind of honorable sacrifice. Defenders might call it the necessary first step toward greater advances. But very little is known about embryonic stem cells. Talk of cures for Parkinson's and Alzheimer's disease rouses hope. More importantly, for researchers and biotechnology venture capitalists, such talk raises a wave of expectation and political pressure that places those with less enthusiastic stances in the position of appearing morally blameworthy for inhibiting progress against suffering.
Nevertheless, if we are to stand for any form of moral respect for human pre-embryos, however modest, we must encourage the search for morally preferable alternatives to cloning, or even eliminate ES cell research altogether. Much more could be learned from other types of stem cells, animal studies, or types of research that would not require cloning or the destruction of embryos.
But advances in the use of cloning techniques, even if only for potential therapeutic application, would lead science further down a path that would make cloning for reproductive purposes easier. As more studies are published illustrating successful cloning techniques, the reproductive option will be encouraged.
Thus, the ethics of the two forms of cloning cannot be cleanly separated. And human reproductive cloning is morally wrong for many reasons. But this larger utilitarian purpose is not the ethic of the Church. If a person can agree to undergo a dangerous malaria vaccine study to help cure disease, why should they be prevented from donating eggs for similar lifesaving research? In the end, we concluded that it would be unduly paternalistic to prohibit women from donating eggs for this research.
At the same time, we established a rigorous informed-consent procedure so that egg donors would be made fully aware of the possible dangers.
We insisted that ovulation-stimulating medications be administered at safe dosages. We wanted to prevent payment from becoming an undue influence that could blind women to the risks. What are the ethical issues relating to the person whose cells are being cloned? It may seem that individuals who provide the cells usually skin fibroblasts that are fused with enucleated eggs in therapeutic cloning research face no risk apart from the remote possibility of an infection at the site of the skin biopsy.
But cloning is a controversial issue that exposes all research participants to novel risks. Cell donors, for example, might find themselves at the center of a media storm if they are identified as having allowed themselves to be cloned. To prevent this, the ethics advisory board insisted on procedures ensuring strict confidentiality for both egg and cell donors unless they choose to come forward. One question that occupied much of our time was whether children could donate cells for this research.
We concluded that in general this is not advisable, because on reaching maturity the child may feel morally compromised by having been made to contribute to a cloning procedure. We made an exception, however, in the case of an infant with a fatal genetic disease.
We knew that a stem cell line based on the childs DNA might be a powerful tool in research aimed at curing the disease. Although the child would probably not survive long enough to benefit from this research, we concluded that the parents had a right to make this decision on the childs behalf. This childs cells have not yet been used in a cloning procedure. Will therapeutic cloning facilitate reproductive cloning, the birth of a cloned baby?
A final major question raised by this research is whether it will hasten the day when people undertake human reproductive cloning. This concern presumes that reproductive cloning is and always will be ethically wrong. Many who hold this view cite the incidence of deaths and birth defects in cloned animals. Others worry about more remote dangers. They point to possible psychological risks to children produced in families in which a parent may also be a childs genetic twin.
They fear that cloned children may face unrealistic expectations to live up to the achievements of their genetic predecessor. And they worry about possible social risks of cloning if societies decide to replicate a limited number of desired genomes on a large scale for military or other purposes.
In opposition to this, some people hail the prospect of cloning. They see it as a new way to provide biologically related offspring for some infertile couples or as a means of reducing the risks of some inherited genetic diseases. In sum, the issue of pathogenic transmission is in the process of being solved, bringing one step further the potential for clinical application of therapeutic cloning in cell replacement therapy.
NtESC are subjected to the same tumorigenicity potential as wild-type stem cells. The formation of teratomas, after in vivo transplantation, is due to co-purification of pluripotent stem cells along with the wanted differentiated cells.
The teratomas resulted from a low concentration of 0. Although the hyperglycemia associated with type I diabetes was reversed, tumorgenesis occurred 20 days post-transplantation, rendering stem cells, whether wild-type or issued from therapeutic cloning, a non-viable option for clinical applications in this instance, unless better isolation methods for the exclusive purification of differentiated stem cells are designed.
The apparition of the primitive streak directing polarized development confers to the two-week embryo a higher moral status 51 as a potential human organism, compared to the earlier embryo at the stage of a randomly-organized group of cells. Consequently, laws prohibiting the culture of embryos for more than two-weeks, which marks the onset of gastrulation and the formation of the primitive streak, are in vigor in several countries such as the United States, based on a decision of the British Warnock Commission 29 in The ethical debate on the moral impermissibility of deliberate destruction of an embryo can be circumvented by a new technique deviced by Chung et al.
They successfully derived human ESC from a single cell without destroying the blastocyst in the process 52 , using the same manipulations normally devoted to genetic screening in preimplantation embryos. This method seems to be promising for solving the ethical concern of killing a human embryo, rendering feasible the prenatal generation of individual-specific cell lines for use in regenerative medicine later on in life.
The main ethical roadblock against therapeutic cloning is the destruction of the generated embryos in order to collect cells that would further be differentiated in vitro. Embryo destruction is viewed as morally objectionable by the Prolife partisans because they grant the early embryo potential for personhood following development to term.
However, the detractors of research using embryos would argue that the potential for personhood ought not to be granted on the basis of probability because a minority - one out of three 54 -of zygotes conceived by natural means might implant in utero and be carried to term. Hence, the argument from potential relies on possibility rather than probability and is based on the belief that morally significant human life beings at conception.
A counterargument put forth by the advocates of embryo research is that, left untouched, it is impossible that the in vitro embryo develops into the mature organism, and in utero implantation cannot occur if the transferred embryo reached the eight-celled stage and beyond Nothing morally compelled one to generate a SCNT embryo that would have otherwise not existed, therefore we are not morally obligated to transfer the latter in utero.
The destruction of an embryo of lower moral significance in the context of justified research to improve the quality of life of existing people of higher moral status ought to be viewed as morally permissible. The engineering of mouse blastocysts lacking the Cdx2 gene, otherwise needed for the generation of the midgut endoderm and trophoblast differenciation, results in non-viable embryos that spontaneously stop dividing, providing a criticized alternative to the destruction of embryos by deliberate human action.
Although several scientific roadblocks remain unsolved, the medical benefits that could be gained from treatments based on therapeutic cloning outweigh the ethical dilemma and calls for further improvements to be clinically applicable.
In sum, therapeutic cloning features great potential as a histocompatible method for cell replacement therapy to restore motility following paralysis, counteract senescence, and repair damages done by stroke, myocardial infarction, liver cirrhosis, severe burns and osteoporosis to name a few.
Used as an alternative to viral vectors, patient-specific cell lines derived through SCNT can be used in conjunction with gene therapy to treat conditions caused by genetic defects among which diabetes, hemophilia, sickle cell anemia, SCID, neurodegenerative disorders such as Parkinson, DMD and many more.
Transgene insertion could be used before in vivo transplantation of the ntESC in order to enhance graft survival, differentiation and integration. Other applications of therapeutic cloning include the diagnosis of epigenetically triggered cancer and the tailoring of a treatment using SCNT, the creation of animal models of human diseases, and could eventually lead to tissue engineering of organs de novo.
Main scientific difficulties include tumorigenicity, in vitro spontaneous differentiation, interspecies transfer of pathogens, low oocyte availability, epigenetic reprogramming of the genome, mitochondrial heteroplasmy and the possibility of graft rejection. Ethical controversy on the source and destruction of embryos as well as the contradictory legislations and scarcity of funding contribute to impede advancements in therapeutic cloning.
Future considerations would be to unify federal and state laws, and establish a clear distinction between therapeutic and reproductive cloning in the redaction of laws pertaining to the SCNT generation of embryos. In this regard, a close understanding of the science and ethical issues pertaining to therapeutic cloning is necessary to ensure improvement in clinical applicability without falling into unregulated abuses.
National Center for Biotechnology Information , U. Journal List Mcgill J Med v. Mcgill J Med. Author information Copyright and License information Disclaimer. Charlotte Kfoury B. Sc is graduating this year with an Honours degree in Biochemistry. She is looking forward to studying medicine at McGill this year, and hopes to do more research in the future.
This article has been cited by other articles in PMC. Abstract Advances in biotechnology necessitate both an understanding of scientific principles and ethical implications to be clinically applicable in medicine. Keywords: therapeutic cloning, SCNT, cell replacement therapy, gene therapy, mitochondrial heteroplasmy, oocyte availability, biomedical ethics.
Current legal status of therapeutic cloning in relation to reproductive cloning Laws regarding biomedicine are generally formulated in vague terms that do not distinguish reproductive from therapeutic cloning. Promises of therapeutic cloning SCNT in the context of therapeutic cloning holds a huge potential for research and clinical applications including the use of SCNT product as a vector for gene delivery, the creation of animal models of human diseases, and cell replacement therapy in regenerative medicine.
Applications in regenerative medicine: recent breakthroughs for diabetes and neurodegenerative diseases Therapeutic cloning constitutes a promising tool in tissue engineering and might offer the possibility of synthesizing organs de novo, which would solve the problems of immune rejection and organ shortage for transplantation.
Oocyte availability: regulations and ethical concerns A major roadblock in the feasibility of human therapeutic cloning is the low availability of oocytes for research purposes. Possible solutions to the oocyte shortage for therapeutic cloning Interestingly, SCNT could provide a solution to low human oocyte availability and a promising therapeutic approach to circumvent infertility.
Mitochondrial heteroplasmy Immune rejection of the ntESC in cell replacement therapy is due to mitochondrial heteroplasmy as a consequence of SCNT since the nuclear donor and ooplasmic host cells are not autologous in most cases. Transfer of animal contaminants The interspecies transmission of pathogens is a nonnegligible issue when injecting a human nucleus into the oocyte of another species, such as bovine or pig Tumorgenesis and spontaneous differentiation NtESC are subjected to the same tumorigenicity potential as wild-type stem cells.
Moral status of the IVF embryo and the argument of potential The main ethical roadblock against therapeutic cloning is the destruction of the generated embryos in order to collect cells that would further be differentiated in vitro. Snustad, Simmons. Principles of Genetics. Evaluation of the embryonic preimplantation potential of human adult somatic cells via an embryo interspecies bioassay using bovine oocytes.
Fertil Steril. Embryonic stem cells: a promising tool for cell replacement therapy. J Cell Mol Med. Arsanjani Mahnoush H. The American Journal of International Law. Pattinson SD. Med Law. Center for Genetics and Society. Dennis C. Australia considers changing laws to allow therapeutic cloning. Nat Med. Zavos PM, Illmensee K. Possible therapy of male infertility by reproductive cloning: one cloned human 4-cell embryo. Arch Androl. Human neural stem cells promote corticospinal axons regeneration and synapse reformation in injured spinal cord of rats.
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