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Cloning is the practice of creating a genetically the same copy of an original creature. And although it seems like twentieth-century idea, cloning is actually a part of natural processes, and had taken place many decades before though it was attainable. Since a variant of the cloning process plays such a large role in stem therapies, it’s worth taking a look at how cloning processes work (Cohen, 2002).
Most public attention has been focused on the area called reproductive cloning – reproducing an entire creature be it frog, sheep, dog, or human being.
As the twenty-first century unfolds, it is far more likely that what has been called therapeutic cloning – cloning used to cure disease – is going to have a more immediate impact on all our lives. Your chances of getting a cloned liver are greater than your chances of seeing a cloned you (Avise, 2004).
Relative to genetic testing, therapeutic cloning is a technology very much in its infancy.
Whereas we can plausibly predict, that genetic testing methods and the scope of such tests will dramatically improve in the proximate future, a like projection in the case of therapeutic cloning is more of a stretch. This view notwithstanding, analysis of current regulation of therapeutic cloning does have something to gain from postulating a future world in which therapeutic cloning is in clinical application (Savulescu & Hendrick, 2003).
One likely application of therapeutic cloning is in the treatment of leukemia, and more broadly in various types of tissue and organ transplantation.
Therapeutic cloning is important for four seasons. First, there is a shortage of tissue for transplantation. Second, there are problems with compatibility of transplanted tissue form another individual, requiring immunosuppressive therapy with serious side effects. Cloned tissue would be compatible without the infectious risks of xenotransplants. Third, the role of transplantation might be expanded to include common diseases such as heart attack and stroke. Fourth, cloning may prove to be a cost-efficient means of preventing disability and morbidity, and of promoting distributive justice (Shannon, 2005).
In considering the ethical aspects of therapeutic cloning there are two separate issues: should embryos produced during in vitro fertilization (IVF), which would otherwise be discarded, be available for research (with the consent of the couple who produced them); and, should we deliberately create embryos for use in research? It is difficult to argue against using embryos that would otherwise be discarded. The main ethical issue raised by both the production of ES cells and therapeutic cloning, is that of destroying embryos for the purposed of research or tissue for transplantation.
If the embryo is considered to have a moral status similar to, say, a child, them embryo research would normally be wrong. On this view, IVF and almost any termination of pregnancy would also be wrong. A less absolute position would be that what is wrong with destroying embryos is a need to respect human life in general. But that wrong need to be balanced against the value of such research. Furthermore, for every live birth, up to five embryos will miscarry. In attempting to have a child by natural conception, we implicitly accept that this loss is a price worth paying to produce a new life. If the loss of embryos is an acceptable price to pay to produce a new life, is it not also an acceptable price to pay to save an existing life (Avise, 2004)?
Tissue Therapy via Therapeutic Cloning
More than 40 years elapsed since Joseph Murray and his colleagues at a Boston hospital successfully transplanted a kidney between identical twins. This landmark approach was later extended by the medical community to other organs (e.g., heart, liver, lung, and pancreas) and to transplants involving more distant relatives and unrelated individuals.
Transplants between unrelated individuals are especially challenging because, unless ameliorative actions are taken, the immune system of a transplant recipient sooner or later rejects the alien cells. To alleviate this problem, donor and recipient typically are matched as closely as possible for genes underlying immune responses, and immune-suppressive drugs also are administered. Such procedures are fairly common and have saved many lives. Nonetheless, modern transplantation surgery remains risky due to inherent immunological intolerances of patients to foreign tissue (Cohen, 2002).
Thus, many research professionals are excited about “therapeutic cloning,” a new genetically modified (GM) approach that in theory should avoid the immunorejection problem. In this procedure, genes in cells to be transplanted originate from the patient, who therefore serves in effect as both donor and recipient. Because the donor and recipient tissues have identical genotypes, presumably the immune system would not recognize the implanted tissue alien. Another reason for enthusiasm about therapeutic cloning is that this research gives scientists welcome opportunities for basic research on human genetic disorders as they unfold during cell and tissue development (Bellomo, 2006).
The notion of therapeutic cloning for tissue or organ reconstruction in humans traces to the development of nuclear-transfer cloning methods for sheep and other farm animals. As applied to human cells, the procedure might work as follows: A suitable cell is removed from a patient and its nucleus is inserted physically into an enucleated egg. The egg then begins to multiply in a test tube, and, from the developing mass, pluripotent cells (those that possess a capacity to differentiate into multiple tissue types) are induced to grow replacement cells needed by the patient.
Nerve cells might be grown to treat Alzheimer’s disease or spinal cord injuries, skin cells could be used to repair burn damage, retinal cells for macular degeneration, pancreatic cells for diabetes, hematopoietic cells for leukemia, neuroglia cells for multiple sclerosis, and so on. When returned to the patient’s body the cloned cells in such tissues or organs ideally would repair or replace the damaged body part, without evoking immunological rejections (Avise, 2004).
Several technical challenges must be overcome before this approach is medically viable. First, nuclear transfer (NT) techniques developed for farm animals will have to be improved and adapted to our species. Second, cells in the proliferating mass must be generated in such a way that they indeed are pluripotent at the outset. Third, the developmental potential of those flexible cells then must be channeled to produce the specialized kind of tissue that the patient requires. Fourth, methods must be devised to put those now-dedicated cells together properly to make therapeutically useful tissue or organ.
This may take place naturally when the cells are placed in a patient’s body, or in some cases it may be accomplished initially in vitro. For example, replacement skin tissue for burn victims might be constructed by seeding the cloned cells onto sheets of a polymeric scaffolding substance. Finally, tissue therapy must be conducted such that the cloned cells do no harm when returned to the patient. It would be disastrous, for example, if even a few cells in the transplanted tissue began to divide in an unregulated, cancerous fashion (Shannon, 2005).
Of course, ethical issues will have to be addressed as well. When the initial oocyte created by NT begins to divide into two cells, then four, then eight, and so on, when does the cloned mass become a new human being worthy of protection under the law? Opponents of therapeutic cloning often contend that an individual arises at the exact moment that the first appears, such that any sacrifice of an early cell mass, even for medical purposes, is tantamount to slaughter.
Proponents of therapeutic cloning view this notion as nonsense. How, they as, can a few amorphous cells be granted legal rights that take precedence over those of sentient human beings is desperate need of cell therapy? Remarkably, in US society, most of the debate over the possible legalization of therapeutic cloning hinges on this one emotion-laden philosophical issue (Bellomo, 2006).
In such public discussions, a common error (or often, an intentional argumentative ploy) is to equate therapeutic cloning with reproductive cloning. Although the initial laboratory steps in the two procedures are identical – both begin by inserting a cell nucleus into an unfertilized egg – that is where the similarity ends. In reproductive cloning, the GM egg would be re-implanted in the womb and allowed to grow into a fetus and baby, the intent being to generate a fully functional and independent human being genetically identical to its predecessor. In therapeutic cloning, the early clump of pre-implantation cells that comes from the GM egg would be grown in vitro and used to produce replacement tissues for medical rehabilitation (Avise, 2004).
Elimination or Treating Heritable Diseases via Therapeutic Cloning
Although therapeutic cloning does not reproduce an entire organism to develop in utero and live life outside the womb, one motivation for reproductive cloning might be therapeutic. Reproductive cloning could allow genetic engineering interventions to correct defective genes before they have a chance to exert detrimental effects. Correction at the earliest stage would also free germ or reproductive cells and hence subsequent generations from carrying the defective gene (Savulescu & Hendrick, 2003).
Certain genetic disorders may enhance certain universal human vulnerabilities, such as those to infection, bleeding, and aging. Beyond increasing these, everyone has inherited vulnerability to some disease or diseases. We would all like to be free from the threat of heart disease, cancer, diabetes, hypertension, and Alzheimer’s disease. Therapeutic cloning might substantially improve the treatment for these diseases since therapy for these is currently limited by the availability or immunocompatibility of tissue transplants (Avise, 2004).
Among the genetic disorders, some are so highly heritable and horrific that we might wish to employ reproductive cloning to enable the use of genetic engineering to correct the defective gene. That would free the clone and all subsequent generations from their ravaging impact (Savulescu & Hendrick, 2003).
However, reproductive cloning is an inefficient and error-probe process that results in the failure of most clones during development. For a donor nucleus to support development it must properly activate genes important for early embryonic development, it must properly activate genes important for early embryonic development and suppress differentiation-associated genes that were transcribed in the original donor cell. Inadequate “reprogramming” of the donor nucleus is thought to be the principal reason for the developmental loss of most clones. In contrast, reprogramming errors do not appear to interfere with therapeutic cloning, because the process appears to select for functional cells (Shannon, 2005).
Ethics of Therapeutic Cloning
Can therapeutic cloning be ethically tolerable? Debates about the theory of proportionality, the slippery slope and the principle of subsidiarity here center again in a little dissimilar way (Savulescu & Hendrick, 2003).
It is uncertain whether the principle of proportionality offers a believable a priori opposition against therapeutic cloning. If it is well thought-out suitable to make embryos for study aiming cryopreservation of oocytes; in vitro maturation of oocytes and the like, then it is contradictory to decline therapeutic cloning in advance as being disproportional (Avise, 2004).
A consequentialist opposition, as a slippery-slope disagreement, is that therapeutic cloning will unavoidably direct to reproductive cloning. This objection firstly presumes that reproductive cloning is necessarily and categorically wrong, a premise still debated. Clearly, it would be premature, if not criminally irresponsible, in view of the serious health risks for children conceived by cloning to start clinical trials on reproductive cloning right now. But what if, somewhere in the future, these risks could be controlled? Would cloning then still be entirely baseless – even if it were ‘safe’ – then it is practical to exclude reproductive cloning, and not to forbid other, non-reproductive, relevance of cloning (Bellomo, 2006).
Are there suitable alternatives to therapeutic cloning? First, it is important to note that therapeutic cloning strictu sensu, starting with the first clinical trials, will not come up soon. Much basic research is needed, about the question whether it will be possible to control the differentiation of human embryonic stem (hES) cells in vitro. This study can, and ought to, be made with additional IVF embryos. At the same time, research into potential ‘embryo-saving’ alternatives for therapeutic cloning should be stimulated.
For the relative ethical examination it is once more essential to evade the drawback of one-dimensionality. Amongst others, the following options are suggested in the literature: a) the use of adult stem cells; b) transferring a human somatic cell nucleus into an enucleated animal egg; and c) the direct reprogramming of adult cells, i.e., to reprogram an adult cell to make it revert to it unspecialized state so that it can then be influenced to develop into a specific type of tissue (this involves the development of undifferentiated cells without the need to create an embryo) (Shannon, 2005).
Summary and Conclusion
Cloning can be divided into therapeutic and reproductive cloning. Therapeutic cloning is the use of cloning technology to produce, for example, tissues for transplantation to people with disease. Reproductive cloning is cloning to produce a liveborn offspring (Avise, 2004).
The possibility of therapeutic cloning focuses on the concept of stem cells. Stem cells have the ability to develop into different mature cell types. Totipotent stem cells are cells with the potential to form a complete animal if placed in a uterus. They are early embryos. Pluripotent stem cells are immature stem cells with the potential to develop into any of the mature cell types in the adult (liver, lung, skin, blood etc.), but cannot by themselves form a complete animal if placed in a uterus.
Human embryonic stem (ES) cell lines obtained from the inner cell mass of the blastocyst or pre-implantation embryo have recently been established. ES cells are pluripotent. Possible future clinical applications of human ES cell technology include: hemopoietic repopulation (‘bone marrow transplant’); treatment of diseases or spinal cord injury; screening of drugs; and as vectors for gene therapy (Cohen, 2002).
We should distinguish reproductive cloning with a therapeutic intent from therapeutic cloning to produce stem cells. Most of us are familiar with the nightmare scenario of reproductively cloning a person in order to use him as possession for “spare parts.” Parents who conceive children in the hope that the new child would be a good match immunologically to donate an organ needed by an existing child contribute to this image. With a child cloned from the original, there would be no doubt that the needed organ would perfectly match the recipient immunologically. Creating a person to be a source of spare parts is not what therapeutic cloning is about (Bellomo, 2006).
Therapeutic cloning provides hope for cures or better medical treatment for people with many diseases. These include many of the genetic disorders for which reproductive cloning with a therapeutic intent might be entertained, but they also include diseases that are not necessarily genetic. A therapeutic cloning, cells are extracted from an embryo to clone specific bodily tissues for medical use, particularly transplantation. Type I or juvenile diabetes is one example of a disease that might be cured by therapeutic cloning to produce stem cells. Without contradiction, we can condemn reproductive cloning and at the same time, if we choose, support research with embryonic stem cells (Cohen, 2002).
Avise, J. C. (2004). The Hope, Hype & Reality of Genetic Engineering: Remarkable Stories from Agriculture, Industry, Medicine and the Environment. New York: Oxford University Press US.
Bellomo, M. (2006). The Stem Cell Divide: The Facts, the Fiction, and the Fear Driving the Greatest Scientific, Political, and Religious Debate of Our Time: AMACOM Div American Mgmt Assn.
Cohen, D. (2002). Cloning. Brookfield, Connecticut: Twenty-First Century Books.
Savulescu, J., & Hendrick, J. (2003). Medical Ethics and Law: The Core Curriculum. New York: Elsevier Health Sciences.
Shannon, T. A. (2005). Genetics: Science, Ethics, and Public Policy : a Reader. New York: Rowman & Littlefield.
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