Earlier this week scientists at the Oregon Health and Science University reported they had produced embryonic stem cells from a cloned human embryo. Here are 9 things you should know about human cloning:
1. Cloning is a form of reproduction in which offspring result not from the chance union of egg and sperm (sexual reproduction) but from the deliberate replication of the genetic makeup of another single individual (asexual reproduction). Human cloning, therefore, is the asexual production of a new human organism that is, at all stages of human development, genetically virtually identical to a currently existing or previously existing human being.
2. Human cloning is achieved by a technique referred to as somatic cell nuclear transfer (SCNT). The process involves introducing material from the nucleus of a human somatic cell (any biological cell forming the body of an organism, though for the purposes of SCNT, usually a skin cell) into an oocyte (a female egg cell that has not yet gone through the process to become an ovum) whose own nucleus has been removed or inactivated. The oocyte becomes an ovum that now no longer needs to be fertilized, because it contains the correct amount of genetic material. This new entity begins dividing and growing, yielding a cloned human embryo.
3. Cloning does not produce an exact genetic replica of the donor (the person the genetic material was taken from to produce the cloned embryo). All human cells, including eggs and sperm, contain small, energy-producing organelles called mitochondria. Mitochondria contain a small piece of DNA that specifies the genetic instructions for making several essential mitochondrial proteins. SCNT transfers the nucleus into the oocyte which contains mitochondrial DNA of the egg donor. Just as in sexual reproduction, the embryo produced by cloning contains genetic material from two different individuals.
4. Due to missing, but crucial interactions between the sperm and egg, genetic reprogramming errors' are inherent to cloning. This leads to random, widespread genetic 'imprinting' and 'epigenetic' defects that are both known causes of cancer. In addition to the 'epigenetic' defects, cells derived from cloning that are injected back into the donor are rejected because of epigenetic mis-expression, genetic differences due to mitochondrial DNA, and the incompatibility of cells too immature in development to interact with adult tissue environments. This is the major stumbling block for using material from cloned embryos for the treatment of diseases.
5. The use of the terms therapeutic cloning and reproductive cloning are misleading. All cloning produces a human embryo and is therefore reproductive in nature. The more accurate, neutral phrasing is cloning-to-produce-children and cloning-for-biomedical-research. These terms make a distinction between cloning that results in the creation of an embryo for subsequent destruction and one that is created in order to continue the normal process of human development.
6. The primary moral objection to cloning for research is that it creates human life solely for the purpose of destroying it; using a human embryo merely as a means to an end. In order to justify the killing of these human beings for their "spare parts", we have to ignore the scientific understanding what makes a member of the human species and argue on the metaphysical definition of what constitutes personhood.' While it is true that many people oppose the cloning of human embryos for valid religious and ethical reasons, the issue is not divided along the typical left/right political spectrum. Even pro-choice advocates and others who hold secular and/or progressive political views find sufficient ethical concerns for opposing the procedure. Daniel Sulmasy, a professor of medicine and a bioethicist at the University of Chicago, told National Public Radio (NPR), "This is a case in which one is deliberately setting out to create a human being for the sole purpose of destroying that human being. I'm of the school that thinks that that's morally wrong no matter how much good could come of it."
7. Currently, the primary justification for therapeutic cloning is as a means of harvesting embryonic stem cells—a process that ends a human life—for research purposes. Despite years of media hype and billions of dollars dedicated to the venture, embryonic stem cell research (ESCR) has never produced any clinically proven therapies—and likely never will. As the Washington Post wrote earlier this week, "few experts think that production of stem cells through cloning is likely to be medically useful soon, or possibly ever." ESCR has been one of the most expensive boondoggles in biomedical history.
8. Cloning not only compounds the ethical concerns of ESCR but adds a significant number of other moral problems. This Machiavellian approach would be difficult to justify even if ESCR were to lead to miraculous cures. But research using harvested embryonic stem cells appears to be an unnecessarily speculative undertaking and a waste of money, life, and medical research. The use of adult stem cells, however, has none of the ethical problems and far fewer of the biomedical complications of ESCR. In fact, more than 70 types of therapies have been developed using adult stem cells.
9. As the President's Council on Bioethics explained in 2005,
The prospect of cloning-to-produce-children, which would be a radically new form of procreation, raises deep concerns about identity and individuality, the meaning of having children, the difference between procreation and manufacture, and the relationship between the generations. Cloning-for-biomedical-research also raises new questions about the manipulation of some human beings for the benefit of others, the freedom and value of biomedical inquiry, our obligation to heal the sick (and its limits), and the respect and protection owed to nascent human life. Moreover, the legislative debates over human cloning raise questions about the relationship between science and society, especially about whether society can or should exercise ethical and prudential control over biomedical technology and the conduct of biomedical research. Rarely has such a seemingly small innovation raised such large questions.
(Although the studies on cloning and ESCR produced by the President's Council on Bioethics were once available at Bioethics.gov, the Obama administration has removed all the work produced by the previous council.)
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