Genetic Engineering and Genetic Cloning
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cloning humans. Although there are many potential benefits to this technology, the prospect of cloning humans has raised many practical, ethical and religious dilemmas that are currently being debated by society. As of now, the actual cloning of humans does not seem likely to occur in the foreseeable future.A controversial issue is the possible application of new techniques in genetic engineering to produce human clones. Up until now genetic engineering and cloning has been used to clone plants, unicellular organisms, amphibians and simple mammals. This has led to significant advances in agriculture, industry, and medicine. Newer techniques in genetic engineering have enabled scientists to clone more complex mammals and opened up the possibility of
Genetic engineering is the changing of an organism’s DNA, genetic material to eliminate unwanted traits or to produce desirable traits. The earliest form of genetic engineering dates back to the scientist Gregor Mendel who did experiments with peas. He bred only the peas with the most desirable traits in order to achieve a healthier and stronger pea (McCuen 8). This method, called selective breeding, is still used today with plants and animals in order to increase food production. Corn plants are selectively bred in order to produce a larger tastier kernel. Another type of genetic engineering called hybridization or crossbreeding involves breeding animals of different species in order to obtain the most desirable traits of both. Male donkeys are crossbred with female horses to produce mules, which are good work animals (Levine 1).
In 1938, Hans Speman proposed cloning a mammal by transplanting an adult cell’s nucleus into a fertilized egg. This process is called nuclear transfer and was initially used to clone a frog in 1952 (Sinha 59). Using this process, nuclear DNA from the body cell of a donor frog was injected into the egg cell of a recipient frog whose nuclear genetic material was removed. The fused cells divided just like a normal fertilized egg and formed an embryo that was genetically identical to the donor frog. In 1980 mice were successfully cloned using a similar procedure. The nucleus of a body cell of an embryo removed from a pregnant mouse was placed into a fertilized egg of another mouse whose own nucleus was removed. The cell was grown in vitro until it divided and became an embryo. It was then implanted into another mouse and allowed to grow to term.
Mammalian clones of sheep were reproduced in this fashion as well in 1984. This type of cloning needed to use embryonic cells. Almost all of an animal’s cells contain the genetic material needed to reproduce that animal. However, as cells differentiate into different tissues and organs, they only keep the genetic material needed to reproduce that organ. Therefore, only embryonic cells can be used for cloning because they have not differentiated into a specific type of tissue and still retain all the genes needed to make a copy of themselves (From Year in Review 1997 1). Although this method of cloning has been successful, most nuclear transfers do not result in live offspring. In addition, there have been a lot of objections raised regarding the use of embryos to clone mammals. Many people object based on religious grounds that the embryo has a soul from the moment of conception and therefore it should not be tampered with. Scientists were hoping that they could clone mammals without the use of embryos (Beddington 3).
In 1996, Ian Wilmut, at the Roslin Institute, accomplished this feat. He was able to successfully clone a sheep without the use of embryonic cells. Dolly the sheep was successfully cloned by transferring the nucleus of a non-reproductive cell, a mammary cell, into an unfertilized sheep egg from which its own genetic material had been removed. Dolly was an exact clone of the sheep that donated the mammary cell. Using a mammary cell was unique since until now only embryonic cells could develop into a full organism. Ian Wilmut was able to reprogram an adult cell to dedifferentiate and therefore the cell retained the genetic material needed to produce an entire organism and not just a mammary cell. The key to this new procedure was to time the cell cycle of the mammary cell with that of the egg. In order to do this nutrients were withheld from the mammary cell, which stopped it from dividing. The nucleus of the mammary cell was transferred into the recipient egg. An electrical current was given to the egg, which provided the energy that was needed for fertilization to occur. The egg began to divide and when it became an embryo it was placed into another sheep. The lamb that was born, Dolly was a clone of the donor of the original mammary cell (Kolata 27). This type of cloning is very exciting. This technique may be used to mass-produce animals that mimic human diseases for research purposes or to create animals with genetically modified organs that could be safely transplanted into humans. It could also be used to mass-produce animals for drug production or to improve livestock (Clone 1).
This new technique can theoretically also be used to clone humans. However, there are technical difficulties in cloning using a human egg. The unfertilized egg of a mammal has a supply of proteins that is used by the embryo until the embryos own genes can make the proteins for itself. Sheep embryos rely on their own genes after four cell divisions which is apparently enough time for the foreign nucleus to take over and reprogram the egg. However, human embryos begin producing proteins at an earlier stage so there is not a lot of time for the egg cytoplasm to reprogram the nucleus that was transplanted. This makes it harder to clone humans than it is to clone sheep. However, mice also begin producing proteins at an early stage and they were successfully cloned in 1998. This shows us that human cloning is theoretically possible even though they produce proteins at an early stage (Beddington 4).
There is currently a great debate going on concerning human cloning and the continuation of cloning research in general. People in favor of human cloning argue that human cloning would be useful in many ways. It would make it possible for infertile couples to have children of their own who are biologically related to them. Instead of having to use donated embryos, the couple could use their own adult cells to fertilize the egg. In addition, if a woman only has one egg, cloning could be used to make many copies of that egg. This would significantly increase her chances of getting pregnant. It would also enable couples who were at risk of having children with a genetic defect able to have perfectly healthy and normal children. For example, defective genes located in the mitochondria of the cell cause some diseases. If a woman carries a defective gene in her mitochondria she could still produce a healthy child by using nuclear transfer. The nucleus of one of her body cells could be placed into an enucleated egg cell from a woman without a defect in her mitochondria. The embryo can then be put back into the womb of the women who donated the nucleus then she can have a healthy child who is biologically related to her (Uses of Cloning 2). Another practical application of human cloning could be used as insurance for a person or his children’s health. Humans might be able to clone their own organs for autologous, self-transplantation. In addition, you could clone a woman’s fertilized egg. Then you could put one egg back into the woman and freeze the other eggs for transplants. If her child ever needed a bone marrow transplant, one of the eggs could be taken out of storage, implanted in her womb and allowed to mature into a baby. The new baby’s bone marrow could be used for to treat the other baby who is genetically identical to it. Human cloning might also be the miracle cure for spinal cord paralysis. Damaged nerves in adults do not regenerate on their own. Stem cells from a paralyzed person could be used to differentiate into his own nerve tissue. Since a large number of stem cells are required to create enough nerve tissue to repair the damage, cloning could be used to create enough stem cells. In addition, human cloning could lead to the understanding of cancer growth. The human egg divides at a similar rate as cancer cells. If information obtained from cloning research allows scientists to stop a human egg from dividing, a technique for stopping the growth of cancer might be
found (Robinson 6).
However, despite the many potential benefits of human cloning many people have raised strong objections to human cloning based on practical, ethical and religious grounds. Some of the practical objections to human cloning are that it is very expensive, technically demanding and inefficient. It took three hundred tries and many years of research to clone Dolly, which means that it will take even longer and many more tries to clone humans. In addition when attempts were made to clone Dolly, many lambs with abnormalities were born. One does not know how many abnormal humans will be born before the technique is successful (Beddington 3).
Numerous ethical objections have been raised as well. This scientific discovery is new and not proven to be safe in humans because we do not know the possible risks associated with manipulating the genes of a fetus or mature person. In addition, since the process is inefficient, many human embryos would be destroyed in the attempt to make one clone. People fear cloning may be used to eliminate a specific gender or to produce babies with certain desirable traits. Many ethicists believe this is tampering with “Mother Nature.” Another concern is that an amoral country could use cloning to create “perfect people.” To some people this is reminiscent of the horrible beliefs of Hitler who tried to create a perfect Aryan race. Alternatively, cloning could be used to create humans with subnormal intelligence to be used as slaves and workpeople. Another ethical concern is that the clone’s life span might be shorter because it was created from an adult cell. Cloning might also have a harmful effect on family relationships. If a child was born from adult DNA cloned from one of his parents he could be considered a delayed twin of one of his parents. This could lead to emotional problems between the parents and the child and parenting problems. In addition if the parent has a disease the child might worry that he will get the same disease as his parent. Many people argue that genetic cloning will decrease genetic diversity making large portions of a population prone to the same diseases (Robinson 7).
Many organizations and religious groups are opposed to cloning humans. The World Health Organization, The American Society of Reproductive Medicine and the three major religions, Judaism, Christianity and Islam do not condone human cloning. The underlying religious concern is that cloning is not natural and interferes with god’s work. The Catholic Church prohibits all types of cloning whereas the Muslims and Jews feel that some aspects of cloning may be permitted if cloning produces ways to counteract infertility or to produce better food or medication (The Cloning Debate: people and organizations 1).
In light of all of the practical, ethical and religious issues, former President Clinton banned federal funding for human cloning. He also asked the National Bioethics Advisory Committee to form an opinion on human cloning. The committee focused its attention on the use of somatic cell nuclear transfer techniques to create children, such as was used in the creation of Dolly. The committee examined issues of safety of the procedure, possible psychological harms to the clone including a diminished sense of individuality and self worth, possible harm to parenting and family life and religious issues. The commission recommended to continue a ban on the use of federal funding for cloning and requested all scientists and firms to listen and abide to this ban. It further recommended that there should be a law to prohibit anyone from trying to create a child through somatic cell nuclear transfer cloning. However, they recommend that Congress review this law after approximately three to five years in order to decide if this ban needs to be continued. This ban only relates to funding for public research. There are no written laws regarding private research (Executive Summary 3).
The current scientific state of the art of cloning indicates that actual cloning of a human being is achievable. We can be sure that many of the processes leading up to the ultimate cloning of a human being will be used to benefit the people of the twenty first century. This will include the use of nuclear transfer and cloning for gene therapy and reproductive medicine. However, ethical and religious dilemmas as well as practical difficulties will not allow the cloning of a human to proceed for the foreseeable future.