Human cloning: Is it possible?
May 07 2012
Though human reproductive cloning is still in its infancy, it is believed to have several benefits
Before beginning a discussion on this topic it is relevant to learn a little about the cloning technology. When discussing cloning in the sense of doing so to make a duplicate of an organism, science refers to it as “reproductive cloning.” For human reproductive cloning, the primary method that scientists will probably use is called “somatic cell nuclear transfer” (SCNT), which is the same procedure that was used to create Dolly.
SCNT begins when doctors take the egg from a female donor and remove its nucleus, creating an “enucleated egg.” A cell, which contains DNA, is taken from the person who is being cloned. Then, the enucleated egg is fused together with the cloning subject’s cell using electricity. This electro-fusion creates an embryo, which is implanted into a surrogate mother through in vitro fertilisation. If the procedure is successful, then the surrogate mother will give birth to a baby that’s a clone of the cloning subject at the end of a normal nine-month gestation period. As mentioned before, the success rate for this type of procedure is very small, working in only one or two, out of every 100 embryos. In fact, Dolly was the result of 276 previously failed attempts.
Given the small chance to produce a reproductive clone, at present, all published attempts to clone humans have failed. For example, in January 2001, a small consortium of scientists led by Panayiotis Zavos, a former University of Kentucky professor, and Italian researcher Severino Antinori said that they planned to clone a human in two years. The attempt simply failed after transplanting the embryo into the surrogate mother. Around the same time, an American couple planned to pay $500,000 to Las Vegas-based company “Clonaid” for a clone of their deceased infant daughter. Again this attempt failed. Then, in 2004, South Korean scientist Hwang Woo-Suk announced that he and his research team had cloned 11 human embryos for the purpose of extracting stem cells. However, after reviewing his work, a panel at Seoul National University concluded that his findings were false.
Although the practice is still far from being achieved, human cloning has been regarded as having several benefits. For example, Zavos and Antinori aimed to develop cloning to aid infertile couples. The group said that the procedure would have involved injecting cells from an infertile male into an egg, which would be inserted into the female’s uterus. This child would look the same as his or her father. Another possibility is of bringing deceased relatives back to life. A now-defunct company called “Genetics Savings & Clones” performed this type of cloning for a woman's dead cat, Little Nicky, in 2004.
Although reproductive cloning among humans might still be a distant dream, a process called therapeutic cloning is becoming popular. Therapeutic cloning is the process by which a person's DNA is used to grow an embryonic clone. However, instead of inserting this embryo into a surrogate mother, its cells are used to grow stem cells. These stem cells could become the basis for customised human “repair kits.” They can grow replacement organs, such as hearts, livers and skin. They can also be used to grow neurons to cure those who suffer from Alzheimer's, Parkinson's or Rett syndrome. And since the stem cells would come from embryo clones using your own cell’s DNA, your body would readily accept them.
In November 2001, scientists from Advanced Cell Technologies (ACT), a biotechnology company in Massachusetts, announced that they had cloned the first human embryos for the purpose of advancing therapeutic research. To do this, they collected eggs from women’s ovaries and then removed the genetic material from these eggs with a needle less than 2/10,000th of an inch wide. A skin cell was inserted inside the enucleated egg to serve as a new nucleus. The egg began to divide after it was stimulated with a chemical called “ionomycin.” However, the results were limited in success: Although this process was carried out with eight eggs, only three began dividing, and only one was able to divide into six cells before stopping.
Similar to therapeutic cloning there are other advantages. For example, another potential application of cloning to organ transplants is the creation of genetically-modified pigs from which organs suitable for human transplants could be harvested. The transplant of organs and tissues from animals to humans is called “xenotransplantation.” Of the animal species that have been cloned successfully, pig tissues and organs are more similar to those of humans. To create a “knock-out” pig, scientists must inactivate the genes that cause the human immune system to reject an implanted pig organ. The genes are knocked out in individual cells, which are then used to create clones from which organs can be harvested. In 2002, a British biotechnology company reported that it was the first to produce “double knock-out” pigs that have been genetically engineered to lack both copies of a gene involved in transplant rejection. However, more research is needed to study the transplantation of organs from “knock-out” pigs to other animals.
Beyond xenotransplantation, direct reproductive cloning has still more advantages. One could use it to repopulate endangered animals or animals that are difficult to breed. For example, in 2001, the first clone of an endangered wild animal was born, a wild ox called a gaur. The young gaur died from an infection about 48 hours after its birth. In 2001, scientists in Italy reported the successful cloning of a healthy baby mouflon, an endangered wild sheep. The cloned mouflon is living at a wildlife centre in Sardinia. However, cloning extinct animals presents a much greater challenge to scientists because the egg and the surrogate needed to create the cloned embryo would be of a species different from the clone.
Due to the inefficiency of animal cloning (only about 1 or 3 viable offspring for every 100 experiments) and the lack of understanding about reproductive cloning, many scientists and physicians strongly believe that it would be unethical to attempt to clone humans. Opponents of cloning point out that while we can euthanise defective clones of other animals, it’s morally problematic if this happens during the human cloning process. Even the Christianity as well as Judaism do not support the destruction of embryo or the creation of human being artificially.
Not only do most attempts to clone mammals fail, about 30 per cent of clones born alive are affected with “large-offspring syndrome” and other debilitating conditions. Several cloned animals have died prematurely from infections and other complications. The same problems would be expected in human cloning. In addition, scientists do not know how cloning could impact mental development. While factors such as intellect and mood may not be as important for a cow or a mouse, they are crucial for the development of healthy cloned humans. With so many unknowns concerning reproductive cloning, the attempt to clone humans at this time is considered potentially dangerous and ethically irresponsible.
The human reproductive cloning is banned by most countries. Physicians from the American Medical Association and scientists with the American Association for the Advancement of Science have issued formal public statements advising against human reproductive cloning. The US Congress has considered the passage of legislation that could ban human cloning. The US government has established strategic roadblocks related to human cloning, although no federal ban exists. First, the government won’t fund research focused on human cloning for reproduction. Also, the FDA, which regulates public cloning research, requires anyone in the US attempting to clone humans to first get its permission. In Japan, human cloning is a crime punishable by up to 10 years in prison. England has allowed cloning human embryos for therapeutic use only. Many individual US states have also passed laws restricting cloning.
In 2005, the United Nations attempted to pass a global ban on human cloning, but was unsuccessful due to disagreements over whether therapeutic cloning should be included.
Unlike the rest of the world, India’s cloning glory has been the buffalo lovingly named “Garima;” it is a darling of the scientists at the National Dairy Research Institute in Karnal, the country's first cloned animal. But its birth has also raised many questions: Should human cloning be permitted in India? India permits cloning of animals, and encourages regulated research in this area. A lab in Hyderabad is already working to clone the Asiatic Cheetah, which went extinct from India in the last century. However, India too has guidelines that prohibit any cloning of whole humans. In 2006, the Indian Council of Medical Research formulated some far-reaching guidelines on biomedical research. In 2007 another set of guidelines that regulate stem cell research were issued, this specifically bans cloning of humans.
According to Ian Wilmut, human reproductive cloning projects would be largely irresponsible. Cloning technology is still in its early stages, and nearly 96 to 98 per cent of cloning efforts end in failure. The embryos are either not suitable for implanting into the uterus, or die some time during gestation or shortly after birth. Those clones that do survive suffer from genetic abnormalities. Clone cells may age more rapidly, shortening their lifespan, similar to what happened with Dolly (which died at the age of 6 years after birth). Some clones have been born with defective hearts, lung problems, diabetes, blood vessel complications and malfunctioning immune systems. One of the more famous cases involved a cloned sheep that was born but suffered from chronic hyperventilation caused by malformed arteries leading to the lungs.
Other opponents cite social problems. A human clone will be no different from the children who are already born today. It will pretty much look like one parent and it will have many of the same behaviour predispositions as that parent. Nobody will be able to distinguish a cloned child from a child who happens to look and behave like one parent. Well, in purely genetic terms, if a woman used this procedure to have a baby, the child, say a girl, would actually be the genetic sister of the mother. But the social situation would make the mother treat the child as her daughter. Thus, there would be a confusion of family heritage.
Some believe that another future problem with cloning would be the growing socio-economic divide between the rich and the poor. For example, it is possible that human cloning technology could be used by parents to provide their cloned children with serious advantages. Now, the problem is that all parents want to give their children some form of advantages. In the US, parents who have money can give their children more advantages than parents who don’t have money. These facts mean that the parents who are unable to afford this technology will have children who are disadvantaged. So, the technology will greatly exacerbate the socio-economic gap between rich and poor.
For now, human cloning remains in a stalemate from a scientific, social, and public policy perspective – perhaps, the future of reproductive human cloning will likely depend on which side gives in first.
(The writer is a faculty member at Carnegie Mellon University, US and knowledge editor, Financial Chronicle)