The question is, is it humane to use "human clones" as organ donors? Is it legal? Is it economically viable?
Cloning can also be used to mass-produce valuable genes, such as insulin for diabetes, growth hormone to make people with dwarfism grow taller, and stem deflectors to fight a wide range of viral infections, in medicine. Prior to Dolly, decades of failed experiments had led people to almost despair that somatic cell cloning of higher animals might not be possible. The "cloning" of cells from a developing embryo, the transplantation of its nucleus, and the production of an individual identical to that embryo, is not relatively difficult. Because embryonic cells have a strong potential for differentiation, they can differentiate into skin, blood, muscle, nerve, and other cells with different functions and genetic characteristics during development, with the reproductive function being carried out exclusively by the sex cell, the sperm or the egg. A sex cell carries only half of the genetic information and requires the combination of a sperm and an egg to develop into a new life. A somatic cell, on the other hand, has a complete set of chromosomes and does not require the involvement of a sex cell. But is it even possible for a mammal to clone a somatic cell that has already been "finalized" to restart its embryonic development, which would be tantamount to reversing the clock of the cell's life back to the beginning?
Dolly is a ****together of the Roslin Institute in Scotland and PPL Medical. Its genetic mother, a Fen-Dorset breed of white sheep, died three years before Dolly was born. The Hannah Institute in Scotland extracted some of the ewe's mammary cells while she was pregnant for cryopreservation, and later made them available to PPL for cloning research - which had later caused some trouble with the authenticity of Dolly's identity. The scientists, led by Ian Wilmut, cultured the mammary cells in the lab and "starved" them in a low-nutrient state for about five days. The nuclei were then extracted and transplanted into the eggs of black-faced Scottish sheep with the nuclei removed. The reason for using the eggs of the Scottish blackface sheep is that the sheep's bodies are mostly white, but their faces are all black, making them easy to distinguish from white sheep.
Stimulated by a microcurrent, the nucleus of the white sheep's cells fused with the nucleus-less egg of the black-faced sheep and began to divide and develop into an embryo, which was implanted in the ewe's uterus to continue its development. Of the 277 eggs that successfully fused with the nucleus, only 29 survived to be transplanted into 13 ewes. 148 days after the transfer operation, on July 5, 1996, a lamb was born - a 1/277th success rate, the others had failed. Until the time of its death, this incredibly low success rate of cloning technology had not substantially improved. This is one reason why the scientific community is generally unconvinced of the authenticity of the identity of the Raelian baby girl clone, Eve.
Wilmut named his masterpiece after his favorite American country music singer, Dolly Parton, and when the identity of the lamb was revealed to the world on Feb. 23, 1997, it was feared that more people in the world would know about it than the singer. The famous photo of an all-white lamb, nestled next to its unrelated surrogate mother, a Scottish blackface, showed the world that a new era in biotechnology had dawned. He is a carbon copy of the Fen Dorset white sheep (or, to be precise, a carbon copy of him in terms of nuclear genetic information. There was also a small amount of genetic information stored in the mitochondria of the cytoplasm, and Dolly's mitochondria were characterized in the same way as that Scottish black-faced sheep that supplied the eggs). For a while, the public cheered, excited or fearful, bewildered, Frankenstein, Pandora's box and "science is a double-edged sword" became popular phrases, some people look forward to the bright future of cloning fine livestock breeds or giant pandas, some people cried out for human cloning or not allowed to clone human beings, some scientists stepped up the cloning of other animals, and scientists have put them to use to clone animals. Cultivated embryonic cell cloned animals launched to share a little light, adding to the situation of lively and chaotic.
In February 1998, there were scientists who questioned the authenticity of Dolly as a somatic cell cloned animal. In pregnant animals, a small number of embryonic cells may reach the mammary gland area along the circulatory system, so these scientists raised questions about whether Wilmut and others had happened to come across one such embryonic cell and whether Dolly was still the result of an embryonic cell clone. The Hanna Institute also kept some mammary cells from Dolly's genetic mother, and NDA analysis quickly proved that Dolly was indeed the product of somatic cell cloning and that there was no possibility of embryonic cell mix-ups.
Since then, cloned mice, cloned cows and many other kinds of cloned animals have been introduced. The first clone of a human being in several years of "only hear the stairs, do not see people down", but also finally at the end of 2002, "reportedly" born, but there is no evidence, the scientific community has not been recognized. To this day, scientists still know a little bit about the cloning process, but do not know the flavor of the reason. Why is the nucleus of a somatic cell able to develop after fusion with an egg? It has been speculated that it may be that the starvation state in a low-nutrient environment renders the somatic cell dormant, with most of its genes switched off, thus losing the specialized characteristics of the somatic cell and becoming similar to the embryonic cell. This is only speculation, however, and has not been proven. The success rate of the cloning process has been very low, with more problems such as miscarriages and malformations. Is this due to problems with cloning itself, or is it simply because the technology is not sophisticated enough to cause damage to the DNA? One cannot yet ask or answer this. As the first somatic cell cloned animal, Dolly's health is being closely watched as it may represent the fate of other cloned animals. For most of his life, Dolly lived a life of luxury and stardom, handling public occasions well, not being afraid of people and having good manners in front of the camera. After mating with the ram "David", Dolly gave birth to her first child, Bonnie, in April 1998, and later had two more children, a **** six children, one of whom died. In terms of fertility, she was no different from a normal ewe. Dolly was almost completely healthy and normal until she was found to have arthritis in early 2002, except for a time when she needed to lose weight because her visitors were feeding her too much.
In May 1999, the Roslin Institute and PPL announced that Dolly's chromosomal telomeres were shorter than those of sheep of the same age, raising concerns about whether cloned animals might age prematurely. Telomeres are structures at the ends of chromosomes that act as protectors for the chromosomes, sort of like the plastic or metal buckles at the ends of shoelaces that hold them in place. Every time a cell divides, the telomere gets a little shorter, to a point where the cell stops dividing and starts a suicide program. Telomeres, and the enzyme telomerase that repairs them, have been a hot topic in aging and cancer research in recent years. Many scientists believe that telomeres may play an important role in the aging process in animals. Some worry that the fact that cloned animals are destined to have shorter telomeres is an inevitable and fundamental problem. Others believe that Dolly's shorter telomeres may be the result of a technical problem in the cloning process, which is not necessarily a common phenomenon in somatic cell cloning and is expected to be eliminated with advances in technology. For example, U.S. scientists used cloned rats to breed cloned rats, a *** cultivated six generations (the last generation of the only cloned rat was eaten by other experimental rats, the experiment was forced to suspend), and did not find that the phenomenon of shortening of telomeres from one generation to the next. Since the number of cloned animals is small and they are generally young, it is difficult to tell which statement is correct. The issue is further complicated by the fact that it has yet to be determined what exactly the relationship between telomeres and aging is, or whether shorter telomeres necessarily lead to premature aging. The possibility of health problems associated with cloning is a direct reason why Dolly's creators strongly oppose human cloning: cloning a human being at the current state of the art would be too irresponsible for the person cloned.
In January 2002, the Roslin Institute revealed that Dolly had been found to have arthritis. This caused a new furor over the health of cloned animals. Arthritis in sheep is common, but it is not unusual for Dolly to develop the disease in the joint of her left hind leg. Wilmut said this could mean that current cloning techniques are inefficient, but whether the cause of Dolly's illness was a genetic defect caused by the cloning process or pure chance may never be clear. Contrary to the views of animal rights advocates, he emphasized that cloning research on animals should not stop there. Instead, further research is needed to figure out the mechanisms involved. Since then, the Roslin Institute has restricted outside access to Dolly.
On February 14, 2003, the institute announced that Dolly had been euthanized due to a progressive lung infection (a progressive disease is one with worsening symptoms). Like arthritis, lung infections are common in older sheep, especially those that live indoors for long periods of time, like Dolly. But sheep usually live for about 12 years, and at 6 1/2 years old, Dolly was arguably in his prime and not old enough to be considered old, and whether his lung disease had anything to do with cloning or not is another difficult question to figure out. Researchers are currently conducting a detailed examination of Dolly's remains, which is of great concern to the scientific community, although the results of the examination may not be able to provide a definitive answer to the above question. Wilmut told the media that the death of Dolly made him "extremely disappointed". He reminded other scientists to keep an eye on the health of cloned animals.
The Roslin Institute had already made arrangements for Dolly's afterlife several years ago. After his remains are examined, he will be taxidermied and put on public display at the National Museum of Scotland. Theoretically, the Natural History Museum or the Science Museum in London would be better suited to house one of the most honored and famous sheep in the history of science, but Scottish scientists have their own reason: "Because she was a Scottish sheep."
Editor/Song Chao
(Globe 2003.3.16 By Wang Yanhong) "
Fan Hongwei, a reporter of this newspaper, reported comprehensively: on November 25, the U.S. Advanced Cell Technology announced that the company had grown human embryonic cells for the first time with cloning technology, which has caused an uproar around the world, with voices of opposition against it.
While the company said their aim was not to clone human beings but to use cloning technology to treat diseases, it was still criticized by many. U.S. President George W. Bush has said he is 100 percent opposed to any form of human cloning. U.S. senators said they would soon pass a bill banning all cloning research. Spokesmen from Brazil, Germany, Italy and the European Union have also spoken out against the idea, arguing that scientific research should not exceed ethical boundaries and that there is a need to strengthen legislation.
U.S. Senate Majority Leader Daschle, however, was more neutral, suggesting that Congress should distinguish between reproductive cloning experiments and therapeutic cloning.
Wilmut, one of the creators of Dolly, the world's first cloned head, agrees. Vermut has long opposed human cloning, arguing that Advanced Technology Cells is more likely to be motivated by business than by technical considerations, and that what they have achieved is a minor breakthrough in terms of scientific achievement.
Within the scientific community, a number of biologists have scoffed at the practice, arguing that the results of the experiment have no scientific significance and are a serious provocation of bioethics. Jean-Paul Lenard, an expert on animal cloning at France's National Institute of Agronomy, said the method used by Advanced Cell Technology was in fact the same as that used to clone Dolly the sheep, and that U.S. scientists' access to early human embryos containing only six cells was far from adequate.
Dr. McGee, a bioethicist at the University of Pennsylvania, even questioned the veracity of Advanced Cell Technology's announcement because many details of the experiments have not been made public.
Three, China is regulating the research of stem cells and cloning technology
The reporter Zeng Wei reported: human cloning is only one step away from us, how to make cloning technology is not to give people problems, but in the scope of human control to maximize the benefit of mankind? Yesterday, this reporter interviewed Professor Li Lingsong, chief scientist of Peking University Stem Cell Research Center.
Professor Li said: "There are three currently recognized international norms, one is firmly opposed to human cloning, the second is that human spermatogonial cells can not be hybridized with animals, and the third is the source of embryonic stem cells used for experiments to be restricted and make specific provisions. Until the relevant regulations and laws in China are in place, our research will follow international norms."
"For some 'gray areas' where international norms are ambiguous, different countries do things differently, for example, the British, who believe in Christianity, stipulate that fertilized eggs after 14 days of in-vitro fertilization should not be used for experiments, while Israel has no such regulations for these 'gray areas', we have to analyze specifically according to our own national conditions."
It is understood that at present, although the international community is generally opposed to human cloning, namely reproductive cloning, but the therapeutic cloning, that is, the use of cloning technology to obtain human stem cells for use in the replacement therapy of diseased tissues and organs, is basically agreed. However, experts believe that therapeutic cloning technology can be used for clinical purposes is still at the stage of cell replacement therapy, and it is still too early to really clone human tissues and organs that can be used for transplantation.
"Stem cell and cloning research requires considerable technology, advanced equipment and a good ethical foundation," Professor Li emphasized, adding, "Research institutes involved in this field must have considerable strength and qualifications, otherwise it could easily get out of hand."
It is reported that a panel of experts convened by the relevant state departments, with the participation of biologists and ethicists, is currently reviewing the current situation of China's stem cell and cloning research, and a "review committee" aimed at regulating China's stem cell and cloning research is in the pipeline.
Four, science and technology essay: cloning of the rational direction of development
Xinhua, Washington, Dec. 11 (Xinhua News Agency reporter Wu Weinong) Every time there is a major cloning progress, a variety of warnings and opposition will be endless. After the recent announcement by the US company Advanced Cell Technology that it has created a human embryo through cloning, the criticisms are again incessant. With regard to cloning research, people should look at the issue in two ways to promote the safe use and healthy development of cloning technology.
It is worthwhile to review the results of Advanced Cell Technology: researchers from this company fused the genetic material of human somatic cells with the empty shells of human egg cells from which the genetic material had been removed, and then induced the development of the fused cells: the researchers obtained three early embryos, two of which developed to the 4-cell stage, and the other to at least the 6-cell stage. Since this proves that the genetic material of a single human cell can be induced to develop into a young embryo, human cloning could be technically a step away from reality.
Controversy has arisen from this. Critics say that because it creates the beginnings of a human being from a single parent, the advance is ethically and morally dangerous. Opponents say that even if not for human cloning, the destruction of cloned embryos to obtain stem cells is unethical. But scientists at Advanced Cell Technology say their goal is not to create clones, but to develop treatments for human diseases, and that their work is "just."
Scientists' experiments on animals herald a new era of regenerative medicine with cloned human embryonic stem cells.