克隆人技术

克隆人

 

简史

 

1952年，罗伯特·布里格斯和托马斯·王的克隆蝌蚪实验首次实现了动物克隆的成功。大约在四年后，第一个克隆的哺乳动物，一只名叫“多莉”的羊，出生于1996年。在多莉产生后，科学家开始考虑发展人类克隆。然而，在2003年，由于多莉在六岁的时候死亡，科学家开始产生怀疑和犹豫。这一事件，再加上宗教界对于克隆的反对，导致2009年颁布了对人类克隆的禁令。根据这项法律，克隆人是不道德的，邪恶的，而且是不受法律支持的；因此，它是非法的。今天，23个国家禁止克隆人技术。然而，支持克隆的科学家和研究人员正在想方设法使克隆人合法化，从而能在这个领域进行进一步研究，获得更大的成就（奈克，2010）。

 

简介

 

“不要非议或者反对克隆，除非你已经深入了解过它”夏普在《新政治家》中这样说道（2000）。

 

在第二十一世纪，迈克尔贝，好莱坞的导演，在他的科幻电影《岛》中以极富表现力的形式展现的克隆主题被许多人争论。这部电影出色地描绘了一个人类克隆工厂对社会可以产生怎样的影响。一位母亲怀孕了，并生下她的孩子，但这个孩子的生命将被科学家们终止，因为她只是原始母亲的克隆品，这位母亲并没有怀孕也不想经历怀孕的痛苦。电影中所展示的人类克隆技术在现实生活还没有达到。然而，这部电影所要表现的就是人类的自私，他们愿意花大量的钱来制造自己的基因复制品，并屠杀自己的克隆产物，以满足他们自己的人生目标，如拥有一个婴儿、接受器官移植等。

 

Human cloning

 

简史-Brief History

 

In 1952, the first successful animal cloning took place when Robert Briggs and Thomas J.King cloned a tadpole. After almost four decades, the first cloned mammal, a sheep named Dolly, was born in 1996. Following the creation of Dolly, scientists started to think about developing human clones. However, scepticism and hesitation began to grow among scientists when Dolly died at the age of six in 2003. This event, combined with the religious community's disapproval of human cloning, resulted in the enactment of the Human Cloning Prohibition Act of 2009. According to this law, human cloning is unethical, immoral, and unlawful; hence, it is illegal. Today, human cloning is banned in 23 countries. Nevertheless, pro-cloning scientists and researchers are seeking to legalise human cloning in order to progress research and achieve more in this field (Naik, 2010).

 

简介-Introduction

 

'Do not come down for or against cloning until you have consulted it' stated David Sharp in the New Statesman (2000).

 

What Michael Bay, the Hollywood director, eloquently shows in his sci-fi film, 'The Island,' is what many people in the 21st century are debating. This movie brilliantly portrays the type of influences that a human cloning factory can have on society. A mother becomes pregnant and delivers her baby, but her life will be terminated by scientists because she is just a clone of the original mother who could not become pregnant or who did not want to go through the pain of being pregnant. The human cloning technology that is shown in the movie has not been reached yet. However, what this movie is trying to show is the selfishness of mankind who is willing to spend considerable amounts of money in order to create genetically identical replicas of themselves and massacre the self-made clones to fulfil their own goals in life like having a baby, undergoing organ transplantation, etc. 

 

This is one of the most controversial issues in the world today. After creation of Dolly (the sheep clone) by Ian Willmut and colleagues at the Roslin Institute in Scotland, which was a great success in animal cloning, the debate about the concept of cloning, both scientifically and ethically, was raised among scientists (Bose, 2009). However, the main debate today is whether humans should be cloned or not. In order to realise why some views are against and some are for this issue, it is important to know some background about this concept first.

 

背景-Background

 

The simplest explanation of human cloning is that it is the production of a replicate (clone) of a human being asexually and without any fertilisation of sperms and eggs (Bose, 2009).

 

The technique used in cloning is called 'somatic (non-sex) cell nuclear transfer' (SCNT). Through SCNT, the nucleus of an egg is removed and replaced by the nucleus of the donor (who wants to be cloned), which is already isolated from the donor cell. An electrical shock (or, sometimes, the application of chemicals) results in the fusion of the donor nucleus and the host egg, which, in turn, starts the cell division process. When the cell division reaches a certain limit (blastocyst developed), it is embedded in the surrogate mother's uterus by in vitro fertilisation. This method of cloning, which was also used to create Dolly, is known as 'reproductive cloning' (Bose, 2009).

 

It is important to bear in mind that 'artificial insemination', 'in vitro fertilisation (IVF),' and 'cryopreservation' are all known as standard reproductive cloning techniques. However, the aforementioned technologies involve sexual reproduction of the embryo, i.e. fertilisation of sperms and eggs. In cloning, SCNT technology is used in the first phase in order to asexually produce a zygote (with fusion, not fertilisation) and next through the in vitro fertilisation technique; the resultant blastocyst (early embryo) is implanted in the mother's womb only if the aim is to produce a human being (reproductiove cloning), otherwise the blastocyst is used to extract stem cells from it (therapeutic cloning) which these cells, in turn, grow into various types of cells, such as pancreatic or nerve cells as demonstrated in Figure 2. (Wilmut et al., 2001)#p#分页标题#e#

 

Another type of cloning is called 'therapeutic cloning.' As explained above, in this case, after the fusion of patient's (donor's) nucleus with the host's egg and development of blastocyst, the inner cell layer of the blastocyst, which is full of undifferentiated stem cells, is used for stem cell research. Therefore, in therapeutic cloning and unlike reproductive cloning, the embryo is not embedded into the mother's uterus and, instead, it is used to isolate stem cells from it as shown in Figure 1 and 2 (Explorestemcells, 2010). These stem cells could then be used within different human body organs, such as the liver, heart, and skin. The advantage of using this method is that since the stem cells have been developed from the nucleus of the patient (i.e., have the same genetic information), the new developed organ will be used to replace the dysfunctional patient's organ without the patient's body rejecting the new organ (Bose, 2009).

 

Many scientists believe that, with therapeutic cloning and embryonic stem cell research, many disorders, especially degenerative nervous system diseases like Alzheimer's and Parkinson's can be treated. This is a very big promise that one can give to the mankind; however, the ethical issues related to this study must not be neglected (Bose, 2009).

 

The benefits and problems of using these two main types of cloning are more discussed in the 'scientific issues' section later on in this dissertation.

 

Nevertheless, there are important realities that must be uncovered about human cloning. It is important to understand that a clone can never be a perfect copy of the donor. Although the genetic material in the nucleus of the donor is used to create the clone, the mitochondrial DNA of the donor is not passed onto the clone. Also, the environment and experiences that builds up someone's character would be different for the donor and his/her clone (Bose, 2009).

 

Due to the lack of sexual reproduction of the clone, it would not have biological parents and he/she would always be called a clone of the DNA donor instead of a son or daughter of the donor. However, like any other human being, it will start its life as a baby despite the fact that it is generated from the cell of an adult (Bose, 2009).

 

The act of human cloning (reproductive cloning) is banned in many countries today; however, some countries like the UK have legalised human cloning research only for therapeutic purposes. Furthermore, even therapeutic cloning is not completely allowed in many countries as most of the religious organisations are against diverting the fate of an embryo in any form and for any purpose (Bose, 2009).

 

The question that may be raised is why anyone would want to clone a human in the first place. There are four different reasons why some people desire to clone a defunct or living person.#p#分页标题#e#

1.There are people who would like simply to replicate themselves. This may be due to the fact that some might think that, by cloning themselves, they will become immortal somehow. This argument clearly shows that it is arisen from a wrong interpretation of cloning. Others might want to be cloned just because they are vain.

2.Some want to replace their deceased loved ones by cloning them. For instance, this could be parents who desire to clone a child and use the cloned child as an organ donor for their dying child or to replace that child.

3.Others believe that, with this technology, famous people can be recreated. Some of the nominees were Einstein, Mozart, Ghandi and Marilyn Monroe.

4.Finally, human cloning can bring another option to provide an opportunity for infertile couples, including homosexuals, to have their own genetic child.

 

However, at present, none of these suggestions are technically practical. For example, of course, it is impossible to reproduce Ghandi as his DNA is probably decayed a long time ago. Nevertheless, what Ghandi did throughout humankind made him the outstanding Ghandi rather than his actual body (Wilmut et al., 2001). To date, there has not been any success in cloning human beings despite several announcements from different scientists like Panayiotis Zavos in 2001 (Bose, 2009).

 

In the next sections, the pros and cons of human cloning will be discussed both in terms of ethical and scientific implications which will make it easier to formulate a logical opinion about this issue.

 

讨论-Discussion

 

Ethical issues

 

There are many ethical concerns, surrounding human cloning, and there is no consensus yet about these ethical issues. Most of the ethical implications are theological concerns and different religious views that believe that human cloning is the act of changing what God wants and changing the way human babies would normally born. Many religious organisations believe that the embryo must be considered as a human being and the act of therapeutic cloning, where stem cells are extracted from the embryo, therefore, is the same as murdering a human being. As a result of this belief, what many people are against about human cloning is the act of terminating one person's life in order for another person to live longer (Putatunda, 2007). This so-called 'instrumentalization' view states, with regard to therapeutic cloning, that embryos must not be treated like an instrument and be produced only to help others to survive, but they should have an opportunity to experience the life like any other human beings who were an embryo (Kuhse & Singer, 2006).

 

Many views concern the social problems that human cloning may create. There is, no doubt that, a child who is created through cloning would face countless challenges in society. How such a child can grow up in a society where there are not--and never were--any parents for him/her is a real challenge. The criminal misuse of this technology and insulting human dignity by creating human clones for other reasons can influence human values in society in many destructive ways (Bose, 2009).#p#分页标题#e#

 

Some of the other morally argumentative discussions are raised against the inhumanity side of human cloning. Some of the main ethical dilemmas are whether human beings have the right to have children regardless of how they are created or whether it is moral to replace our defective organs with the new healthy ones from clones. Terminating the life of an embryo in order to isolate stem cells from them in therapeutic cloning is condemned by some humanitarian organisations (Putatunda, 2007).

 

The next sections will discuss specific segments that relate to ethical issues on human cloning. These sections cover some of the main views on using embryos and stem cells in therapeutic purposes, and a brief overview of different perspectives on the concept of human dignity, autonomy, and reproductive cloning.

 

About embryos

 

The current UK rules and regulations states that embryos more than fourteen days old must not be used in research. This does not mean that a balostocyst younger than two weeks should not be respected. In fact, the rules clearly state that early embryos should be used in research only if there are no alternatives, such as adult stem cells, and only with consent. A precise record keeping must also be carried out to ensure that all embryos are treated the same (Wilmut et al., 2007). On the other hand, from a different perspective and as opposed to what many theological associations believe, the embryo is just a ball of cells and must not be considered to be a person. In other words, the embryo is not equivalent to a human being and, as a result of this, human rights should not apply to a bunch of cells that have no brain, personality, character, self-awareness, memory, etc. Therefore, the act of therapeutic cloning is not immoral as it uses a bunch of cells that contain DNA like human skin cells to extract stem cells from and save thousands of lives. It only becomes wrong when the embryo is starting to develop a brain (mental life) and shows the appearance of the capacity to think. However, at this stage, an embryo is just a cluster of cells (Putatunda, 2007). Therefore, whilst many people believe that an embryo has the potential to become a human and, hence, must be respected, others believe that this does not mean that just because the embryo has this potential and must be authorised to have the same rights as a person. As John Harris stated in The Value of Life, "We are all potentially dead but that does not mean we should be treated as if we are dead" (Wilmut et al., 2007).

 

As a result of this, many scientists justify the use of blastocysts in research. Nevertheless, this, in turn, raises other uncertainties like whether the blastocyst is aware or whether the blastocyst feels pain (Wilmut et al., 2007).

 

Therapeutic cloning and stem cells

 

In order to rationally investigate the ethical issues surrounding therapeutic cloning using embryonic stem cells in research and therapy, it is important to briefly look at some of the main ethical issues raised over the past few years.#p#分页标题#e#

 

Technically, stem cells can be isolated from adults (e.g. skin), from umbilical cord blood, from foetal tissue, and from embryonic tissue. However, scientists believe that embryos are the best sources of stem cells for therapeutic cloning today. Therefore, this raises the question of whether, in future, embryos will be created just to be used as a source to harvest stem cells. Another issue that has been raised by the European Group on Ethics is the woman's right since mothers are the means necessary to create embryos. There are also issues regarding the anonymity and security of the donors and the confidentiality of their genetic information. The commercial uses and transport of the donated tissues and genetic material globally, which could result in many criminal cases are crucial issues which are linked to peoples safety and security and must be attentively considered (Kuhse & Singer, 2006). A similar debate is currently taking place, in the UK, on whether everyone's DNA must be kept on the database or only criminal's DNA.

 

"Replication" not "reproduction"

 

With regard to reproductive cloning, since creating an individual using SCNT technology is a process of replication and not reproduction, some believe that this is not natural and completely disregards human dignity. However, this might be a kind of eluding technique that especially political systems would use nowadays in order to avoid the controversial arguments that surround an issue, such as human cloning. It is always easier to justify a banning policy by claiming that a particular law is issued due to breaching human dignity moralities rather than basing it on religious views (Caulfield, 2003).

 

Eugenics, human dignity and autonomy

 

In addition, the "autonomy" and "uniqueness" of an individual are other factors that must be considered. The genetic information of a person is what makes the person unique and different from others. From the human dignity defender's perspective, who believe autonomy and uniqueness are the precursors of human dignity, the act of reproductive cloning not only disregards the clone's autonomy, but it also ruins the uniqueness of the donor, which is unacceptable and immoral. Again, some might say these arguments are scientifically wrong as genome's role in human uniqueness is only in terms of human appearance and not personalities in terms of defining individuals. Hence, the act of copying someone's genome does not necessarily ruin his/her uniqueness or his/her human dignity. For example, identical twins' dignity and uniqueness are not jeopardised only because of having identical genomes (Williamson, 1999).

 

Reproductive cloning

 

Apart from the social and religious views, some scientist involved in cloning and embryology researches like Ian Wilmut and Richard Gardner have clearly explained some of the serious ethical problems that human cloning can bring about. For example, with regard to the act of reproductive cloning, there is still lack of sufficient and satisfactory amount of knowledge in order to clone a human being (as explained below).#p#分页标题#e#

 

Reproductive cloning has yet to be completely proved by scientists. Even during the process of creating Dolly, 272 embryos were wasted. In other words, Dolly was created after trying to clone a sheep 272 times. .This means that 272 embryos for various reasons were either not developed normally or were eliminated for being imperfect. From those embryos that were developed properly, some of them miscarried and a significant number of the sheep born were severely abnormal and, as a result of this, died shortly after delivery or had to be euthanized (Wilmut et al., 2001). To date, no clone including Dolly has lived to a ripe old age. Dolly was euthanized by lethal injection as she had been suffering from lung cancer and crippling arthritis and died at the age of six. This happened whilst most Finn Dorset sheep live to the age of 11 or 12. Just imagining treating a human embryo the same way would create so many ethical dilemmas (HGPI, 2009).

 

Scientific issues

 

Human cloning is not as simple as just replicating a person. There are various scientific and technological obstacles to performing this study.

 

In terms of science, human cloning has its own benefits and problems, especially therapeutic cloning. One of the main advantages of using stem cells isolated from embryos is that the cells are pluripotent. This means that these cells are able to differentiate into any cell type in the human body except embryo cells. Hence, pluripotent cells have the potential to grow and produce healthy organs or to treat any body organ (tissue) diseases by replacing defective cells; for instance, this could involve using pluripotent cells to replace abnormal red blood cells in sickle-celled anaemia disease or to replace damaged heart tissue, thereby preventing cardiovascular diseases (Explorestemcells, 2010).

 

Another major benefit of therapeutic cloning is that, as mentioned in the introduction, since the patient's own genetic material is used to produce the cloned embryo and stem cells isolated from it, the risk of rejection by the immune system of the patient during organ transplantation is reduced. Otherwise, if the cells are from another donor, the patient's immune system would recognise the foreign proteins on the transplanted cells and start to attack these cells and reject the transplanted organ (Explorestemcells, 2010).

 

Therapeutic cloning can also help scientists to progress in stem cell research, which, in turn, will open many doors to treating different diseases (Explorestemcells, 2010). Furthermore, gene therapy is one of the major development procedures that can be achieved by cloning. Gene therapy allows the replacement of defective and abnormal genes with healthy and normal ones. Rejuvenation is another factor that many scientists believe can be achieved through production of clone tissues (Pakhare, 2007).#p#分页标题#e#

 

One of the main advantages of using reproductive cloning is infertility treatment. Through human cloning technology, many infertile couples can have a chance to have a child without going through many painful procedures that are currently used for infertile couples (Pakhare, 2007). This is due to the fact that, in reproductive cloning, the fusion of sex cells is not involved and, instead, SCNT methods are used.

 

However, some of these positive features mentioned about human cloning are just a theory like rejuvenation, and it is not completely approved by all scientists. Human cloning is not as simple as just replicating a person. There are various scientific and technological obstacles to performing this study. A number of drawbacks and risks from using human cloning are mentioned below.

 

Risks

 

One of the main problems of using therapeutic cloning is that the success rate in producing a viable egg is very low. As explained in the case of Dolly, 277 SCNT attempts took place to create a stable, fused egg that resulted in a somewhat viable offspring. Statistics shows that almost 90% of the attempts to produce viable animal clones have failed (Pakhare, 2007).

 

This shows that the cloning technology of today is not very highly advanced and the process of SCNT is not as easy as it may sound. It also means that cloning, especially with this high rate of failure, could be a very expensive technique. It can take hundreds of attempts and thousands or even millions of dollars to attain a viable zygote (Explorestemcells, 2010).

 

Furthermore, the cloned animals tend to die prematurely after cloning. This is due to their fragile immune system, which results in the progression of many disorders and infectious activities after creation, such as tumours, arthritis (in Dolly), etc. Some of the cloned animals die early because they have 'Large Offspring Syndrome' in which their organs are abnormal and often larger than their counterpart's organs. This results in the disorganisation of metabolic activities, which, in turn, leads to the development of many other disturbances and, ultimately, causes death (Pakhare, 2007).

 

Another risk of cloning that concerns scientists is the telomere shortening mechanism. Telomeres are DNA sequences located at either ends of chromosomes, which shorten in sequence each time DNA replication occurs. Hence, the overall length of chromosome is reduced after each replication. Studies show that, as the animals' (or humans) age increases, its telomeres contract further (Betts et al., 2006). Therefore, the clone that arises from a nucleus, taken from an old donor through SCNT, must die early as the chromosomes of this newly created clone are already old (Yang et al., 2000). For instance, in the case of Dolly, the chromosomes seemed to have been shrunk and, hence, it aged faster than its counterparts. However, this phenomenon is still not completely proven as, in some cases, such as in a cloned cow and a mouse, it has been seen that telomeres are quite longer than their counterparts (Pakhare, 2007).#p#分页标题#e#

 

Some more ethical issues in science

 

The process of extracting stem cells from the embryo during therapeutic cloning results in the destruction of the embryo being used. This is the main reason why many views are against stem cell research as they believe killing an embryo is equivalent to killing a human being. However, some people believe that equalising a cluster of cells with a human is completely wrong and advantages of therapeutic cloning with regards to treatment of many diseases outweigh the disadvantages of it (Explorestemcells, 2010).

 

In addition, since reproductive cloning also uses SCNT to create an embryo, there is still the concern that a scientist may take therapeutic cloning further to clone a human being. As described above, no one has ever been successful in cloning a human being; however, it is still alarming for the political, scientific, and religious communities that, with the current knowledge of cloning today, some may attempt to go beyond therapeutic cloning (Explorestemcells, 2010).

 

Possible future developments

 

As explained previously, the main issues surrounding human embryonic stem cell (HESC) research are raised only due to the fact that the embryo is destroyed in the process of extracting stem cells from it. If an alternative way to obtain non-embryonic pluripotent stem cells could be developed, this problem could be overcome. This research is mainly crucial in the U.S. due to different policies that are raised against the federal funding of HESC research. One of the newest ways to approach these alternative pathways is by using the 'Altered Nuclear Transfer' (ANT) technique. Through ANT, the somatic cell nucleus and egg cytoplasm are modified first and, subsequently via SCNT technique, the somatic nucleus is transferred to the egg. The advantage of this method is that it prevents the resultant zygote from developing the potential capabilities of becoming an embryo whilst simultaneously allowing it to produce pluripotent stem cells. ANT has already been experimented on with mice by silencing the Cdx2 gene of the somatic cell nucleus before transferring it to the egg. The result was the production of non-embryonic biological entity that contained healthy and normal pluripotent stem cells. Other studies show that this is also achievable by silencing Cdx2 genes in the egg prior to nuclear transfer. Therefore, finding alternative ways are also possible solutions to get around this problem (Hurlbut, 2007).

 

Another idea that scientists brought forth for discussion after cloning Dolly that they hope to apply in medical centres in the near future is the idea of creating 'designer babies.' This idea was mainly proposed in order to help humankind by using the combination of nuclear transfer and genetic modification. This theory believes that the prevention of children with severe genetic disorders being born can be done by artificial selection of the best possible genetic information, using genetic engineering and IVF techniques. Designer babies ensure the presence and absence of particular wanted and unwanted genes ameliorating the offspring's characteristics (Steinbock, 2008). Since IVF was finally accepted by many public organisations after extreme debate, the action of genetically modifying human embryos may also be accepted one day as routine even if it is not applied on a large scale. However, surely moral issues surrounding this technology would make it difficult to carry on this technique. Some believe that the 'designer babies' technique, like human cloning, is "playing God." Others believe that this is a kind of prejudice and discrimination to disallow a disabled child to be born. Many fear the negative long-term effects that this can have on society. For instance, a child's sense of independence might change knowing that his parents had interfered with his birth to change his natural birth in some ways (Wilmut et al., 2007).#p#分页标题#e#

 

Nowadays, several other techniques are being offered to patients with genetic diseases in medical centres, such as gene therapy. Therefore, some people believe that the genetic make-up of an individual must not be manipulated before birth; however, it is fine to do that after birth, such as through gene therapy. 

 

结论-Conclusion

 

Having discussed some of the main ethical and scientific issues, there are still some unreasonable and illogical criticisms about cloning that have been raised due to the lack of understanding and knowledge about this issue. Misconceptions about human cloning in terms of confusing it with other biomedical and genetically-related techniques, such as 'designer babies' and 'genetic selection' results in false information and judgment about this procedure. As opposed to what many people believe, human cloning is not able to select perfect genes or sex and result in a self-designed perfect human being. Therefore, so many arguments about human cloning, especially religious ones that are based on these perspectives and similar information, are due to superficial and shallow thinking (Vaknin, 2003).

 

In conclusion, a government needs to completely analyse an issue like human cloning before proposing different laws about it and banning it. Restricting research about the issue not only does not solve the problem, but it also makes the conflicts of this matter worse, and it may result in the abstruse and secret execution of illegal human cloning.

 

I, too, have instinctive concerns regarding the application of reproductive cloning. I believe that not only does this type of cloning not have many scientific uses that can help humanity, but it also only brings psychological and mental problems to society. Therefore, there is no doubt why reproductive cloning must be banned and tightly regulated.

 

Regarding stem cell research I believe the ethical guidelines and boundaries must be identified instead of banning the research completely. As mentioned in the context of this dissertation, there are many advantages that can be achieved through stem cell research that must not be neglected. For example, in China, the investment in stem cell science is growing whilst the instruction and rules about this study are also tightly controlled (Sample, 2005).

 

Furthermore, using human dignity and sanctity of life as the centre of the arguments does not help to logically analyse and investigate the benefits and drawbacks of the technique. As nobody is anti-human dignity, such arguments can only act as a barrier that does not allow further study of this technology. As Beyleveld and Brownsword noted (1998), "From any perspective that values rational debate about human genetics, it is an abuse of the concept of human dignity to operate it as a veto on any practice that is intuitively disliked".#p#分页标题#e#

 

Finally, we need to make use of advantages that this technology can bring to mankind. As noted by Wilmut et al, (2001), "Human cloning is now on the spectrum of future possibilities - and we, more than anyone else, helped to put it there. We wish this were not the case, but there it is and will remain for as long as civilisation lasts."

 

Of course, we can use alternatives if there are any, but if the only way to save thousands of lives is by using therapeutic cloning, as long as the benefits of such process outweighs the ethical and moral issues, we need to rethink our policies in terms of what we ban and what we limit.