Reproductive cloning of humans

About Reproductive Cloning

Reproductive cloning is the production of a genetic duplicate of an existing organism. A human clone would be a genetic copy of an existing person.

Somatic cell nuclear transfer (SCNT) is the most common cloning technique. SCNT involves putting the nucleus of a body cell into an egg from which the nucleus has been removed. This produces a clonal embryo, which is triggered to begin developing with chemicals or electricity. Placing this cloned embryo into the uterus of a female animal and bringing it to term creates a clone, with genes identical to those of the animal from which the original body cell was taken.

More than eighteen cloned mammals have been produced with SCNT, but claims by rogue scientists to have cloned a human child have been false.

New techniques, such as the derivation of induced pluripotent stem cells via cellular reprogramming, suggest other potential methods of reproductive cloning. 

Human reproductive cloning is almost universally opposed. Overwhelming majorities reject it in opinion surveys. Many international agreements and countries (though not the United States) formally prohibit it.

Some oppose reproductive cloning because of safety considerations. Animal cloning is seldom successful, and many scientists believe that reproductive cloning can never be made safe. Human reproductive cloning would also threaten the psychological well-being of cloned children, open the door to more powerful genetic manipulation technologies, and raise other social and ethical concerns.

Human cloning is the creation of a genetically identical copy of a human. The term is generally used to refer to artificial human cloning, which is the reproduction of human cells and tissue. It does not refer to the natural conception and delivery of identical twins. The possibility of human cloning has raised controversies. These ethical concerns have prompted several nations to pass laws regarding human cloning and its legality.

Two commonly discussed types of theoretical human cloning are: therapeutic cloning and reproductive cloning. Therapeutic cloning would involve cloning cells from a human for use in medicine and transplants, and is an active area of research, but is not in medical practice anywhere in the world, as of 2015. Two common methods of therapeutic cloning that are being researched are somatic-cell

nuclear transfer and, more recently, pluripotent stem cell induction. Reproductive cloning would involve making an entire cloned human, instead of just specific cells or tissues.

Methods

Somatic cell nuclear transfer (SCNT)

In somatic cell nuclear transfer ("SCNT"), the nucleus of a somatic cell is taken from a donor and transplanted into a host egg cell, which had its own genetic material removed previously, making it an enucleated egg. After the donor somatic cell genetic material is transferred into the host oocyte with a micropipette, the somatic cell genetic material is fused with the egg using an electric current. Once the two cells have fused, the new cell can be permitted to grow in a surrogate or artificially. This is the process that was used to successfully clone Dolly the sheep (see section on History in this article).

Induced pluripotent stem cells (iPSCs)

Creating induced pluripotent stem cells ("iPSCs") is a long and inefficient process. Pluripotency refers to a stem cell that has the potential to differentiate into any of the three germ layers: endoderm (interior stomach lining, gastrointestinal tract, the lungs), mesoderm (muscle, bone, blood, urogenital), or ectoderm (epidermal tissues and nervous system). A specific set of genes, often called "reprogramming factors", are introduced into a specific adult cell type. These factors send signals in the mature cell that cause the cell to become a pluripotent stem cell. This process is highly studied and new techniques are being discovered frequently on how to better this induction process.

Depending on the method used, reprogramming of adult cells into iPSCs for implantation could have severe limitations in humans. If a virus is used as a reprogramming factor for the cell, cancer-causing genes called oncogenes may be activated. These cells would appear as rapidly dividing cancer cells that do not respond to the body's natural cell signaling process. However, in 2008 scientists discovered a technique that could remove the presence of these oncogenes after pluripotency induction, thereby increasing the potential use of iPSC in humans.

Comparing SCNT to Reprogramming

Both the processes of SCNT and iPSCs have benefits and deficiencies. Historically, reprogramming methods were better studied than SCNT derived embryonic stem cells (ESCs).[9] However, more recent studies have put more emphasis on developing new procedures for SCNT-ESCs. The major advantage of SCNT over iPSCs at this time is the speed with which cells can be produced. iPSCs derivation takes several months while SCNT would take a much shorter time, which could be important for medical applications. New studies are working to improve the process of iPSC in terms of both speed and efficiency with the discovery of new reprogramming factors in oocytes.[citation needed] Another advantage SCNT could have over iPSCs is its potential to treat mitochondrial disease, as it utilizes a donor oocyte.[9] No other advantages are known at this time in using stem cells derived from one method over stem cells derived from the other.

Human reproductive cloning is the creation of an individual who has identical nuclear genetic material (DNA) to an existing human being, and who is allowed to develop to term and beyond.  Human reproductive cloning is widely regarded as unethical and inappropriate and is specifically prohibited in many jurisdictions.  An initiative at the United Nations General Assembly led to the United Nations Declaration on Human Cloning, which calls on all states to prohibit all forms of human cloning.

Basic scientific concepts 

A gene is a hereditary unit consisting of a sequence of DNA that occupies a specific location on a chromosome. Chromosomes consist of long coiled chains of genes and are found within all nucleated cells in the human body.  Human beings normally have 23 pairs of chromosomes; one of each pair is inherited from the genetic mother and one from the genetic father.   In sexual reproduction, a child receives half of their genes from the mother (contained in the egg) and half from the father (contained in the sperm).  The combination of maternal and paternal genes which occurs at fertilisation forms the basis of human genetic variety and diversity.  A small amount of genetic material is contained within mitochondria within the egg and this mitochondrial DNA is passed on to the child entirely from the mother. In embryo splitting, an early human embryo divides into two genetically identical embryos which are then capable of developing independently.   This process may happen spontaneously and is the mechanism whereby genetically identical twins (technically described as monozygotic twins) are formed.  Embryo splitting can also be induced artificially.   In reproductive cloning the entire genetic code (except for the mitochondrial DNA) is reproduced from a single body cell of an adult individual.  The most common cloning technique is somatic cell nuclear transfer (SCNT). The procedure is as follows1: 

The nucleus is removed from an egg leaving the cytoplasm and mitochondria (cellular components derived from the mother)

A body (or somatic) cell is taken from an adult individual who is to be cloned.  The DNA is extracted from the nucleus and inserted into the prepared egg.

The new cell is then induced to divide using either chemical or electrical stimulation, thereby commencing the development of an embryo.

After several days the dividing embryo is then placed into the womb of the recipient and allowed to develop to term. The result is a clone – an individual that is the genetic duplicate of the individual from whom the original body cell was taken. To date this process has not been proven to occur in a human being.  If it did so, it is important to note that the resulting child would neither be the individual’s son or daughter, nor their twin brother or sister. The child would truly be a new category of human being – a clone.

 Hans Spemann, an eminent Germany scientist, conducted the first nuclear transfer experiment in 1928, in which he transferred the nucleus of a salamander embryo cell to a cell without a nucleus. This was followed up in 1952 with experiments carried out by Robert Briggs and Thomas J. King, using embryonic donor cell nuclei from amphibia2.  Earlier attempts by the two had failed, but by the completion of the project they had been successful in cloning thirty-five complete embryos and twenty-seven tadpoles from one-hundred and four successful nuclear transfers3. At the time they were unaware of the work of Hans Spemann4. The work of Briggs and King helped initiate decades of substantial research into cloning research.John Gurdon of Oxford University, discovered in 1962 that differentiated cell nuclei could also result in cloned offspring, the result of which proved that as differentiation occurred, there was no loss of genetic material. Whilst this attracted the attention of many, some scientists doubted the validity of Gurdon’s work, uncovering flaws in his work5.Research and development continued into nuclear transfer work in the use of mammals in the 1970s all the way through to the 1990s, resulting in the conception of the first mammal cloned from an adult nucleus taking place in 1996, by Ian Wilmut and Keith Campbell of the Roslin Institute, Scotland. The birth of the clone, “Dolly” the sheep, was first announced in the journal, Nature, in 1997 and initiated worldwide discussion about the possibility of cloning humans6.  Since the birth of Dolly the sheep, there have been many more mammals that have been cloned from differentiated cells. These include: 

Horses – On May 28th 2003, “Prometea” a Haflinger foal, was the first cloned horse and the first to be born from and carried by its cloning mother. Prometea was born after a natural delivery and a full-term pregnancy in Laboratory of Reproductive Technology, Cremona, Italy.

Mice – In 1998, Ryuzo Yanagimachi and Teruhiko Wakayama of the University of Hawaii announced that they had cloned fifty mice from adult cells since October of 1997.

Lambs – In July 1997, Ian Wilmut and Keith Campbell built upon the success of “Dolly” the sheep and successfully cloned “Polly”, a Poll Dorset lamb cloned from skin cells grown in a lab and genetically altered to contain a human gene7.

Cats – “Little Nicky” was born on 17th October 2004 and was the first commercially produced cat clone.

These results all point to the possibility of somatic nuclear transfer eventually being successful in all mammals, including humans. Yet it is still the most commonly held opinion that reproductive cloning of humans should be opposed.  Despite this widespread opposition to reproductive cloning, some scientists have nonetheless pursued this goal, and several claim to have successfully cloned humans, and even to have brought some to term.

The first human clone, a healthy 7-pound girl named Eve, was born on the 26th of December 2002, according to Clonaid, a private company linked to the Raelian religious sect.  (The Raelian’s believe that human life was created in an alien laboratory, and that human cloning provides the opportunity for human immortality.)  The claim was never verified.

In 2003 Panayiotis M Zavos, Professor Emeritus of Reproductive Physiology and Andrology at the University of Kentucky, claims to have cloned a human embryo but to have cryopreserved it at an early stage of development.

In November 2002, Dr Severino Antinori announced that he had successfully used cloning to induce pregnancy in three women, with birth of the first child expected in January 2003.  There is widespread skepticism about the truth of these claims.

Arguments Against Reproductive Cloning

1. Reproductive cloning would foster an understanding of children, and of people in general, as objects that can be designed and manufactured to possess specific characteristics.

2. Reproductive cloning would diminish the sense of uniqueness of an individual. It would violate deeply and widely held convictions concerning human individuality and freedom, and could lead to a devaluation of clones in comparison with non-clones.

3. Cloned children would unavoidably be raised "in the shadow" of their nuclear donor, in a way that would strongly tend to constrain individual psychological and social development.

4. Reproductive cloning is inherently unsafe. At least 95% of mammalian cloning experiments have resulted in failures in the form of miscarriages, stillbirths, and life-threatening anomalies; some experts believe no clones are fully healthy. The technique could not be developed in humans without putting the physical safety of the clones and the women who bear them at grave risk.

5. If reproductive cloning is permitted to happen and becomes accepted, it is difficult to see how any other dangerous applications of genetic engineering technology could be proscribed.

Rebuttals to Arguments Against Reproductive Cloning

1 and 2. This will be true only if we allow it to be true. There is no reason that individuals and society can't learn to embrace human clones as just one more element of human diversity and creativity.

3. The problem of "expectations" is hardly unique to cloned children. Most parents learn to communicate their expectations about their children in a moderate and ultimately positive way.

4. Every medical technology carries with it a degree of risk. Cloning techniques will eventually be perfected in mammals and will then be suitable for human trials.

5. Human society can accept or reject any proposed technology on its own merits.

Arguments in Favor of Reproductive Cloning

1. Reproductive cloning can provide genetically related children for people who cannot be helped by other fertility treatments (i.e., who do not produce eggs or sperm).

2. Reproductive cloning would allow lesbians to have a child without having to use donor sperm, and gay men to have a child that does not have genes derived from an egg donor (though, of course, a surrogate would have to carry the pregnancy).

3. Reproductive cloning could allow parents of a child who has died to seek redress for their loss.

4. Cloning is a reproductive right, and should be allowed once it is judged to be no less safe than natural reproduction.

Rebuttals to Arguments in Favor of Reproductive Cloning

1. The number of men and women who do not produce eggs or sperm at all is very small, and has been greatly reduced by modern assisted-reproduction techniques. If cloning could be perfected and used for this limited group, it would be all but impossible to prevent its use from spreading. Further, this argument appropriates the phrase "genetically related" to embrace a condition that has never before occurred in human history, one which abolishes the genetic variations that have always existed between parent and child.

2. Even if cloning were safe, it would be impossible to allow reproductive cloning for lesbians or gay men without making it generally available to all. Policy and social changes that protect lesbian and gay families are a much more pressing need.

3. Throughout history, parents who have lost children have grieved and sought consolation from family and community. "Replacing" the deceased child by cloning degrades and dehumanizes the child, its replacement, and all of us.

4. Rights are socially negotiated, and no "right" to clone oneself has ever been established. Furthermore, there is an immense difference between a woman's desire to terminate an unwanted pregnancy and the desire to create a genetic duplicate of another person. There is no inconsistency between supporting the former and opposing the latter.

Summary Comment

Most advocates of human cloning also advocate the genetic modification of the human species. Human cloning is a blunt form of eugenics-it "copies" an existing genome-while inheritable genetic modification allows the creation of "designer babies" through manipulation of individual genes. But cloning technologies are needed if inheritable genetic modification is to become commercially practicable. This is the deeper and more far-reaching motivation behind much of the advocacy of human cloning.

The Center for Genetics and Society believes that when all the arguments are considered together the case for allowing human cloning is not compelling, and that the harms of doing so are great.

PROS OF REPRODUCTIVE CLONING

1. Reproductive cloning can help parents with no eggs and sperm create genetically related children.

2. Reproductive cloning can help lesbians to have children without the use of donor sperm. And it would allow gay men to have children without the use of donor eggs and a suragette. Though a surrogate would have to carry the clone

3.  Reproductive cloning would allow people who have a child who has died to seek redress for their losses. 

4. Cloning is a reproductive right and once it is said to be safe as natural reproduction.

5. Animals who are endangered can be cloned to save their species.

CONS OF REPRODUCTIVE CLONINGHere's examples of how reproductive cloning can be negative:

1. Reproductive cloning will foster an understanding that children are designed and replicated for certain traits.

2. Reproductive cloning would diminish the idea of uniqueness. It would violate the widely held convictions concerning human individuality and freedom, and could lead to devaluation of clones in comparison with non-clones.

3. Cloned children would undoubtitly be raised in the shadow of their genetic donor.

4. Reproductive cloning is considered unsafe. At least 95% of mammals cloned have resulted in failure. 

5. Reproductive cloning can be considered unethical and against "god's" wishes. Many people believe that because clones were created by man, they will be unable to feel and empathize.

CONCLUSIONCloning is a type of asexual reproduction. A child created by cloning would be an exact replica of an existing or deseased person. If you cloned yourself the clone would not be like your sister, or brother, it would be an exact copy of you. A majority of people do not believe that reproductive cloning is ethical. Most advocates of human cloning also advocate for genetic modification of the human species. The technologies needed for reproductive cloning are not up to safety stadards. Many countries have banned research on reproductive cloning. This means that the technologies for reproductive cloning are not going to be improved quickly. There is still a lot of research that needs to be done on reproductive cloning.

Is adult human DNA cloning moral?

Some say yes: 

Some talents seem to be genetically influenced. Musical ability seems to run in families. Cloning using the DNA from the cell of an adult with the desired traits or talents might produce an infant with similar potential.

A heterosexual couple in which the husband was completely sterile could use adult DNA cloning to produce a child. An ovum from the woman would be coupled with a cell from the man's body. Both would contribute to the child: the woman would provide the "factory" for creating cells; the man would provide the "genetic information." They might find this more satisfactory than using the sperm of another man.

Two lesbians could elect to have a child by adult DNA cloning rather than by artificial insemination by a man's sperm. Each would then contribute part of her body to the fertilized ovum: one woman would donate the ovum, which contains some genetic material in its mitochondria; the other woman the nuclear genetic material. Both would have parts of their bodies involved in the conception. They might find this more satisfactory than in-vitro fertilization using a man's sperm.

Some say no:

There is no guarantee that the first cloned humans will be normal. The fetus might suffer from some disorder that is not detectable by ultrasound. They may be born disabled. Disorders may materialize later in life. Such problems have been seen in other cloned mammals. There is no reason to assume that they will not happen in humans.

Cells seem to have a defined life span built into them. "Dolly" was created from a cell that was about six years old; this is middle age for a ewe. There were some indications that Dolly's cells were also middle-aged. She was believed to be, in essence, about six years old when she was born. She was expected to live only for five years, which is shorter than the normal life span of 11 years. If this is also true of humans, then cloned people would have a reduced life expectancy. The cloning technique could take many years off their life. [These fears proved to be unfounded. "Dolly" has grown into a comfortable middle age with signs of normal aging for her age.]

Dolly was conceived using a ewe's egg and a cell from another ewe's body. It is noteworthy that no semen from a ram was involved. If the technique were perfected in humans, and came into general usage, then there would be no genetic need for men. All of the human males could be allowed to die off. [The author of this essay is a male and does not think kindly of such a future. However, some readers might not object to this eventuality.]

Large scale cloning could deplete genetic diversity. It is diversity that drives evolution and adaptation. It prevents an entire species from disappearing because of susceptibility to a disease. [It is doubtful that cloning would ever be used at a level to make this a significant threat.]

Some people have expressed concern about the effects that cloning would have on relationships. For example, a child born from an adult DNA cloning from his father would be, in effect, a delayed twin of one of his parents. That has never happened before and may lead to emotional difficulties.

There are religious objections to cloning.

Most pro-life supporters believe that a fertilized ovum is a full human person. When its nucleus is removed during cloning, that person is, in effect, murdered.

A secondary concern is the whole business of collecting surplus embryos and simply storing them in a deep-freeze as a commodity.

Some claim that cloned humans may be born without souls. They speculate that the soul enters the body when a sperm fertilizes an ovum. Since there is no sperm involved in cloning, perhaps the fetus would develop without a soul. There is no way to know whether a soul is present; it has no weight, it cannot be seen, touched, smelled, heard, or detected in any other way. In fact, many people believe that souls do not exist. Speculation on this topic can never be resolved.

At the current stage in cloning research using adult DNA, the random appearance of genetic defects, noted above, appears to be an overwhelming problem. Such dangers would seem to put an indefinite halt on all ethical cloning of humans.