After Dolly the sheep, why haven't humans cloned yet?

In 1996, Dolly the sheep caused a stir around the world after becoming the first mammal to be successfully cloned from an adult cell. Many commentators argue that this will catalyze a golden age of cloning. Many conjectures, the first human cloning is only a few years away.

Some argue that human cloning may play some role in eliminating genetic diseases, while others believe that cloning may eventually eliminate birth defects. However, research by a group of French scientists in 1999 showed that cloning can actually increase the risk of birth defects.

All these claims are baseless, the most important thing is to add the successful cases of human cloning as evidence since after Dolly the sheep. In 2002, Brigitte Boisselier, a French chemist and devout supporter of Raëlism (a UFO religion based on the idea that aliens created the human race) announced, she and a group of scientists successfully transferred the first clone, named Eve. It is worth mentioning, however, that Boisselier is unwilling - or indeed cannot - to provide any evidence for this, and so it is widely considered to be a hoax.

Dolly the sheep.

The question is why almost 30 years since Dolly, humans have not been cloned yet? Is it primarily for ethical reasons, is there a technological barrier, or is it simply not worth doing?

The National Human Genome Research Institute (NHGRI) says that cloning is a broad term, as it can be used to describe a wide range of processes and approaches, but generally has the purpose of creating genetically identical copies of a biological entity.

According to the NHGRI, any human cloning attempt would use "reproductive cloning" - an approach in which mature somatic cells, most likely skin cells, would be used. used. The DNA extracted from this cell is placed into the donor egg cell, which has had its own DNA-containing nucleus removed. The egg then begins to develop in a test tube before being implanted in an adult woman's uterus to form a fetus.

However, while scientists have cloned many mammal species, including cattle, goats, rabbits and cats, humans have not made the list. Hank Greely, a professor of law and genetics at Stanford University who specializes in the ethical, legal and social issues arising from advances in the biological sciences, says that up until now, there isn't any good reason to clone a human. Human cloning is a particularly dramatic act and one of the most controversial topics in American bioethics.

The ethical concerns surrounding human cloning are also diverse. Among these, potential issues include psychological, social and physiological risks, meaning cloning can lead to a very high probability of loss of life, or concerns surrounding cloning of human beings. eugenics advocates use. Not to mention that cloning can be seen as a violation of the principles of human dignity, freedom and equality.

Until now, there wasn't any good reason to clone a human.

In addition, mammalian cloning has historically resulted in very high mortality and developmental abnormalities in cloned species. Another core problem with human cloning is that instead of creating a clone of the original, it creates an individual with their own thoughts and views. We've all known clones - which are identical twins that are copies of each other - so we also know that the clones are not the same person. A human clone will have only the same genetic makeup as that person, but will not share other traits such as personality, morals or a sense of humour: these will be unique to each person.

Humans are not simply a product of DNA, but are also affected by many other factors, although they can reproduce genetic material, they cannot accurately reproduce the living environment, creating a unique environment. identical education, or two people with the same life experience.

If scientists cloned a human, would there be any benefit, scientifically or in other ways? The researchers stress that ethical concerns cannot be ignored. However, if ethical considerations were to be eliminated altogether, one theoretical benefit would be to produce genetically identical humans for research purposes.

Greely also states that, regardless of his personal opinion, some of the potential benefits associated with human cloning also seem redundant because of scientific developments in other respects. He says the idea of ​​using cloned embryos for purposes other than creating babies, such as producing human embryonic stem cells that are identical to donor cells, was widely discussed in the early days. 2000s, but this research circuit became irrelevant, and was subsequently not extended. After 2006, the year so-called induced pluripotent stem cells (iPSCs) were discovered, these are "adult" cells that have been reprogrammed to resemble cells in early development .

Shinya Yamanaka, a Japanese stem cell researcher and 2012 Nobel laureate, discovered it when he figured out how to bring adult mouse cells back to an embryo-like state using just four genetic factors. . A year later, Yamanaka, along with the famous American biologist James Thompson, sought to do the same with human cells.

A diagram showing induced pluripotent stem cells (iPSCs) and their potential for regenerative medicine.

So instead of using embryos, we can effectively do the same thing with skin cells. This development in iPSC technology has essentially made the concept of using cloned embryos both unnecessary and scientifically inferior.

Currently, iPSCs can be used for disease modeling, drug discovery, and regenerative medicine. Greely also suggests that human cloning may no longer be an attractive area of ​​scientific research, which may explain why it has seen so little development in recent years. He points out that editing the human genome is now a more interesting topic for many people, for example, who are curious about the concept of creating "super-infant". Germline editing, or germline engineering, refers to a series of processes that make permanent changes to an individual's genome. If we know how to effectively implement these changes to become heritable, that means they will be passed down from parent to child.

However, such editing is still not fully understood and controversial. For example, the Bioethics Committee of the Council of Europe states that ethics and human rights should guide all activities using human genome editing technology, and the application of genome editing technology. to human embryos raises many ethical, social and safety problems, especially since any modifications in the human genome could be passed on to future generations.

There is also strong support for such engineering and correction technologies to provide a more complete understanding of the causes of diseases and future treatments, with significant potential for research in this field and improve human health. George Church, a geneticist and molecular engineer at Harvard University, is one of the advocates, saying the field has the potential to attract more scientific interest in the future, particularly in the future. especially when compared to conventional cloning.

Cloning-based germline editing is often more precise, can involve more genes, and is more efficiently distributed to all cells than somatic genome editing. However, he still cautioned that he needed to be cautious and acknowledged that such editing has not yet been mastered. Potential limitations that need to be addressed include safety, effectiveness, and equity for all of us.