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Why hasn’t anyone cloned yet?

Nearly 30 years after Dolly the sheep was born, human cloning has not yet become a reality and the field has also developed little in recent years.

Image of the cloned sheep Dolly in Roslin, Scotland, September 2, 1997.  Photo: Asahi Shimbun

Image of the cloned sheep Dolly in Roslin, Scotland, September 2, 1997. Image: Asahi Shimbun

In 1996, Dolly the sheep caused a stir around the world when she became the first mammal to be successfully cloned from an adult cell. Many argue that this will set the stage for the golden age of cloning technology, even predicting that human cloning will happen within just a few years. Some argue that human cloning can be somewhat helpful in eliminating genetic diseases and birth defects (although research by a group of French scientists in 1999 showed that cloning can increase the risk of genetic defects). congenital).

Cloning is a broad term because it can be used to describe a variety of processes and approaches, but the goal is always to make genetically identical copies of a biological entity, according to the Institute for Ministry of Health Research. National Human Gene (NHGRI).

According to the NHGRI, there is a high probability that any human cloning attempt will use “reproductive cloning” – a method that uses adult somatic cells, possibly skin cells. The DNA extracted from this cell is inserted into the egg cell of a donor whose nucleus has been removed from its own DNA. The eggs will begin to develop in a test tube, then implant in the uterus of an adult female.

To date, scientists have cloned many mammals such as cattle, goats, rabbits and cats. However, nearly 30 years after the success of Dolly the sheep, humans still have not made the list.

First of all, human cloning raises many ethical concerns. Mammal cloning has also historically had a very high mortality rate and resulted in developmental abnormalities.

Another important issue is that instead of creating a carbon copy of the original, cloning creates an individual with its own thoughts and opinions. “We all know about clones – identical twins are copies of each other. So we also know clones aren’t the same person,” said Hank Greely, a professor at the University Stanford, explained.

The clone will only have the same genetic makeup as the original but not in other aspects such as personality, morality or sense of humor. These are unique to both parties. Humans are not simply a product of DNA. One can reproduce genetic material, but it is not possible to accurately recreate the living environment, the educational environment, or cause two people to have the same life experience.

Ethical considerations aside, one theoretical benefit of human cloning is to create genetically identical individuals for research purposes, Greely says. However, he still expressed his disapproval of human cloning.

Some of the benefits from human cloning have also become unnecessary due to today’s scientific advances, Greely said.

Japanese researcher Shinya Yamanaka.  Photo: Alexander Mahmoud

Japanese researcher Shinya Yamanaka. Image: Alexander Mahmoud

Shinya Yamanaka, a Japanese researcher who won the 2012 Nobel Prize, discovered induced pluripotent stem cells (iPSCs) in 2006. These are “adult” cells that have been reprogrammed to resemble cells in early development stage. Yamanaka has found a way to bring adult mouse cells back to an embryo-like state using just four genetic factors. The following year, Yamanaka and American biologist James Thompson, did the same with human cells.

When iPSCs are reprogrammed to an embryonic pluripotent state, they allow the development of an unlimited source of all types of human cells needed for therapeutic purposes. Therefore, instead of using embryos, one could do the same thing with skin cells. Developments in iPSC technology have made the use of cloned embryos unnecessary. Today, iPSCs can be used in disease modeling, therapeutics and regenerative medicine.

In addition, Greely suggested that human cloning may no longer be an exciting scientific research area. This also explains the lack of development in this field in recent years.

As Greely points out, human germline genome editing is now a more interesting topic to the public. For example, there are many people who are curious about the concept of creating “super babies”.

Germline editing is one or a series of processes that make permanent changes to an individual’s genome. These changes can become heritable when effectively implemented, meaning they pass from parent to child. Such editing is controversial and still not fully understood.

George Church, a geneticist and molecular engineer at Harvard University, supports Greely’s idea that germline editing could attract more scientific interest in the future, especially since compared with “traditional” cloning.

“Clone-based germline editing is often more precise, can be used for more genes, and delivers to all cells more efficiently than somatic genome editing,” he said. However, Church says caution is needed because the scientific community is still not fully aware of such editing.

Thu Thao (According to Live Science)

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