It was a glorious day in Edinburgh, Scotland. Old friends and fellow scholars Ian Wilmut and Alan Thrawson went on a hike. Twenty years ago. High above the city, Wilmouth confessed that he had a secret. As part of a major study, he and several of his colleagues successfully gave birth to a sheep in the laboratory - not from an egg and sperm, but from DNA taken from the mammary gland of an adult sheep. They cloned a mammal.
“I was overwhelmed,” says Thrawson, who is now - as then - a stem cell biologist at Monash University in Melbourne, Australia. He recalls how he sank heavily on a stone nearby. It was a hot day, but Thrawnson felt a chill run through his body: he realized the consequences. "It changed everything."
Mammal cloning challenged the scientific dogma of the day. The success gave rise to gloomy and fantastic predictions: people will begin to clone. Diseases will disappear. Dead children will be reborn. Today, twenty years after the birth of Dolly the sheep on July 5, 1996, the influence of cloning on basic science has surpassed all expectations, while there have been practically no changes in society related to cloning and Dolly in particular.
Dolly, center, the first cloned sheep in the world
In 2016, human cloning remains impracticable, provides no scientific benefit, and carries an unacceptable level of risk. Nobody even thinks about such a feat. Animal cloning also remains limited, although it appears to be evolving. Agricultural cloning is being used in the US and China to capitalize on the genes of several unusual specimens, scientists say, but the European Parliament voted last year to ban cloning animals for food. One scientist in South Korea charges $ 100,000 to clone pets, but the level of demand for such a service is unclear.
The biggest impact that cloning has had, according to scientists, is in advances in stem cells. Stem cell biologist Shinya Yamanaka says Dolly's cloning prompted him to start developing stem cells extracted from adult cells - leading him to the Nobel Prize in 2012.
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"Dolly the sheep told me that nuclear reprogramming is possible even in mammalian cells, and prompted me to start my own project," Yamanaka writes. He used adult cells - first from mice, although technology now allows it to be done with human cells - to make stem cells that could form a wide variety of other cells, retracing the path from embryo to adult, but of a different nature. Since such cells are created artificially and can be used for many purposes, they are called induced pluripotent stem cells (iPS). The rise of iPS cells has reduced the need for embryonic stem cells, which have long been an ethical controversy, and today iPS cells are at the heart of much stem cell research.
Dolly's birth was transformative because it proved that the nucleus of an adult cell possesses all the DNA needed to give birth to another animal, says stem cell biologist Robin Lovell-Badge, head of stem cell biology and developmental genetics at the Francis Crick Institute in London. Prior to that, researchers removed adult frogs from frog embryonic cells, or embryonic stem cells from adults - and at this their development came to a standstill.
“Dolly was the first example that you can take an adult cage and have an adult,” says Lovell-Badge. "That is, you can reprogram the nucleus of an adult cell back to an embryonic state."
Dolly died on February 14, 2003 at the age of six from a lung infection common in animals that are not allowed to go outside. It had nothing to do with the sheep being cloned, Wilmut says.
The lamb, made from mammary gland cells, was named after Dolly Parton, an American singer known for her big breasts and her voice too. “It was not disrespectful to this woman and women in general,” Wilmut says. No, it helped humanize a research project that might otherwise be out of touch with everyday life. - Science and its presentations sometimes look terribly serious. I think it was good for us - we became more like people."
Wilmut believes Dolly's birth could have been a fluke. He and his colleagues tried to make clones from fetal cells and used adult cells for experimental control - without expecting them to produce their own embryos. “We did not set ourselves the task of cloning adult cells. We planned to work, ideally, with embryonic stem cells or something similar, says Wilmut. "Success in working with adult cells was an unexpected bonus."
The original goal of the study was to use the animal's milk production system as a factory to produce proteins for the treatment of human diseases. But interest in this idea has declined along with the proliferation of inexpensive synthetic chemicals.
Wilmut believes that cloning a person is possible - but not necessary. The cloning technique that brought Dolly to life did not work on the primates. He believes that this goal can be achieved using other methods, but is strongly opposed to human cloning.
“Just because it can work doesn't mean we have to do it,” he says. "Most likely, we will face problems at birth, during childbirth." For example, one of the sheep in his laboratory, which was cloned shortly after Dolly, developed lung problems that soon led to her death.
"I would not want to become a person who would clone a child and then I looked at him and said: very sorry." With the latest advances in gene editing, the need for cloning has receded further into the background. Now there are fewer reasons to do it than before.
Thrawson believes there must be a large market for cloned cattle embryos.
In 2008, the US government decided that there was no difference between cloned and non-cloned cows, goats and pigs, so it was allowed to do this, but mostly for breeding, and not for meat production. China's Boyalife Group plans to produce at least 1,000,000 cloned cattle - not much when you look at the total number of animals slaughtered annually in the country.
In theory, cloning could be used to bring back endangered species. Even its use for the restoration of woolly mammoths, giant pandas and even Neanderthals has been discussed - a thought that Lovell-Badge dismisses as "pretty silly." Thrawson says he still has a cache of northern wombat skin samples stored in liquid nitrogen in case anyone wants to restore the species. However, cloning requires an adult cell. To create a clone, you need a working kernel, which most extinct species do not have.
Some scientists are now using cloning techniques to produce embryonic stem cells, thereby eliminating the need to harvest new embryos. The so-called somatic cell nucleus transplant could help scientists better understand early human embryogenesis and stem cell biology, according to Paul Knopfler, a biologist at the University of California, Davis who was not involved in Dolly's cloning. Knopfler says he sees "no immediate therapeutic benefits in this work, but that may change in the future."
The idea of cloning a deceased loved one - a person or a pet - is not widely supported anywhere, in part because the environment influences the behavior of an individual. The genetics may be identical, but will the new clone still be the same beloved individual? Lovell-Badge believes that the only possible reason for cloning a pet could be in special properties - for example, in a subtle instinct or in an expensive breed - and even then, it is not clear if this instinct will be innate or acquired. But to clone a person … He believes that we will never do it.
ILYA KHEL