The breakthrough could lead to customised cells to help treat and even cure a range of diseases, from Alzheimer’s to multiple sclerosis.
However, it also raises the spectre of babies being cloned in laboratories. This could allow couples who lose a child to pay for the creation of a ‘duplicate’.
While human embryos have been cloned before, none have had healthy stem cells extracted from them. The latest advance means scientists are now even closer to being able to clone children.
The US team behind the work stress that they want to find treatments for incurable diseases – but critics fear there is little to stop a rogue scientist from copying their work to try to clone humans.
Dr David King, founder of the campaign group Human Genetics Alert, called for an international ban on human cloning and said it was ‘irresponsible in the extreme’ to have published details of the stem-cell technique.
The world first was achieved at Oregon Health and Science University, with a technique similar to the one used to clone Dolly the sheep.
First, Dr Shoukhrat Mitalipov took eggs donated by healthy young women and removed their DNA.
He then placed skin cells inside the hollowed-out eggs and used a zap of electricity to make them start developing into embryos.
When the embryos were five or six days old, and around the size of a pinhead, Dr Mitalipov successfully harvested them for stem cells.
These cells, known as ‘master cells’, are capable of turning into every type of cell in the body and are widely seen as a potential repair kit for diseased, damaged and worn-out body parts.
Dr Mitalipov has spent many years refining the technique, which involves feeding the eggs caffeine at a key point in the process.
He said: ‘Our finding offers new ways of generating stem cells for patients with dysfunctional or damaged tissues and organs.
‘Such stem cells can regenerate and replace those damaged cells and tissues and alleviate diseases that affect millions of people.
‘While there is much work to be done in developing safe and effective stem-cell treatments, we believe this is a significant step forward in developing the cells that could be used in regenerative medicine.’
Using a sliver of the patient’s skin at the start of the process would ensure that stem cells would be a perfect match for their body.
This would raise the odds of the treatment being successful, and remove the need for powerful drugs to suppress the patient’s immune system.
Tailor-made cells could also be used to learn more about a person’s illness, and test drugs to find those that work best.
Chris Mason, a professor of regenerative medicine at University College London, said Dr Mitalipov’s work, detailed in the journal Cell, looked like ‘the real deal’.
Dr Paul De Sousa, of Edinburgh University, said that improving our understanding of women’s eggs could lead to new treatments for infertility. However, other scientists warned that the new research brings us closer to babies being cloned to order.
In Britain, the law states that cloned embryos have to destroyed after 14 days, and it is illegal to implant them in a woman. Other countries have more relaxed rules for so-called reproductive cloning.
Josephine Quintavalle, of campaign group Comment on Reproductive Ethics, questioned the need for the research, given that another, more simple way of making customised stem cells already exists.
She said: ‘The suspicion has to be that the real interest is not stem cell therapy per se, given that other uncontroversial approaches are already so successful. Let’s hope that the goal is not out and out reproductive cloning.’
Dr Mitalipov said he has failed to create baby monkeys via cloning, and that it is therefore unlikely his technique could be used to clone humans.
Others claim that creating a five-day-old bundle of cells is a far cry from someone giving birth to a fully-formed cloned baby.
However, Dr King warned: ‘Scientists have finally delivered the baby that would-be human cloners have been waiting for: a method for reliably creating cloned human embryos.
'This makes it imperative that we create an international ban on human cloning before any more research like this takes place.
‘It is irresponsible in the extreme to have published this research.’
In 2004 Hwang Woo-suk of South Korea claimed to have cloned the first human embryo and extracted stem cells from it.
It later emerged that his data was fabricated, and he was convicted of embezzlement and other charges.
Thursday December 12th 2019