LONDON – New guidelines released on Wednesday remove a decades-old obstacle to stem cell research, recommending that researchers be allowed to grow human embryos for longer under limited conditions.
The “14 day rule,” an international ethical standard that limits laboratory studies of human embryos, has been in place for decades and has been enshrined in law in countries like Britain and Australia. Scientists previously had to destroy human embryos grown in a lab before they were 14 days old.
Some researchers have favored revising the rule to study the development process in more detail, while opponents argue that such experiences at any time cross a moral boundary and it is not clear that the change would advance the development. research.
The initial limit was arbitrary and precluded the study of a critical period of embryo development – typically between 14 and 28 days, said Robin Lovell-Badge, a stem cell expert at London’s Crick Institute and chairman of the group behind the new guidelines.
“We think a lot of birth defects develop quite early in this time,” Lovell-Badge said. “By better understanding these first steps, it could allow us to adopt simple procedures to reduce the amount of suffering.”
The guidelines, last updated in 2016, were published by the International Society for Stem Cell Research, whose standards are widely accepted by countries, medical journals and the research community. He did not specify how many more embryos could be cultured.
In order for British scientists to start making embryos beyond two weeks, the law governing this research would have to be changed. Any easing of the rule would still require a “close examination” by national regulators, Lovell-Badge said.
It is “not a green light” for scientists to expand research on human embryos, said Kathy Niakan of the University of Cambridge who helped draft the guidelines, adding that “it would be irresponsible.”
Niakan said a public dialogue involving scientists, regulators, funders and the public to discuss any potential objections should be undertaken. She said broad public support was needed before work could continue, and countries could also use a specialized monitoring process to assess the scientific merits of the research.
Marcy Darnovsky, executive director of the Center for Genetics and Society, said the scientific rationale for the new guidelines was still lacking.
“When an embryo is in a petri dish outside the body, are you really going to be able to say anything meaningful about a miscarriage or embryonic development?” she said.
Darnovsky was also concerned that the guidelines did not place a limit on how long human embryos could grow.
The company also offered advice on other contentious stem cell issues, including the requirement for strict monitoring of the transfer of human embryos to the uterus after mitochondrial donation – a process in which two eggs and one sperm are used to create an embryo.
The guidelines ban, for now, any genetic modification that would pass changes on to future generations – similar to the work done by Chinese scientist He Jiankui, who stunned the world when he announced in 2018 that he had made the first ones. babies modified by the gene.
Such work is prohibited at this time, but Lovell-Badge and others recognize that it may one day be permitted “if it is found to be sufficiently safe and has been used in sufficiently limited circumstances”, said said Hank Greely, director of the Center for Law and the Biosciences. at Stanford University.
The guidelines also ban human cloning, the transfer of human embryos into an animal uterus and the creation of human-animal chimeras, saying the work “lacks scientific justification or is ethically concerning.”