A group of five gene-edited macaque monkeys has been cloned using skin cells in a move the scientists behind the work say will help understand human diseases.
As clones, all the monkeys have the same DNA altered, resulting in symptoms seen in human conditions including anxiety, depression and schizophrenia.
By creating primates with identical genes and symptoms, the researchers hope to test new treatments for diseases ranging from brain disorders to cancers.
In this case, they knocked out the gene responsible for BMAL1, a substance that affects the body’s circadian rhythms.
The scientists then took cells from ones of the donor monkeys that had been gene edited and displayed symptoms including reduced sleep time and those associated with mental health problems.
They used these donor cells to clone a group of monkeys with the same disease-causing mutation.
“Disorder of circadian rhythm could lead to many human diseases, including sleep disorders, diabetic mellitus, cancer and neurodegenerative diseases,” said Dr Hung-Chun Chang, a senior researcher for the project at the Chinese Academy of Sciences.
Upon the announcement of the cloned monkeys early last year, other scientists welcomed it as an impressive technical achievement.
However, they also warned of ethical issues associated with cloning primates. In the attempt to create Zhong Zhong and Hua Hua, the scientists went through dozens of cloned embryos and monkeys that only survived a few days.
Primate research is tightly controlled, meaning it is unlikely such techniques will be widely applied.
But the scientists behind the work said cloning allows the number of monkeys used to be reduced, due to uniform genetic background cutting out unhelpful noise from the resulting data.
“This line of research will help to reduce the amount of macaque monkeys currently used in biomedical research around the world,” said Professor Mu-ming Poo “Without the interference of genetic background, a much smaller number of cloned monkeys carrying disease phenotypes may be sufficient for pre-clinical tests of the efficacy of therapeutics.”
The advent of cloned monkeys brought fears that the technique would soon be applied to humans, although these were dismissed by scientists.
Gene editing in humans also remains highly controversial, with another Chinese researcher – the disgraced Professor He Jiankui – facing global condemnation after he told the world he had created the first gene-edited babies.
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