- Written by Parab Ghosh
- science correspondent
Chinese researchers have cloned the first rhesus macaque. Rhesus monkeys are widely used in medical research because their physiology is similar to humans.
They say drug testing could be faster because genetically identical animals produce similar results, increasing the certainty of trials.
Previous attempts to clone rhesus macaques either failed to give birth or the offspring died after a few hours.
One animal rights group said it was “deeply concerned” by the development.
In mammals, sexual reproduction produces offspring that consist of a mixture of genes from the father and mother. Cloning uses techniques to create genetically identical copies of a single animal.
The most famous cloned animal, Dolly the sheep, was created in 1996. Scientists reprogrammed another sheep’s cells into embryos that form cells that can grow into any part of an organism. These embryos were implanted into Dolly’s surrogate mother.
writing in diary natural communication, the researchers say they did essentially the same thing using rhesus macaques. They said the animal has remained healthy for more than two years, indicating that the cloning process was successful.
Dr Fallon Lu, from the University of the Chinese Academy of Sciences, told BBC News that “everyone was beaming with happiness” at the successful outcome.
But a spokesperson for the Royal Society for the Prevention of Cruelty to Animals (RSPCA) said the organization believes the suffering caused to the animals outweighs the immediate benefit to human patients.
Rhesus macaques live in the wild in Asia, from Afghanistan to India, Thailand, Vietnam, and China. These are used in experiments to study infectious diseases and immunity.
The first macaque monkey was cloned in 2018, but rhesus macaques are preferred by medical researchers because they are genetically similar to humans.
The problem with reprogramming adult cells into embryos is that in most attempts, mistakes are made in the reprogramming, and very few cells end up being born, and even fewer cells are born healthy (most 1–3% in mammals). And rhesus macaques proved even more difficult, with no births until the research team succeeded two years ago.
They found that in the failed rhesus macaque attempt, the placenta, which provides oxygen and nutrients to the growing fetus, was not properly reprogrammed by the cloning process and therefore did not develop normally.
The researchers got around this problem by not using the outer part of the cloned embryo, the part that develops into the placenta. As the diagram below shows, they removed the internal cells that develop into the animal’s body and inserted them into an uncloned external embryo, hoping that it would develop into a normal placenta.
The researchers used 113 embryos, of which 11 were implanted, resulting in two successful pregnancies and one birth.
They named this monkey “Retro” after the scientific method used to produce it called “trophoblast replacement.”
The RSPCA said it had serious concerns about the research.
“This research has no immediate applications. We envision that human patients will benefit from these experiments, but real-world applications will take years and these experiments Many more animal “models” may be needed to develop this. Technology,” the spokesperson said.
“The RSPCA is deeply concerned by the high number of animals experiencing suffering and suffering in these experiments, and by the very low success rate. Primates are intelligent, sentient animals. It’s not just a research tool.”
Professor Robin Lovell-Budge of the Francis Crick Institute in London, who is a strong supporter of animal research when the benefit to the patient outweighs the suffering of the animal, has similar concerns.
“Keeping animals with the same genetic makeup reduces sources of variation in experiments, but you have to ask yourself if it’s really worth it.
“Their number of attempts was huge. To get one live animal, many embryos had to be used and transferred into many surrogate mothers.”
Professor Lovellbadge is also concerned that scientists have only delivered one baby.
“One birth does not allow us to draw any conclusions about the success rate of this technique. It is nonsense to suggest that it can. We need at least two, but preferably more.”
In response, Dr Fallon Lu told BBC News that the research team’s aim was to obtain more cloned monkeys while reducing the number of embryos used. He added that all ethical approvals have been obtained for the study.
“All animal experiments in our study were set up by the Animal Use and Care Committee of the Shanghai Institute of Biological Sciences, Chinese Academy of Sciences (CAS), and the Institute of Neuroscience, Center of Excellence in Brain Science and Intelligence, CAS. Guidelines were followed. This protocol was approved by the Animal Use and Care Committee of the CAS Center for Excellence in Brain Sciences and Intelligence Technology.