Will ReTro pioneer a new generation of monkeys cloned for scientific experimentation?
Chinese researchers have cloned the first rhesus monkey; a species widely used in medical research as its physiology is similar to that of humans.
Cloned lab monkeys could speed up drug testing. Genetically identical animals give similar results and provide greater accuracy in tests.
Previous attempts to clone a Rhesus produced no births or the creatures died a few hours later.
An animal rights organization claimed to have done so a “deep concern” about this cloning.
Sexual reproduction in mammals results in offspring made up of a mixture of genes from the father and mother. In the case of cloning, techniques are used to create a genetically identical copy of a single animal.
The most famous cloned animal, Dolly the sheep, was born in 1996. Scientists reprogrammed another sheep’s skin cells to become embryos, made up of basic cells capable of growing into any part of an organism. These embryos were implanted into Dolly’s surrogate mother.
In a magazine article Nature communications, researchers say they did essentially the same thing, but with a rhesus monkey. They claim that the animal remained healthy for more than two years, which indicates that the cloning process was successful.
Dr. Falong Lu del University of Chinese Academy of Scienceshe told the BBC that “everyone was beaming with happiness” at the result.
But a spokesperson for Britain’s Royal Society for the Prevention of Cruelty to Animals (RSPCA) said the organization believes the suffering caused to animals outweighs any immediate benefit to human patients.
Rhesus monkeys are found in the wild in Asia with populations in Afghanistan, India, Thailand, Vietnam and China. They are used in experiments to study infections and immunity.
The first monkeys (macaques) were cloned in 2018, but medical researchers prefer rhesus monkeys due to their genetic similarity to humans.
Zhong Zhong was one of the first macaques cloned in 2018
Complications
The problem with reprogramming adult cells to become embryonic is that in most attempts errors are made in the reprogramming. Therefore, very few embryos are born and even fewer are born healthy: between 1% and 3% in most mammals.
This proved even more difficult with rhesus monkeys, with no births until the research team succeeded two years ago.
They found that in failed rhesus attempts, the placentas, which provide oxygen and nutrients to the growing fetus, had not been properly reprogrammed through the cloning process and therefore did not develop normally.
The researchers solved the problem by not using the part of the cloned embryo that then develops into a placenta: the external part.
They removed the internal cells – which develop in the animal’s body – and inserted them into a non-cloned external embryo, hoping it would develop into a normal placenta.
back
The researchers used 113 embryos, of which 11 were implanted and achieved two pregnancies and one live birth.
They named the monkey “ReTro,” after the scientific method called “trophoblast replacement” used to produce the animal.
The RSPCA said it had serious concerns about the investigation.
«There is no immediate application for this study. “Human patients are expected to benefit from these experiments, but any real-life application would take years and multiple animal ‘models’ will likely be needed to develop these technologies,” a spokesperson said.
“The RSPCA is deeply concerned about the large number of animals experiencing suffering and distress in these experiments and the very low success rate. “Primates are intelligent and sensitive animals, not just research tools,” he concluded.
ReTro was created using the same Dolly technique, but with one further modification
Concerns after rhesus monkey cloning
Professor Robin Lovell-Badge of the Francis Crick Institute in London also expressed concern. This strongly supports animal research when the benefits for patients outweigh the suffering of the specimens.
He indicated that “having animals with the same genetic makeup will reduce a source of variation in experiments. But “you have to ask yourself if it’s really worth it.”
»The number of attempts they needed was enormous. They had to use many embryos and implant them into many surrogate mothers to get a live-born animal,” she said.
The professor is also concerned because scientists have produced only one live birth.
»No conclusion can be drawn about the success rate of this technique in the case of a single birth. It’s crazy to say you can do it. You need at least two, although preferably more.”
In response, Dr Falong Lu explained to BBC News that the team’s goal is to get more cloned monkeys while reducing the number of embryos used.
It said it had obtained all ethical approvals for the research.
“All animal procedures in our research adhered to the guidelines established by the Animal Care and Use Committees of the Shanghai Institute of Biological Sciences, the Chinese Academy of Sciences (CAS), and the Institute of Neuroscience of the Center of Excellence in CAS Brain Science and Intelligence Technology.
The protocol, he said, was also approved by the Animal Care and Use Committee of this major Chinese research center based in Shanghai.
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2024-01-17 13:09:03
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