Chinese researchers have successfully cloned a rhesus monkey (Macaca mulatta) using an innovative technique that addresses common developmental defects observed in cloned embryos. Notably, rhesus monkeys are phylogenetically close to humans, sharing about 93 percent of their DNA and this makes them valuable models for studying human physiology, anatomy, and diseases. The new method is different from what was used to clone Dolly the sheep. The monkey, named ReTro, is now over two years of age, marking a milestone in primate cloning.
For the first time, researchers at the Chinese Academy of Sciences in Shanghai have achieved successful cloning of a rhesus monkey using a modified cloning approach that involved replacing the placenta, which plays a crucial role in supporting the growth and development of the fetus, of the cloned embryo with a placenta from embryos produced by in-vitro fertilisation (IVF).
By doing so, the scientists reduced developmental defects that typically hinder the survival of cloned embryos, ultimately leading to the first successful cloning of the species.
The conventional cloning technique, known as somatic cell nuclear transfer (SCNT), has historically resulted in low birth and survival rates for cloned embryos, especially in primates. This is the technique used to clone Dolly the sheep and other mammals.
Previous attempts to clone long-tailed macaques in 2018 yielded only two surviving monkeys out of 109 cloned embryos. In 2022, a rhesus monkey cloned using SCNT survived for less than 12 hours.
What was the obstacle?
The researchers found that the placentas were not reprogrammed during the cloning process resulted in abnormal development. To overcome this issue, researchers, instead of using the entire cloned embryo, including the part that forms the placenta, which is the outer layer, scientists extracted the inner cells, which contribute to the animal's body development, and introduced them into a non-cloned outer embryo.
This innovative technique was designed to encourage the development of a normal placenta. This resulted in the creation of a "natural placenta" while maintaining the cloned nature of the fetus.
The researchers successfully implanted 11 cloned rhesus monkey embryos into seven surrogates, resulting in two pregnancies. One of the surrogates gave birth to ReTro, a healthy male rhesus monkey that has thrived for more than two years. However, challenges remain in improving the cloning process.
Scientists envision using cloned monkeys for drug testing and behavioural research, aiming to reduce the number of animals used in experiments and eliminate genetic background interference.
(With inputs from agencies)
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2024-01-17 08:05:05Z
CBMijQFodHRwczovL3d3dy53aW9uZXdzLmNvbS9zY2llbmNlL2NoaW5lc2UtcmVzZWFyY2hlcnMtY2xvbmUtcmhlc3VzLW1vbmtleS13aXRoLW5ldy10ZWNobmlxdWUtZGlmZmVyZW50LWZyb20td2hhdC11c2VkLWluLWRvbGx5LXRoZS1zaGVlcC02ODA4MDbSAZEBaHR0cHM6Ly93d3cud2lvbmV3cy5jb20vc2NpZW5jZS9jaGluZXNlLXJlc2VhcmNoZXJzLWNsb25lLXJoZXN1cy1tb25rZXktd2l0aC1uZXctdGVjaG5pcXVlLWRpZmZlcmVudC1mcm9tLXdoYXQtdXNlZC1pbi1kb2xseS10aGUtc2hlZXAtNjgwODA2L2FtcA
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