Two decades after the first mammal – Dolly the sheep – was successfully cloned, scientists in China have become the first to use the same technique to clone monkeys. By breaking this primate cloning barrier, the researchers may have made it possible for humans to be cloned in the future.
The long-tailed macaques – named Zhong Zhong and Hua Hua – were born eight and six weeks ago. They were cloned using the same technique used to clone Dolly and countless other species – including dogs, cats, cows and pigs – which involves removing the nucleus from a non-embryonic cell and transferring it into a denucleated egg cell, known as somatic cell nuclear transfer.
Perhaps the most useful application of this newfound ability to clone primates is in the creation of genetically-identical monkeys for research purposes. While mice are often used to study human disease, monkeys are a more closely-related species to humans making them a better model organism for drug development.
But some are concerned the breakthrough will lead to human cloning – an idea rife with ethical questions.
“Humans are primates. So (for) the cloning of primate species, including humans, the technical barrier is now broken,” said Muming Poo, supervisor for the research which was conducted at the Chinese Academy of Sciences Institute of Neuroscience in Shanghai. The research was published in the journal Cell.
But Poo goes on to explain that the team has no intentions on using this technology to clone a human.
“The reason … we broke this barrier is to produce animal models that are useful for medicine, for human health,” said Poo. “There is no intention to apply this method to humans.”
The Chinese researchers overcame earlier barriers to cloning primates by using nuclei collected from fetal cells, and by regulating genes involved in embryonic development. After performing the technique on 127 egg cells, the researchers were only successful at producing two live births, however the team expects more cloned monkeys to be born in the coming months.
“It remains a very inefficient and hazardous procedure,” said Robin Lovell-Badge, a cloning expert at the Francis Crick Institute in London. “The work in this paper is not a stepping-stone to establishing methods for obtaining live born human clones. This clearly remains a very foolish thing to attempt.”