A medical frontier has been broken with the announcement that Chinese biologists successfully cloned two macaque monkeys.
This is the first time that true clones of a primate species have been born, opening a door to both sophisticated medical breakthroughs and moral quagmires.
The process, now detailed in the journal Cell, was developed over several years by a team at the Chinese Academy of Sciences in Shanghai. If it proves to be reproducible, the technique could create large groups of monkeys with pre-engineered genetic backgrounds – ideal subjects for studying human diseases and testing new treatments.
In multiple statements and interviews, the researchers emphasized that they have no intention of applying their findings to human cloning attempts.
“For the cloning of primate species, including humans, the technical barrier is now broken,” said study author Mu-Ming Poo to National Geographic. “However, the reason we chose to break this barrier is to produce animal models that are useful for human medicine.”
"With all this improvement, along with the high standards of ethical concerns, I think that Chinese society will accept this,” Poo continued. “I hope that societies in Western countries will realize once we demonstrate the cloned monkeys’ usefulness in curing disease, they will gradually change their mind.”
The prototypical, identical female long-tailed macaques are now six and eight weeks old, and appear healthy thus far. Named after a word for the Chinese people, Zhong Zhong and Hua Hua were created using somatic cell nuclear transfer (SCNT) – the same cloning technique that produced Dolly the sheep in 1996.
SCNT is performed by removing the nucleus of an unfertilized egg cell and replacing it with the nucleus of an existing cell taken from a donor of the same species. Now containing the full set of genetic information required to create a living organism, the egg is chemically induced to divide inside a controlled incubator environment. When the resulting clump of cells is large enough, it is then implanted into a surrogate mother's uterus to be carried to term.
Clones of 23 mammal species have been generated using SCNT in the past, yet previous attempts to extend the technique to primates have failed. The challenge lay in correctly programming a single-celled clone egg to act like a normal embryo: Though each contains a full set of DNA, it needs special cues to know which genes to express and which to ignore in order to develop.
The Shanghai team’s breakthrough came when they applied two programming molecules to one-celled clones that were made from the nuclei of early skin cells of other macaque embryos.
Prior experiments using a type of cells found in adult macaque ovaries also led to the birth of clones, but they died shortly after. Of the 21 attempts this time, only two healthy births were achieved.
The next steps will be to ensure that Zhong Zhong and Hua Hua grow and progress normally. As of right now, they are being bottle fed and constantly monitored by staff at the academy’s Nonhuman Primate Research Facility.
If everything proceeds to plan, monkeys like these two will replace the existing populations of primate lab animals used in research for human genetic diseases, cancer, and more.
“It'll be interesting to see how this research shapes the debate over the use of non-human primates as lab animals,” National Geographic science expert Michael Greshko told IFLScience via email. “Will it reduce the number of primates needed to perform medical experiments, as the study's authors hope? How much does that lessen the ethical burden of using primates in the lab at all?”
[H/T: National Geographic]