The research team had previously tried to use adult donor cells with the SCNT method, but the cloned macaques died a few hours after birth. Earlier research established that, for reasons that are still unclear, monkey cell nuclei are more resistant to the SCNT process than other mammals, such as mice and cows.
"We tried several different methods, but only one worked," said Sun. "There was much failure before we found a way to successfully clone a monkey."
The researchers plan to continue improving the technique and generating more macaque clones, using international guidelines for animal research set by the US National Institutes of Health.
“We are very aware that future research using non-human primates anywhere in the world depends on scientists following very strict ethical standards,” said Muming Poo, a co-author of the study.
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Meanwhile, the researchers report that Zhong Zhong and Hua Hua are being bottle fed and are growing normally for macaques of their age. The monkeys will be closely monitored to track physical changes and intellectual development.
The research was supported by grants from Chinese Academy of Sciences, the CAS Key Technology Talent Program, the Shanghai Municipal Government Bureau of Science and Technology, the National Postdoctoral Program for Innovative Talents, and the China Postdoctoral Science Foundation.
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