Meet Zhong Zhong and Hua Hua, the first monkey clones produced by method that made Dolly

The first primate clones made by somatic cell nuclear transfer are two genetically identical long-tailed macaques born recently at the Chinese Academy of Sciences Institute of Neuroscience in Shanghai. 

Researchers named the newborns Zhong Zhong and Hua Hua - born eight and six weeks ago, respectively - after the Chinese adjective "Zhonghua," which means Chinese nation or people. The technical milestone, presented January 24 in the journal Cell, makes it a realistic possibility for labs to conduct research with customizable populations of genetically uniform monkeys.

"There are a lot of questions about primate biology that can be studied by having this additional model," says senior author Qiang Sun, Director of the Nonhuman Primate Research Facility at the Chinese Academy of Sciences Institute of Neuroscience.

"You can produce cloned monkeys with the same genetic background except the gene you manipulated. This will generate real models not just for genetically based brain diseases, but also cancer, immune, or metabolic disorders and allow us to test the efficacy of the drugs for these conditions before clinical use."

Zhong Zhong and Hua Hua are not the first primate clones - the title goes to Tetra, a rhesus monkey born in 1999 through a simpler method called embryo splitting (Chan et al., Science 287, 317-319). This approach is how twins arise naturally but can only generate up to four offspring at a time.

Zhong Zhong and Hua Hua are the product of somatic cell nuclear transfer (SCNT), the technique used to create Dolly the sheep over 20 years ago, in which researchers remove the nucleus from an egg cell and replace it with another nucleus from differentiated body cells.