Meet Zhong Zhong and Hua Hua, cloned monkeys inspired by Dolly

25 Jan 2018

Photograph of Zhong Zhong, one of the first two monkeys created by somatic cell nuclear transfer. Image: Qiang Sun and Mu-ming Poo/ Chinese Academy of Sciences

More than 20 years after the cloning of Dolly the sheep, Chinese researchers have unveiled two monkeys cloned using the same process.

Two monkeys have caught the attention of the whole world after it was announced that the tiny long-tailed macaques are actually clones, called Zhong Zhong and Hua Hua.

Born eight and six weeks ago, respectively – and named after the Chinese adjective ‘Zhonghua’, which means Chinese nation or people – the monkeys are the first primate clones made by somatic cell nuclear transfer (SCNT).

The cloning technique was first brought to the world’s attention by Dolly the sheep in 1996, the first mammal cloned from an adult somatic cell.

The results of the latest major genetic milestone were published to Cell by a team of researchers from the Chinese Academy of Sciences Institute of Neuroscience in Shanghai, with the intention of making it possible to conduct research with customisable populations of genetically uniform monkeys.

The title of the first cloned monkey, however, goes to a rhesus monkey called Tetra, born in 1999 using a process similar to how twins are born.

How they were born

This latest SCNT breakthrough is of massive importance. The SCNT method involves removing the nucleus from an egg cell and replacing it with another nucleus from differentiated body cells.

The reconstructed egg then develops into a clone of whatever donated the replacement nucleus. In this instance, it overcame a previous hurdle whereby monkey cell nuclei had proved resistant to SCNT.

So, to tackle this challenge, the research team introduced epigenetic modulators after the nuclear transfer. These modulators switch on or off the genes that are inhibiting embryo development.

The team’s success rate increased when it transferred nuclei taken from foetal differentiated cells such as fibroblasts, a cell type in the connective tissue.

Sadly, Zhong Zhong and Hua Hua were not the first attempts at cloning with this new method, with a number of the previous clones only living for a few months after birth.

Hua Hua

Zhong Zhong’s twin, Hua Hua. Image: Qiang Sun and Mu-ming Poo/ Chinese Academy of Sciences

‘Frankenstein experiments’

Speaking of what this breakthrough means to the science, senior author of the paper, Qiang Sun, said the team has no intentions of developing human clones, and is only interested in the benefits for clinical research.

“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.”

Meanwhile, president of People for the Ethical Treatment of Animals (PETA), Ingrid Newkirk, has taken to Twitter to strongly criticise the news, calling it “Frankenstein experiments”.

Colm Gorey was a senior journalist with Silicon Republic