Zhongzhong and Huahua are the first monkeys cloned by the same method that created Dolly the sheep.
SHANGHAI—For the past decade, Mu-Ming Poo, the director of the Institute of Neuroscience in Shanghai, has been on a quest to make monkeys that can be used to study human disease. Today, researchers in his institute announced a major milestone: the births of Zhongzhong and Huahua, the first two monkey clones created using the same technique behind Dolly the sheep.
Their names together form “Zhonghua,” meaning the Chinese nation or people, a nod to their national importance. China has invested heavily in primate research in recent years—as the United States and Europe have pulled back.
After Dolly’s birth in 1996, scientists quickly figured out how to clone mice, pigs, dogs, cats, cows, and more. But primates long proved elusive. In 2003, after scientists at the University of Pittsburgh used 716 eggs and failed to create a single clone, it was suggested that primate cloning—and by extension human cloning—is impossible using this method.
In a recent interview in Poo’s office in Shanghai, he told me that human cloning is absolutely not his intention. That, he said, requires its own ethical debate. But he wants to use cloning to the expand the number of genetically modified monkeys, which are becoming easier to make using CRISPR.
For example, in 2016, scientists at the Institute of Neuroscience in Shanghai created monkeys with a mutated form of the gene MECP2, which is linked to autism spectrum disorder. The genetically modified creatures ran in circles and avoided other monkeys—behaviors that may echo children with the MECP2 mutation.
Yet, says Poo, the monkeys led to “very little” progress in understanding the disorder. “It is a feasibility demonstration that we can manipulate genes in monkeys, but it’s not a disease model,” he says. Different monkeys had copies of the gene in different parts of their genome, and their resulting behaviors varied. The technique used to create the MECP2 monkeys did not give scientists enough control. Similar problems can arise with CRISPR, a gene-editing technique that has been widely adopted in different organisms across the world. You can’t test new drugs on monkeys whose manifestations of disease are so different from one another.
With cloning, it is possible to genetically modify monkey cells in a dish, grow the cells in large numbers, and then create clones from them. The last step requires taking DNA out of the genetically modified cells and putting it into an egg—a procedure called somatic-cell nuclear transfer. Zhongzhong and Huahua were created this way, as was Dolly the sheep. (In 1999, scientists created Tetra the cloned monkey by splitting an eight-cell embryo into two, similar to the way twins are normally formed. This technique can create only a limited number of genetically identical monkeys.)
