Five clones of a gene-edited macaque monkey with circadian rhythm disorders are pictured at the Shanghai Institute of Neuroscience of Chinese Academy of Sciences on Thursday. China cloned the monkeys to research methods for treating mental diseases including depression. Photo: IC

China has cloned the first five monkeys from a gene-edited male macaque that has circadian rhythm disorders, which can help discover methods to treat mental diseases such as depression.Scientists at the Institute of Neuroscience of the Chinese Academy of Sciences published two articles on the National Science Review, a Chinese academic journal in English, on Thursday to announce the pioneering work on cloning five monkeys from a gene-edited macaque monkey by somatic cell nuclear transfer, according to the institute's statement.The statement said the successful case shows that China has the ability to clone monkeys with diseases on a large scale and apply it to researching the cognition function of brains and other serious diseases.Besides these, the achievement can apply to research and the development of new medicines to improve the success rate of developing medicines.The five monkeys cloned from a male macaque with circadian rhythm disorders are closer to human in physiology, so they can be considered as better models for research on mental disease treatments.Cloned monkeys with circadian rhythm disorders are more beneficial to research and relevant disease treatment than to other common animal models such as mice.Disorders of circadian rhythm are associated with many human diseases, including sleep disorders, depression, diabetic mellitus, cancer and neurodegenerative diseases, such as Alzheimer's disease, the statement noted.Researchers at the institute removed a core circadian regulatory transcription factor of several macaques during the experiment and selected one whose symptoms, such as sleeping disorders and anxiety, were the most severe, as the donor to be used to clone five monkeys.China had cloned two monkeys successfully at the end of 2017, which are called Zhong Zhong and Hua Hua, the Xinhua News Agency reported on Thursday.However, different from Zhong Zhong and Hua Hua that had been generated by using fibroblasts from an aborted fetus, the new clones were made using a gene-edited young adult male monkey, the report said.These two cloned monkeys are healthy, and whose research value is lower than gene-edited monkeys, according to a China National Radio article.