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FFive clones of a gene-edited long-tailed macaque, with several symptoms of genetic disease, have been successfully bred, a team of scientists in Shanghai announced this week. The original monkey had been modified with CRISPR / Cas9 gene editing technology to give its clones a disrupted circadian rhythm so that scientists could learn to treat human beings with related disorders. The psychological effects of gene editing on monkeys have, unsurprisingly, aroused the anxiety of ethicists.
Researchers from the Institute of Neuroscience of the Chinese Academy of Sciences published their findings in two separate articles Thursday in the newspaper National Science Journal. In the paper, they explain that the ability to produce gene-modified clones will help them study disturbed circadian rhythm diseases, including Alzheimer's disease, depression, and other sleep problems.
"Circadian rhythm disorders could lead to many human diseases, including sleep disorders, diabetes mellitus, cancer and neurodegenerative diseases. Our BMAL1-knockout monkeys could therefore be used to study the pathogenesis of the disease as well as for therapeutic treatments, "says Hung-Chun. Chang, senior author of both articles and researcher at the Institute of Neuroscience of the Chinese Academy of Sciences, said in a statement.
The original monkey was transformed into an embryo by destroying its BMAL1 gene, badociated with sleep-wake regulation, and the five newborns produced with TNCS all have an identical genome, lacking the BMAL1 gene. The researchers used somatic cell nuclear transfer, the same technique used to clone Dolly the sheep more than two decades ago, to clone the monkey and produce five cloned offspring.
Exactly one year ago, the same researchers announced that they had successfully cloned two macaques, named Hua Hua and Zhong Zhong. As Amber Tong reported for News on the end points At that time, the challenges posed by the cloning of primates made this achievement a momentous event. Adding to this the successful cloning of primates with gene deletions mediated by CRISPR, the researchers went to great lengths to study the biological mechanisms of genetic diseases.
Other scientists are of course skeptical. First, the team used psychiatric disorders resulting from cloned monkeys, including "behaviors resembling anxiety, depression, and schizophrenia" – as signs of the success of the experiment. Bioethicist Carolyn Neuhaus of the Hastings Center told Gizmodo that the research raises many questions, in particular the fundamental concern that this suppression of gene does not produce the same effects in the man as in the monkey. Whether or not the case, the researchers inflicted a lot of suffering on these animals just to find out.
"If I was a member of an ethics committee, I was very hesitant to approve [this research] because of the incredible amount of damage done to animals, "said Neuhaus. "I would expect the scientists who propose this research to have very good answers to the very difficult questions about their methods and the expected benefits of their research."
In addition, cloning of monkeys remains difficult, expensive and requires a lot of work. Researchers have created more than 300 embryos, but only five have developed enough to implant them in a surrogate.
"The efficiency is still very low. This remains a big problem for cloning technology, "said an anonymous Shanghai-based life scientist who was not involved in the story. Morning of South China.
Researchers are not discouraged, as the benefits of cloned monkeys could be important for drug research. After all, large groups of cloned animals would help eliminate some of the variations seen in animal testing, because all monkeys would be expected to respond to a drug in the same way. And in fact, Mu-ming Poo, Ph.D., principal investigator at the Academy's Institute of Neuroscience and one of the authors, said the research could actually reduce the suffering suffered by monkeys in the scientific laboratories.
"This line of research will help reduce the amount of macaque monkeys currently used in biomedical research around the world," he said. L & # 39; Independent. "Without interference from the genetic background, a much smaller number of cloned monkeys carrying pathological phenotypes might be sufficient for preclinical tests of treatment efficacy."
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