CRISPR gene-edited monkeys cloned in China
New research out of China has confirmed the birth of five gene-edited monkey clones. Two recently published papers describe how a CRISPR-gene-edited long-tailed macaque has been successfully cloned, demonstrating the first time in the world a gene-edited monkey has been effectively cloned.
The scientists first created a donor monkey using the CRISPR gene-editing technique to knock out the expression of a gene known to play a role in regulating the animal's circadian rhythm. It has been suggested that by editing this single gene the monkey would subsequently exhibit a variety of different symptoms, such as anxiety, depression and even schizophrenia-like behavior.
"Disorder of circadian rhythm could lead to many human diseases, including sleep disorders, diabetic mellitus, cancer, and neurodegenerative diseases, our BMAL1-knock out monkeys thus could be used to study the disease pathogenesis as well as therapeutic treatments," explains Hung-Chun Chang, senior author on the new study.
The second stage in the research involved identifying a successful and healthy CRISPR-edited specimen and creating a number of identical clones using a method called somatic cell nuclear transfer. The same team demonstrated the efficacy of this cloning technique last year, revealing the world's first successful birth of healthy long-tailed macaque clones.
The idea behind this research is to create gene-edited animals that display certain disease phenotypes allowing for effective medical experimentation. By having the ability to clone those specific animals one can create a number of genetically similar subjects, thus removing the variations in treatment responses that can occur from animal to animal.
"We believe that this approach of cloning gene-edited monkeys could be used to generate a variety of monkey models for gene-based diseases, including many brain diseases, as well as immune and metabolic disorders and cancer," says Qiang Sun, a senior author on the study.
The timing of this research announcement comes at a time when the ethics of gene editing are a hot topic of conversation. Earlier this week the Chinese government officially condemned He Jiankui, the scientist who controversially revealed last year he had successfully birthed the world's first gene-edited human babies.
While He's work is under investigation from Chinese authorities for allegedly violating ethical research standards, and even forging certain documents, the ethical veracity of this new research is being questioned by some scientists around the globe. In an interview with Gizmodo, bioethicist Carolyn Neuhaus suggested this particular genetic edit and cloning experiment lacked any strong scientific hypothesis and instead was more about simply showing that this technique is possible.
"…if I were on an ethics review committee, I would be very hesitant to approve [this research] because of the incredible amount of harm to the animals," says Neuhaus. "I would expect the scientists who are proposing this research to have very good responses to very hard questions about their methods and the expected benefits of their research."
While in and of itself the research may seem purposeless and cruel, the Chinese scientists claim the long-term benefits of this kind of innovation include actually reducing the number of macaque monkeys used in biomedical research. Just last year a US government study revealed 76,000 nonhuman primates were utilized in US laboratory research in 2017 alone. The majority of these primates were rhesus macaques.
The Chinese scientists suggest, if successful, the research will allow future animal testing to be more efficient and require smaller numbers of monkey subjects.
"Without the interference of genetic background, a much smaller number of cloned monkeys carrying disease phenotypes may be sufficient for pre-clinical tests of the efficacy of therapeutics," says Mu-ming Poo, co-author on the new research.