A team of Chinese researchers announced on Wednesday that five gene-edited monkey clones were born at the Institute of Neuroscience of the Chinese Academy of Sciences in Shanghai, China.

In their most recent research, the Chinese scientists used CRISPR/Cas9, a gene-editing tool, to knock out the gene BMAL1 in the donor monkey at the embryo stage. They also used the donor's fibroblasts to clone the five monkeys using somatic cell nuclear transfer. This is the same method that was used to clone Zhong Zhong and Hua Hua, the first two cloned monkeys in China.

According to the research team, they previously bred gene-edited monkeys. In their latest experiment, they cloned an adult male that had shown the most severe symptoms.

"Our approach is to perform gene editing in fertilized embryos to first generate a group of gene-edited monkeys, and then select one monkey that exhibits the correct gene-editing and most severe disease phenotypes as the donor monkey for cloning," Sun Qiang, the lead author of the study, explained in a press release.

BMAL1 Knock-Out Monkeys

Knocking out the BMAL1 gene will affect the operation of the animal's biological clocks, resulting in several medical conditions, sleep disorders, hyperactivity, depression, schizophrenia, and the like.

"Disorders of circadian rhythm could lead to many human diseases, including sleep disorders, diabetes mellitus, cancer, and neurodegenerative diseases," said Hung-Chun Chang, senior author of the study and investigator from ION. "Our BMAL1 knock-out monkeys could thus be used to study the disease pathogenesis as well as therapeutic treatments."

Ethical Concerns Over Mass Cloning Of Animals

All five born macaques share identical genes that include the mutation, giving rise to another ethical issue within the scientific community. There are ethical concerns over mass cloning of animals with medical conditions brought about by humans.

While the research is intended to back efforts in testing and developing drugs for the treatment of various human diseases in the succeeding years, this development comes on the heels of the recent controversy involving the gene-edited human babies.

However, the Institute of Neuroscience of the Chinese Academy of Sciences is said to be in strict adherence to international animal research.

The Chinese researchers aim to better the technique used to boost cloning efficiency. They also expect that more gene-edited macaque clones with disease-causing gene mutations will become available for biomedical research in the near future.

This major research was published in a couple of articles in the journal National Science Review on Thursday, Jan. 24.