Genetically Engineered Monkeys are Being Used in Autism Studies

Zhong Zhong and Hua Hua, two cloned long tailed macaque monkeys are seen at the Non-Primate facility at the Chinese Academy of Sciences in Shanghai (Image: Cell/ via Reuters)

At a symposium at Shenzhen Institutes of Advanced Technology (SIAT), scientist Guoping Feng and others alluded to the potential of using CRISPR gene editing on the primate brain in a theoretical talk. After exploring the reality behind the idea, Feng has collaborated with a china-based breeding facility, despite his lab being located in the US, reported The Atlantic. The breeding facility does not itself genetically engineer monkeys but supplies thousands of Macaques to international pharmaceutical and research laboratories for the price of around $1,500.

Before CRISPR, the genetic engineering of primates was a laborious process capable of a very limited number of edits. Few research groups even attempted it; even fewer succeeded. With CRISPR, monkeys can now be genetically engineered almost as easily as mice. One of the major challenges with studying these animals is simply creating enough monkeys for the study.

Studies in the Feng lab have been focused on using mice models to study autism however the research was limited due to stark differences between the human and mouse brain. Rodents do not have a full prefrontal cortex – the area of the brain associated with personality, decision-making, and higher cognitive function. And they don’t socialize the way humans do. Avoidance of eye contact, for instance, is a classic sign of autism in humans, but eye contact is physically impossible which has resulted in autism researchers becoming increasingly sceptical of mouse models. The behaviour of these monkeys has also been catalogued for decades, making it an incredibly useful model for this type of research.

Due to their similarities to humans, monkeys are increasingly being used in China to study human disease, with the first ever monkey cloned early this year. However, in the US, the use of primates for this purpose remains highly controversial, with the Humane Society of the United States and the American Anti-Vivisection Society working to end the practice.

Although saying this, in an attempt to finally reinforce the safety and effectiveness of CRISPR for use in treatment of human disease, scientists turned to monkeys.

Will CRISPR Work in Monkeys Confirm Safety for Use in Humans?

American scientists worry that the United States is falling behind China on primate research. “I have two big concerns,” says Michael Platt, a brain scientist at the University of Pennsylvania who studies primates. “The United States is not investing heavily in these [primate] models. Therefore we won’t have the access that scientists have in China.” The second, he says, is that “we might lose the talent base and expertise for actually doing primate neuroscience.”

The first monkey to be born with a knock out of the autism-associated gene of interest, Shank3, was born in 2015. The first step in Feng’s work is to use the Shank3 monkeys to identify the changes the mutations cause in the brain. Then, researchers can use that information to find targets for drugs, which could be tested in the same monkeys

Primates should only be used if other models do not work, says Feng, and only if a clear path forward is identified.