(Originally published by SynBioBeta, June 15, 2016)
In science headlines around the world, ‘gene editing’ has replaced ‘gene therapy’ in the past few years. You may see gene editing, one of today’s hot topics in science referred to by the acronym CRISPR, which is Clustered Regularly Interspaced Short Palindromic Repeats. CRISPR has many different applications in research. Countries all around the world vying to be the top in research are using it widely. China is no exception.
This past October, your newsfeed may have been peppered with photos of muscular dogs. Dr. Liangxue Lai of the Guangzhou Institutes of Biomedicine and Health used CRISPR to engineer beagles with twice the muscle mass. While these beagles might be useful for the military and the police, the team also plans on editing dog’s DNA to mimic human illnesses such as Parkinson’s or muscular dystrophy. Dogs are well positioned to be animal models for human diseases because of how similar to us metabolically, physiologically and anatomically they are.
In this glimpse into animal genome editing in China, Dr. Yong Li’s micropigs sit alongside Dr. Lai’s beagles. Working at the Beijing Genomics Institute (BGI), in Shenzhen, Dr. Li and his team used another gene-editing tool, called TALEN, to turn off the genes that respond to growth hormone, in a small breed of pig called Bama. Similar to dogs, pigs are also close to humans physiologically and genetically.
Pigs are usually inconvenient as animal models. They weigh over 100 kg and thus are too expensive to feed and require larger doses of drugs. The mini-pigs, cloned from fetal cells, are only 15 kg, about the size of a medium dog.
Thus far, Dr. Li says that the micropigs have been useful in studying another hot topic, the bacteria in our gut, because their small size makes it easier to replace the bacteria in studies of fecal transplants. They also plan to study a type of dwarfism caused by a mutation in the gene they turned off to create the micropigs. Dr. Li and his team have been selling the micropigs as pets, using the money from the profits to fund their research.
If these beagles and micropigs weren’t surprising enough, last year also saw the first genetic editing of human embryos. Dr. Junjiu Huang at Sun Yat-Sen University made headlines with a study that cut and replaced DNA in non-viable human embryos. The embryos were non-viable because they were created from eggs that were fertilized by two sperm.
Non-viable embryos like this often come about when doctors fertilize eggs during in vitro fertilization. The cells can start division but due to the abnormal collection of genes, they stop dividing when they are still only a small clump of cells.
Human embryo gene editing is legal in China. In the United States, federal funds cannot be used for such research, but it is legal in several states. UK scientists also recently received the go-ahead for editing human embryos. The debate rages on about the ethics of human embryo editing, with viewpoints including: ‘it should never be allowed’ and ‘it should only be allowed for the purposes of research’.
Researchers are focusing on increasing the success rate and safety of the procedure. While CRISPR can precisely target a certain gene that researchers want to disable or modify, the embryos sometimes require mutations in other places, which might introduce other problems to the embryo. In a study from April 2015, CRISPR only managed to modify DNA in a fraction of the embryos, and sometimes it inserted DNA in the wrong place.
A big part of the conversation surrounding CRISPR is about ethics. You can hear more about this from Dr. Yong Li at SynBioBeta Activate China. Here, we will focus on a few highlights of human and animal genome editing research in China.