A team lead by researchers in Beijing, China, is reporting that they have successfully used the CRISPR-Cas9 to insert a mouse gene into 12 piglets. The gene in question, UPC1, helps the piglets to burn fat to regulate body temperature more effectively, granting them the name ‘low-fat’ piglets. This change may help farmers to save money that would otherwise be spent on heating and extra food during winter. The research was published in PNAS yesterday.

Uncoupling protein 1 (UPC1), a gene that is carried by most mammals, enables an organism to burn up brown adipose tissue reserves in order to increase the organism’s body temperature. Modern pigs do not carry a functional copy of this gene or an equivalent that produces the same effect and, as a result, farmers frequently have to cover the cost of installing, maintaining, and running heated facilities for their pigs. Without the gene, pigs are also susceptible to fat deposition and this can increase the risk of neonatal mortality and decrease production efficiency.

To try to mitigate these issues, the team used the CRISPR-Cas9 system to insert mouse adiponectin-UPC1 into the endogenous porcine UCP1 locus of several embryos. These embryos were then inserted into 13 female pigs, 3 of whom became pregnant. The result was a combined litter of 12 apparently-healthy piglets.

From a gene editing perspective, this would appear to be an incredible achievement. However, there are also some problems that need to be considered, such as how these edits would affect the piglets throughout their lifetime. As this research is still very recent, we have no insight as to the long term effects that this gene editing may have, or what side effects may become apparent over time.

A more cultural consideration is how genetically modified (GM) pork would be received by the public. GM foods have seen a mixed reception around the world, with countries like China and the USA proving particularly resistant to them. In the USA, for example, both GM salmon and GM non-browning apples have been slow to move through FDA approval processes and even after AquaBounty’s salmon was approved, it remains unavailable for sale in the States.

As yet, there is no information on whether or not the meat from these piglets would taste different to unmodified pork, but it is likely that it would be leaner.

Despite concerns about the possible future of this work within the agricultural industry, the successful use of CRISPR-Cas9 in living organisms is an immense achievement.