'Woolly' mouse with mammoth traits created

Mice have been created with woolly mammoth-inspired traits using genome editing in de-extinction efforts.

The woolly mammoth became extinct around 10,000 years ago, although the last known group survived until about 1650 BC. Now, the biotechnology company Colossal Biosciences in Texas, aims to restore the mammoth from extinction by genetically engineering Asian elephants with woolly mammoth traits for cold adaptation.

'The Colossal woolly mouse marks a watershed moment in our de-extinction mission,' said Colossal Biosciences CEO Ben Lamm. 'By engineering multiple cold-tolerant traits from mammoth evolutionary pathways into a living model species, we've proven our ability to recreate complex genetic combinations that took nature millions of years to create.'

The team used several genome editing approaches, including CRISPR/Cas9 and cytosine base editors, to alter the normal function of ten genes involved in hair follicle development and fat metabolism in mice.

Different approaches were used to create the mice. The team either edited the mouse zygotes, or edited mouse embryonic stem cells and injected them into mouse embryos, prior to transfer into the surrogate. This allowed them to edit up to seven genes at once and reduced the timeline for producing the mice.

Genome-edited mice were produced with various hair phenotypes including wiry coats, wavy hair, altered hair colour, and woolly coats. However, the genome-edited mice did not show any changes in body mass index.

However, the paper, published as a preprint in bioRxiv, has not yet been peer-reviewed and the de-extinction effort has been met with scepticism from experts.

'This technology offers an exciting opportunity to test some of our ideas about extinct organisms,' said Dr Louise Johnson, evolutionary biologist from the University of Reading, who was not involved in the study. 'It is an interesting piece of work, but the idea that we could bring something back from extinction is false hope.'

The team aims to conduct future experiments looking at the effects of high fat diets and temperature preferences in the mice.

'Based on the results presented by the authors, their methods for generating transgenic mice with the desired changes appears to be both rapid and highly efficient, which would be extremely desirable when testing for the function of genetic changes in any context, whether it has implications for conservation or disease biology,' said Dr Saad Arif of Oxford Brookes University, who was not involved in the study.