Colossal Biosciences, a Texas-based company, genetically engineered a woolly mouse, marking an achievement toward its goal of resurrecting extinct species like the woolly mammoth. The woolly mouse is a tiny mammal engineered to express multiple mammoth-like traits, including longer, frizzier, and more golden fur, as well as curled whiskers with a rough, woolly texture, according to MIT Technology Review.
Through a combination of gene-editing techniques, Colossal scientists altered the mouse genome, achieving high efficiency in the expression of cold-adapted traits. Using CRISPR/Cas9, the team edited seven genes in single-cell zygotes from lab mice, employing a strategy that combined three editing technologies and made eight edits simultaneously, some with editing efficiencies as high as 100%.
"The Colossal Woolly Mouse showcases our ability to use the latest genome editing tools and approaches to drive predictable phenotypes. It is an important step toward validating our approach to resurrecting traits that have been lost to extinction and that our goal is to restore," said Beth Shapiro, chief science officer at Colossal, according to a report by New Atlas.
The woolly mice have thicker coats than ordinary mice, made up of longer hairs with a woolly texture, and they also express several engineered traits other than hair length and texture. The mice also have the woolly mammoth's accelerated fat metabolism, which helped the mammoth survive Earth's last ice age, a key difference between mammoths and Asian elephants, reported Wired.
"The Colossal Woolly Mouse marks a watershed moment in our de-extinction mission," stated Ben Lamm, CEO of Colossal Biosciences. Colossal Biosciences aims to de-extinct the woolly mammoth, thylacine, and dodo, with progress reported on the dodo project and the assembly of the most complete Tasmanian tiger genome. The animal that Colossal ultimately brings to life will not be a mammoth, but a genetically edited Asian elephant serving as a proxy species for the real woolly mammoth.
Lamm said that the team is on track to generate a proxy woolly mammoth, with the first woolly mammoth calves expected as early as 2028. "It makes the most sense for Colossal to test our end-to-end process from computational analysis to multiplex editing to a living animal in a mouse model that is a fraction of the time it takes to grow an elephant through gestation," he explained.
Not every fertilized egg develops into a gene-edited mouse, and most of the genetically edited embryos did not result in live offspring, with less than 10% achieving this outcome. However, this does not deter the team. "What we found is in 23 days, versus 22 months, it worked. This is a very, very big step for us because it proves that all of the work we've been doing for the last three years on the woolly mammoth is exactly what we predicted," said Lamm, co-founder and CEO of Colossal.
Colossal's research team used a dataset of 121 mammoth and elephant genomes to identify genes responsible for hair length, thickness, and metabolic adaptations to cold. They identified genes that make the coat coarse, curly, and long, with most of the edited genes involved in hair type, reported Wired.
Other scientists have weighed in on Colossal's progress. "The engineering of cold-tolerant traits from woolly mammoths into a living model species is a fascinating scientific breakthrough, showing how far gene editing has advanced in recent years," said Associate Professor Damien Fordham from the Environment Institute at the University of Adelaide.
"The technology could potentially rescue living species from extinction through engineering of their phenotypes," he added. However, some experts express skepticism. "In my professional view, we won't be seeing a woolly mammoth, a dodo, or a thylacine for decades, because it's not a matter of changing seven genes; you would have to change thousands, and you have to do the reproductive biology too," noted Professor Merlin Crossley, a molecular biologist at the University of New South Wales.
Colossal Biosciences claims that genetically engineering living animals to resemble extinct species is the next best thing to restoring ancient beasts. One of Colossal's main arguments for de-extinction is that by reintroducing creatures that mimic extinct animals, they can help restore ecosystems to the way they were before those animals went extinct, according to ABC News. "We as a society should really be thinking about increasing the tools we have at our disposal to help species survive whatever is going to happen in their habitats," said Shapiro.
The article was written with the assistance of a news analysis system.