Colossal Biosciences, the world’s first company dedicated to bringing back animals from extinction, just got one step closer to its ambitious goal.
The company announced today that it has successfully engineered what it calls the colossal woolly mouse. These genetically modified mice have had seven genes edited to express mammoth-like traits, allowing them to better adapt to cold environments.
“The colossal woolly mouse marks a watershed moment in our de-extinction mission,” said Colossal Biosciences co-founder and CEO Ben Lamm in a statement. “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.”
Colossal has made headlines in the past for its plans to bring back the woolly mammoth, the Tasmanian tiger, and the dodo bird. The Texas-based company, with a team of 170 scientists and additional labs in Boston, Dallas, and Melbourne, uses advanced gene-editing technology to try to produce organisms genetically close to long-lost species. The company also helps fund animal preservation projects. Its efforts have led to notable advancements in science and technology.
The company announced last year that its scientists had assembled the most complete Tasmanian tiger genome to date from a century-old pickled head. Colossal scientists were also the first to generate elephant induced pluripotent stem cells (IPSCs) — cells that could potentially be developed into any tissue in the body — in a lab.
Its latest breakthrough marks the first time a living animal has been engineered to express multiple cold-adapted traits based on the study of mammoth genes. By editing seven genes simultaneously, scientists significantly altered the mice’s coat, making it longer, wavier, and lighter in color — features reminiscent of the woolly mammoth’s adaptations to freezing climates. They also modified a gene linked to lipid metabolism, which affects body weight. These changes were guided by computational analysis of 59 mammoth genomes ranging from 3,500 to over 1.2 million years old.
To advance its de-extinction research, Colossal is using mice as a quick and efficient testing ground for genetic tweaks aimed at bringing back the woolly mammoth. Due to their short 20-day gestation period and well-established gene-editing methods, mice let scientists rapidly study traits like hair growth, fat distribution, and cold tolerance. Although they’re not a perfect stand-in for elephants, they still offer valuable clues about how mammoth adaptations worked and which genetic changes might be most important for bigger species, Colossal scientists wrote in a preprint paper — an unpublished and non-peer-reviewed study describing their experiments. Future research on the colossal woolly mouse will further explore how multiple genes interact to shape physical traits.
“The Colossal Woolly Mouse demonstrates remarkable progress we’ve made in precise genome engineering, including optimized delivery methods, innovative multiplexing and combinations of gene targeting strategies,” said George Church, a professor of genetics at the Wyss Institute and Harvard Medical School and co-founder of Colossal. “We are showing that we can now rationally design and construct complex genetic adaptations, with profound implications for the future of multi-gene de-extinction and engineering.”