Researchers in Scotland were able to grow a complete organ from scratch in an animal for the first time ever.
Scientists at the Medical Research Council centre for regenerative medicine at the University of Edinburgh started with cells from a mouse embryo and then these cells were genetically "reprogrammed" and started to transform into a type of cell found in the thymus, the BBC reported.
Prof Clare Blackburn said it was "tremendously exciting" that they were really able to generate a fully functional and fully organised organ starting with reprogrammed cells in really a very straightforward way.
Experts said the research was promising, but still years away from human therapies. However, patients who need a bone marrow transplant and children who are born without a functioning thymus could all benefit. Ways of boosting the thymus could also help elderly people.
The study is published in Nature Cell Biology.