For the first time, scientists have used transplanted laboratory-created cells to grow an organ inside an animal - a development that could in the future be used for human patients.
Researchers at the Medical Research Council Centre for Regenerative Medicine at the University of Edinburgh managed to 'reprogramme' mouse cells called fibroblasts. Mixing them with other key cells, the team were able to grow a fully-functional organ called a thymus - which produces T-cells to help fight disease - in the mouse.
The researchers hope that "with further research, the discovery could lead to new treatments for people with a weakened immune system", although human treatment is likely to be some time away.
In the video below, Prof Clare Blackburn discusses the research and its possible implications: