Turning on a single gene can regenerate the thymus in elderly mice, causing the immune system organ to double in size and make more white blood cells.
The study represents the first time that gene manipulation has regenerated an already aged organ in a live animal, the researchers say. The results are all the more striking because the regeneration occurred after manipulating only one gene. This may have implications for regenerative medicine research on other organs, as fewer gene targets may be needed than previously thought to trigger repair or renewal.
'The exciting thing really is the manner in which [the research was] done', first author Dr Nick Bredenkamp of the Medical Research Council (MRC) Centre for Regenerative Medicine told BBC News. 'We've targeted a single gene and we've been able to regenerate an entire organ'.
The thymus is an important organ for the immune system and produces infection-fighting cells called T-cells. It is also one of the first organs to degenerate in old age, when it shrinks and T-cell production slows. This leads to a weaker immune response to infection in older people.
For this study, researchers genetically engineered mice so that a gene which is usually only active in the young thymus (FOXN1) could be turned back on in thymus cells by administering a chemical.
The researchers used this system to turn on FOXN1 in elderly mice after the thymus had begun to degenerate. The thymus of treated mice grew larger and changed in structure so that it resembled the thymus of a much younger mouse.
The regenerated thymus also produced more T-cells, although the researchers have not yet tested the treated mice to see whether the extra T-cell production does in fact boost their immune response to disease.
Professor Clare Blackburn, who led the research, said: 'Our results suggest that targeting the same pathway in humans may improve thymus function and therefore boost immunity in elderly patients, or those with a suppressed immune system'.
She added: 'However, before we test this in humans we need to carry out more work to make sure the process can be tightly controlled'.
The research is published in the journal Development.