A three-drug trial regrew the thymus in 7 of 9 men

A small trial called TRIIM gave nine healthy men a year of growth hormone alongside two drugs meant to offset its side effects, then measured whether the thymus, which normally fades after childhood, had regrown.

MRI scans showed thymic tissue replacing fat in 7 of the 9 men, and blood tests found their immune cell profiles shifting toward a younger pattern. Using an epigenetic clock that reads chemical marks on DNA, the team found the men's epigenetic age sat about 1.5 years below where it started, roughly 2.5 years younger than a year of normal aging would predict.

On one clock, GrimAge, the gain was still present six months after treatment stopped, and a larger follow-up trial is testing the same combination in more volunteers. Only nine men took part in the original study, none of them women, and there was no placebo group, so the result is a promising signal rather than a settled finding.

Nine men, one shrinking organ, reversed.