Researchers have demonstrated that they can produce a functionally youthful thymus in old mice by increasing levels of a single protein. There have been suggestions that such an approach might be made to work - tweak signal protein levels such that they are similar to those that existed during the early development of the thymus - but I have to admit that I wasn't expecting anything so impressive at this stage. It is an important advance if verified in other labs, as regeneration of the thymus is one of the methods by which the failing immune system in older people could be restored to greater function, at least partially ameliorating this one aspect of frailty in the aged.
One of the issues that contributes to the age-related decline of the immune system is a comparative lack of a supply of fresh immune cells, those capable of tackling new threats. The thymus, where these cells mature, has evolved to pump out a large supply of immune cells in childhood but it then atrophies soon afterwards - a process known as thymic involution. The adult thymus is a shadow of its former self and delivers only a trickle of new immune cells.
The SENS Research Foundation has been funding work on tissue engineering of the thymus, as a part of a portfolio of work on the foundations of human rejuvenation, and I'm sure that this will be a welcome addition to the list of potential strategies for thymic regeneration:
British scientists have for the first time used regenerative medicine to fully restore an organ in a living animal, a discovery they say may pave the way for similar techniques to be used in humans in future. The [team] rebuilt the thymus - an organ central to the immune system and found in front of the heart - of very old mice by reactivating a natural mechanism that gets shut down with age. The regenerated thymus was not only similar in structure and genetic detail to one in a young mouse, the scientists said, but was also able to function again, with the treated mice beginning to make more T-cells - a type of white blood cell key to fighting infections.
[The researchers] targeted a part of the process by which the thymus degenerates - a protein called FOXN1 that helps control how key genes in the thymus are switched on. They used genetically modified mice to enable them to increase levels of this protein using chemical signals. By doing so, they managed to instruct immature cells in the thymus - similar to stem cells - to rebuild the organ in the older mice.