"Scientists have shown that a protein they previously demonstrated can make the failing hearts in aging mice appear more like those of young health mice, similarly improves brain and skeletal muscle function in aging mice. In two separate articles scientists report that injections of a protein known as GDF11, which is found in humans as well as mice, improved the exercise capability of mice equivalent in age to that of about a 70-year-old human."-link
It is interesting that with age biological factors change in a way that is detrimental to the organism. Not simply due to damage, but in some cases due to detrimental changes in regulation that the body could easily prevent(as seen by the fact that interventions such as caloric restriction with adequate nutrition being able to revert many of the changes in gene expression, iirc.). It suggests that it might actually be an orchaestrated process, and if so one that we should with knowledge be able to intervene in.
It had previously been seen that the longest lived nondividing cells in an animal could live about twice as long when transplanted to a longer lived animal, probably longer if the transplant recipient was even longer lived. Yet despite having such a robust mechanism to keep individual cells alive present in the original animal, nature lets the original animal decay and die with needlessly short life.
In primates some are said to live about a decade while others live for over a century, yet the genetic differences are likely not that much. Might the changes from animals that live a century to those that live multiple centuries and show no aging, be likewise as small?