Aging is quite ubiquitous, though not universal. Some organism age very quickly and die within a day, while others are very long lived and can live for hundreds or event thousands of years. Further, there are even organisms that due not age at all and are potentially biological immortal.
The regenerative capabilities of Aging organisms degrease with increasing age. The reason for this reduction is not entirely clear.
It can be due to three different aspects or a combination of those:
There are numerous adult stem cells compartments in the body, which regenerate different Tissues. Restoring the quantity and quality as well as the youthful environment of stem cells may recharge the regenerative capacity of an organisms. This strategy can be accomplished with regenerative medicine and has already shown to be successful in prolonging youthfulness.
There is now a body of data accumulating that the third point, mentioned above, is the most crucial, while point 1 and 2 or more or less effects of point 3. This means that the Aging process is mediated by changes in systemic Factors, like hormones. Actually Aging is a tightly controlled process. There are genes which control the Aging process and manipulating these genes can greatly affect the speed of Aging. In rodents knocking out a single gene can increase the lifespan by up to +55%. In other model organisms single gene knockout even achieved an extension of the lifespan by 10-fold.
There is even recent data that indicates the Aging process is in fact reversible, i.e. rejuvenation is possible.
So with focused research on reverting the Aging Factors that cause with increasing age that stem cells loss their ability to regenerate it will be achievable to constantly rejuvenate an organism. Though there are so many changes with Aging that it is hard to differentiate what is "cause"" and what is merely "effect". The challenge is to discriminate the factors that are drivers rather than the passengers. Therefore, we need computational approaches that are able to find the needle in the haystack of the myriads of changes by taking advantage of the increasing amount of biological data as well as increasing computational power.