The commentary linked below takes a look at some recent work on the topic of cellular reprogramming and the rejuvenation it appears to cause inside cells. In the grand scheme of things, it really hasn't been that long since researchers first discovered how to reprogram somatic cells into induced pluripotent stem cells. These artificially altered cell populations have the same characteristics as embryonic stem cells, able to generate any type of cell in the body given the right stimulus and environment. Reprogramming is so easy to carry out that it swept through the research community with great rapidity, and the improvements and further experimentation started almost immediately. Along the way, numerous researchers have found that reprogramming old cells in this fashion appears to revert a number of characteristic signs of cellular aging. Damaged mitochondria are removed, some epigenetic markers are altered in the direction of youthfulness, and so forth.

It is understood that cells are, in principle, capable of rejuvenation. Something must happen to repair the damage and epigenetic changes of aging in between that point at which aged germ cells get together and the point at which a young embryo is growing. Parents are old. Babies are young. A range of intriguing research on early embryonic development suggests the existence of a program of cleansing and repair that operates when the embryo is still only a handful of cells. It is not unreasonable to think that cellular reprogramming as it currently exists is triggering some fraction of those developmental rejuvenation mechanisms as something of a side-effect. The interesting question is whether or not there are useful near future medical applications that might result from a greater understanding and control of cellular rejuvenation of this nature.

The most obvious application is that any sort of cell therapy using the patients own cells is probably going to be improved if the cells are more rather than less youthful. Since reprogramming has this effect, and researchers are working towards using induced pluripotent stem cells in therapies, this will probably happen by default at the outset, and then be improved via degrees of optimization as the field of regenerative medicine progresses. On the other hand, safely inducing some form of rejuvenation-like repair or alteration of cell state in site in the body and brain sounds like a much more challenging proposition. It isn't at all clear that such an approach is even possible or plausible; a greater understanding is needed when it comes to exactly how rejuvenation is being achieved in reprogrammed cells. For example, it may well be the case that some of what appears to be rejuvenation is in fact a selection effect. Reprogramming typically has a low rate of success when you look at the number of cells in a sample that are converted, and perhaps those are all less damaged examples. But see what you think of this commentary and its references:

Stem cells for all ages, yet hostage to aging