|
Several research groups and companies are working on in vivo applications of cellular reprogramming. Since its discovery, reprogramming has been used to produce induced pluripotent stem cells from any other type of cell. That process has been found to reverse age-related changes in epigenetic patterns and mitochondrial function characteristic of cells in old tissues. Introducing the factors capable of reprogramming cells into a living animal may produce effects akin to stem cell therapy by converting a small number of cells into induced pluripotent stem cells, followed by stem cell signaling that beneficially affects tissue health more broadly. Alternatively, many cells may have their epigenetic markers reset to a more youthful state without losing their identity to become induced pluripotent stem cells. Or both. Beyond this, there is certainly the threat of cancer or structural damage to tissue through the conversion of too many cells, and this class of therapy will require careful development to ensure safety, even as the mouse data continues to look quite interesting. David Sinclair has been pushing an epigenetic-centric view of aging of late, with analogies to information systems and computing. The most interesting part of the the supporting work suggests that DNA repair of double strand breaks has the side-effect of driving alteration of the epigenome in characteristic ways with age. That will be an important connection between stochastic nuclear DNA damage and deterministic global effects throughout the body, should the evidence continue to hold up. As this illustrates, however, epigenetic change is a downstream issue in aging, a reaction to events and a changing environment, not a first cause. Fixing it may or may not turn out to be particularly useful in the broader picture of aging, depending on exactly where it sits in the web of cause and consequence. As a comparable example, hypertension is a major downstream issue in aging. It is far removed from root causes such as cross-link formation and inflammation, but is also a proximate cause of many forms of further dysfunction, such as pressure damage to delicate tissues in the brain. Controlling hypertension without addressing its causes is both possible and beneficial - but the benefits are limited by the fact that those root causes are still there, chewing away at the body in a thousand other ways. |