Mechanisms of cellular rejuvenation.

Aging leads to changes on an organismal but also cellular level. However, the exact mechanisms of cellular aging in mammals remain poorly understood and the identity and functional role of aging factors, some of which have previously been defined in model organisms such as Saccharomyces cerevisiae, remain elusive. Remarkably, during cellular reprogramming most if not all aging hallmarks are erased, offering a novel entry point to study aging and rejuvenation on a cellular level. On the other hand, direct reprogramming of old cells into cells of a different fate preserves many aging signs. Therefore, investigating the process of reprogramming and comparing it to direct reprogramming may yield novel insights about the clearing of aging factors, which is the basis of rejuvenation. Here, we discuss how reprogramming might lead to rejuvenation of a cell, an organ, or even the whole organism.