The Emerging View of Aging as a Reversible Epigenetic Process

The achievement of animal cloning and subsequent development of cell reprogramming technology are having a profound impact on our view of the mechanisms of aging in complex organisms. The experimental evidence showing that an adult somatic nucleus implanted into an enucleated oocyte can give rise to a whole new individual strongly suggests that the integrity of the genome of an adult nucleus is fully preserved. Here, we will review recent experimental evidence showing that pluripotency gene-based cell reprogramming can erase the epigenetic marks of aging and rejuvenate cells from old individuals reversing most signs of aging and that when induced pluripotent stem cells are differentiated back to the cell type of origin, the rejuvenated cells share many of the features of wild-type counterparts from young donors. This evidence supports the idea that progressive epigenetic dysregulation may be the key driver of organismal aging and challenges the conventional view of aging as an irreversible process. The model of aging as an epigenetic process provides an elegant explanation of a number of age-related processes difficult to explain by conventional theories of aging.