Sooner or later, researchers will turn up good biomarkers for aging and longevity - tools that are needed to properly evaluate therapies that aim to repair the biochemical damage of aging in humans. Here is another candidate biomarker: "Aging is a complex process resulting from, among other, dynamic non-linear interactions between genetics and environment. Centenarians are the best example of successful aging in humans, as they escaped from, or largely postponed, major age-related diseases. Ionic fluxes changes play a key role in several patho-physiological cellular processes, but their relation to human aging is largely unexplored. In the present study we have [compared] potassium (K+) current recordings from dermal fibroblasts (DF) obtained from young, elderly and centenarian donors. We found that in DF from elderly donors, but not from centenarians, K+ current amplitude is significantly smaller with respect to DF from young donors. Moreover, cell membrane capacitance of DF from elderly donors is smaller with respect to young donors and centenarians. ... The maintenance of 'young' K+ currents and the peculiar age-related remodeling of K+ channel subtypes in centenarian's DF is likely associated with successful aging and might provide a predictive marker of longevity."