You might recall the demonstration of extended healthy longevity in mice by localizing the antioxidant catalase to the mitochondria - a strategy replicated by other researchers to some success. Here is an update on that work: "We describe the effects of mitochondrially targeted catalase (MCAT) expression on end-of-life pathology in mice using detailed semiquantitative histopathological evaluation. We previously reported that the median and maximum life spans of MCAT mice were extended relative to those of wild-type littermates. We now report that MCAT expression is associated with reduced malignant [tumor] burden, reduced cardiac lesions, and a trend toward reduced systemic inflammation ... Combined disease burden and comorbidity are also reduced, and MCAT expression is not associated with any detrimental clinical effects. The results suggest that oxidative damage is involved in aging of [mice] via modulation of a subset of age-associated lesions. Antioxidant interventions targeting mitochondria may therefore be a viable strategy for prevention or postponement of some age-associated diseases."

Link: http://www.ncbi.nlm.nih.gov/pubmed/18772469