Biomarkers in Longevity Science
Chris Patil looks at gene expression profiles as a biomarker of aging: "The discovery (and approval) of anti-aging pharmaceuticals is hindered by at least one major practical impediment: Measurement of the simplest biological endpoint of interest - length of lifespan - takes a long time. ... Consequently, much attention has been paid to the idea of aging biomarkers, i.e., phenotypes that can be measured throughout the lifespan and that reflect the percent of lifespan that has elapsed. ... essentially, anything quantifiable that correlates biological age with chronological age is fair game. ... Gene expression measurements are excellent biomarkers: they are both quantitative ('I am expressing three times as much of gene A at age 2 than I was at age 1'), and also robust - because one can measure all of the genes in the genome simultaneously, using microarrays or similar approaches, small perturbations in the levels of single transcripts don't obscure the overall picture. This might not be the case for biomarkers that focus on single phenotypes like bone density, since individual genetic variation might mask the aging signal in the data." For all that researchers are amassing data on gene expression changes with aging in various tissues, the only way to establish the relevance of a potential biomarker for sure is the long way - wait and watch.