Strategies for Engineered Negligible Senescence

Strategies for Engineered Negligible Senescence (SENS) is the term coined by British biogerontologist Aubrey de Grey for the diverse range of regenerative medical therapies, either planned or currently in development, for the periodical repair of all age-related damage to human tissue with the ultimate purpose of maintaining a state of negligible senescence in the patient, thereby postponing age-associated disease for as long as the therapies are reapplied.

The term "negligible senescence" was first used in the early 1990s by professor Caleb Finch to describe organisms such as lobsters and hydras, which do not show symptoms of aging. The term "engineered negligible senescence" first appeared in print in Aubrey de Grey's 1999 book The Mitochondrial Free Radical Theory of Aging, and was later prefaced with the term "strategies" in the article Time to Talk SENS: Critiquing the Immutability of Human Aging De Grey called SENS a "goal-directed rather than curiosity-driven" approach to the science of aging, and "an effort to expand regenerative medicine into the territory of aging". To this end, SENS identifies seven categories of aging "damage" and a specific regenerative medical proposal for treating each.

Negligible senescence

Negligible senescence is the lack of symptoms of ageing in a few select organisms. Negligibly senescent organisms do not have measurable reductions in their reproductive capability with age, or measurable functional decline with age. Death rates in negligibly senescent organisms do not increase with age as they do in senescent organisms.

Negligibly senescent organisms have no "post-mitotic" cells; they reduce the effect of damaging free radicals by cell division and dilution. Another related mechanism is that of planarian flatworms, which have “apparently limitless telomere regenerative capacity fueled by a population of highly proliferative adult stem cells.”

There are many examples of species for whose organisms scientists have not detected an increase in mortality rate after maturity. In other words, they are equally likely to die at any given age after maturity; or, alternatively, it could be that the mean lifespan of the organisms is so long—multiple millennia—that researchers' subjects have not yet had the chance to live up to the time when a measure of the species' longevity can be made.