The Strategies for Engineered Negligible Senescence (SENS) are a synthesis of scientific research, existing scientific knowledge, a call to action, and the proposals put forward by biomedical gerontologist Aubrey de Grey. SENS is mentioned often at the Longevity Meme; why is it important for people interested in healthy life extension? "Strategies for Engineered Negligible Senescence" means, in plain non-scientific terms, "a proposed way to develop a cure for aging."

Learn More in "Ending Aging" Aubrey de Grey and Michael Rae have written Ending Aging: The Rejuvenation Breakthroughs That Could Reverse Human Aging in Our Lifetime. In this book they explain, as best we know based on the biotechnology and scientific knowledge of today, how we can band together, build a mighty research infrastructure, and greatly extend our healthy life spans soon enough to matter. Ending Aging is perhaps the best presently available introduction to the science and rationale of SENS, and is highly recommended.

De Grey proposes that scientists know more than enough to get started on the development of working longevity medicine - therapies that can halt or reverse the root causes of age-related degeneration. SENS combines the following:

• science from varied fields within biology and medicine to make the case
• a proposed roadmap for the near future of rejuvenation research
• ethical and utilitarian arguments for moving to defeat age-related degeneration as rapidly as possible
• research programs funded by the Methuselah Foundation prior to 2009, and now by the SENS Foundation.
• the support of a number of prominent philanthropists

The Science of SENS

de Grey proposes that there are most likely only seven categories of biological process that lead to degenerative aging and age-related disease, and that all have been known for almost twenty years. That no new categories have been discovered since the late 1980s - over a time of great progress in all fields of biology and medicine - strongly suggests that there are no other significant causes of age-related degeneration and disease. In principle, scientists can already describe potential therapies that could address each of these processes. The basic tools required for these therapies have in many cases already been demonstrated in the laboratory or in trials for more limited uses. Some tissues lose cells with advancing age, like the heart and areas of the brain. Stem cell research and regenerative medicine are already providing very promising answers to degeneration through cell loss. We must eliminate the telomere-related mechanisms that lead to cancer. de Grey suggests selectively modifying our telomere elongation genes by tissue type using targeted gene therapies. Mitochondrial DNA is outside the cellular nucleus and accumulates damage with age that impairs its critical functions. de Grey suggests using gene therapy to copy mitochondrial DNA into the cellular nucleus. Other strategies for manipulating and repairing damaged mitochondrial DNA in situ were demonstrated for the first time in 2005. Some of the proteins outside our cells, such as those vital to artery walls and skin elasticity, are created early in our life and never recycled or recycled very slowly. These long-lived proteins are susceptible to chemical reactions that degrade their effectiveness. Scientists can search for suitable enzymes or compounds to break down problem proteins that the body cannot handle. Certain classes of senescent cell accumulate where they are not wanted, such as in the joints. We could in principle use immune therapies to tailor our immune systems to destroy cells as they become senescent and thus prevent any related problems. As we age, junk material known as amyloid accumulates outside cells. Immune therapies (vaccines) are currently under development for Alzheimer's, a condition featuring prominent amyloid plaques, and similar efforts could be applied to other classes of extracellular junk material. Junk material builds up within non-dividing, long-life span cells, impairing functions and causing damage. The biochemistry of this junk is fairly well understood; the problem lies in developing a therapy to break down the unwanted material. de Grey suggests searching for suitable non-toxic microbial enzymes in soil bacteria that could be safely introduced into human cells. If you have an interest in the science of SENS, you will find more information at the SENS Foundation website, and an excellent overview in detail and depth in the book Ending Aging: The Rejuvenation Breakthroughs That Could Reverse Human Aging in Our Lifetime.

Progress in any one area of SENS science is likely to lead to therapies for a class of age-related diseases. It is not unreasonable to expect the research community - motivated as it is to seek cures for specific diseases - to slowly fill in the gaps in SENS as time moves on. For example:

• Alzheimer's researchers are working on immune therapies to address both amyloid plaques and other forms of junk material suspected to cause neurodegeneration.

• At least one research group is attempting to develop repair techniques for damaged mitochondrial DNA in order to treat certain classes of age-related illness

• Stem cell and regenerative medicine is a large and well funded field largely focused on using existing biological mechanisms to build new, replacement tissue for the body.

• Researchers are investigating the manipulation of telomeres in order to prevent or treat cancer.

• Groups are working on compounds to break down accumulated biochemical junk outside cells.

Making gains in SENS science in unrelated bits and pieces is likely to be a slow path for progress towards meaningful healthy life extension, however. Curing any one age-related condition is a wonderful thing for sufferers, but it will not increase healthy life span for anyone else - nor will it lead directly to therapies that can extend healthy life span without further investment and work. It would be much more cost-effective to directly address the root cause of aging and age-related disease.

Modest philanthropic funding for this direct research commenced in 2005 under the administration of the Methuselah Foundation, and has grown to more than $7 million in 2009. The first lines of SENS research to be funded are:

• LysoLENS research aims to discover and utilitize bacterial enzymes capable of safely degrading the accumulation of junk material inside cells.

• MitoSENS research lays the groundwork for the biotechnologies needed to copy vulnerable mitochondrial genes into the comparative safety of the cellular nucleus.

Other lines will follow. Far greater funding is needed in order for a much broader community of scientists to move rapidly along this direct path, however.

The Ethics of a Cure for Aging

In many ways, the hardest part of the path ahead for supporters of healthy life extension lies in convincing people that SENS and similar scientific projects should be funded. The science is much more certain than the state of funding, fundraising and public support. This is a strange state of affairs when you stop to look at it. As Aubrey de Grey notes: Aging really is barbaric. It shouldn't be allowed. I don't need an ethical argument. I don't need any argument. It's visceral. To let people die is bad. I work to cure aging, and I think you should too, because I feel that saving lives is the most valuable thing anyone can spend their time doing, and since over 100,000 people die every single day of causes that young people essentially never die of, you'll save more lives by helping to cure aging than in any other way. Many people demonstrate a certain willful blindness to the death and suffering caused by aging, a blindness that is not present for age-related disease like cancer or Alzheimer's. Yet if you support medical research to cure disease, prevent death and relieve suffering, then you should also support medical research to prevent and repair age-related degeneration. How is suffering and death caused by the general deterioration of aging any different from suffering and death caused by a specific age-related condition we understand and have given a name? You can read more about the ethics of seeking a scientific cure for aging at the SENS website.

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Last updated April 7th, 2009