A new class of anti-ageing drugs has shown very promising results during trials on mice – demonstrably increasing both ‘healthspan’ and lifespan. Six human trials are now underway with another six planned. Should they show the same promise, the drugs, called senolytics, could conceivably be available within a few years. Scientists involved in the trials believe that senolytics could have a huge impact on increasing human lifespans and, even more importantly, our overall health in later life.
For some time there has been evidence that age-related decline and a whole range of chronic, age-related diseases and conditions are linked to the build-up of senescent, or ‘zombie’ cells. The human body’s normal, healthy cells ‘divide, die and get cleared away’ in a cycle that keeps our organs regenerating. However, as we age, the ‘clearing away’ part of this cycle becomes less efficient. Old, decaying cells start to be missed out by our body’s clean up system. They no longer divide to produce new, healthy cells and linger in their decaying state, producing harmful chemicals that spread to surrounding cells, also turning them into senescent, zombie cells.
Higher concentrations of senescent cells have been linked to diseases such as Alzheimer’s and diabetes as well as a host of other age-related conditions. It is now believed the ageing process itself is the single biggest causal factor for most chronic diseases, rather than that they lead to ageing.
Dr James Kirkland of the Robert and Arlene Kogod Centre on Ageing, part of the Mayo Clinic, explains:
“Around 10 years ago we began to explore the notion that ageing may be an upstream cause of all of these conditions and not only be a risk factor but could actually be causal.”
And now there is also a growingly popular theory that the build-up of senescent cells is what causes ageing. Or at least that they are a major contributor to the process. Animals injected with senescent cells have been seen to begin to quickly show signs of accelerated ageing and developing diseases normally associated with older creatures.
Cleaning these cells away, as our bodies efficiently do themselves when younger, could therefore represent a ‘mechanism-based’ treatment of chronic diseases and the ageing process itself. It would be treating the root of the problem rather than simply alleviating symptoms.
Senolytics drugs do exactly that and target sesescent cells in a similar way to how antibiotics target bacteria. Trials on mice conducted at the Mayo Clinic saw the natural lifespan of subjects increase by up to 36%. The mice also remained healthier as they aged. Notable improvements were apparent after only one course of the drugs.
“Cardiovascular function improved within five days of a single dose of the drug in the mice, while periodic doses delayed age-related symptoms, spine degeneration and osteoporosis”.
Further testing is required before senolytics could be used to treat humans but the researchers are optimistic. Fears over potential side effects are also reduced by the fact that it looks like only very occasional courses of treatment would be necessary to take advantage of the drugs’ positive effects.