What causes aging?
Is it possible to reverse it?
What can you do to live a longer and healthier life?
One theory about aging involves the accumulation of senescent cells or I as I like to call them ‘zombie cells’ because these cells are very different from normal cells (emphasis on very). Instead of functioning as a normal cell does their gene expression changes which just means they produce different proteins.
Can’t be that bad? Oh, but it is because these proteins are pro-inflammatory which means they cause a whole host of effects such as uncontrolled tissue death. But worst of all is the spread of zombie cells which is like a rotten strawberry in a bowl of fruits, releasing toxins that cause the healthy cells to become dysfunctional.
The negative effects of zombie cell accumulation have been proven in recent experiments by Ming Xu and others at the Mayo Clinic. By injecting previously healthy young adult mice with one million senescent cells caused a significantly lower maximal walking speed, hanging endurance, and grip strength 1 month after transplantation compared to mice transplanted with control cells.
One million may sound like a lot but the average mouse is made up of over a trillion cells.
Chronic inflammation can lead to a whole host of diseases from rheumatoid arthritis to Alzheimer’s.
What scientists are doing to stop this?
Don’t worry there is a lot of research in this field.
One company Oisín is planning on loading a suicide gene into nanoparticles (tiny packets that can be modified to make sure that the drug is not broken down on its way to its target.) that will be delivered to all cells bit only activated in cells that express high levels of a marker for zombie cells called P16.
However, we must be careful for “Not every cell that expresses high p16 is senescent; and not every senescent cell has high p16,” says James Kirkland, a researcher who studies aging at the Mayo Clinic.
Another technique is senolytics which is the process of killing senescent cells using drugs. Two drugs which have been tested on human adipose fat) cells are dasatinib and quercetin. Xu said. “We observed a reduction in the inflammatory cytokines in these tissues, while key adipokines were not affected. This demonstrates that these senolytic drugs can decrease inflammation without a global killing effect.”
Adipokines are cell proteins which are released by cells and have anti-inflammatory effects which lead to the production.
Higher levels of adiponectin (an adipokine) are associated with greater insulin sensitivity and metabolic health. You wouldn’t want senolytic drugs to inhibit adiponectin at the same time as they are influencing inflammatory cytokines levels.
What you can do to remove your zombie cells?
Yes, there are ways that you can ensure you age healthily. It may be hard to implement at the start but remember it will be worth it in the end.
Exercise and fasting have both been shown to reduce the number of senescent cells.
Don’t think you have to go all out and fast for days because intermittent fasting has been shown to in animal models to promote autophagy, or cellular “self-eating” that helps clear out damaged cellular components including misfolded proteins.
Intermittent fasting may also help reduce inflammation and oxidative stress processes associated with cellular senescence. For example, oxidative stress shortens telomeres, the protective DNA caps at the ends of your chromosomes, which can lead to a cell becoming senescent.
Researchers have also found that exercise reduced the number of p16-positive senescent cells in transgenic mice fed a fast food diet.
Research into reversing aging or stopping it for good raises many questions, because if we do discover a way to increase our lifespan or end aging. What effects will this have on society, culture and our already struggling planet?
We need to discuss these questions before we produce any viable treatments arrive, so we are ready for the consequences instead of being caught unaware as we have with climate change.
Ming, X .,et al (2018) ‘Senolytics improve physical function and increase lifespan in old age’, Nature Medicine, 24(), pp. 1246- Toussaint, O. , Salmon, M. , Pascal, T. , Magalhaes, J. P. and Chainiaux, F. (2005). https://www.nature.com/articles/s41591-018-0092-9
Stress‐induced Premature Senescence (SIPS). In eLS, (Ed.). doi:10.1038/npg.els.0003865 1256. Available at: https://www.nature.com/articles/s41591-018-0092-9
Paige Brown Jarreau (2018) Don’t Be a Zombie: Senolytics, Exercise and Fasting Fight Off Senescent Cells, Available at: https://medium.com/lifeomic/dont-be-a-zombie-senolytics-exercise-and-fasting-fight-off-senescent-cells-cc720d88240 (Accessed: 02/03/19).
Zoë Corbyn (2018) Want to live for ever? Flush out your zombie cells , Available at: https://www.theguardian.com/science/2018/oct/06/race-to-kill-killer-zombie-cells-senescent-damaged-ageing-eliminate-research-mice-aubrey-de-grey (Accessed: 03/03/19).