This is a very difficult question to answer, even for those of us who are experts in the biology of aging. At the institute where I work, we study why our cells age and how we can improve this process. The quick answer is that technically it can be reversed, but in reality, it’s not that simple.
What we do know is that aging is malleable. For example, the environment can change how long you live — whether you live for a longer or shorter period of time. And since the 1980s, we also know that we can genetically modify it to extend or shorten the lifespan of almost all the model organisms we have studied. We already have extensive knowledge about which cellular pathways need to be altered to achieve this. But reversing the process is another matter: it’s a question that has emerged in the last 10 years, meaning it’s very new. Although we already have some evidence that it can be done.
Within cells, there are certain genes that, when overactivated, can cause a cell that is already differentiated — that is, already developed for its function: kidney, brain, skin, etc. — to become pluripotent again; and then, once more, it could become a specialized cell of the organism. These genes are called OSKM (the initials of their names: Oct4, Sox2, Klf4, and c-Myc), also known as Yamanaka factors after the researcher who discovered them. In cell cultures, when these factors are overactivated — but somewhat less so, or intermittently — the cell can rejuvenate without fully reverting to pluripotency.
Several research groups, including those led by Spanish scientists Juan Carlos Izpisúa and Manuel Serrano, have overexpressed these Yamanaka factors in mice and have managed to rejuvenate some of their tissues or organs according to certain physiological parameters and also their biological age — measured using epigenetic or transcriptomic clocks. The problem with genetically modifying these factors is that they can cause side effects, one of the most important being the potential development of tumors.
When it comes to organisms like ours and many others, we have also observed temporary rejuvenation. For example, if strong stress occurs — such as fasting, surgery, or even pregnancy — the organism ages very quickly (also measured by epigenetic and transcriptomic clocks). But after some time passes, it returns to the age it had before the stress. We also know there are interventions, like specific diets or medications, that can make this rejuvenation happen faster.
This means that technically aging can be reversed, although only temporarily or partially. However, it is important to note that so far, reversing aging in older adult organisms has not been achieved. I work with the worm Caenorhabditis elegans, and once we have an adult worm, we cannot make it younger. We don’t know if this will ever be possible, but given the evidence we already have from cell cultures, I believe we might achieve it within a few decades.
Finally, if we think of aging as something linear — you start at zero and keep aging — what we currently know is that we can make life last longer, and improve health at this stage. For example, C. elegans worms live for 30 days, but we can make them live 60 days, and that longer-lived worm of 50 days behaves like a 20-day-old worm, with comparable health.
If these worms are rejuvenated, for example through fasting during the larval stage, once they come out of fasting they will continue to age. Therefore, what we have never seen is that the aging process can be paused forever or that immortality can be reached.
Victoria Eugenia Martínez Miguel holds a PhD in the Biology of Aging and is a researcher at the Max Planck Institute for Biology of Ageing (Germany).
Question sent via email by Marcos.
Coordination and writing:Victoria Toro.
The advice provided in this column is general in nature and does not replace medical consultation. If you have questions about your specific condition, please consult your healthcare professional.
Sign up for our weekly newsletter to get more English-language news coverage from EL PAÍS USA Edition
Source link
