Research into senescent cells could result in extended human lifespans and significant policy implications
Improved housing, sanitation, and healthcare have significantly increased humans’ life expectancy, and biomedical advances have the potential to further extend people’s lives. The life expectancy of a person born in 1860 was only about 39 years; a person born today can expect to live about 79 years. Now some researchers are studying whether altering humans’ senescent cells could increase lifespans to an even greater extent.
Cellular senescence – a process by which cells stop replicating after a set amount of time – is vital to prevent devastating cancers, but also contributes to age-related diseases. Every time a cell replicates, its DNA accumulates a low number of errors. If cells replicate unchecked, these errors can snowball, forming masses of non-functioning cells that damage healthy tissues. For example, the cells responsible for malignant cancers, which can be deadly, do not show any sign of senescence. On the other hand, senescent cells, which are alive but no longer dividing, can build up in a person’s tissues, release harmful chemicals, and contribute to age-related health issues.
Reducing the numbers of senescent cells in peoples’ bodies could extend human lives. Studies in mice have shown that removing senescent cells can help mice live longer and maintain their physical abilities. Treated mice lived, on average, 36 percent longer than mice that retained senescent cells. Furthermore, old mice given a drug that reduces the number of senescent cells were able to survive COVID-19 in significantly higher numbers than old mice not given the drug. While these results are promising, whether the results can be reproduced in humans is an open question. Some early trials in humans testing drugs that reduce populations of senescent cells are targeting specific diseases, such as age-related macular degeneration, glaucoma, and chronic obstructive pulmonary disease.
If it becomes possible to further diminish the effects of aging over the next few decades, there would be substantial policy implications. For example, greater longevity could mean older Americans experience longer periods of dependency on their families or the government, increasing retirement and medical costs. People might also stay healthier for longer, which may necessitate an increase of the retirement age. As this research into human longevity matures, it is important that policymakers consider the fiscal, legal, and medical implications of extending human lives.
This CSPI Science and Technology Policy Snapshot expands upon a scientific exchange between Congressman Bill Foster (D, IL-11) and his new FAS-organized Science Council.