Cellular senescence, or the ultimate death of a cell as it reaches its replication limit, has been a hotly debated issue among biologists for decades, principally, “Is it important in increasing longevity?” A new battery of research seems to confirm that senescence does play an important role not necessarily in increasing lifespan, but in increasing “healthspan”. Put a different way, by removing those cells that are damaged or breaking down, one can increase the amount of their lifespan that they are healthy and vital. Though the research is still in its infancy (this has only been tested on mice), the implications for increasing humans’ healthy years could be potentially game-changing.
Consider a plant in your garden. Each spring you can revitalize that plant by trimming away the dead stems and leaves that, although sucking up valuable resources, are not actually providing anything to the health of the planet. Trimming back the detritus for a new year. That is essentially the principle behind Mayo Clinic gerontologist Darren Baker’s experiment. The genetically modified mice in the experiment were monitored by Baker’s team, who destroyed cells in the mice that were producing a protein called p16Ink4a (or just p16, for short). This protein is largely a tumor-inhibitor, but it’s also a red flag that the cell is approaching its replication limit (or senescence). The team would kill off the cell, rather than allowing it to languish, and the body would then absorb and excrete it as normal. The issue, according to Baker, is that cells don’t simply die. They languish, excreting inflammatory enzymes and other pollutants into the body as they whither. “The bottom-line question is,” Felipe Sierra, Director of the Aging Biology department at the National Institute of Aging, “what happens when you increase or decrease cellular senescence in an animal?”
The treated mice, which were genetically modified to die of heart failure after a certain point, did not live any longer than the other control mice, but they were healthy and vital up until the very end whereas the untreated mice deteriorated significantly. Imagine a world in which senior citizens are healthier, stronger, and more resilient to diseases and other external threats longer? Though the targeting of senescent cells doesn’t seem to improve lifespan, it would make entire generations of the elderly more vital and increase the quality of life for many people well beyond what it is now. The costs of healthcare, much of it due to expensive end-of-life treatments, may also shrink as people are better able to “weather the storm” of old age. In a culture obsessed with longevity and staying younger longer, this development is sure to turn some heads and some wallets.