Senescence is a term that is often used in biology to describe the condition or process of deterioration with age, as in senescent or aging cells. Senescence is the process by which cells irreversibly stop dividing and enter a state where they no longer grow yet are still alive and do not undergo cell death. Senescence can be caused by unrepaired DNA damage or other cellular stresses. The study of aging cells, or senescence, is important to understand not only why we age, but to understand the role that aging cells, and the substances they secrete, have on human health and disease.
How do researchers study senescence?
Researchers have found that clearing the body of its old, damaged cells slows aging and extends life. In one a 2011 research study mentioned in a 2016 article in The Atlantic entitled “Clearing the Body’s Retired Cells Slows Aging and Extends Life,” scientists developed a technique for singling out and removing senescent cells. Using this technique, they found that if they purged healthy, middle-aged mice of their old or senescent cells two times a week, they could increase the rodents’ average lifespan by a quarter. As the mice continued to get older, they lost less body fat, had healthier hearts and kidneys, developed fewer cataracts, were more active and actually seemed to improve in health. This was the first time in a decade that aging, or senescent, cells were found to contribute to aging.
As described in the Atlantic article, in an average person, senescent cells actively secrete molecules that are designed for good but have a negative impact on tissues. These molecules are designed to signal the body that there are damaged, aging cells present and that the body should clear them out. This process is meant to keep us healthy, but as we age, our immune system no longer works as efficiently as it once did. The aging cells start building up, and the body stores the secreted molecules instead of destroying them, which causes health problems and disease.
Why it important to study senescence?
In a study published in Oncotarget Volume 6, Issue 31, entitled “Senescent stromal cells induce cancer cell migration via inhibition of RhoA/ROCK/myosin-based cell contractility,” researchers caused connective tissue cells to age and found that those aging, or senescent, cells caused immune system cells to secrete substances that make disease worse (pro-inflammatory substances). In this study, these substances in turn caused changes to breast cancer cells that were previously unable to move, enabling them to move throughout the body. This is important to understand the process behind why cancer cells spread in the body.