Aging helps set the stage for cancer and other major diseases long before symptoms appear. In this program, UC San Diego’s Robert A.J. Signer, Ph.D., explains that aging is not just a passive backdrop to disease. It is an active biological process that reshapes the conditions that allow illness to emerge. That idea matters because it suggests that understanding aging could help delay several diseases at once and extend healthspan, the part of life lived free of major disease.
Signer centers that story on stem cells. These rare cells can make more of themselves, produce the specialized cells a tissue needs, and persist for long periods of time. In the blood system, that job is enormous. Blood-forming stem cells in the bone marrow help sustain more than 35 trillion blood cells, including about 2 million new red blood cells every second. Signer notes that this constant renewal depends on only about 100,000 stem cells.
When those cells malfunction, the consequences are serious. Too little renewal can lead to degenerative disease. Too much self-renewal can lead to cancer. Aging makes these problems more likely, even in cells built for longevity.
Signer explains that one key to stem cell longevity is stress control. His research finds that stem cells keep protein production unusually low compared with other cells. That helps prevent mistakes and keeps damaged proteins from piling up like cellular trash. As stem cells age, however, those quality-control systems are challenged. The buildup triggers stress-response programs designed to protect the cells.
One of those programs involves protection in healthy stem cells, helping manage stress and preserve function. But the same response can also strengthen mutant precancerous stem cells. In clonal hematopoiesis, mutated blood stem cells gradually expand and become dominant with age. Signer says this common precancerous condition has no approved treatment and is associated with increased risks of cardiovascular disease, inflammation, cancer, and death.
The larger takeaway is both sobering and hopeful. The same systems that help stem cells survive aging can also be turned toward disease. But by understanding how stress, aging, and stem cell biology interact, researchers can begin to design therapies that protect healthspan, prevent precancer from advancing, and open new paths toward disease prevention.
Watch: Aging Blood Stem Cells and the Roots of Cancer