Senescent Cells and Longevity: What Do We Know So Far?

When cells are damaged, they typically undergo a biological process known as apoptosis. Some cells, however, resist removal and can harm neighboring cells. These cells are called senescent cells. Senescent cells may be associated with certain common conditions, such as cancer and dementia, and they may have an impact on lifespan.

Normally, when a cell becomes mutated or injured, it stops diving to avoid passing the damage on to daughter cells. Senescent cells also stop multiplying, but they excrete molecules such as cytokines, growth factors, chemokines, and proteases, that affect the function of nearby cells and incite local inflammation.

What are the dangers of senescent cells?

Senescent cells can harm healthy cells in many ways, including:

• DNA damage. Senescent cells may trigger irreparable DNA damage in nearby healthy cells.
• Protein damage. The protease secreted by senescent cells may eliminate proteins.
• Lipid damage. Senescent cells could damage the membrane of nearby cells.
• Mitochondria damage. Senescent cells may trigger changes to the mitochondria function, dynamic, and form in nearby cells.

The damage that senescent cells cause to nearby cells can affect a person’s ability to withstand stress or illness, recuperate from injuries, and learn new things.

Senescent cells could be related to conditions such as cancer, diabetes, osteoporosis, cardiovascular disease, stroke, Alzheimer’s disease, dementia, and osteoarthritis.

Studies conducted in mice have demonstrated a causal link between senescence and aging. The scientists first transplanted a small number of senescent cells into healthy young and middle-aged mice, and measured how those cells impacted strength, endurance, and other measures of physical health. One month after transplantation, mice who received the senescent cells had impaired walking speed, physical endurance, and grip strength compared to control mice. Notably, middle-aged mice transplanted with senescent cells had a higher risk of death.

One cause of senescence is damage to the telomeres, which are repetitive DNA structures located at the end of chromosomes. Shortened telomeres are associated with liver cirrhosis, chronic obstructive pulmonary disease, and other disorders, and they correlate with an increase in mortality in people over the age of 60.

Can senescent cells be detected or reduced?

Detection and identification of senescent cells is still a challenge. There are some biomarkers that can be used to detect senescence, and flow cytometry can be used as well.

Treatment of mice with dasatinib plus quercetin was shown to improve general health and have significant effects on chronic degenerative diseases and age-related pathology. Dasatinib poses risks, including neutropenia and platelet deficiency, leaving the body vulnerable to infection. This regimen has not been tested in humans, and it is important to note that people should not try this regimen outside of a clinical trial, as it has not been proven safe.

One study showed fisetin was effective at reducing the markers of senescence without killing healthy cells, and it extended the median and maximum lifespan of mice. Fisetin is found in many fruits and vegetables; strawberries have a particularly high concentration. It is also available as a dietary supplement, and it has no reported side effects.