The Truth About So-Called Zombie Cells

Zombie cells are just like they sound — damaged and ineffective cells that linger, haunting and infecting nearby cells like rotting fruit in a basket. Normally, damaged cells die off, but zombie cells live on even when they’re too defective or old to work.

Instead of helping the body thrive, they secrete inflammatory molecules that harm nearby healthy cells. Scientists believe the zombie cells may drive chronic illness and aging, offering an exciting new target for longevity and anti-aging treatments.

"Zombie cells" and senescence

The scientific name for zombie cells is senescent cells because they’ve gone through cellular senescence. This means they've stopped dividing due to old age or damage, but they continue living. Research suggests that senescent cells are always present throughout the body but accumulate with age. At the right time and place, the molecules and compounds secreted by these cells benefit the body.

For example, beneficial senescent cells help regulate various temporary processes like embryonic development, childbirth, and wound healing. Impressively, they also help suppress tumors.

However, cellular senescence is a double-edged sword. Prolonged build-up of senescent cells may speed up aging and spur chronic illness.

The danger of lingering zombie cells

The nickname “zombie cells” typically refers to harmful senescent cells. These accumulating cells have deteriorated but resist self-destruction — called apoptosis, the natural cellular death that occurs when a cell is no longer useful.

In 1960, scientist Leonard Hayflick discovered that human cells don’t grow forever, contrary to what scientists believed at the time. After a certain number of replications, Hayflick found that a cell would stop replicating even though it continued to live and use up nutrients. He showed that cells have the capacity to only divide a limited number of times. Eventually, they lose that ability and can no longer replicate.

After this groundbreaking discovery, scientists hypothesized that senescence may be linked to aging. As a result, the cellular senescence theory of aging was developed but is still very new and not fully understood.

Today, only a few clinical studies are investigating human treatment to slow senescence or eliminate zombie cells. Most studies about senescence have only been completed in vitro (research using test tubes and Petri dishes) and in vivo (research performed in living organisms, usually animals).

Science has a long way to go before confidently recommending treatment targeted for zombie cells.

What causes zombie cells to accumulate?

According to current research, scientists believe the main cause of accumulated senescent cells is DNA damage. This is mostly due to oxidative stress from stressors like:

Treatments to reduce accumulated zombie cells

As the fascination with the senescence of cells grows, research is underway to deepen our understanding. The National Institutes of Health (NIH) created the NIH Cellular Senescence Network (SenNet) to explore, identify, and catalog different senescent cells in the body. One goal is to develop future treatments that target unhealthy senescent cells.

Current theories and studies for treatment are wide-ranging. Challenges abound since the field of cellular senescence is young. Scientists aren’t sure how to target only the harmful senescent cells and protect the beneficial ones. Another monumental challenge is delivering treatment safely to humans. How long treatments should last and what adverse effects they may cause is still to be determined, among many other unknowns.

Senolytics

Currently, clinical studies on humans are looking at whether senolytics are effective against zombie cells. Senolytics — also called senomorphics — are drugs or supplements that help senescent cells enter apoptosis rather than live indefinitely.

Anti-cancer drugs, like dasatinib and navitoclax, are a current focus for researchers. Metformin is another possible senolytic. Metformin is a treatment for type 2 diabetes mellitus, but studies suggest it also expands longevity, even in non-diabetic patients.

Other promising senotherapeutics include natural, plant-based compounds that have senolytic ability. Current science points to these possible therapeutics:

• Quercetin. A natural flavonoid found in fruits and vegetables, like capers, red onions, organic tomatoes, berries, grapes, citrus fruits, and green tea. Quercetin may help slow and eliminate zombie cells in skin, kidneys, hearts, and veins.
• Flavonoids. Fisetin and procyanidin C1 may also help prevent senescence. Procyanidin C1 is found in cinnamon, grapes, and unripe apples, while fisetin is in strawberries, apples, persimmons, kiwi fruits, and grapes.
• Ginseng. An antioxidant-rich herb that may help prevent the senescence of bone marrow cells and reduce inflammation, oxidation, and organ aging.
• Resveratrol. Resveratrol and other herbal extracts have also shown possible anti-senescence properties. Resveratrol is found in peanuts, pistachios, grapes, red wine, blueberries, cranberries, bilberries, and dark chocolate.
• Curcumin. An antioxidant found in turmeric may have an anti-aging effect by protecting telomeres. It is also a potent anti-inflammatory and possibly an antitumor compound.

The senolytic effects of these antioxidant molecules mean dietary interventions are a promising non-pharmacological therapeutic against zombie cells.

Other senotherapeutics

As the cellular zombie war wages on, scientists are researching several other possible weapons:

• Probiotics. Healthy gut bacteria help reduce free radicals and relieve oxidative stress, which may suppress senescence.
• Melatonin. Helps protect DNA and mitochondrial damage, making it another possible treatment.
• Stem cells. Have shown senolytic activity in bone marrow, cardiac, and kidney cells.
• Radio electric asymmetric conveyor technology. It was shown in one study to help reduce senescence in stem cells. This technology delivers very low-intensity radio electric frequencies that send microcurrents through tissues, producing certain biological effects. Interventions like these, however, do not target only harmful senescent cells, which means they could have adverse effects on the helpful cells.
• Anti-aging vaccines. Another intriguing treatment scientists are currently researching.
• Various other approaches. Approaches using proteins, peptides, or nanoparticles to target specific zombie cells are also being studied.

Lifestyle interventions

The science of senescence is complex. Until we know more, experts recommend using diet, exercise, and lifestyle changes to face rogue zombie cells. Here are a few strategies to consider:

• Protect yourself from oxidative stress. Limit exposure to UV rays, pollution, smoke, etc.
• Increase dietary antioxidants. Eat a healthy amount of fruits, vegetables, and healthy fats.
• Protect your sleep. Sleep deprivation may activate senescence according to current research.
• Exercise regularly. Animal and human studies show that moderate and habitual exercise may boost mitochondrial function, prevent senescent cell accumulation, and reduce age-related and inflammatory diseases.
• Cautiously consider fasting. Research suggests that overfeeding mice may increase zombie cells. At the same time, restricting calories has shown to be a powerful longevity tool. However, fasting and caloric restriction can have serious detrimental effects when implemented poorly. For senescence, science hasn’t confirmed how much fasting is sufficient and which foods to cut. Furthermore, there is no scientific consensus about whether fasting affects zombie cells.
• Protect your gut microbiota. Since gut bacteria may help suppress senescence, feeding your microbiota with prebiotics could be a potent therapeutic.
• Take up gardening and visit parks. A 2020 study published in The Journals of Gerontology demonstrated that horticulture therapy may reduce senescence and chronic inflammation.

While humans crave the “fountain of youth,” it will take science many years to prove which interventions truly increase longevity and slow aging. In the meantime, a healthy lifestyle is a sure bet for living well for as long as possible.