Scientists have been exploring ways to remove or repair these harmful cells, but there has been a major obstacle. Researchers have struggled to reliably identify senescent cells hiding among healthy cells in living tissue.

DNA Aptamers Help Researchers Identify Senescent Cells

A team at Mayo Clinic now says it has found a promising new strategy. Writing in the journal Aging Cell, the researchers describe a technique that uses molecules called “aptamers” to tag senescent cells.

Aptamers are short strands of synthetic DNA that naturally fold into complex three dimensional shapes. Those shapes allow them to attach to specific proteins found on the surfaces of cells.

Working with mouse cells, the scientists screened more than 100 trillion random DNA sequences and identified several rare aptamers capable of binding to proteins associated with senescent cells. Once attached, the aptamers effectively flagged the cells for identification.

“This approach established the principle that aptamers are a technology that can be used to distinguish senescent cells from healthy ones,” says biochemist and molecular biologist Jim Maher, III, Ph.D., a principal investigator of the study. “Though this study is a first step, the results suggest the approach could eventually apply to human cells.”

A Chance Conversation Sparked the Discovery

The project began with an unexpected idea shared during a casual conversation between graduate students at Mayo Clinic.

Keenan Pearson, Ph.D. — who recently earned his degree from Mayo Clinic Graduate School of Biomedical Sciences — had been studying how aptamers might be used against brain cancer or neurodegenerative diseases while working with Dr. Maher.

Elsewhere on campus, Sarah Jachim, Ph.D., — who was also completing graduate research at the time — was studying aging and senescent cells in the laboratory of Nathan LeBrasseur, Ph.D.

The two students crossed paths during a scientific event and started discussing their thesis projects. Dr. Pearson began wondering whether aptamer technology could be adapted to recognize senescent cells.

“I thought the idea was a good one, but I didn’t know about the process of preparing senescent cells to test them, and that was Sarah’s expertise,” says Dr. Pearson, who became lead author of the publication.

Researchers Pursue a “Crazy” Idea

The students presented the idea to their mentors as well as researcher Darren Baker, Ph.D., whose work focuses on therapies targeting senescent cells.

Dr. Maher says the concept initially sounded “crazy,” but intriguing enough to investigate further. The mentors ultimately embraced the collaboration.

“We frankly loved that it was the students’ idea and a real synergy of two research areas,” says Dr. Maher.

The research advanced quickly. Early experiments produced encouraging findings sooner than expected, leading the team to bring in additional students from several labs.

Then-graduate students Brandon Wilbanks, Ph.D., Luis Prieto, Ph.D., and M.D.-Ph.D. student Caroline Doherty contributed specialized techniques, including advanced microscopy and analysis of a wider variety of tissue samples.

“It became encouraging to expend more effort,” Dr. Jachim says, “because we could tell it was a project that was going to succeed.”

New Clues About the Biology of Zombie Cells

The study may offer more than just a new way to identify senescent cells. It also uncovered information about the cells themselves.

“To date, there aren’t universal markers that characterize senescent cells,” says Dr. Maher. “Our study was set up to be open-ended about the target surface molecules on senescent cells. The beauty of this approach is that we let the aptamers choose the molecules to bind to.”

Several of the aptamers attached to a variation of fibronectin, a protein found on the surface of mouse cells. Researchers do not yet understand exactly how this fibronectin variant relates to senescence, but the finding could help scientists better define what makes senescent cells unique.

Future Potential for Aging and Disease Treatments

The researchers caution that additional studies will be needed before aptamers can reliably identify senescent cells in humans.

Still, the technology could eventually become much more than a detection tool. Scientists believe aptamers might one day carry therapies directly to senescent cells, allowing highly targeted treatment approaches.

Dr. Pearson says aptamers are also less expensive and more adaptable than traditional antibodies, which are commonly used to distinguish different types of cells.

“This project demonstrated a novel concept,” says Dr. Maher. “Future studies may extend the approach to applications related to senescent cells in human disease.”

The research was conducted at Karolinska Institutet as part of the Swedish Physical Activity and Fitness study (SPAF). Scientists followed several hundred randomly selected men and women in Sweden from ages 16 to 63, repeatedly measuring their fitness and strength over a span of 47 years.

The study was published in the Journal of Cachexia, Sarcopenia and Muscle.

Rare Long Term Fitness Data

Most previous studies on aging and physical performance relied on cross sectional comparisons between different age groups. In contrast, the SPAF project repeatedly tested the same individuals over decades, making it one of the few long running studies of its kind.

By tracking the same participants over time, researchers were able to build a much clearer picture of how the body changes through adulthood and aging.

Physical Decline Begins Around Age 35

The results showed that physical capacity starts decreasing as early as age 35, even among people with different training backgrounds. After that point, the decline continues gradually and becomes more pronounced with advancing age.

Researchers examined changes in fitness, muscular strength, and endurance, all of which followed a similar downward trend over time.

Still, the study also found important evidence that exercise remains highly beneficial at any age. Participants who became physically active during adulthood improved their physical capacity by 5-10 percent.

Exercise Still Makes a Difference

“It is never too late to start moving. Our study shows that physical activity can slow the decline in performance, even if it cannot completely stop it. Now we will look for the mechanisms behind why everyone reaches their peak performance at age 35 and why physical activity can slow performance loss but not completely halt it,” says Maria Westerståhl, lecturer at the Department of Laboratory Medicine and lead author of the study.

The researchers plan to continue following the participants as they age. Next year, the group will be tested again when participants reach 68 years old.

Scientists hope the ongoing work will help reveal how lifestyle habits, overall health, and biological processes influence the way physical performance changes across a lifetime.

Researchers led by the University of Liverpool uncovered strong evidence that traces of original organic molecules, including collagen, still exist inside dinosaur bones dating back roughly 66 million years. The discovery adds powerful new support to a controversial idea that has divided paleontologists for more than 30 years.

Preserved Collagen Found in Dinosaur Bone

The fossil at the center of the study is a 22-kilogram Edmontosaurus sacrum, part of the dinosaur’s hip region, recovered from South Dakota’s famous Hell Creek Formation. Edmontosaurus was a large duck-billed plant eater that lived alongside Tyrannosaurus rex near the end of the Cretaceous Period.

Using a combination of advanced laboratory methods, including protein sequencing and several forms of mass spectrometry, scientists detected remnants of collagen embedded within the fossilized bone. Collagen is the primary structural protein found in bone tissue and one of the hardest biomolecules to explain away as contamination when identified in this context.

Researchers from UCLA also identified hydroxyproline, an amino acid strongly associated with collagen in bone. According to the team, this represented an important confirmation that degraded collagen fragments were genuinely present inside the fossil.

Professor Steve Taylor, chair of the Mass Spectrometry Research Group at the University of Liverpool’s Department of Electrical Engineering & Electronics, said:

“This research shows beyond doubt that organic biomolecules, such as proteins like collagen, appear to be present in some fossils.”

“Our results have far-reaching implications. Firstly, it refutes the hypothesis that any organics found in fossils must result from contamination.”

A Debate That Has Divided Paleontology

Claims of preserved soft tissues and proteins in dinosaur fossils have sparked fierce debate since the early 2000s. Some scientists argued the reported materials were modern contamination or bacterial residue rather than authentic dinosaur molecules.

One of the most famous discoveries came in 2005, when paleontologist Mary Schweitzer and colleagues reported soft tissue structures inside a Tyrannosaurus rex fossil. Later studies identified possible collagen and blood vessel-like structures in additional dinosaur specimens, including hadrosaurs related to Edmontosaurus.

The new Edmontosaurus analysis stands out because researchers used multiple independent testing methods to examine the same fossil. By combining microscopy, chemical analysis, and protein sequencing, the team aimed to rule out contamination and strengthen the case that the molecules were original to the dinosaur itself.

The findings were published in Analytical Chemistry in 2025 under the title “Evidence for Endogenous Collagen in Edmontosaurus Fossil Bone.”

Why This Discovery Matters

If proteins can survive in fossils for tens of millions of years, scientists may gain an entirely new way to study extinct animals.

Tiny molecular traces could potentially reveal evolutionary relationships between dinosaur species that are difficult to identify from bones alone. Researchers may also learn more about dinosaur growth, aging, physiology, and disease.

Taylor noted that scientists may now need to revisit fossil samples collected over the past century. Cross-polarized light microscopy images taken decades ago could contain overlooked evidence of preserved collagen in ancient bones.

“These images may reveal intact patches of bone collagen, potentially offering a ready-made trove of fossil candidates for further protein analysis,” Taylor explained.

“This could unlock new insights into dinosaurs, for example revealing connections between dinosaur species that remain unknown.”

The Mystery of Molecular Survival

The discovery also raises a fascinating scientific question: how did these molecules survive for so long?

Proteins normally break down over time, especially across geological timescales. Yet some fossils appear capable of preserving microscopic biological structures under specific conditions.

Scientists are increasingly investigating whether mineral interactions inside bone may help shield fragments of collagen from complete decay. Recent studies exploring fossil biomolecules suggest that certain burial environments and microscopic bone structures may create stable conditions that slow chemical breakdown dramatically.

Edmontosaurus fossils are already famous for their exceptional preservation. Some specimens discovered over the last century retained detailed skin impressions and other soft tissue features, earning the nickname “dinosaur mummies.”

More recent paleontology research has continued uncovering surprisingly detailed soft tissue preservation in Edmontosaurus specimens, including evidence of fleshy structures and preserved skin anatomy.

Together, these discoveries are reshaping how scientists think about fossils. Instead of viewing them solely as stone replicas of ancient bones, researchers are beginning to see some fossils as possible molecular time capsules that still preserve traces of prehistoric biology millions of years later.