A massive cell-by-cell map of aging reveals it’s a synchronized, body-wide process—and scientists may finally know where to intervene.
As people grow older, their risk of developing conditions such as cancer, heart disease, and dementia rises sharply. For decades, medical research has tackled these illnesses individually. Increasingly, however, scientists are asking a bigger question. Instead of treating diseases one by one, could slowing the aging process itself reduce the risk of many of them at once? To do that, researchers first need to understand exactly what changes inside the body over time and what sets those changes in motion.
A new study published today (February 26) in Science offers one of the clearest pictures yet. Researchers at The Rockefeller University built an expansive atlas showing how aging alters thousands of distinct cell subtypes across 21 mammalian tissues. By examining nearly 7 million individual cells from mice at three life stages, the team identified which cells are most affected by aging and uncovered clues about what drives their decline.
“Our goal was to understand not just what changes with aging, but why,” says Junyue Cao, who heads the Laboratory of Single Cell Genomics and Population Dynamics. “By mapping both cellular and molecular changes, we can identify what drives aging. That opens the door to interventions that target the aging process itself.”
One of the most unexpected findings was that many aging-related changes occur in a coordinated way across multiple organs. The researchers also found that nearly half of these changes differ between males and females.
Building a Body-Wide Aging Atlas
To map aging at this scale, Cao’s team, led by graduate student Ziyu Lu, refined a method known as single-cell ATAC-seq. This technique examines how DNA is packaged inside individual cells, revealing which regions of the genome are accessible and active. Those accessible regions provide important insight into a cell’s identity and function.
The researchers applied this approach to millions of cells collected from 21 organs in 32 mice at three ages: one month (young adult), five months (middle-aged), and 21 months (elderly).
“What’s remarkable is that this entire atlas was generated by a single graduate student,” Cao says. “Most large atlases like this require large consortia with dozens of laboratories, but our method is far more efficient than other approaches.”
In total, the team identified more than 1,800 distinct cell subtypes, including many rare populations that had not previously been described. They then tracked how the numbers of these cells shifted as the mice progressed from young adulthood through middle age and into old age.
Aging Changes Cell Populations Earlier Than Expected
Scientists once believed aging mainly altered how cells functioned, not how many of each type were present. This study challenges that assumption. About one quarter of all cell types showed meaningful changes in their abundance over time. Certain muscle and kidney cell populations declined sharply, while immune cells expanded significantly.
“The system is far more dynamic than we realized,” says Cao. “And some of these changes begin surprisingly early. By five months of age, some cell populations had already begun to decline. This tells us that aging isn’t just something that happens late in life; it’s a continuation of ongoing developmental processes.”
The team also observed that similar cellular shifts were happening simultaneously in different organs. Identical cell states rose and fell in parallel across tissues. This pattern suggests that body-wide signals, possibly circulating factors in the bloodstream, help coordinate aging across distant parts of the body.
Another striking discovery involved biological sex differences. Roughly 40 percent of aging-related changes varied significantly between males and females. For instance, females displayed much broader immune activation with age.
“It’s possible this could explain the higher prevalence of autoimmune diseases in women,” Cao speculates.
Genetic Hotspots and the Future of Anti-Aging Therapies
In addition to measuring changes in cell numbers, the researchers analyzed how accessible regions of DNA shifted over time within those cells. Out of 1.3 million genomic regions examined, about 300,000 showed notable age-related changes. Around 1,000 of those changes appeared across many different cell types, reinforcing the idea that common biological programs drive aging throughout the body. Many of these shared regions were associated with immune function, inflammation, and stem cell maintenance.
“This challenges the idea that aging is just random genomic decay,” Cao says. “Instead, we see specific regulatory hotspots that are particularly vulnerable, and these are precisely the regions we should be studying if we want to understand what drives the aging process.”
When the team compared their findings with earlier research, they discovered that immune signaling molecules called cytokines can produce many of the same cellular effects seen during aging. Cao suggests that medications designed to adjust these cytokines might one day help slow coordinated aging processes across multiple organs.
“This is really a starting point,” Cao says. “We’ve identified the vulnerable cell types and molecular hotspots. Now the question is whether we can develop interventions that target these specific aging processes. Our lab is already working on that next step.”
The full aging atlas is publicly available at epiage.net.
Reference: “Organism-wide cellular dynamics and epigenomic remodeling in mammalian aging” by Ziyu Lu, Zehao Zhang, Zihan Xu, Abdulraouf Abdulraouf, Wei Zhou and Junyue Cao, 26 February 2026, Science.
DOI: 10.1126/science.adw6273
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