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How do our bodies age?
We might have an answer
TL;DR: Scientists have discovered that as we age, fewer types of blood stem cells dominate cell diversity, which results to an increase risk in acquiring diseases.
Start with this quick glossary terms
Term | Meaning |
---|---|
Stem cells | Special cells that can become many different types of cells. |
Clone or clonal | A group of identical cells that originate from one ancestor cell. |
Clonal dominance | When a few clones multiply so much that they dominate others. |
DNA Methylation | A natural process where small chemical tags attach to DNA, which help cells “remember” their roles without changing the genetic sequence itself. |
Epigenetics | Changes in gene function without changing the DNA sequence (like software updates). |
EPI-Clone Method | A tracing method that uses DNA Methylation patterns as barcodes that track stem cell clones. |
You know how when you turn 50, it seems like your body’s biological metabolism starts to go south? No one really understands how our body biologically ages, until recently.
A study pioneered by Michael Scherer and colleagues have found some very interesting findings about how our blood ages. They discovered that as we grow older, our blood stem cells divert from diversity to total domination.
Here’s what it basically means.
In youth, our stem cells are diverse and dynamic and constantly rejuvenates themselves. You know - the typical youth things.
But once we hit 50 or something, fewer stem cells start overtaking blood production, which leads to reduced cellular diversity. And as a result, it usually leads to more inflammation and weakened immune systems.
How did they do it and what did they find?
Scientists at the Centre for Genomic Regulation and the Institute for Research in Biomedicine in Barcelona developed a method called EPI-clone. This method uses naturally occurring markers called DNA methylation, which are tiny chemical tags like barcodes that are attached to our DNA, as markers to trace individual stem cells (like those tags zoo keepers use on penguins) in mice and humans.
Essentially, analysing these barcodes allowed them to track how blood stem cell populations changed over decades.
And based on their 30-page journal paper, I’ve boiled down these three key findings:
Diversity → Dominance. Like I mentioned in the beginning, younger blood = diverse, balanced stem cell populations; and older blood = fewer stem cells and produces many cells of lower quality which are referred to as “clones”.
If it’s old, it’s not always bad. Many older stem cells were found to still possess those youthful properties, BUT still, those dominant clones resulted to poorly functioning cells.
It’s not that simple. Age-related blood clonal expansions happen with and without known genetic mutations. So ageing is indeed influenced by more than just DNA changes, and that’s why it’s so hard to identify how humans age.
Our findings show that ageing in the blood isn’t just driven by genetic mutations. Instead, it’s largely due to the gradual dominance of certain stem-cell clones which create a less diverse (and weaker) blood cell population over time.
Adapted from M. Scherer et al., “Clonal tracing with somatic epimutations reveals dynamics of blood ageing,” Nature, May 2025, doi: https://doi.org/10.1038/s41586-025-09041-8.
Why do we care?
The advances in research like this could directly impact your health in a number of ways. If we know which blood stem cells dominate as we age, we could theoretically predict who’s at risk of certain diseases decades in advance. Moreover, future blood tests might detect early risks for inflammation-related conditions like heart disease and cancers. We could also perhaps develop treatments that target those harmful clones or cell mutations, and rejuvenate the blood’s diversity and delay ageing effects! The potential is endless.
So if you could take a simple blood test today to predict your health risks with crazy accuracy decades earlier, would you?
Talk soon,
Krish
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