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Stem cells have an important role throughout our bodies,
replenishing other cells to keep our tissues healthy.
But, just like our bodies as a whole, stem cells can age and lose their function.
This aging process isn’t entirely understood, but a new study in the journal
Science Advances indicates that stem cell function has to do with their size.
It turns out that, for stem cells, the bigger they are, the harder…
it is for them to do their job.
This study specifically looked at hematopoietic stem cells,
the ones that produce new blood cells.
These blood stem cells are some of the smallest cells in our bodies,
but the longer they’re around, the more they divide and replicate their DNA,
and the more often that DNA incurs damage.
Now, cells can repair damaged DNA to some extent.
And during repair, these stem cells continue to grow in size.
So, as they get older, they tend to get larger.
And these larger, older cells tend not to be as good at generating new blood cells.
This is true in us humans, as well as in other mammals such as mice.
Now, you might think that loss of function has to do with their damaged DNA,
but this study actually showed it has to do with their larger size.
When researchers treated blood stem cells from mice with a drug
called rapamycin, which prevents cell growth,
the cells stayed small and maintained normal functioning,
even after developing and repairing DNA damage.
On top of that, the researchers bred mice with a mutation
that reduced their ability to protect against DNA damage.
Without the mutation, cells aged and grew larger in response to damage.
But with it, the cells stayed small and kept dividing, even with the damaged DNA.
Now, this may seem like a strange correlation, but the researchers think it might
have to do with the amount of space inside the cell.
The larger the cell, the more sparsely distributed certain proteins are,
which might make it harder for cells to function properly.
But this might not just be a fluke of a cell’s life cycle.
This aging process might serve a purpose.
See, as cells accumulate genetic damage, they run the risk
of becoming cancerous, dividing and proliferating uncontrollably.
So, maybe a loss of function with age
works to help keep cancerous growth in check.
All in all, this is an important step in understanding the details of cellular aging.
With more study, researchers might be able to develop treatments
to restore the function of blood stem cells.
That could help lead to treatments for people with blood-related diseases.
And if the same rules about cell size hold true for other types of stem cells,
these sorts of treatments could be even more broadly useful.
But let’s turn from revitalizing our bodies, to revitalizing our environment.
A new study in Nature Sustainability provides an assessment
of the Great Green Wall program,
a major effort to restore degraded ecosystems across Africa.
The program was started in 2007 under the leadership of the African Union,
and now includes the concerted efforts of more than 20 African countries.
And the news is promising for the effort’s long-term success.
Here’s some background: the Sahel region is a belt that stretches across
sub-Saharan Africa from the Atlantic Ocean to the Red Sea.
It’s an area that suffers from a great deal of land degradation.
The climate crisis has hit the region hard, and that’s led to a lot of the land
becoming less suitable for farming and productivity.
This is bad for biodiversity,
but also for the humans who rely on the land for food, jobs, and stability.
The Great Green Wall is a massive initiative to create a coast-to-coast band of
improved environments across the region, aiming to restore the land by planting
trees, revitalizing grasslands, and a variety of other efforts.
Since its origins in 2007, the program has restored landscapes across
4 million hectares, but the ultimate goal is to cover 100 million hectares in total.
This new study is an assessment of the initiative:
what’s been done so far, what obstacles need to be overcome,
and what the overall benefits will be.
The study is very comprehensive, and it includes a lot of discussion
about the political side of environmental preservation.
They note, for example, how important it is to have cooperation
between multiple governments and private landowners in order for land restoration
to have lasting effects.
And unfortunately, they also point out that one of the major obstacles
in the way of the project has been conflict in the region,
which can hinder access to key environments.
And, of course, they discuss money.
A major project like this requires major funding, which can be a hurdle.
Fortunately, money can also be a motivator.
And this assessment indicates that if the project is done right,
it won’t only be good for the environment, but for the economy as well.
The study estimates that over several years, every investment of of one
US dollar will ultimately return, on average,
a dollar and twenty cents under their base scenario.
And since they estimate a total cost of between 20 and 70 billion dollars
for the entire restoration plan, that’s quite an economic benefit to look forward to,
and hopefully a good incentive for funders.
The Great Green Wall has the potential to improve the lives of people
all across the Sahel region,
and to improve the resilience of nature in the face of dangers like climate change.
And this study tells us what it will take for it to really be a success.
But it seems like the prospects are good.
Of course, this is a massive effort,
and it’s never simple to solve these kinds of problems.
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