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Stem cell research has led to some amazing discoveries and has the potential to treat or even cure some of our deadliest diseases, from diabetes to Alzheimer's.

But let's face it, where researchers get those stem cells is controversial.

Many of the stem cells we use come from embryos, which means the ethics of the practice are hotly debated, and the cells are in limited supply.

So what if we had a more plentiful and less contentious source?

Turns out, there's an unexpected place where stem cells are abundant: period blood.

Meaning that statistically, half of you watching this video make the future of medicine every month.

So let's talk about stem cells.

What are they and why do they matter so much?

Stem cells are the most flexible kind of cells in your body, and as they reproduce, they can differentiate into specific and different kinds of tissues.

They're kind of like an Eevee; they'll turn into something different based on the environment they're subjected to.

But instead of a Fire Stone, the stem cells get, like, a liver cell stone or something.

These little cells are all the buzz in the world of regenerative medicine, the field focused on healing or replacing tissues that have been damaged by trauma, disease, congenital abnormalities, or even just aging.

Basically, regenerative medicine is the stuff we do to try to help a body heal its own tissues.

And for a while, the most promising thing we've been able to throw at this problem has been stem cells.

So the hope in stem cell therapies is that you can take your stem cells and turn them into, say, neurons, and then put those healthy cells into someone whose neurons are diseased.

Theoretically, embryonic stem cells or ESCs offer the most potential.

They're so great because of their extreme plasticity.

They're able to become any tissue or organ in the body, which makes sense since embryos need to go on to differentiate until all those bits as they grow.

In practice, however, embryonic stem cells have had limited use because of two major problems.

First, the ethics of destroying an embryo, even in the name of life-saving research, are still hotly debated.

Second, fresh embryonic stem cells are just hard to come by.

Most are embryos left over from in vitro fertilization, which means that of the very small pool of IVF embryos to harvest from, science only gets the extras.

With this dubious future for embryonic stem cells, the hunt for cells with similar plasticity, more renewable sourcing, and better publicity began.

Enter mesenchymal stem cells or MSCs, cells that are harvested from adults and thus avoid the ethical dilemmas and bad PR of the embryonic ones.

When it comes to plasticity, not all stem cells are created equal.

Embryonic stem cells are valued because they are pluripotent, meaning they can turn into any adult cells, no matter what part or layer of the body that tissue comes from.

But not all stem cells are like this.

There are some that can only turn into a few kinds of cells, and those less adaptable stem cells just don't have as many potential applications.

Mesenchymal stem cells aren't pluripotent, but they're pretty darn close.

They can become bone, muscle, blood vessels and connective tissue cells, and even liver cells, which is kind of a huge deal.

But while mesenchymal stem cells are ethically less complicated and demonstrate similar plasticity to embryonic stem cells, they're not exactly easy to get into your Petri dish.

You mostly get them through invasive procedures like bone marrow donation, liposuction, or apheresis, which is blood filtering,

or at least that was the case until a new source of mesenchymal stem cells was discovered: menstrual fluid.

Scientists had a hunch that the uterus might be utilizing stem cells for its monthly redecorating.

So, in 2007, they collected menstrual fluid, isolated the cells, and got to work testing them to see if they were actually stem cells.

There are two basic tests that confirm whether a cell is a stem cell or not: can it clone and can it differentiate into other types of cells.

The answer to that was yes, on both accounts.

The isolated menstrual cells were not only able to double over 68 times, they doubled faster than the mesenchymal stem cells isolated from other body parts.

Bone marrow stem cells have been the gold standard for mesenchymal stem cell research, but they take anywhere from two to eight days to double their population.

In contrast to this, the menstrual cells took an average of just over 19 hours to double, which means they can double way faster than bone marrow-derived MSCs.

And this also means they double faster than the mesenchymal stem cells derived from other places like umbilical cord blood, adipose tissue or Wharton's jelly,

a thick gelatinous tissue that cushions the blood vessels of the umbilical cord.

But while cloning is important, it's only half of what it means to be a stem cell.

The other half deals with differentiating into many types of tissues, which is that plasticity we've been talking about.

The plasticity of mesenchymal stem cells can vary, depending on where they're derived from.

For example, studies suggest that those from the umbilical cord can't differentiate into fat cells and those from the placenta can't become bone cells.

Menstrual stem cells, however, were able to differentiate into all nine different tissue types the researchers tested, developing into everything from neurons and liver cells to fat and bone cells.

So in terms of being stem cells, menstrual MSCs not only meet the criteria but also outperform MSCs derived from other bodily locations.

And it turns out that these overachieving cells can also do a lot of what we want them to do in regenerative medicine too.

In a 2010 study, researchers simulated stroke conditions in neurons from rats to see how menstrual MSCs might affect outcomes in oxygen-deprived rat neurons.

This involved researchers harvesting human menstrual stem cells then placing them in a media perfect for growing neurons in the hope that they would differentiate into exactly that.

They then injected them into the brains of rats who had suffered a stroke.

And sure enough, they found that the rats who were given these menstrual stem cells had fewer behavioral and motor deficits than the control group that got no treatment.

And a 2018 study looking at Alzheimer's in mice found that injections of menstrual mesenchymal stem cells into the brain could not only correct learning and memory deficits in diseased mice,

but even helped to remove the plaques in their brains.

Researchers have also studied how menstrual stem cells can treat mice with diabetes and found that those stem cells can step in for the pancreas to make insulin.

Menstrual MSCs have even been used to restore liver function, improve COVID-19 outcomes, reduce inflammation from hernia, meshes, diminish in fertility and accelerate wound healing.

Plus, surveys show that people are already willing to donate and most perceive their periods more positively, knowing the incredible positive impact their menstrual donation could make.

But before you show up to the Red Cross with your Diva cup, it's important to note that menstrual fluid donation sites are not widely available yet.

For those of you that are eager beavers, though, there are a few options.

There's a facility in India that has already begun menstrual blood banking

And one company in Florida charges for private menstrual blood banking as well.

There are even some clinical trials in the United States that are enrolling participants to collect menstrual blood during gynecological visits.

Periods are no walk in the park.

But the next time you find yourself dreading your next visit from Aunt Flo, remember that someday it might be your menstrual fluid that goes on to cure somebody else's Alzheimer's.

Researchers are figuring out how to slot something we already have into a space where we're missing solutions.

And in that way, their work is kind of like an advanced geometry puzzle which you can find plenty of at brilliant.org.

Brilliant has online courses in math, science and computer science, like their advanced geometry puzzles course.

That course is a collection of 68 quick and fun puzzles that ask you how hard it is to measure a skyline and see if you're capable of cutting something exactly in half.

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