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Our immune system generally does a good job at keeping us alive
by fighting off foreign invaders like bacteria and viruses.
But sometimes, it's your own body that’s an invader in the form of cancer cells,
which are experts at evading the immune system.
According to a study published this week in the journal Nature, there may be a way
to “train” the immune system outside the body to keep leukemia patients
in remission for up to a decade.
One of the many kinds of cells that make up our immune system are T cells.
Each T cell specializes in identifying andor attacking just one kind of invader.
To do their job efficiently, T cells are covered in special proteins, called receptors,
designed to match up with antigens,
proteins at the surface of invaders like bacteria and viruses.
So, a T cells receptors are kind of like chemical keys on the hunt for their lock.
But some diseases, like cancer, are experts at dodging T cells’ keys.
One way they can do this is by not having enough detectable antigens
dotting their cellular surfaces.
The good news is that scientists have figured out a way to take some T cells
out of a patient’s body and train them to better recognize cancer cell antigens,
and then put them back into the patient to fight the cancer.
It’s called chimeric antigen receptor, or CAR, T cell therapy.
The T cell training regimen is actually a form of genetic engineering.
Through a rather long and complicated process, a snippet of DNA is eventually
added to the T cell’s genetic code, giving them instructions
to make a tailored receptor for the cancer cell antigen.
So when the new tailored receptor latches onto its target,
the T cell calls for backup by releasing a flood of molecules called cytokines.
Together, the cytokine molecules and the army of T cells
cause inflammation that, ideally, kills their target.
While CAR T cell therapy has been approved for a few types of cancer,
there hasn’t been a lot of research looking at long-term effects.
Like, how long will a single infusion of T cells last in the body
and keep the patient in remission?
So back in 2010, Two patients with chronic lymphocytic leukemia
received a single dose of CAR T cells.
Within the year, it worked so well they both entered remission.
And here’s the kicker, they’ve stayed that way, without any additional treatment.
The latest bloodwork was collected a couple of years back.
And the team found both patients still had
some of the CAR T cells in their bloodstreams.
Just trucking along after all that time.
While these are some great results,
it doesn’t mean that every leukemia patient is going to hop onto this therapy.
When the study first happened, there was a cohort of 14,
but only two of those patients were included in this ten-year follow-up.
Also, this treatment is known for having some pretty nasty side effects,
like trouble breathing and even seizures.
Still, further studies may improve CAR T-cell side effects
making it a great option to keep cancer at bay.
Speaking of body hacks…
Last week in the Journal Science Advances, a study announced it’s possible
to help African Clawed Frogs regrow the upper part of their amputated leg.
We humans may be able to stitch cuts back together,
or even regrow a decent chunk of our liver.
But in general, we aren’t known for having regeneration superpowers.
We’re not like lizards or crabs,
which can regrow way more complex body parts, like entire limbs.
The way it works in these critters is that their brain recognizes they’ve lost a chunk
of their body, and unspecialized cells, called stem cells,
suddenly flow to the stump and start getting jobs.
So they go from unspecialized cells to bone cells, muscle cells,
nerve cells, and so on.
Their body already went through the process of making that limb once,
so the instructions are still there to make another one.
And humans have stem cells, too.
But when we lose a limb, instead of sending STEM cells,
our body sends instructions to cover it over with scar tissue ASAP,
so we don’t bleed out or catch an infection.
The team of scientists wanted to know if they could find a way to trigger
limb growth in humans, so they turned to 115 female African clawed frogs.
As adults, that species lacks regenerative abilities.
If they lose a limb, it's gone for good.
To test their hypothesis, scientists cut off part of one back leg.
The frogs were either left to heal on their own as a control group,
or got their wound covered with a small silicone cap
filled with silk proteins and a 5-drug cocktail.
Each of the drugs had its own job to do, prevent inflammation
and the formation of scar tissue, and stimulate regular tissue growth.
During a previous study, the team had just used one drug,
which did grow something back, but it was more of a spike than a leg,
so it looked like a fleshy growth with the first stage of bone regrowth showing.
In this new study, the caps, called BioDomes, were kept on for 24 hours,
and then the team observed what ended up growing over the next year and a half.
Just a few days in, the team observed that, for the frogs that got the drugs,
the molecular instructions their bodies had used as embryos had reactivated.
And over those 18 months, they ended up regrowing a kind of leg.
While none would be mistaken for a copy of the frog's other leg, two-thirds of the
frogs given the drugs had regrown way more complex tissues and leg shape.
They even managed to regrow what researchers are calling toes, but no toe bones.
The legs could even respond to touch, and the frogs could use them for swimming.
And all that with just a day of treatment!
Of course, this research is on amphibians.
Human trials are a long way away.
A lot more work is needed to figure out what the perfect drug cocktail
needs to be to regrow the best limb possible.
So maybe decades in the future, people could choose if they want to regrow
a missing arm or have the benefits of a robotic one instead.
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