When you die, there are a lot of things you can do with your dead body--bury it, cremate
it, have your ashes loaded into fireworks so you can rain down on people on the 4th
of July, but some people will choose to have their dead bodies, or body parts, frozen until
technology of the future has advanced enough to bring them back to life?
Cryonics is rapid freezing and then storing of a dead person in liquid nitrogen.
This is a process called vitrification.
I first heard about cryonics in 2002, when I learned that Baseball Hall of Famer and
former Red Sox superstar Ted Williams’s head had been cryogenically frozen.
Cryogenics--which is not the same thing as cryonics--is a general term that means freezing
something to preserve it--and it actually works well for cells and pieces of tissue.
So I couldn’t help but wonder: will Ted Williams’ frozen head be revived in 200
years and attached to giant robotic spider legs?
Based on what we know about chemistry and how complicated the human brain is, the answer
is--well… let’s just talk about it.
If you want to be cryogenically frozen and can afford it, once you’re legally pronounced
dead an emergency response team from the cryonics facility you’ve chosen is supposed to come
collect you as quickly as possible, pack you in ice, give your dead body oxygen and sometimes
inject a chemical like heparin to keep your blood from clotting.
The whole thing comes at a pretty steep cost, well over $100,000 for your whole body, but
a discounted rate for only freezing your head.
Once you get to the facility where your dead, frozen body will be stored, the Freeze Team
will start to replace your blood with a cryoprotectant--a solution designed to keep ice from forming
in your cells.
Why is ice bad?
Look at this cell.
It’s full of water.
And as that water freezes, it arranges itself into a structure that takes up more space
than the liquid water did, so your cells… uhh… explode.
Exploded cells are not a good thing if you’re hoping to be revived one day: as you thaw,
you’d essentially turn to mush.
So to try and prevent that, the Freeze Team uses that cryoprotectant.
Sounds… reasonable-ish in theory, but there are lots of issues.
Let’s start with what we know.
Scientists /have/ found ways of cryoprotecting cells and the structures within them, as well
as some tissues--but let’s be clear, these are cells in a test tube, not cells spread
throughout the organs and tissues of what was once a living human being.
There are many cryoprotective agents out there, including highly toxic formamide, methanol,
and dimethyl sulfoxide, but glycerol is probably the best-known.
Glycerol is far less toxic and was used way back in 1949 to successfully freeze and thaw
sperm from birds.
That discovery was the basis for developing in vitro fertilization--or IVF--in humans.
When glycerol solution is added to cells in a test tube, water leaves the cells as glycerol
heads into them through the process of osmosis.
During freezing, glycerol will form hydrogen bonds with water, interfering with water molecules
interacting with each other.
This keeps ice crystals from forming, or at least keeps the ice crystals that do form
much smaller, protecting cell membranes from being sliced to smithereens.
To cryoprotect mammalian cells researchers often use somewhere between 10 and 20% glycerol
solution, yet in the past some cryonics facilities reported using around a 70% glycerol solution.
Since then, these facilities have moved away from using glycerol and instead use a combination
of other cryoprotectants that they consider less toxic.
What will any of these things do to a human body?
We have no idea.
Hundreds of frozen bodies--or heads--are hanging out in chambers of liquid nitrogen, and at
this point no one has tried to reanimate any of them.
Removal of cryoprotectants, like glycerol, and then rehydration of a dead body is a complex
and--thus far unstudied--issue with cryonics.
And, let’s remember, cryonics is supposed to keep you preserved for centuries, even
millenia, until technology has hopefully progressed to the point where you can be brought back
to life.
But...no one has even frozen cells even in a tube for that long.
Even with our best available cryogenic technology, if you were to take 1 million skin cells,
freeze them in liquid nitrogen (properly!), and then thaw them in a year, hundreds of
thousands of them would die within a few days of being thawed.
That’s a best-case scenario, with cells in a test tube.
And that’s because although the structure of a cryoprotected, frozen cell might look
normal, the process of being cryoprotected, dehydrated, frozen, and then thawed messes
with the function of things like proteins and DNA inside the cell, and that’s unavoidable
with our current technologies.
To ensure that more cells could survive we would need to find ways of reducing or blocking
that stress.
There are many reasons to be skeptical of cryonics--so why are some people convinced
that bringing a person back to life after being frozen and thawed might be possible?
Some of that hope might come from a study done a few years back.
In 2015, researchers:
Took 100 worms and put them in a petri dish with bacteria (what C. elegans eat) and exposed
them to this chemical [benzaldehyde], a chemical with an almond-like odor, for 8 hours.
The idea was to teach the worms that benzaldehyde = food.
One day later, they froze half the worms in 15% glycerol at -80 degrees C for two weeks
Then, the frozen worms were thawed and put in a little petri dish racetrack.
The never-frozen worms were put in their own petri dish.
Both dishes had benzaldehyde closer to the “finish line.”
And it was off to the races!
The idea is that if the frozen and thawed worms could remember their training, they’d
move towards the benzaldehyde just like the never-frozen worms.
And they did.
BUT there are some huge differences between this and cryonics.
First, researchers frequently store C. elegans in liquid nitrogen for long periods of time
and then thaw them out for experiments.
C. elegans have genes that allow them to produce different compounds and proteins that protect
them from dying during freezing.
We don’t.
Second, these worms were frozen alive.
With cryonics, a person is frozen /after/ they’re pronounced legally dead, and at
that point their brain cells are already dying.
To make matters worse, the entire cryoprotection process for a human body, or even just a head,
takes a /long/ time, so many more brain cells will die before a corpse gets to the point
where it can be stored in liquid nitrogen indefinitely.
Third: the human brain has billions more neurons than a C. elegans has in its entire body and
is WAY less understood.
So it’s like comparing apples and…
Sarah Jessica Parker.
Finally, all this study did was test whether worms could associate a smell with food.
That’s very different than what cryonics promises to do: bring YOU back, with all your
memories, thoughts, consciousness, personality and your pesky crippling anxiety… after
being… dead… and frozen… and then thawed… and refilled with someone else’s blood.
So, with all of this said, anyone can make the argument that we have no idea where technology
will be at centuries from now.
If hanging out suspended in liquid nitrogen, relying on future humans to hash out all the
kinks still sounds like a good idea to you, by all means, but you could also put those
hundreds of thousands of dollars toward, I dunno, a lot of other things.