You’re looking at a 3D bioprinted lung-mimicking
air sac, that’s able to pump air into airways,
mimic blood flow and was built using living
cells.
Granted it’s smaller than a penny, but this
lung-mimicking air sac could bring us one
step closer to understanding how we could
replicate human organs using a patient’s
cells which could one day help to avoid organ
rejection.
The team behind this model is trying to replicate
the complicated architectural structures of
our organs using 3D bioprinting and used the
lung as their proof of concept.
Jordan: “It is a very complicated structure,
yet it has extremely clear readouts for its
function.
If we have a mimic of lung tissue, we can
pump in deoxygenated red blood cells.
We can ventilate in the airway oxygen, and
we can see to what extent those red blood
cells will take up the oxygen that we've been
putting into the air sac.”
Being able to print multiple independent vessel
architectures has been one of the biggest
challenges in the world of artificial organs.
That’s because our organs are, well, pretty
complicated.
You see, each tissue has its own knotted mess
of blood vessels, which are physically and
biochemically mixed.
And they serve crucial purposes by supplying
organs with essential nutrients.
Take the liver for example.
It has over 500 functions, like producing
bile for digestion and maintaining the right
amounts of blood sugar within the body.
All these functions depend on the intricate
network of vessels to get their necessary
nutrients.
It’s this multi-vascular architecture that
makes mimicking and replicating human organs
so difficult.
If we could figure it out, the payoff would
be huge.
Over 100,000 people are waiting for organs
in the U.S. and bioprinting healthy organs
could be a way to address this shortage by
supplying replacement organs.
It could also reduce the incidents of organ
rejection since bioprinted organs would contain
the patient’s own cells.
But, working with living cells isn’t easy.
They’re extremely fragile outside of the
body and once they’ve been extracted, they
need to be placed into their final structure
as quickly as possible to ensure survival.
The cells are then encapsulated within a hydrogel,
a water-based material which emulates a cell’s
environment, to allow them to survive for
longer periods.
So how did Jordan and his team print the lung
model?
They used a technique called stereolithography
apparatus for tissue engineering, or SLATE.
It’s an open-source bioprinting technology
that uses additive manufacturing to create
soft hydrogels layer-by-layer by using light
from a digital projector.
So this is a light-based polymerization system.
So we have a light-sensitive liquid, that
when you shine the right color of light at
the right intensity of energy, the right number
of photons hit that sample, you can convert
that liquid into a solid only in that region.
But using light also created some issues,
since the light could get into previously
solidified layers, thus disrupting the intended
pattern.
To address this, the team searched to find
an element that could block light and that
was biocompatible.
And the winner was food dye.
Jordan: “These biocompatible food additives
that all of us are eating all the time anyway,
we already know that they're biocompatible.
They're compatible with live cells, and they
can be used as potent photo absorbers to block
the light penetrating previous layers, getting
us our complex architecture.”
The food dyes were able to confine the solidification
to a thin layer, creating the desired internal
structures.
In the end, these tissues proved to be sturdy
enough to withstand blood flow and pulsating
breathing, the rhythm that mimics the pressures
and frequencies of how we breathe.
So this model may be tiny,
but it’s just the beginning for Jordan and
his team.
They plan to make more complex designs and
scale them up.
And in the spirit of teamwork and advancing
research, they’ve made their work’s source
data freely available.
Jordan: “We're using open-source to be able
to make the 3D printer, we're giving back
to the open-source community our designs.
But I think scientists in general, get a little
bit nervous about releasing things into the
open, because they're like, "Well, what are
people going to use this for?
I don't really know."
You actually want to open-source your stuff
because you don't know what people are going
to use it for.
And that's really the power behind open-source,
and it's really the power behind science.”
And thanks to collaborative efforts like these,
we’ll one day be able to 3D bioprint organs
to help address the organ shortage.
If you liked this video, check out our other 3D printing video where a new 3D printer can shape objects,
all-at-once, using specialized synthetic resin and rays of light.
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