>>Narrator: What if we could drastically improve how we treat the lung, from a chronic disease like
asthma or emphysema, to the underdeveloped lung of a premature infant?
Researchers at the University of Michigan have brought us one step closer, by using
stem cells and a biomaterial scaffold to grow mature human lung tissue.
Medical research has been moving fast towards the creation of what are called “organoids”
which are essentially tiny balls of human tissue that resemble organs.
They have some similar structures, but are in no way complete or fully functional.
So far, scientists have successfully grown a number of different varieties of these organoids,
like those resembling the kidney, the gastrointestinal tract and even the brain.
But it gets challenging for organs with more elaborate structures.
Here’s a biomedical engineer to break it down:
>>Shea: The lung has a really complex architecture and that architecture is just critical to
its function.
It provides the ability for there to be certain blood passing through, air on the other side
to allow for the oxygen exchange with the blood.
And that combination of multiple cellular types, the architecture and function, and
getting all of those aspects to be recapitulated, that’s the major challenge with something
as complex as the lung.
>>Narrator: Scientists grow organoids a variety of ways, but most often they start with stem cells.
These are cells that have the potential to develop into any cell type in the body, given
the right instructions.
The scientists take the stem cells and mix them with various proteins and steroids, which
tell the stem cells what type of tissue to form.
This is how the researchers at Michigan began developing the lung organoids.
Once the organoid started to grow, they had the option to either let it continue maturing
in the petri dish, called an “in vitro” environment, or they could implant it into
a host organism’s tissue, an “in vivo” environment.
They tried both, but the tissue remained immature in each case.
It just wasn’t developing the structures you would expect to see in the lung, like
a network of airways.
Briana Dye, the lead author on this study, was running out of options.
>>Dye: So I was kind of losing hope at this point.
And, we tried the scaffold, we put it in the fat pad, and we looked at 4 weeks after, and
the tissue was still there, it wasn’t fully mature.
But I was like, okay, we’re getting somewhere.
So we took it out to eight weeks, and I was amazed.
I was amazed at seeing all the cell types that were there.
So the scaffold was what really had the tissue to take off in vivo.
>>Shea: The scaffold as we had made it in this particular instance is a material that was
just very highly porous.
And so it very much looks like kind of the porosity that you would see with a kitchen
sponge.
And the cells can just be loaded in very easily, seeded, it provides supports for cell attachment.
And then the material actually goes away over time.
It’s made of these biodegradable polymers, the same material that biodegradable sutures
are made out of.
>>Dye: So the lung organoids then went in through the pores and adhered to the scaffold and
then was able to grow together and form this kind of ball of tissue that had these
airway-like structures throughout it.
>>Narrator: The successful results from this study are very fundamental in nature, meaning it will
likely take years of continued research along many different paths for its effects to reach
actual patients.
But the possibilities of more effective drugs and regenerative lung tissue are now very
real thanks to this new lung tissue model.