[Music] Hello, and welcome to Open Science.
I'm Angel Otero from NASA Headquarters in Washington, DC.
Today, I'm pleased to introduce Dr. Eduardo Almeida and Dr. Liz Blaber from the Ames Research
Center in California's Silicon Valley.
Your team is doing exciting work with stem cells in space.
First of all, Eduardo, tell me about stem cells.
Well, stem cells are cells in the body that are responsible for tissue regeneration.
That is adult stem cells.
And so, we have reservoirs of these cells in the bone, in muscle, in the intestine,
in the skin.
And as our tissues wear out, those cells rebuild the tissues.
They repair fractures in bone.
They remake the skin.
They remake your red blood cells.
They remake your immune system.
So, those stem cells are really important for health because they are responsible for
maintaining the body during adult life.
Thank you.
And what is tissue regeneration, and how do stem cells assist maintaining tissue health
in bone, muscle, and immune systems?
Well, that's precisely what I was talking about.
Tissue regenerative health is the process by which, let's say, the bone marrow produces
these lineages of cells that go on to remake the tissue.
So, for instance, if you do not have good regenerative health in the bone marrow, you
may have an immune dysfunction, or you may not make enough blood, or your bone may not
be repaired at a normal rate.
So, the importance of stem cells is in maintaining regenerative health in the whole body throughout
adult life.
Thank you.
Liz, how does space flight affect tissue health and stem cells, and how is the process of
tissue regeneration affected by space flight?
So, when we talk about space flight, we're really talking about two main factors, radiation
and exposure to microgravity.
So, radiation is--primarily causes breaks in the DNA, or DNA damage.
And--but, our main research area is looking at microgravity or mechanical unloading, so
removing the load from the organism.
So, we first started looking at this a few years ago with the Russians on Foton-M2 and
Foton-M3, and we were looking at stem cell-based tissue regeneration in an amphibian, the newt.
And what Eduardo did in this experiment was he cut the newt tail off and then sent the
animals to space.
And what the newts do in space is they de-differentiate and form a stem cell pool in the tail that
can then re-differentiate and form all the lineages that are required in the tail.
So, that's, you know, the bone, the muscle, the blood vessel, nerves, everything in the
tail.
And what we found was that the newts that were sent to space actually had a less differentiated
tail than the ones on the ground.
So, normally in stem cell differentiation and in tissue-based regeneration, what happens
is that the stem cell will first proliferate and renew itself, and then it will produce
progeny cells that then go on to differentiate.
And what we found was that in the newt tails, a lot of the cells that were there were at
a more stem cell-like state.
So, they were proliferating still as a stem cell, not as a differentiated progeny cell.
So, in the newt tails that were on the ground, they had pigment.
They had a downward slope.
They had a cartilage ridge.
And the ones in space were still at an earlier stage of regeneration.
And we also studied this process in both embryonic stem cells on experiments on STS-131 and STS-135,
and also in a whole organism, a mammalian organism, the mouse.
And what we found in both the embryonic stem cells and the adult stem cells from the mouse
bone marrow was the same story.
So, we found that the stem cells stayed as stem cells, and instead of differentiating,
they maintained their pluripotency or their ability to maintain stem-ness.
And so, what we think is that some of these--you know, because the stem cells form all the
lineages in an organism, so for the adult stem cells, you have pools of stem cells that
conform, for example, in the bone marrow.
Bone marrow has mesenchymal stem cells and hematopoietic stem cells.
These stem cells form the bone, the muscle, the cartilage.
The hematopoietic stem cells form red blood cells, white blood cells, and so on.
And so, what we think is that maybe some of the tissue degeneration effects that we see
in space are due to this inability or potential inability of stem cells to differentiate into
terminal cells and instead maintaining their pluripotency in space.
Thank you.
So, Eduardo, your research was in stem cells for mice.
So, how are they similar or dissimilar to human cells?
Well, the mouse is a model for a human, obviously.
There are a lot of similarities, and there are a lot of things that are different.
So, like any model, we use what we can learn from the mouse model, and a lot of the genetic
material is similar.
There's a lot of homology.
And the same is true for a number of the molecular and cellular mechanisms that, let's say, are
involved in bone loss or regenerative processes.
But, there are differences.
And so, one approach that we take is to use comparative physiology and comparative cell
and molecular biology, and we look at multiple systems.
A good example of that is the work we've done with the newt model, with the mouse model,
with the stem cell model in culture.
And so, from all these different experiments, you put together a puzzle that hopefully gives
us a good perspective of what's happening in the human in space flight.
Thank you.
So, Liz, why is the space biology program interested on doing stem cells research in
microgravity?
: So, the space biology program really--its goals are to understand how living organisms
respond to space.
And, for example, in our research, we found that, you know, stem cell differentiation
and tissue-based regeneration is partially inhibited in space flight.
And this has really big consequences for long duration space flight.
So, a lot of our regenerative processes are really fast.
If you think about red blood cell turnover, the turnover of your intestinal epithelium,
things like that happen rapidly.
But, some of the processes take months to years to develop, and we found that after
15 days, 30 days of space flight in mice that we're seeing deficits in this regeneration
process.
So, this--you know, for long duration space flight, this will have a lot of consequences
for tissue degeneration that we can't foresee at the moment.
So, space biology is really helping us to understand the fundamental response of an
organism to space so that then we can apply it to our future missions to keep our astronauts
healthy and other living organisms healthy in space.
Thank you.
And I think it also helps dovetail with what the human research program is doing.
: Exactly.
So, it's a good follow--lead in to the human research program research.
So, Eduardo, how can the stem cell research in microgravity help us back here on Earth?
Well, there are a lot of medical implications for regenerative health.
So, this is a field that has exploded recently.
There is a lot of research, a lot of important breakthroughs in regenerative medicine and
then stem cell biology.
And so, we're starting to understand much better than before how stem cells work, how
they can help in repairing damaged tissues.
So, there's great, great potential for stem cell regenerative-based regenerative medicine
to be used for health and medicine.
And NASA has a unique platform in microgravity to remove the mechanical stimulus of gravity
from these stem cells and to understand really what's the importance of gravity at one g
on Earth for maintaining health.
We are finding that a lot of health processes depend on exercise, memory, for instance,
muscle mass, bone mass.
All these are linked to the regenerative processes that stem cells perform for us.
And so, our work is pointing to a finding that gravity, mechanical stimulation from
gravity from living here on Earth is really an important component of promoting stem cell
health.
And so, NASA has that platform on ISS that lets us then take away that mechanical stimulation.
And that is a unique way of understanding the fundamental processes.
So, it's a kind of experiment that cannot be performed anywhere else on Earth.
Really, you require access to space and to the microgravity environment to answer the
question, the hypothetical question, what if you take gravity away.
What happens then to the stem cell regenerative processes?
As Liz has indicated, we're really finding that the patterns of gene expression in stem
cells, in the bone marrow, for instance, show that they are not progressing normally from
the stem cell to the differentiated tissue that functions in repair of the bone, let's
say, or in formation of blood and the immune system.
And so, that's really a very seminal finding because it tells us that our environment on
Earth requires that gravity stimulation for normal health.
And so, for long-term space exploration, we have to have these kind of findings in consideration
in order to understand how to design habitats for astronauts for long-term voyages to Mars.
And it's a part of doing basic science and understanding how life is shaped by gravity
on Earth.
Thank you.
Very interesting.
Thank you both for the work being doing in your research group.
It's great to have this exciting science being done off the Earth for the Earth.
And thank you for joining us.
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