Stem Cell Universe with Stephen Hawking Page #4

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of animal-model

spinal cord injury.

This is the proof

that Paul and Mark's work

is actually healing

spinal cord injuries.

This rat was once paralyzed

in its front right leg.

Now it can pick up food with it.

This rat was paralyzed

in one of its hind legs.

Now it can walk across the

obstacle course of this cage.

It's not complete recovery,

but that is a huge amount

of recovery

after an injury

as severe as that.

This is just the beginning.

It show a potential.

We still face

a lot of challenges,

like can this wire connect

to the right target?

We have good hope.

Mark and Paul have shown

that the biological fortress

of the spine can be conquered,

that stem calls can grow

any tissue anywhere.

But not everything

that grows inside us is good.

Cancer is our greatest

medical foe.

Some fear

stem cells with cause cancer.

But others believe they are

our best hope to defeat it.

There's nothing better

in this world for me

than spending a summer afternoon

in an English garden.

Here, nature Springs forth

a myriad of growth.

But not everything in a garden

is a gardener's friend.

We have weeds

inside our bodies, too.

We call them cancer.

Just like any other tissue,

cancer grows from stem cells.

If we can learn

how to destroy them,

we could wipe out cancer

at its root.

U.C. Davis Professor

Paul knoepfler

is leading the attack

on cancer stem cells.

He sees them

as the great enemy within,

floating around inside us,

waiting to unleash havoc.

We've come to learn

in the last few decades

that cancers have

two main types of cells.

There's sort of a generic

cancer cell,

and then there's these

stem cells within the cancer

that we call

the cancer stem cells.

Paul thinks our

current attempts to beat cancer

are a bit like

his daughter Melanie

playing a game of Marco polo.

In our analogy

of the cells in the pool,

we have the general cells

of the tumor, the red cells.

They're not very harmful.

But the yellow cells, those rare

ones, are the cancer stem cells.

And they're the ones

we really need to worry about

because they can grow

an entire new tumor.

The yellow stem cells

are responsible

for all of

the cancer's growth...

Good job, Mel.

...just as

Paul's daughter struggles

to grab hold of a yellow ball

because she can't see

that her friends

are moving them.

Keep going.

Get all those balls

out of the pool.

So, researchers

have been struggling

to zero in on the really

dangerous cells in a tumor.

Hey.

All right, Melanie.

Time's up.

You can take your blindfold off.

Look.

You got all the red balls

out of the pool,

but we didn't tell you

that your friends here

had all those yellow balls,

which are the cancer stem cells.

And it's important to find those

to help cure the cancer.

Paul's search

for these killer cells

is not driven

by scientific interest alone.

He is also a cancer survivor.

So, I've been studying cancer

for a really long time.

And then one day, I found out

that I, myself, had cancer.

And so, that was

a very scary experience.

When you are a researcher,

it's kind of impersonal.

You're studying cells

and test tubes.

And then all of a sudden

when you have cancer,

it's a totally different

experience.

Paul had surgery

to remove his tumor

and is in remission.

But he may still have

cancer stem cells in his body.

One day, they could spring

back into action.

Surgery only gets

part of the tumor in most cases.

And so I have to face the fact

that there could be

residual cells

floating around in my body,

and some of those

might be cancer stem cells.

And those could cause

the cancer to come back

in a few years or in a decade.

Like Melanie's friends

sneaking away from her

as she reaches blindly for them,

cancer stem cells can slip past

chemotherapy,

radiation, and surgery.

The cancer stem cells

are more migratory

that just the average cell

in the cancer.

And so that means

that they can kind of

jump ship from the tumor, float

around in your bloodstream,

and lodge somewhere else

in your body

and just kind of wait there

like a sleeper cell

to potentially cause a tumor

later on.

Paul is perfecting a way

to detect these deadly cells.

He has found

that some of the same proteins

that trigger DNA reorganization

in embryonic stem cells

are also active

in cancer stem cells.

All cells really have

proteins on their surfaces

that are kind of like

identity codes.

And what we're hoping is that

cancer stem cells will express

a slightly different pattern

than other cells in the tumor.

And so, that pattern

might be like a signature

for us to hone in on to identify

the cancer stem cells

and then essentially zap them

and kill them.

And what we're hoping is that will

lead to fewer recurrences in patients.

Killing cancer stem cells

may finally bring us victory

in the long war

on this dreaded disease.

But stem cell research

could deliver

an even greater prize

for all of us...

a genuine

medical fountain of youth.

I relish the rare

opportunity I've been given

to live the life of the mind.

But I know I need my body

and that it will not

last forever.

As we age

and we make copies of cells,

tiny errors

creep into our genes.

This process seems inevitable,

but stem cell researchers

disagree.

One of them

is Dr. Vincent Giampapa.

He believes our body's own

natural reserves of stem cells

can stem the tide of decay.

The origin of the aging process

really starts in our stem cells

because that is a reservoir

of the regenerative power

and the ability to have

our body cells renewed

and repaired as we age.

The stem cells we have

in our adult bodies

are not all-powerful

like embryonic stem cells.

They are specialized

to replenish

specific tissues we need

to maintain ourselves

like blood, bone,

skin, and muscle.

As we age, however,

this repair system

begins to break down.

What we've learned recently is

there is a clock, if you will,

inside the cells

that actually changes

or, if you will,

ticks as each year goes by.

And as that happens, certain genes get

turned off and other genes get turned on.

Our DNA is not frozen

over our lifetime.

Our environment

and the choices we make

influence and change

our genetic profile.

So, if we live

in a healthy environment,

that genetic clock is slower.

If we live in an unhealthy or stressful

environment, the genetic clock accelerates.

We can think of the DNA

inside one of our body's

stem cells like a newspaper.

So, this morning, I picked up

this newspaper in my driveway,

and I have a nice,

clean newspaper.

But I might drop that newspaper

in the street

and it might wrinkle

or get dirty.

As the day goes on,

I might spill

some coffee on this newspaper.

It might even rain

this afternoon.

The key thing here is,

I'm not gonna be able to get

another copy of this newspaper.

But as we age, what happens

to those young cells

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