Stem Cell Universe With Stephen Hawking

I have spent my life

exploring the mysteries of the cosmos.

But there's another universe that fascinates me,

the one hidden inside our bodies...

...our own personal galaxies of cells.

Today, we are on the brink of a new age in medicine,

an age where we will be able

to heal our bodies of any illness,

all because of cell inside us...

...which have special powers.

They are called stem cells.

These microscopic miracle workers

are, however, barely understood.

Implanting them into our bodies could unleash biological mayhem.

Are stem cells magic bullets or ticking time bombs?

I haven't lived a very normal life.

Since my 20s, I haven't had to deal with the distractions

that come from being able-bodied.

I have led a life of the mind.

Stem cells may give you that same freedom...

...allowing you to pursue your wildest dreams

without ever having to worry

about the limitations of your body.

Dr. Robert Lanza is one of the pioneers

of stem cell therapies.

He is already using them

to help patients regenerate damaged body parts.

Right now, we're in clinical trials

to try to treat blindness using retinal cells

that were generated from stem cells.

We've also been able to create entire tubes of red blood cells

that transport oxygen just like normal, transfusable blood.

Robert's work developed

from studying how stem cells create

not just body parts, but entire bodies.

They do this for all of us when we start out

as nothing more than a fertilized egg

floating in the womb.

So, imagine I'm floating down the fallopian tube.

And first, there's one of me, and then there's two of me.

Then there's gonna be four of me and eight of me.

And we continue on dividing.

And eventually, when I get downstream,

I'll be a ball of about 100 cells.

These embryonic stem cells are blank cells.

They have not yet become a specific type of tissue.

But soon, they start transforming

into specialized bone cells, muscle cells,

and nerve cells.

Nine months later,

they form a complete person.

Once we are born, however,

these blank embryonic stem cells disappear.

We lose the power that they alone possess

to regenerate all of the tissues in our bodies.

Robert is working on restoring that power.

So, when you think of a regular cell,

whether it's a skin cell, a heart cell, or a blood cell,

it turns out that that cell carries out

a very specific function.

And it carries out that function for its entire life.

So, the question is, what tells that cell what to do?

And that's where DNA comes in.

The way DNA is packed into the nucleus of each cell

determines what function it's going to have.

DNA's long double helix

is wound around a huge number of tiny, molecular balls

in a structure called chromatin.

As we grow in the womb, certain proteins interact

with the chromatin of a blank embryonic cell

causing parts of its DNA to become unspooled.

The parts that are unspooled determine the type of cell this is going to be.

A heart cell will have one DNA arrangement.

A skin cell, another.

This process of cell specialization

appeared to be irreversible...

Until a breakthrough experiment in 1962.

What scientists did is they actually took

an adult cell in the case of a frog, an intestinal cell,

and they put it into an empty egg.

And what had happened is that that egg

actually acted like a little time machine

and brought the DNA back in time to a point

where it could actually generate an entire tadpole

and then, eventually, an entire frog.

Biologists now believe key proteins in the egg

undo all the specialized DNA arrangements in the adult cell.

They return it to its original state...

A blank embryonic cell

awaiting instructions on what to become.

So, we learned from this research

that we could actually generate embryonic stem cells

that would grow forever, that were essentially immortal,

and that could be turned into virtually all the cell types in the body.

Robert has spent the past two decades

developing techniques that instruct embryonic stem cells

to turn into specific tissues.

I think we have the capacity to do all sorts of amazing things

that science never had the ability to do before.

Stem cells are likely

to revolutionize medicine in the next several decades.

But harvesting material from human embryos

is highly controversial.

Some see it as damaging one potential life

to help another.

There is, however, another way

to harness the immense power of stem cells.

Kristin Baldwin is one of a group

of stem cell researchers

who hopes to make harvesting eggs or embryos obsolete.

All she uses is a patient's skin cell.

So, the old way that we used to make personalized stem cells

was to take the skin cell

and take the DNA out of its nucleus,

picking it up and carrying it over into an egg

which doesn't have any DNA,

and the egg can change the DNA

and turn it into a stem cell that has your genome.

But now there's a new way, and all that it takes

is for us to put these four genes

into the nucleus of the skin cell and then wait.

And what these genes do is reorganize the DNA

so that it starts to look like stem cell DNA.

And once that happens, it changes the cell around

and the cell starts to shrink

and not look like a skin cell anymore

and loses its outside.

And over the course of a week,

it starts to look like an embryonic stem cell.

And the only difference now between this and an embryonic stem cell

is that it has your DNA in it.

The four genes inserted into the cell

create four proteins that exist naturally in an egg.

Those proteins appear to trigger skin cell DNA

to arrange itself just the way it is

in an embryonic stem cell.

Kristin was not the first to create these cells,

which scientists call induced pluripotent stem cells,

or IPS cells.

But Kristin was the first to explore

whether these manufactured stem cells

are really the same as the natural versions.

So, an ideal IPS cell or embryonic stem cell

should be able to make

all the cell types that you want equally well

and at the same time, not make unwanted cell types...

In particular, cancer.

But some of the cells

actually fail to make cell types that you'd like

and others can actually cause cancer,

and this is a worry.

So, what we are working on is to try to find a way

to either improve the way we make the cells

so that they're all the first kind, the good kind,

or to find a way to test for the differences

and identify the ones that will be bad.

Kristin and her research team took some skin cells from a mouse

and turned them into a colony of IPS cells.

From them, they grew thousands of colonies

of different adult tissue types.

Eventually, after months of exhaustive screening,

Kristin identified a colony of IPS cells

that never turned cancerous

and seemed to be moldable into any cell type.

So, now that we've made the IPS cells,

we'd like to make them into specific cell types in a dish,

especially those which are useful for us in medicine.

One type of cell that we can't get from people is a heart cell,

so we can see if we could

turn the IPS cells into heart cells in a dish.

So, in fact, when we do this, we can make heart cells.

So that's great.

Another type of cell we'd like to make

are brain cells, neurons,

because we can't get those from people.

And so, we ask the IPS cells,

"can you make neurons in a dish?"

And, in fact, they can.

But Kristin wasn't content with making a few key cell types.

She wanted to put her IPS cells to the ultimate test.

What we wanted to do

is take the IPS cells

and try to make a whole organism out of those.

And so, to do that, we wanted to make a mouse.

What we did is we took the IPS cells

and we then put them into a pregnant female,

and we waited.

And when the mouse had its babies,

much to our surprise, we found live mice

that we could later prove came only from the IPS cells.

So now, this mouse is a clone

of the original mouse that we took the skin cell from.

And it's a way of showing

that the IPS cells should be able to work as well

to make all the kinds of cells that we want

as the embryonic stem cells can.

Kristin's work has shown

that it is possible to manufacture embryonic stem cells

without taking them from an embryo.

But the technique is still very new and not without danger.