cc >> Again, welcome to the second
DART talk. Tonight, we're fortunate enough
to have a guest speaker. Clive Svendsen is both professor
of anatomy and neurology, and is also the director
of the Stem Cell and Regenerative Medicine Center.
By trade, he's a neuro stem cell biologist, focusing on
brain regeneration following disease trauma.
His lab has extensive experience in the growth and
differentiation of human neural stem cells.
His lab uses novel molecular and cellular techniques,
and detailed transplantation programs to assess function.
In combination with the clinical facility at Waisman Center, he
and his colleagues are developing neural stem cell
banks, which they hope might be moved into the clinic.
Please join me in welcoming Clive.
( applause ) >> Thanks very much for that
introduction. So, I'm going to start kicking
off the discussion section. I'm happy to be here, and very
supportive of DART and what it's setting out to achieve.
And hi to all of you on campus for braving the weather.
It's pretty bad out there. So if you're sitting out there
at home, nice and toasty and warm, watching this, or if
you're here, I hope you enjoy it.
*So I thought to get into the mood of things, I'm Clive
Svendsen, and I approve of this message.
Most of you are going to be voting tonight.
And elections and politics are very important for everything
that we do. *On campus, here, at the
University of Wisconsin, we are developing, as mentioned in the
video that opened up the session, new ways to treat and
hopefully one day prevent or cure different disease types.
And on campus, we have a widespread of professors working
in this area. I think across the country,
Wisconsin is probably one of the strongest in regenerative
medicine in stem cell biology. That accumulated in the
formation of the UW Stem Cell and Regenerative Medicine
Center. These are the faculty that are
involved in the center. Many of their names you may be
familiar with. Many have talked.
We're all aiming to try and bring stem cells, in one way
learn about stem cell biology, and in another way, to try and
bring this to the clinic through this program.
So that's my advertisement for the Stem Cell and Regenerative
Medicine Center, which DART is a part of.
We're happy to have DART on board to represent the students
at the UW. *So for the talk tonight, I
thought I'd start with basic neuroscience, just to get you
warmed up, because that's what I am, a neurobiologist.
I sort of fell into stem cells a few years ago, around 15 years
ago now, to ask a specific question about a neurological
disease called Parkinson's Disease.
I'll discuss that. Of course I'm going to talk
about stem cells, and how they may be used in transplantation
therapies. And at the end, I'll discuss
some of the therapies that are being thought about using stem
cells. *This field is, if you like, a
minefield for ethical issues. It involves the use of fetal
tissue, in some cases, embryos in others.
So as I go through the talk, I'm going to highlight some of what
I consider are the main ethical challenges of this field.
I think that's quite appropriate.
As young students, you should be aware of some of these issues
and where we are with them. There's some very exciting new
data from the University of Wisconsin and Japan that
actually addresses some of these ethical issues directly.
*I'd like to start with the 101, what's in a brain.
And this is my son. When I asked him what's in a
brain when he was nine, he said it's pretty simple.
From this cartoon comic, we have a Mr. Brainy who controls
everything. So it's not quite that simple.
When he got to be 12 or 13 years old, he gave me a new vision of
this. He said he found some Web site
that had some exciting areas of the brain.
So I asked him what it was. He said that it's this.
That's not that exciting. Let's see what's inside.
He said, wait, dad, this is exciting.
Wow, that's great-- *Essentially, this shows you
what's inside your head. So if you're sitting here
watching this video, you're using parts of your brain.
The brain itself is one of the most complex organs in the
universe. There are around 50 billion
individual cells in the brain. And I'll discuss those in a
second. And the structure of the brain
is such that it allows us to be who we are.
By now, it allows you to be a UW student.
And if your GPA is good, it'll allow you to go on and do good
things after being a student. And if we get down to more the
nitty gritty, as we say in England, of what's inside the
brain, how many of you know how many cells are in the brain?
How many different types of cells?
Put your hand up if you do know. There's nobody putting their
hand up in here. So that's a good sign, I'll tell
you. *There are three major types of
cells in the brain. The first type of cell is the
neuron, which we all think about as being an important component
of the brain. The neurons conduct impulses in
the brain. And they compose of a cell body,
shown here in blue. They have a lot of connection to
other cells around the rest of the brain.
So the neuron is the thing that we normally think about.
*But if I want you to take home one thing from this talk, is
that neurons in the brain are important, but they have to have
support cells. There are two types of support
cells in the brain that comes along with the neuron.
One is oligodendrocyte, and the other is astrocyte.
Now the oligodendrocyte, does anybody know what an
oligodendrocyte does in the brain?
Okay, the oligodendrocyte is involved in remyelination.
This is a cartoon where you'll see what happens.
The oligodendrocyte cell provides the insulation to nerve
cells in the brain. Without the insulation, nerve
cells would all crosstalk. And there's a disease called
Multiple Sclerosis in which the insulation dies in the brain,
and you get the crosstalk, and you get the symptoms of Multiple
Sclerosis. Other diseases I'll mention in a
moment involve the loss of neurons.
*And we're now finding that these cells, the astrocytes,
where they fit in, is they sit alongside the neurons and nurse
them. They're rather like the
nursemaids for these very delicate neurons in the brain.
And the astrocytes are very important support cells for
maintaining neuron function. So there's three types of cells
in the brain, the neuron, the astrocyte and the
oligodendrocyte. *The most famous neurobiologist
is this man, Santiago Ramon y Cajal, who did some of the first
drawings of the brain. And in fact, this is an
interesting chap. His papers are still cited
today, more than any other neuroscientist, almost a century
later. He predicted many, many things.
His father, actually, wanted him to be an artist.
Sorry, his father wanted him to be a doctor and go
to med school. He wanted to be an artist.
But his father won out, so he ended up going to med school.
And the first thing he did when he got to med school and got to
a lab, was to start drawing everything he saw.
He was a brilliant drawer. And the drawings that he did, he
interpreted from the brain what was going on.
So he made many predictions about the brain.
And the one that I'm going to focus on how is this depressing
thought. *That is, we're born with a
certain number of neurons, which decrease with age, and I had to
put alcohol in because we're in Wisconsin, the drinking
university of the universe, apparently.
And everything must die in the brain or spinal cord.
Nothing can regenerate. This is pretty depressing if
you're a UW student and starting to get older.
We're losing brain cells every day.
That was what Cajal told us. So what's the hope for brain
repair from stem cells as we get into medicine?
*So neurological diseases, it's worse than just the cells dying.
There's also neurological diseases.
And many of you know these diseases.
Alzheimer's Disease causes a loss of memory.
And Reagan, unfortunately, got this disease.
Stroke, Margaret Thatcher, a friend of Reagan, in the end,
succumbed to stroke in England. She was the Prime Minister of
England. Multiple Sclerosis.
Huntington's disease. All these affect different parts
of the nervous system. And the one I'm going to focus
on, the two that my lab work on, the first one is Parkinson's
disease. This chap is Michael J. Fox,
who has Parkinson's disease. He set up a foundation based on
Parkinson's disease, which gives out money to researchers.
The other one is a horrible name, Amyotrophic Lateral
Sclerosis. This is something, ALS, is
better known as Lou Gehrig's disease.
Lou Gehrig, of course, is the famous baseball player who
succumbed to ALS. *I'm not going to have time to
discuss our work in ALS. I'm really going to give
Parkinson's as a model for stem cell therapy.
But a lot of the things I'm telling you about with
Parkinson's are applicable to other neurological diseases.
Maybe we can discuss that as we go through.
*So what is Parkinson's disease? This is the typical example of
an elderly gentleman with Parkinson's.
He has the stooped gait. The inability to move, so the
posture and movement is basically restricted.
And often, these patients have an arresting tremor.
It's caused by a loss of dopamine neurons.
*And if you can see, this is a brain section, a spinal cord, a
mid-brain section from a Parkinson's patient.
And you see this black area here.
This is the dopamine neurons in the brain, pigmented black.
It's called the substantia nigra, this area of the brain.
This is from a normal patient, without Parkinson's.
This is from a Parkinson's patient.
You can see these dopamine neurons are missing completely
from the Parkinson's patient. *And the result of losing
dopamine, so here's now a picture of the human brain.
And the dopamine neurons sit very deep in the base of the
brain. This is looking at the frontal
aspect of the brain. And they project their axons all
the way up to here. This area of the brain is called
the striatum. This is where the cell bodies
are that I told you about, down here, in the brain stem.
So this is a cell body, and it projects up here to the
striatum. *These neurons release a
neurochemical called dopamine. And dopamine, you have to think
of like the oil in the engine of a car.
Dopamine allows you to move. When these neurons are pumping
out dopamine, you have smooth movement.
So when I'm moving now, trying to move this mouse around, I'm
making small amounts of dopamine, which is allowing me
to do this fluid movement. *What happens in Parkinson's,
something happens to those dopamine neurons.
That's a million dollar question.
We don't know why they die, but the dopamine neurons die in
Parkinson's disease. The dopamine goes down, and you
get this syndrome of Parkinson's disease.
*This is a chap we'll come back to later who has Parkinson's
disease. And you can see from this video,
we've asked him to put his hand on his knee there and turn it as
fast as he can. I think you can see from this
video that he can hardly turn his hand, moving very slowly.
And he's got this resting tremor, where his hand is
bouncing up and down. *So this is the syndrome of
Parkinson's disease. We don't know what causes it.
There's really no cure for Parkinson's.
There's drugs that you can take for Parkinson's disease that
reduce the symptoms, but the disease keeps going and the
drugs become less effective. *Recently on campus, people in
neurology have been trying to implant stimulators, which we
don't know exactly how they work, but you can put this
little electrode in part of the brain and stimulate it, and get
good results in Parkinson's disease.
Again, that doesn't stop the continuation of the disease, the
progression. So the stimulators don't work
after a certain amount of time. It's not a therapy that is
really treating the disease. *So what about replacing those
dopamine neurons? What if we could put new
dopamine neurons back in the brain?
So the question is, is brain transplantation possible?
So if you go back in history, and think what can we do, you
might think brain transplants, unless you're Steve Martin, the
least likely area to get into. Steve Martin, the man with two
brains. We have the screw-cap technology
there. *Actually, there is a history of
brain transplantation. I picked this out from a British
paper in 1510. This is the first-ever brain
transplant. It reads here, "A gentleman
otherwise well, had the idea his brain was rotten.
He went to the King," and in England, we have kings and
queens rather than presidents, "begging him to command [the
physician] and myself to open his head, remove his diseased
brain and replace it with another.
We did many things to him, but it was impossible for us to
restore his brain." I hate to think what happened
to this poor chap. But this was a first attempt at
whole brain transplantation, which obviously, isn't the way
forward. That would be a big problem
psychologically for the patient, they had a whole new brain, I
think in a slightly different way.
He might look pretty old, this guy, but if you look here, he
actually has a laptop computer. And he's actually got a special
mouse here, he's communicating, going home for dinner, I think.
*So the key here is adult brain transplants don't work.
It's not like a kidney, where you can take it from the
deceased patient and put it into another patient.
We have to be more subtle in the brain, so putting new cells in.
It is interesting, actually, that the adult brain does have
cells that divide. Neural stem cells are present in
the brain. So when you're all sitting here
thinking, there's a part of your brain that's making new cells.
There's two regions of the brain.
One is here, in the middle, called the subventricular
region. And one is here, in the
hippocampus region. The hippocampus is very
important for learning and memory.
And there is a theory that new neurons are born as you think
and are very important for things like depression.
If you get depressed, it seems like potentially, you make less
neurons in the brain. So there are new neurons
produced in the brain, in both the rat and the human.
However, if we wanted to take these out and grow make new
neurons from them, they don't grow very well in the culture
dish. And they don't make these
critical dopamine neurons that you need for Parkinson's
disease. *So adult tissues don't seem to
work very well for Parkinson's disease, for making these
dopamine neurons. So researchers then turn to the
fetal brain, rather than the adult.
During development we start, as you know, as a little egg.
It's fertilized. This is the timeline for human
development, up here to 40 weeks.
The brain gets bigger and bigger during development.
If you go in at around 21 weeks, you can isolate tissues.
And in Parkinson's, they actually go at around eight
weeks. You can isolate tissues from the
human brain, which can be used to generate these dopamine
neurons. *Actually, this is being done in
rodents, in rats. So here, I'm showing you a
picture of where you take the part of the brain that makes
dopamine neurons. If you remember from that
picture earlier. This is the part of the brain
that would make a dopamine neuron.
You take it out. You chop it into small pieces
from this rat fetal tissue. And then you mix it up
in a tube. Then you transplant these cells,
not the whole brain, just these cells, back into the rat.
So now you've given the rat new dopamine neurons.
*And in those early studies, in the '60s and '70s, this is a rat
now with Parkinson's disease. You see here are the neurons
of the dopamine positive, with a stain for the dopamine.
This is the other side of the area where the dopamine neurons
are. This is where they project to,
that area called the striatum. If you can see, all the dopamine
is missing from the striatum. And this animal has had a
transplant. Can you see this area here has
dopamine in it? This is because that fetal
tissue cells went into the rat brain, and lived, and started
making new dopamine neurons. They were tricked into thinking
they were developing normally. But actually, you'd taken them
away from the fetal environment and put them into the adult rat
brain, and they started making dopamine neurons.
*So you say this is great for curing rats, making dopamine.
What about Parkinson's patients? Well, this is being done.
The first trial was done in England and Sweden, actually, in
1987. They did a brain transplant on
human patients. And even back then, there were
ethical issues about using aborted fetal tissue that was
used in Sweden for this trial. But the Swedish did the
experiment in patients. *And this is an example of what
happens in a human patient. Here's the drill hole in the
brain, where they took a drill and made a small hole in the
patient's brain. They then put a needle in and
injected the fetal tissue directly into the patient's
brain. See this glowing area here, this
is a PET scan, showing that the fetal tissue has made new
dopamine neurons in this Parkinson's patient.
So this patient has new dopamine neurons in the brain.
And the neurons do release dopamine, and they do function.
In fact, there's been 350 patients in the world, including
in America, who received these kinds of transplants.
And many are doing very well in terms of reducing some of their
medication. But it's not a cure for
Parkinson's disease. *This is where we get into the
world of stem cells and replacement for using fetal
tissue. The fetal tissue that is used is
basically unreliable. There are a lot of ethical
concerns of using aborted fetal tissues in many countries.
And you can't really control the dopamine that's released from
these cells. So we're looking, and many years
ago, for alternatives to using fetal tissue, to see if we could
get these transplants to work, but not using fetal tissue.
And stem cells are the things that, perhaps, would offer an
alternative for this. *Now, I'm going to move to the
third part of the talk, which is the stem cell biology, and how
this plays into this model of Parkinson's disease I'm talking
about, and Parkinson's disease in general.
So just to jump now to a discovery that was made here in
Wisconsin by Jamie Thomson. And that is, if you take very
early embryos, when they're developing, at around five to
seven days, the embryo at this stage is the size of a pin head.
It has an outer cell layer here, this purple area.
This golden area in the middle here, is an area called the
inner cell mass of the embryo. Now, if you destroy the embryo
to remove that inner cell mass, and put the cells into a dish,
you can get those cells to grow as human embryonic stem cells.
They will divide, practically indefinitely in culture.
*These cells are what's called pluripotent.
They can make any lineage in the body.
They can make heart, brain, blood, bone.
They keep dividing. So they're kind of like the gold
dust, if you like, of stem cell biology.
They can divide in the dish. And if you give them the right
conditions, they can make muscle cells, pancreatic cells, and
nerve cells. *And a lot of the work going on
here in Wisconsin is actually focusing on how to take
embryonic stem cells down these different routes.
And during these DART talks, you'll hear from other
professors who are working on different areas of biology,
including heart and pancreas, and trying to see if these cells
can be used in a cell therapy way for these diseases.
*Along with this, comes ethical challenges.
You have to look carefully at this slide.
But there are ethical challenges with creating embryos and then
destroying them. This has raised a lot of concern
around the world. And some countries just won't
condone destroying embryos in order to isolate these powerful
stem cells, which I'll tell you in a minute, can make dopamine
neurons for Parkinson's disease. *I think that's led us to look
for alternatives. And one of the big questions
was, for these pluripotent kind of cells, do we need to use
embryos? And the answer was, until
recently, yes. But just a few months ago, two
groups, one from Japan, Takahashi, et al, and Dr. Yu,
here in Wisconsin, as part of Jamie Thomson's lab, discovered
that they could do a trick. It's quite amazing.
This goes back to every cell in your body, theoretically, has
the potential to make a new you. The cells in your body contain
the DNA, the whole DNA complement that made you in the
beginning. So every cell, when your cells
divide, they just remember the amount of DNA you have when you
were first born. So, every cell in your body has
enough information to make a whole you.
*And many of you remember Dolly, the sheep, proving that for the
first time in 1997. They took an adult cell from a
sheep, and they made it into a whole animal.
That needed therapeutic cloning, reproductive cloning, where the
cells are put into an egg, and the egg was made to divide.
And they made a clone of that animal.
But it proved that adults cells in your body have the potential
to make a whole new animal. *What these two groups did, was
they said, well, if that's true, if every cell in our body can
make a whole human being, theoretically, what if we took
cells, in this case, from a Parkinson's patient, or from any
person, and we got skin cells, say, or fibroblasts from under
the skin and we grew them in a culture dish.
Now, skin cells, or fibroblasts, can only make more fibroblasts.
Normally, they can't make other types of tissue.
What they did, was they put a number of genes, two of these,
Oct-4 and Sax-2. These are genes that control
this pluripotency. They control plasticity of
cells, and make them very powerful.
When they put these genes into the skin cells a magic thing
happened. That is, they appeared to turn
into what looked like embryonic stem cells.
*So now they turned these, induced pluripotent stem cells
So potentially now, you can take a skin cell from a patient, put
these genes in and turn them into these pluripotent cells.
*And the Japanese group, they showed that these cells could
then be made into new epithelial cells, which are the origins of
the central nervous system. These cells could then be grown
and differentiated into neurons. *So now we can get to our
dopamine neuron using an adult cell.
And what's particularly nice about this is, and we'll talk
about transplants in a moment, but there is an issue with
rejection. If you transplant cells from one
person to another, they'll generally reject.
You have to take strong immunosuppression.
Now if we could take cells from the same person and develop
embryonic, or induce pluripotent cells, those could be used as a
source for transplantation back into the same patient after
doing all these tricks. So that's an important point.
*The other point is that actually, if you think about it,
you can now take cells from any patient with a disease that you
don't understand and grow those cells in a dish and make neurons
from that patient. So you could take cells from a
Parkinson's patient, make dopamine neurons, and ask
questions about how the disease process works.
In the culture dish, you could could look at drugs, perhaps, to
slow down the death of those neurons.
So this is opening up a lot of different avenues.
*The advantage of going back to the Parkinson's story and using
these types of cells is practical advantage.
We can control, perhaps, the number of dopamine neurons in
the graft that you couldn't control with fetal tissue.
And if you engineer those cells and do some tricks, you can
actually maybe tell them to release dopamine within the
transplant. So now your patient could take a
pill and switch on his dopamine or switch it off again.
Those are the sort of things that we may be able to do with
these types of cells. *This is work from a colleague,
who's among one of the first groups to isolate neural cells
from human embryonic stem cell. It just shows you, I don't want
to go into the details. You go through different stages
from embryonic stem cells through to neural tissue, and
then he took the neural tissue through to dopamine neurons.
They're shown in red here. These are the dopamine neurons
developing. So he can take these embryonic
stem cell and hopefully soon, IPS cells, through to dopamine
neurons. So now we can generate human
dopamine neurons. This has potential for replacing
fetal tissue. *I'll stop in a moment for
questions. But just to show you a warning
on two different things. Human embryonic stem cells are
very powerful. But with great power comes a
great price. Spiderman.
And the price is that these cells are so powerful, they may
keep dividing when you put them in the brain.
If there are any of the powerful embryonic stem cells left, they
could form something called a teratoma.
And in the brain, we're very worried about that, because
particularly in the spinal cord, you don't want to have a lump
growing that can affect brain function and cause pressure.
So we have to be very careful that these cells are not going
to form tumors. But this is a practical issue
that is being worked on. Many groups around the world are
working on resolving this issue right now.
But we can dopamine neurons. *So what about these cells, and
why aren't we putting these cells into patients.
The story really ends a little sadly, I think.
Because the results of the fetal tissue transplants has not been
completely successful. So the problem that some of you
may have already realized, is we're replacing dopamine neurons
in the brain of the patient. But we're putting the dopamine
neurons in the transplant up here, in the striatum.
The dopamine neurons are all the way down here, which is in the
brain stem. Why don't we put the dopamine
neurons back in the brain stem? Well, if you put them back in
the brain stem, they don't reconnect and put the circuit
back together. They can't grow their long axon
back to this part of the brain. This is very important for cell
therapy in the brain, neuroma therapy.
You have to be able to reestablish that long connection
in order to get it to work. And what the patients are
showing, is it's nice if you put the dopamine neurons back here,
because they're at where they should be for releasing the
dopamine. So they'll release the dopamine,
but the patients suffer some side effects and they don't have
full function or recovery, because you couldn't get the
circuit back. What we'd love to be able to do
is what I'm showing you now, you can see this faintly coming in
on the screen, is put the cells back here and then encourage
them to make a new connection, so they now they complete the
circuit. People are working on that, but
we're not there. We're nowhere near that yet in
animals or in Parkinson's patients.
Until we can get that circuit reconnected, I think it's going
to be difficult for dopamine neuron therapy in Parkinson's
disease to work. So I think we have a lot of work
ahead of us. *Now in the next part of the
talk, I'm going to move more to a different approach, asking the
question, well, if we can't replace the dopamine neurons
correctly in the circuit, is there any way we can protect
them and stop them from dying? This is neural protection I'm
talking about. But I'll briefly stop for
questions, if anybody has a questions about Parkinson's.
( inaudible ) So around a small percent of
Parkinson's patients have an inherited form of the disease.
This is common with many neurological diseases.
There's a mutation in a gene, which in a small percentage,
less than five percent of Parkinson's patients, that
mutation is known to cause Parkinson's disease.
And there's around ten or 15 other mutations that are known
to cause Parkinson's. But if you add all those
mutations up, there's still around 90% of Parkinson's
patients who we call sporadic, which means there's no known
mutation. We can't find a mutation.
It just happens. So when we look at the causes of
Parkinson's, it's very difficult with those 90% to know what's
causing it. We can't seem to find a gene.
The most, what we're really coming down to in all
neurological diseases, I think, is that we all have different
sets of genes and risk factors. And that risk factor will
probably interact with your environment at some point in
your life. So my father, for instance,
smokes a lot of cigars. He's approaching 80 and he's
healthy. He smokes cigars, he always
inhales. He has, probably a very low
risk for lung cancer, and doesn't carry risk genes for
that. Other people can have a few
cigarettes and get lung cancer. They may have a lot of risk
factors for lung cancer. So I think Parkinson's is maybe
like that. There are risk factors, we just
don't understand what those factors are yet.
That's a good question. I wish we knew what caused
Parkinson's, because I wouldn't be spending all this time trying
to cure it. I'd be trying to work out if,
you know, the mechanism. Twenty years ago, if you said
well, in 2008, will you know what causes Parkinson's?
I would have said of course we will by then.
But we still don't know what causes Parkinson's disease,
except in a few families, where there's a mutation.
Yeah? ( inaudible )
That's a good point. These cells, when you put the
dopamine neurons back here, like I showed you.
So they make dopamine and they actually release it.
But you're right, there's nothing to connect to them to
tell them when they should be sending their signals.
They're not in the right circuit.
They do get connections, but they're the wrong kind of
connection. In fact, the patients often get
these movements called dyskinesia.
So dopamine will be made by the new neurons, but it's not in the
circuit correctly. So the patients have problems
controlling themselves. And some of the neurologists say
we now have Parkinson's disease and we also have Parkinson's
plus graft disease, which is a new disease completely because
we put these dopamine neurons in the wrong place.
But they can reduce the medication, that's the good
thing. But they lose control of some of
the movement, which is a bad thing.
I think we need to understand most of the clinical trials with
with new dopamine have stopped because of the problems of these
side effects of the transplant, putting the neurons in the wrong
place. And like you said, they're not,
whatever fires them or drives them isn't correct either.
They're outside the circuit. If we can get them back where
they die, which is down in the brain stem, that would be great.
Then we've got to make them put a new connection out to get the
dopamine to the right place. ( inaudible )
Well, what's interesting is there actually are, if you
get the cell body back, the old connections that came in
are still there. They just sit there dormant.
If they find a new cell body back where it died before, if we
can put a new one back, they will reconnect with it quite
often in other models. So we think that if we can get
the cell back there, they may get the appropriate connection
back. When the cell dies, whatever was
connected to it before sort of dies back a little bit.
But if you put a new cell in, it'll reconnect and reestablish
the whole circuit. I should've repeated the
question. But I think, maybe, hopefully,
it was obvious from my answer. All right?
Okay, I will move on into a slight detour.
*I realized pretty early on that this was going to be a
challenge, replacing neurons in the brain.
So this part of the story is using stem cells, not to replace
neurons, now you have to change your thinking here a little bit.
Remember I mentioned in the beginning there were different
types of cells in the brain. Neurons are very important.
Support cells are also very important.
What I'm going to tell you now is we might be able to use stem
cells to provide drugs to the brain that are very difficult to
get in. *What I'm going to talk about is
this one. Glial derived neurotrophic
factor, GDNF. This is known to be a powerful
drug for Parkinson's disease. It's rather like fertilizer for
these dopamine neurons. If you put it on a dopamine
neuron, the dopamine neuron is happy.
It sprouts fibers out. It survives better.
It protects neurons in the brain in many different models.
It has a long term effect in monkey models of Parkinson's.
*So why aren't we using it in patients?
If you give this drug, it doesn't penetrate the
blood-brain barrier. It gets stuck outside the brain.
It doesn't get into the brain. So we can't get it in.
So there are different ways. We can't just give it as a pill,
so how about we just drill a hole in the brain and put a pump
in? That's sort of a neurosurgery
approach. And in fact, they did that.
They put a pump in a number of years ago and they injected the
GDNF directly into the brain. They put it into the ventricles
in the middle of the brain. And it turned out the GDNF still
can't get to where it needs to get, which is down here, this
part of the brain that has the dopamine in it.
I showed you on the slide before.
*So in Bristol, the neurosurgeon colleague started now to put
this catheter directly into where the dopamine terminals are
to get the GDNF out. The GDNF will be taken back and
protect the dopamine neurons and cause sprouting in the brain.
That was the theory. *So this was published a few
years ago. What we did, was this is an
x-ray of one of the patients. This is in England.
There were five Parkinson's patients.
You can see from this x-ray, the neurosurgeon put tubes in with a
thin catheter that went into the brain, targeting the part that
has lost its dopamine. So we're trying to get the GDNF
to stimulate plasticity, if you like.
*Plasticity means those dopamine fibers, which are old and
pulling back, suddenly get the fertilizer, like your grass, and
they grow. That plasticity means new growth
of fibers in the brain, reinnervating areas that have
deinnervated and are sick. *So this was the idea.
This is a cross-section. This is the pump that the
patients have to use. This pump goes under the skin.
You can see this chap here has one pump on this side and one
pump on this side. This is a little bit of plumbing
to the tubing under the skin and that into the head.
*This is the patient that we saw before, with Parkinson's
disease. He was actually one of the
patients in this initial trial in England that we did.
This is him before. And if we look at him after the
GDNF therapy, we saw quite a dramatic effect in this patient.
There were five in this group, many of whom showed a similar
effect once they got the GDNF. The idea is the GDNF is going
into the brain and allowing that plasticity and regrowth to
occur. GDNF is normally during
development, when the system is developing.
This is reintroducing it, if you like, in an adult.
*All I want to show you on this slide is that this is a score
for Parkinson's, 70 is bad, 20 is good.
You can see that when they started, these patients were up
around 70. And at the end, at 24 months,
they were down to around an average of 30.
They came down in their scores for Parkinson's disease, as the
video showed. *As a biologist, I was more
interested in the biology of the brain.
What we showed is that GDNF, in this section through the brain.
Now we're looking at a PET scan, which shows dopamine activity in
the brain. This is before, one patient
before they received GDNF. This is after, in the same
patient. If you can look at this spot.
It's missing here. Now the dopamine levels are
going up, because the fibers are sprouting in the brain of this
patient, in response to GDNF. So this was really encouraging
for us. This is another way of looking
at this data. The red spots mean an increase
in dopamine, on average of these five patients.
*One patient died of a heart attack three years after
receiving this therapy. We looked at his brain.
Inside the brain you can see this is the side that had the
GDNF, around this area. The dopamine markers were all
increased. There is the side that didn't
get the GDNF. He only had the pump in one
side, this chap. It didn't show that increase.
Again, this was published recently.
*We think GDNF is an interesting molecule.
There was a larger trial done by Amgen, but I don't have time to
go into the details. But there were some complexities
of the pump and delivery device, and the size of the catheter
that delivers the GDNF to the brain.
In the larger group of patients, they only saw very small
effects. And then for complex reasons,
Amgen decided that they weren't going to pursue this any more
because the delivery techniques were awkward, and a number of
other reasons. *But I want to now put another
idea in your minds. And that is, instead of using
these complex pumps and delivery through a pump, which is a
technique that's quite awkward and difficult, maybe we could
use cells to deliver the GDNF. The simple idea is we take the
stem cells I've shown you, we put them in the brain by
injection. And they'll migrate and
integrate. Now, they'll provide support
cells. Those support cells would pump
out GDNF. *The cells we used for these
studies were actually derived from the same post-mortem fetal
tissue that was used for the Parkinson's patients.
We just used the cortex part of the brain that's not needed in
this fetal tissue to expand the cells.
We expand the cells. Now we combine gene therapy,
which you'll hear about more later on, I think, with stem
cell therapy. *How do we do it?
We use the old enemy of man, HIV, the lentivirus.
But we gut it. We take out all the bad things
and we just leave in, and we actually reinsert something into
that lentivirus that we want. In this case, we gutted it and
put in the GDNF gene, that we have said was very useful, into
the lentivirus. We then put the lentivirus onto
the stem cells and let it do its business.
And what it does, as you will note in your biology classes,
the lentivirus inserts its RNA into the cells, and makes the
cells produce, normally, more copies of itself.
But of course, we've engineered it so now the cells make GDNF
instead of lentivirus. *So we now produce a cell line
that makes GDNF. I've colored them green.
And when you look at these cells in the dish, they actually
pump out GDNF into the media in the culture dish.
And now, what we want, a small mini-pump.
This is in collaboration with a number of different people, both
in Switzerland and here in my lab.
*Now the cells that we want to pump out GDNF are very active.
These are neural stem cells. I just thought I'd show you this
video to show you what they look like when we put them down.
So this sphere of cells here, this ball of cells, is called a
neurosphere. Within there, there are 100,000
individual stem cells. Now when we give those
neurospheres a substrate, something to stick to, we use
lamina. What happens is the sphere
sticks down and it starts to turn into brain cells.
And when you're watching this video, if you look around the
edge of the video, you'll see individual cells migrating out.
Up here, there's a good example of a few.
These are all individual brain cells growing out from these
stem cells. What they're doing is they're
turning into neurons, astrocytes and oligodendrocytes that I
talked about right at the beginning.
They're doing it right in front of your eyes.
This is a time lapse movie over three days.
You can see the cells as they migrate out.
Yeah? ( inaudible )
The question is are they differentiating to brain cells
because of the environment. The answer is yes.
If we have them in a different environment, they keep growing
as stem cells. We put them in an environment
where we put them on a substrate, which means, in this
case, lamina, which is a substrate they stick to.
And we take away the growth factors, which is this case, is
called EGF and FGF, that make them divide.
So now they start to differentiate.
The environment is directing their differentiation.
They stop dividing and they start differentiating.
Those signals, we can control quite well.
That's why they're doing this. In fact, they make a whole
neuronetwork on the dish. We're worried that if we leave
them too long, they'll start thinking.
These are human brains, basically, in the dish.
We might get arrested for creating brains in a dish.
We'll have to give them the New York Times to see if they can
read it, or the Daily Cardinal. So right now, we haven't created
any thinking monsters in the lab.
But I will touch on that in a moment, because it's important
when we start talking about transplants.
*So this is what they do, they make cells that include neurons
and astrocytes, those two important cell types
that I mentioned before, when they differentiate.
And along with a colleague who is the principle investigator on
the stem cell bank that we have here in Wisconsin, the
NIH-approved stem cell bank, we are working on making these
neurospheres, these cells I just showed you, releasing GDNF,
making big banks of it. *Now the GDNF isn't important
for that differentiation, back to your question.
Those cells want to turn into neuro tissue.
We keep them dividing by putting them in things that make them
divide. But when they go into the brain,
or if we take away the things that make them divide, they
naturally want to make nerve tissue, neurons and astrocytes.
But we keep them dividing in the bank, so we now have a large
stock of these cells for clinical transplantation.
Any other questions at this point before I go to my last
series of slides? Yeah?
The microphone is coming around, I think.
Is the GDNF going to make them into dopamine-releasing
neurons, or is it going to make all types of neurons.
Because, then wouldn't there be the question of is it going to
start making all this new brain tissue and screw up connections
that already exist? >> Great question.
You have to get away from dopamine neurons.
The cells, when you grow the cells from the tissue I was
talking about, the fetal tissue, and you expand them.
They don't make many neurons anymore.
They make many glial cells, or astrocytes.
Those astrocytes, when you put them in the brain, I'll show you
in a minute, they make nearly all astrocytes.
They're no longer making neurons.
The astrocytes release the GDNF. The GDNF is going to work on the
dopamine neurons that are still left in the patient with
Parkinson's disease. So we're not trying to put new
neurons in anymore. We're trying to just use these
cells as delivery cells. Making astrocytes that then pump
out the GDNF. So we're not trying to do neural
replacement. Luckily, when you grow them like
this, you keep expanding them, they stop making neurons after a
while, especially after transplantation.
Yeah? That's a great question.
You're following the talk very carefully.
Just in general, I'm saying, because the GDNF is a growth
factor. And when it's delivered, even if
it's delivered to certain places, and it's still going to
promote a lot of sprouting of the neurons that are in that
area, that might not even include dopamine neurons?
You want to be careful. And in fact, that's a good
point. If you just give GDNF to the
whole brain, you get aberrant sprouting.
And for some of the early clinical trials, they put it in
the cerebral spinal fluid. It got to areas that caused pain
and another syndrome, which was a vibration and a tingling in
the neck. So you have to target it.
We target it by putting some cells, and I'll show you some
slides in a minute. We put the cells right in the
area where the dopamine fibers are.
So the only fibers that really respond are the dopamine ones.
Other fibers don't really respond too much to GDNF.
Or if they do, it's not in a bad way.
A really good point. This is why stem cell release of
the drug in a very located area is very important.
If you put it in the wrong area, you might get aberrant sprouting
or bad plasticity, which can cause serious problems.
So we want to try to keep focused an area, and keep it
where the dopamine fibers are. All right?
Okay, all quiet. *So we'll move now to
transplants to address some of these issues.
For the transplantation part, again, I told you about fetal
tissue early on in the talk. Everybody remembers that long
ago. Now we're going to do the same
thing with the neural stem cells I talked about.
Here they are, growing balls neurospheres, releasing GDNF.
We basically incubate them in tripsom.
And these experiments are actually being done today here
at the UW in our lab. We collect them.
We dissociate them to a single cell suspension, these
neurospheres. And then we inject them into the
rat. These rats have induced
Parkinson's disease. So we kill off dopamine neurons
in one side of the brain in these rats, like I showed you
earlier on. The rats, actually, rotate in a
direction that goes away from where the dopamine neurons were
lost. This is a way of testing your
therapy. So if the rats rotate it means
it has the dopamine neurons that died.
If the rats go in a straight line, it means they have
dopamine neurons on both sides. So what we want to try to do is
put these cells in and get the rats to stop rotating.
*This is from old work done in the last century.
This is when you know you're getting old, when you can say
that. In 1997, we published some
papers showing the cells can survive.
This is a series of section through the rat brain.
And every black dot is a human cell that's gone into the rat
brain. And you can see a focus of cells
in the middle of the transplant. What's cool is the way it
migrated. If you look, you can see they've
migrated out into all areas of the striatum.
They haven't gone into the cortex, which is up here, and
other regions of the brain. So going back to your question,
we've managed to target the region of the brain that we need
the cells to release GDNF in, which is where the terminals are
for the dopamine neuron. *It's not to say that other
terminals might not react somewhat to the GDNF, but it
doesn't seem to have a detrimental effect.
These cells, just to go back again to that great question,
don't make neurons. They're just making these
astrocytes, or support cells. They're releasing the GDNF.
*And if we look in more detail, this is high-powered.
Every black dot-- The beauty of doing human cells
to rats, and these are human neuro stem cells, is you can
track them with specific markers.
In this case, we use a marker, the human nuclear protein.
So every black dot is a human cell.
And where there's no black dots, like up here, there's no human
cells. The rat doesn't have this
protein. So we can track the cells.
We can see that the cells integrate into this part of the
brain. This animal had a rather large
graft. *And if they get into the wrong
place, just to show you, this is the corpus callosum, which
crosses the midline. The cells can migrate into other
regions through white matter. So you have to target
efficiently, in order to get the graft in the right place.
*This is just showing you now GDNF in two different animal
sections. This brown staining is showing
you where the GDNF is actually being expressed.
So the GDNF is being made by the cells.
There's no GDNF on this side, because we didn't transplant the
animals on that side. We just did a transplant on this
side. So the cells have gone in,
they've migrated to fill out this side, and now they're
pumping out this GDNF. This work was done a few years
ago. *We've recently repeated these
studies in the lab. In this case, we've measured
these rotations I mentioned before.
These animals have had a transplant.
And the thing to look at is when they have GDNF, their rotations
come down, which means the fibers are functional, and
they're producing dopamine. These rats are no longer
rotating in circles. And if you look carefully,
you'll see that the dopamine neurons are protected with the
GDNF released from the cells. It's not complete protection,
but it's enough to have functional effects.
*I think with this therapy, we're talking about in
Parkinson's, slowing down the disease progression, or helping
the fibers that are left sprout more and be more plastic by
giving them this rejuvenation factor, if you like.
*This whole idea of putting cells in the brain, this is what
we call a chimera, which means it's a human animal kind of
brain. We've got human cells.
And if you get enough human cells in an animal brain, the
question is, will it start thinking like a human.
And it might sound funny to you to a degree.
But actually, this is a serious issue.
And we've been instructed by certain, and Stanford in
particular has been told, that if they get mice that have over
50% human brains, they have to stop the experiment, because
they might start thinking. Now we feel that the risks are
pretty small, having a rat or a mouse with a human brain.
The difference in size is pretty enormous.
This is a human brain, not a real human brain.
The difference in size is enormous.
And I think the rat brain, we'll constrain the human cells,
so I don't think the rat will necessarily become human by
doing these chimeric experiments.
I think we're safe to use rats, particularly adult rats.
*However, I think the other issue, with these kinds of
transplants, if you look at Alzheimer's, for instance, if
you replace enough neurons in the brain for cognitive
deficits, like Alzheimer's, you may change the personality of
the person. This is a whole other talk.
But if you have lost your memory, we put new stem cells
back in, now they're making neurons, the new neurons, you
might not get grandmother back, you might get somebody else.
That might be a good thing or a bad thing.
But it's an issue in terms of how replacing neurons, again, is
very complex. We're just trying to prevent
cells from dying. *Finally, if you're putting stem
cell transplants in the brain, back into primates, this becomes
an issue. Because actually, if you go into
very early developing primates, we may end up with a primate
human chimera, which could actually start thinking
differently. And in fact, NIH, the federal
rules, actually restrict putting human stem cells back into early
primate embryos for that very reason.
So I think there are limits on what we can do.
But I think human cells to rat is probably quite safe.
These debates are going on around the world.
*So that's the transplantation for Parkinson's.
We can get the cells in. They make GDNF.
So where are we, in terms of using this in a clinical
therapy? There are clinical trials going
on in Parkinson's disease right now, where those viruses I
talked about, they're using direct viral gene therapy.
They're putting a virus in the brain of patients that make
something like GDNF. These patients are walking
around, now there's about 30 patients, with this production
from direct gene therapy. *One of the issues using cells
to deliver these proteins to the brain, is how do you regulate
it, how do you switch it on and off?
What if GDNF is bad after two years?
The cells are going to be there. They're going to be pumping it
out, whether you used a virus to put it in or the cells,
whichever way you do it, how are you going to regulate it?
Right now, there is no way that if I put cells into your brain
that I could switch it off. GDNF would be made forever,
basically. So I think we're kind of
concerned in Parkinson's disease that this is going to be a
problem. We'd like to be able to regulate
it. So a lot with the work in the
lab, is looking at how we can switch on and off the GDNF
production. And there are molecular tricks
you can do. You can make an inducible motor,
it's called, for the gene. That means we can give another
drug and switch on and off GDNF production.
So the patients will take a tablet and then GDNF will come
out of the cells for about four hours.
That wears off and the GDNF shuts off again.
So this is really exciting, if we can get this to work.
Because now we can put the cells in, but the patients have to
take a second tablet in order to activate that GDNF release.
*Drug companies love this because they can charge money
for that tablet that switches the gene on and off.
That way, you know, what you want is a tablet that you give
the patient every day. It's difficult to understand
commercially how to make money from these transplants, because
once you put the cells in, the gene will be made forever.
And there's no more to pay. You just go home.
So this is an interesting area. *So regulation is really
important. But assuming we can get that, we
are looking at monkey models with Parkinson's here at the
Primate Center at the University of Wisconsin.
We've been treating monkeys with MPTP, which gives them a form of
Parkinson's disease. Then we've been doing stem cell
injections of GDNF secreting cells.
These are some examples from some data that's just going to
come out. We put cells in making GDNF.
This is another rating scale, like I showed you before, but
this time for monkeys. And you can see the monkeys have
Parkinsonian symptoms because they have this high score.
Then two of the monkeys come down very well after the
transplant. The other one comes down a
little bit. It's just a pilot study.
But this comes down to a region that shows significant effects
after transplant in this model, but in a small group of animals.
We need to repeat this with a larger group.
*When we look at the monkey brain, which is much bigger,
this is GDNF staining. You can see we had three
different transplant locations. The graft were the same size as
the rat, but because the brain is so much bigger in the monkey,
it looks smaller. You can see we've targeted three
areas. This is another animal we've
just targeted one area. *If you look at dopamine in
those areas, wherever there are cells making GDNF, as shown
here, you get more dopamine markers, shown in this spot
here. So we've had plasticity and
regeneration of dopamine fibers growing toward those areas where
the GDNF is being made in the primate level.
So this is evidence that this technique could work in humans.
And again, we're just waiting for the regulation and release
data to come through before using it.
*So our final data slide will summarize a little bit what I've
said today. And I think one of the take home
messages is, for this Parkinson's talk, is that GDNF
released from stem cells can increase plasticity in
Parkinson's. It can make those old fibers
that are dying, regenerate. And we've got evidence that it
protects the ongoing cell death of the dopamine neurons in
models that we've used. Will it work on Parkinson's
disease? We don't know that until we do
the clinical trial. Nobody really knows that until
you go into patients. We don't have the best model of
Parkinson's in animals. We're assuming it'll do
something from all the data that we have, but we don't understand
yet whether it will work. If were generally just to
overview what I've told you about these three cell types
that I started with in the cartoon, what's really hard to
do, I think, for stem cell therapy and regenerative
medicine for the brain, is the first thing, which I started
with, which is replacing lost neurons in the brain.
This is complicated. We need integration of the
cells, long-distance connections.
It's really tough. *If you want to take a
myelinated cell, like an oligodendrocyte, which is an
in between cell, it may be possible to remyelinate.
With Multiple Sclerosis, people are talking about using these
cells to remyelinate. There are many locations of
these plaques in MS. It's complicated to think we could
target all of those in MS, but there are discussions about
that. That gets easier.
*The last thing, which I've discussed, is using this cell,
the astrocyte, from the neuro stem cell, modify it to produce
a growth factor like GDNF. And then use the stem cells to
deliver this drug to the brain. *I don't have time to talk about
it, but we've got very encouraging data from our work
in ALS, which is a model of Lou Gehrig's disease, that this GDNF
can protect motor neurons very nicely in the spinal cord.
And in fact, because ALS as a prognosis, is about four years
from the time of being diagnosed with ALS to death, there's a
really big need. There's no drugs or stimulators
for ALS whatsoever, for Lou Gehrig's disease.
There's a big need for this type of therapy.
And I'm not worried about switching on and off the GDNF
for ALS patients. I think it would be fine to
leave it on. The risks are minor compared to
the alternative, which is dying. So I think we have to modify our
approaches, depending on the type of disease.
*And so, that may be the first use of stem cells in the brain,
providing either astrocyte support--
There's some evidence in ALS that the astrocytes themselves
are sick. So just replacing the astrocyte
may help the motor neurons a lot in movement.
But if they're making growth factors, even better.
*Just to leave you a last thought, Einstein's brain was
collected for prosperity. They looked at it.
They dissected it. They were expecting to see many
more neurons, obviously. And what they found was he had
more astrocytes. He had more support cells in his
brain, but the same number of neurons.
So don't underestimate how important support cells are in
the brain. And it's turning out that these
astrocytes that we used to think, are next to this neuron,
actually modulate a lot of things in the brain, signal
transmission, synapses, how signals are sent through the
brain. So actually, just replacing the
astrocytes might have a bigger clinical effect than we ever
imagined. This is a whole new area of
neuroscience that's just becoming very exciting right
now, is how neuro function is modulated by astrocytes, and how
this may be a way to get new therapies.
Maybe we can't turn everybody into Einstein, but I think it
would be interesting to see how we can use these to treat
diseases. *So to finish up my Waisman
Center slides, this is where I work, just down the road.
It's a beautiful sunny day in Wisconsin today.
This is slight artifact, I think, from the PowerPoint.
I'd like to thank the many people involved with this work
in my lab, who I've mentioned along the way, and collaborators
who are, again, from in this case, from UW-Madison, Marina
Emborg, who did the primate work.
And in Lausanne, in Switzerland, Patrick Aebischer, who provided
us with the viruses. And of course, these are
important funding agencies. We get money from wherever we
can. We've been funded by
the Michael J. Fox Foundation, Department of Defense, the
National Institutes of Health, the ALS Association,
to mention a few. So I'll stop there
and take any final questions. And applause!
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