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Stem Cells In The Brain -

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Stem Cells in the Brain

(25/06/2009)

TRANSCRIPT

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For extended interviews and footage, click here to visit our exclusive online edition of Stem Cells

NARRATION:

Everything you do, every thought you have is dependent on the most important organ in the body: the
brain. We have somewhere between ten and a hundred billion brain cells at the peak of our life.

DR RODNEY RIETZE:

We can perform approximately a hundred and twenty-three teraflops of calculations

NARRATION:

And that's just in one second! It is an incredibly powerful machine.

PAUL WILLIS:

So let's try and put that into perspective. Let's imagine that the human brain is a computer and
that each synapse or neuronal connection is equivalent to one byte of information represented by a
single grain of sand - if I were to have a pile of sand in my hand that represented the amount of
computing information that's going on in your brain when it's flat out for one second, how big do
you reckon that pile would be? It would be 3766m high and that's about the size of Mt Fuji.

But this incredible processing ability of our brains doesn't last. It naturally declines as we age.
And current research suggests that that decline starts in our 20s.

NARRATION:

But could it be possible to slow down or even prevent this decline? If stem cells existed in the
brain could this provide the answer?

DR RODNEY RIETZE:

A stem cell really is that cell at the top of the pyramid that has ultimate proliferate and
regenerative capacity. And its job is to not only form the organ but to regenerate it over time.

NARRATION:

In 1992 the journal - Science - announced a landmark discovery - stem cells did exist in the adult
brain.

PAUL WILLIS:

So you knew that the brain stem cells were there but trying to find them would be like trying to
find one slightly smaller grain of sand on a whole beach - how did you feel when you first saw one?

DR RODNEY RIETZE:

It really was fantastic. I mean a lot of people were against us and didn't think we could do it.
And when we finally did it, it was a true eureka moment.

NARRATION:

In 2001 Rodney Rietze and Perry Bartlett located and isolated adult stem cells in the brain. And
with less than .01% of the cells being stem cells this was an astounding find.

DR RODNEY RIETZE:

So ultimately it's the job of stem cells to regenerate the brain so you can think of them as
soldiers that are fighting the war against ageing and what we found is that half way through your
life you've lost half your stem cells.

PAUL WILLIS:

What can you do about it?

DR RODNEY RIETZE:

Well our idea was what would happen if we started replacing the soldiers or preventing them from
being lost would that affect the brain and allow it to regenerate throughout its life - delaying
ageing.

NARRATION:

So Rodney and colleague, Dan Blackmore, set off into the unknown: Could stem cell numbers in the
brain be increased, and, if they could, would the brain have a better chance of regenerating?

DR RODNEY RIETZE:

So we knew that exercise was good for the brain, we knew that when you exercised that parts of the
brain involved in memory had new neurons being produced. And we said, well shouldn't physical
exercise then stimulate stem cells? So it really was an obvious question from the literature.

NARRATION:

Time for studies in the lab - animal of choice for most medical researchers: the humble lab mouse.

DR RODNEY RIETZE:

We put the mice on a running wheel and we ran them for a period of twenty-one days and then
harvested the stem cells and asked did we increase or decrease, or alter at all the number of stem
cells in young, middle aged and old mice.

We saw significant increase all the way up to eighteen months of age. However the surprise here is
twenty-four months there's a fifty percent decline in stem cells. So what worked in the first three
quarters of your life, isn't working in the last quarter of your life.

NARRATION:

That's all very well for a mouse, but what could this mean for you and I?

PAUL WILLIS:

So while for the first three quarters of your life exercise is good it increases the number of
neural brain cells, it actually works against you when you get old?

DR RODNEY RIETZE:

Up to around the age of sixty-five physical exercise seems to be good for you. After sixty-five you
need to change your strategy.

PAUL WILLIS:

Other strategies that may increase brain stem cells include mental exercises like crosswords but
these are yet to tested on mice

NARRATION:

But back to the physical exercise...

PAUL WILLIS:

There was another catch - if the mice were forced to exercise the number of brain stem cells didn't
increase; exercise had to be voluntary - and I can relate to that.

DR RODNEY RIETZE:

The other really interesting thing is if you put a mouse on a running wheel and it's by itself it
also negates the effects. So you need to have voluntary exercise and you also need to be part of a
community for the physical exercise really to make a difference. So what physical exercise is
accomplishing is increasing the number of stem cells.

NARRATION:

The increased number of stem cells in the brain generates new nerve cells. But increasing cell
numbers is only part of the picture - the new nerve cells now need a purpose. And that's really
where mental strain is thought to come in.

NARRATION:

A stimulating environment energises the new nerve cells and integrates them into the brain - it's
use it or lose it. So, like adults exploring new technology, or a baby playing in the park. If
starved of stimulation the new cells will wither and die.

DR RODNEY RIETZE:

So you have survival and you have integration. And without those two things you're not going to see
the effects you're looking for, the improved cognitive ability or the ability to do something for
your entire life.

NARRATION:

So what's the next step? If we want our brains to maintain a healthy number of stem cells do we
have to be slaves to the treadmill? Or perhaps there's cause for a new drug to be designed?

DR RODNEY RIETZE:

I don't think there's a magic bullet that will allow us to lay in bed and smoke cigarettes and eat
Doritos and, and just not have to worry about physical exercise. However what probably is on the
horizon is being able to say, let's slow that decline, or if you have a stroke, let's stimulate
those stem cells and get them to do their job just a little bit better as we age.

PAUL WILLIS:

In the meantime if I get some exercise I'll not only be doing my brain some good I might even lose
a few kilos. Oy!!