Science_Illustrated_Australia_-_Issue70_2019

By Bo Christensen

T

he enemy has entered without

your knowledge, and suddenly

you are facing a highly trained

killer who is already eating

into the rest of your defence.

Luckily, you know the strategy – you have

seen the attacker before, and you know

exactly which counter-attack is required to

defeat him this time.

Every day your body is attacked by

hungry viruses, bacteria and parasites that

try to enter your cells and use them to

mass-produce themselves. Fortunately

your immune system makes sure that the

vast majority of these alien organisms never

gain a foothold sufficient that you can feel

their effects. However, your immune system

could also become its own worst enemy. The

defence troops, your immune cells, might

get so confused as to who is friend and who

enemy that they attack the body’s healthy

tissue, affecting joints and skin as in people

suffering from arthritis and psoriasis. But

the attack could also affect the brain and the

nervous system that controls everything

from our motions to our memory. And when

that happens, it may at worst cause disability.

The state is chronic and known as multiple

sclerosis, meaning ‘many scars’.

Multiple sclerosis can cause paralysis

and highly impaired motor function, but it

can also affect your ability to learn and

understand what happens around you, and

so your ability to live an ordinary life. At this

point in time, doctors are treating the dis-

ease with drugs that aim to curb the activity

of the immune cells so they do not attack

nerve cells to the same extent. However, the

drugs cannot halt the immune system com-

pletely, because if they did, the patients

Inject your own cells into your blood vessels and protect the brain against attacks.

New stem-cell treatment has had a surprising effect on sclerosis, and scientists are

close to finding a cure which might eliminate the crippling disease once and for all.

STEM CELLS SAVE THE

BRAIN FROM SCLEROSIS

Insulation ensures

quick signals

By means of special high-fat cells,

the brain’s nerve cells can quickly

exchange electrical impulses.

BEFO

RE (^) F
IGHT
Ions flow into
the nerve cell
1 When a nerve cell receives a signal from a neighbouring cell,
electrically-charged sodium ions flow
into the cell through an ion channel.
This causes a voltage difference that
makes other ion channels of the cell open.
Signal jumps to
the end terminal
3 The insulation makes the signal jump from gap to gap, so it will
quickly reach the end of the nerve cell,
where it liberates neurotransmitters
to the neighbouring cell.
Myelin insulates
the cell in sections
2 The nerve cell’s projection is wrapped in an insulating myelin
sheath produced by the brain’s auxiliary
cells. Between each insulation section
is a gap where the ion channels allow
ions in and out of the cell.
KEN
(^) IKE
DA
MA
DSE
N/S
HU
TTE
RST
OC
K
Neighbouring cell
Myelin sheath
Electrical signal
Neurotransmitters
Ion channel
Sodium ion
Auxiliary cell
Nerve cell
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