WEBVTT

00:00:06.728 --> 00:00:08.488
Insulin pumps improve the lives

00:00:08.488 --> 00:00:13.438
of many of the 415 million people 
with diabetes around the world

00:00:13.438 --> 00:00:16.245
by monitoring blood sugar, delivering 
insulin,

00:00:16.245 --> 00:00:20.245
and preventing the need for constant 
finger-pricking and blood testing.

00:00:20.245 --> 00:00:25.305
These small machines include a pump and
a needle, which can sense glucose levels,

00:00:25.305 --> 00:00:26.655
feed back to the pump,

00:00:26.655 --> 00:00:30.275
and then calculate how much insulin 
to deliver through the needle.

00:00:30.275 --> 00:00:33.595
But they have a catch: they’re temporary.

00:00:33.595 --> 00:00:37.705
Within a few days, glucose sensors have to
be moved and replaced.

00:00:37.705 --> 00:00:42.595
And it’s not just glucose monitors and 
insulin pumps that have this problem,

00:00:42.595 --> 00:00:46.284
but all bodily implants, 
at different time scales.

00:00:46.284 --> 00:00:50.994
Plastic prosthetic knees have to be 
replaced after about 20 years.

00:00:50.994 --> 00:00:54.311
Other implants, such as those used for 
cosmetic reasons,

00:00:54.311 --> 00:00:57.031
can meet the same fate in about 10.

00:00:57.031 --> 00:01:01.561
That isn’t just a nuisance: it 
can be expensive and risky.

NOTE Paragraph

00:01:01.561 --> 00:01:05.296
This inconvenience happens because of 
our bodies’ immune systems.

00:01:05.296 --> 00:01:08.706
Honed by several hundred million 
years of evolution,

00:01:08.706 --> 00:01:10.016
these defensive fronts

00:01:10.016 --> 00:01:14.366
have become exceptionally good 
at identifying foreign objects.

00:01:14.366 --> 00:01:15.706
Our immune systems boast

00:01:15.706 --> 00:01:20.036
an impressive arsenal of tools to tackle,
intercept, and destroy

00:01:20.036 --> 00:01:22.926
anything they believe shouldn’t be there.

00:01:22.926 --> 00:01:25.766
But the consequence of this constant 
surveillance

00:01:25.766 --> 00:01:29.766
is that our bodies treat helpful 
implants, like insulin pumps,

00:01:29.766 --> 00:01:34.366
with the same suspicion as they would
a harmful virus or bacteria.

NOTE Paragraph

00:01:34.366 --> 00:01:37.482
As soon as the insulin pump has been 
implanted in the skin,

00:01:37.482 --> 00:01:41.842
its presence triggers what’s known as a
“foreign body response.”

00:01:41.842 --> 00:01:44.054
This starts with free-floating proteins

00:01:44.054 --> 00:01:47.144
that stick themselves to the surface 
of the implant.

00:01:47.144 --> 00:01:49.534
Those proteins include antibodies,

00:01:49.534 --> 00:01:52.194
which attempt to neutralize the new object

00:01:52.194 --> 00:01:55.624
and send out a signal that calls other 
immune cells to the site

00:01:55.624 --> 00:01:58.154
to strengthen the attack.

NOTE Paragraph

00:01:58.154 --> 00:02:00.164
Early-responding inflammatory cells,

00:02:00.164 --> 00:02:02.514
like neutrophils and macrophages,

00:02:02.514 --> 00:02:05.094
respond to the emergency call.

00:02:05.094 --> 00:02:08.284
Neutrophils release little granules filled
with enzymes

00:02:08.284 --> 00:02:12.014
that try to break down the surface 
of the insulin pump’s needle.

00:02:12.014 --> 00:02:14.484
Macrophages secrete enzymes too,

00:02:14.484 --> 00:02:16.764
together with nitric oxide radicals,

00:02:16.764 --> 00:02:21.424
which create a chemical reaction that 
degrades the object over time.

00:02:21.424 --> 00:02:25.571
If the macrophages are unable to dispatch 
the foreign body rapidly,

00:02:25.571 --> 00:02:30.867
they fuse together, forming a mass of 
cells called a “giant cell.”

00:02:30.867 --> 00:02:34.031
At the same time, cells called fibroblasts

00:02:34.031 --> 00:02:39.011
travel to the site and begin to deposit
layers of dense connective tissue.

00:02:39.011 --> 00:02:43.005
Those enclose the needle that the pump 
uses to deliver insulin

00:02:43.005 --> 00:02:45.275
and test for glucose levels.

00:02:45.275 --> 00:02:47.755
Over time this scaffolding builds up,

00:02:47.755 --> 00:02:51.325
forming a scar around the implant.

NOTE Paragraph

00:02:51.325 --> 00:02:54.765
The scar functions as an almost 
impenetrable wall

00:02:54.765 --> 00:02:57.095
that might start to block vital 
interactions

00:02:57.095 --> 00:02:59.615
between the body and the implant.

00:02:59.615 --> 00:03:03.205
For example, scarring around pacemakers
can interrupt

00:03:03.205 --> 00:03:07.475
the electrical transmission that’s 
crucial for their functioning.

00:03:07.477 --> 00:03:11.387
Synthetic knee joints may give off 
particles as they’re worn down,

00:03:11.387 --> 00:03:15.047
causing immune cells to inflame 
around these fragments.

00:03:15.047 --> 00:03:19.887
Tragically, the immune system’s attack
can even be life-threatening.

NOTE Paragraph

00:03:19.887 --> 00:03:23.400
However, researchers are finding ways 
to trick the immune system

00:03:23.400 --> 00:03:28.210
into accepting the new devices we 
introduce into our bodily tissues.

00:03:28.210 --> 00:03:31.677
We’ve discovered that coating implants 
with certain chemicals and drugs

00:03:31.677 --> 00:03:33.997
can dampen the immune response.

00:03:33.997 --> 00:03:37.987
Those basically make the implants 
invisible to the immune system.

00:03:37.987 --> 00:03:41.307
We’re also making more implants 
out of natural materials

00:03:41.307 --> 00:03:44.077
and in forms that directly mimic tissues,

00:03:44.077 --> 00:03:46.547
so that the body launches a weaker attack

00:03:46.547 --> 00:03:50.997
than it would if it came across a 
completely artificial implant.

00:03:50.997 --> 00:03:53.131
Some medical treatments involve implants

00:03:53.131 --> 00:03:56.791
designed to regenerate lost 
or damaged tissues.

00:03:56.791 --> 00:04:00.301
In those cases, we can design the implants
to contain ingredients

00:04:00.301 --> 00:04:02.591
that will release specific signals,

00:04:02.591 --> 00:04:06.811
and carefully tailor our bodies’
immune reactions.

NOTE Paragraph

00:04:06.811 --> 00:04:11.018
In the future, this way of working
alongside the immune system

00:04:11.018 --> 00:04:14.088
could help us develop completely 
artificial organs,

00:04:14.088 --> 00:04:16.308
totally integrative prostheses,

00:04:16.308 --> 00:04:18.858
and self-healing wound therapies.

00:04:18.858 --> 00:04:22.268
These treatments might one day 
revolutionize medicine–

00:04:22.268 --> 00:04:25.878
and transform, forever, 
the bodies we live in.