Could a blind eye regenerate? - David Davila
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0:06 - 0:08Imagine that day by day,
-
0:08 - 0:11your field of vision
becomes slightly smaller, -
0:11 - 0:13narrowing or dimming
-
0:13 - 0:16until eventually you go completely blind.
-
0:16 - 0:19We tend to think of blindness
as something you're born with, -
0:19 - 0:23but in fact, with many diseases
like Retinitis pigmentosa -
0:23 - 0:25and Usher syndrome,
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0:25 - 0:27blindness can start developing
when you're a kid, -
0:27 - 0:30or even when you're an adult.
-
0:30 - 0:33Both of these rare genetic diseases
affect the retina, -
0:33 - 0:38the screen at the back of the eye
that detects light and helps us see. -
0:38 - 0:42Now imagine if the eye
could regenerate itself -
0:42 - 0:45so that a blind person could see again.
-
0:45 - 0:49To understand if that's possible,
we need to grasp how the retina works -
0:49 - 0:53and what it has to do
with a multitalented creature -
0:53 - 0:55named the zebrafish.
-
0:55 - 0:58The human retina is made
of different layers of cells, -
0:58 - 1:01with special neurons
that live in the back of the eye -
1:01 - 1:05called rod and cone photoreceptors.
-
1:05 - 1:08Photoreceptors convert
the light coming into your eye -
1:08 - 1:12into signals that the brain uses
to generate vision. -
1:12 - 1:15People who have Usher syndrome
and retinitis pigmentosa -
1:15 - 1:19experience a steady loss
of these photoreceptors -
1:19 - 1:23until finally that screen in the eye
can no longer detect light -
1:23 - 1:26nor broadcast signals to the brain.
-
1:26 - 1:31Unlike most of your body's cells,
photoreceptors don't divide and multiply. -
1:31 - 1:35We're born with all
the photoreceptors we'll ever have, -
1:35 - 1:38which is why babies
have such big eyes for their faces -
1:38 - 1:40and part of why they're so cute.
-
1:40 - 1:43But that isn't the case for all animals.
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1:43 - 1:47Take the zebrafish,
a master regenerator. -
1:47 - 1:53It can grow back its skin, bones, heart
and retina after they've been damaged. -
1:53 - 1:57If photoreceptors in the zebrafish retina
are removed or killed by toxins, -
1:57 - 2:03they just regenerate and rewire
themselves to the brain to restore sight. -
2:03 - 2:06Scientists have been investigating
this superpower -
2:06 - 2:11because zebrafish retina are also
structured very much like human retina. -
2:11 - 2:15Scientists can even mimic the effects
of disorders like Usher syndrome -
2:15 - 2:19or retinitis pigmentosa
on the zebrafish eye. -
2:19 - 2:23This allows them to see how zebrafish
go about repairing their retinas -
2:23 - 2:27so they might use similar tactics
to fix human eyes one day, too. -
2:27 - 2:30So what's behind
the zebrafish's superpower? -
2:30 - 2:35The main players are sets of long cells
that stretch across the retina -
2:35 - 2:37called Müller glia.
-
2:37 - 2:40When the photoreceptors are damaged,
these cells transform, -
2:40 - 2:42taking on a new character.
-
2:42 - 2:46They become less like Müller cells
and more like stem cells, -
2:46 - 2:49which can turn into any kind of cell.
-
2:49 - 2:50Then these long cells divide,
-
2:50 - 2:54producing extras that will eventually
grow into new photoreceptors, -
2:54 - 2:59travel to the back of the eye
and rewire themselves into the brain. -
2:59 - 3:03And now some researchers even think
they've found the key to how this works -
3:03 - 3:06with the help of one of two chemicals
that create activity in the brain -
3:06 - 3:09called glutamate
and aminoadipate. -
3:09 - 3:11In mouse eyes,
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3:11 - 3:15these make the Müller glia divide
and transform into photoreceptors, -
3:15 - 3:17which then travel
to the back of the retina, -
3:17 - 3:21like they're replenishing a failing army
with new soldiers. -
3:21 - 3:24But remember, none of this has happened
in our retinas yet, -
3:24 - 3:28so the question is how do we trigger
this transformation of the Müller glia -
3:28 - 3:30in the human eye?
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3:30 - 3:33How can we fully control this process?
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3:33 - 3:36How do photoreceptors
rewire themselves into the retina? -
3:36 - 3:39And is it even possible
to trigger this in humans? -
3:39 - 3:43Or has this mechanism been lost
over time in evolution? -
3:43 - 3:45Until we tease apart
the origins of this ability, -
3:45 - 3:49retinal regeneration will remain
a mysterious superpower -
3:49 - 3:51of the common zebrafish.
- Title:
- Could a blind eye regenerate? - David Davila
- Description:
-
View full lesson here: http://ed.ted.com/lessons/could-a-blind-eye-regenerate-david-davila
We tend to think of blindness as something you're born with, but with certain genetic diseases, it can actually develop when you’re a kid, or even when you’re an adult. But could blind eyes possibly regenerate? David Davila explains how the zebrafish’s amazing regenerative retinas are causing scientists to investigate that very question.
Lesson by David Davila, animation by Eli Enigenburg.
- Video Language:
- English
- Team:
- closed TED
- Project:
- TED-Ed
- Duration:
- 04:07
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Jessica Ruby edited English subtitles for Could a blind eye regenerate? - David Davila | ||
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Jennifer Cody edited English subtitles for Could a blind eye regenerate? - David Davila |