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Now, single jab that could prevent blindness
ANI13 October 2009, 11:25am IST
A single jab can now prevent people from losing their vision, thanks
to researchers
at Trinity College Dublin, Ireland, who have developed a new
method to inject drug into the blood by weakening the otherwise
impermeable blood-retina
barrier
.
The blood-retina barrier normally prevents molecules in the blood
from reaching the
retina.
Presently, drugs to treat age-related macular degeneration, the
leading cause of
blindness in the west, have to be injected into the eyeball once a
month, which can
cause eye infections and even blindness in 1 out of 50 injections.
But now, researchers led by Matthew Campbell have now restored the
vision of mice
by temporarily weakening the blood-retina barrier to let drug
molecules injected
into the blood slip through.
Using a technique called RNA interference (RNAI); they could block
the production
of claudin-5-a protein that normally helps make the blood-retina
barrier impermeable.
"Its proof of principle," New Scientist quoted Campbell as saying.
However, RNAI therapy is not yet safe enough for use in people, as it
would breach
the blood-brain barrier as well as the blood-retina barrier. The team
is already
working on a way to block claudin-5 production in the eye only.
This method involves gene therapy using a modified virus that makes
the RNA only
in the presence of an antibiotic called doxycycline. With the novel
approach, patients
would need only one initial injection into their eye to deliver the virus.
Then once a month they would take the antibiotic orally, and two days
later the drug
to treat blindness would be injected in their blood. By then the
blood-retina barrier
would be sufficiently weakened to allow the drug to pass through.
Although the existing drugs to treat age-related macular degeneration
would be too
big to pass through the barrier, there are other molecules in
development that are
small enough.
Some of these could be taken orally when the barrier goes down.
The study has been published in Proceedings of the National Academy
of Sciences .
Topics:
health
Blindness
infection
eye
Blood
Retina
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