Download Hearing for those who have lost it”

“Hearing for those who have
lost it”
Flipping a Broken Switch?
Mechanics of Hearing
The 1,000s of sensory receptors are
made up of tiny hairs in the inner ear .
Sound waves are amplified by the
hairs, which vibrate when exposed to
sound waves.
The hair-vibration open ion channels
(chemical channels) that let
neurotransmitters flow in – triggering
electrical activity in cochlear neurons.
Electrical activity in the cochlea is
passed on to the brain for processing.
The Procedure
• For volunteers who have lost their hearing
through damage (constant exposure to high
decibels) or disease.
• Injection of a virus containing a gene that
should trigger the regrowth of sensory
receptors in the ear.
– The virus has been stripped of its DNA, which has
been replaced with a gene that will hopefully
trigger sensory receptor regrowth (has worked in
mice).
Questions
• Why are they using an engineered virus
carrying the gene that triggers hair growth?
• What happens once the virus is inside the
inner ear?
• How does the gene work once it has been
delivered?
Gene Incorporation
• The virus “injects” the gene into the genome of
the cells that make the inner ear’s hairs.
• Once incorporated into the DNA of the cells, it
throws a switch to restart the cells that control
the growth of the hairs.
• The procedure has been performed successfully
in mice and has been approved for trials in
people who have lost their hearing.
– Replaces cochlear implants.