My name is Michael Young
from the Schepens Eye Research Institute,
Massachusetts Eye and Ear,
Harvard Stem Cell Institute.
I'm in the Department of Ophthalmology
at Harvard Medical School,
talking to you today
about translating retinal stem cells.
So the disease that we focus on
in my laboratory
for treating with stem cells
is retinitis pigmentosa.
The retinitis pigmentosa
are a group of hereditary diseases
that cause retinal degeneration
and there are a lot of different diseases,
there are actually hundreds
of different mutations
that can lead to retinitis pigmentosa,
but the common feature is that
rod photoreceptors typically die first.
there is no effective treatment at present
for this disease.
What is new in this field
is that there are a host of new regenerative
and neuroprotective strategies
available to treat retinitis pigmentosa.
So these include gene therapy,
neuroprotection with growth factors,
implants such as prosthetic chips
that are being devised
to integrate with the visual system
in a variety of different ways,
a brand new field called optogenetics
in which non-photosensitive cells
are induced to become photosensitive
through gene transfer technology;
And what I'm going to talk to you today
about, principally, is cell replacement.
I'm really talking mostly
about replacing rods and cones.
So the diseased retina has been
thought of as a structure
that can be repaired for many years,
but most of these attempts have failed.
But these retinal transplants
we'll call them, have been performed
without the use of stem cells,
so with embryonic tissue, fetal tissue,
even adult tissue
but not expanded stem cells;
And these grafts have failed principally
because they did not connect to the host.
So what's new is that stem cells
can overcome this barrier
and integrate with the host.
But this brings up a new challenge
and that is to harness
the plasticity of these cells,
and that means differentiation -
getting these cells to become
the type of cells
that we really want them to become.
And in the case of the work
I'm talking about today,
that really is rod photoreceptor.