Google – AFP, 21 July 2013
A mouse at
a research facility in Illkirch-Graffenstaden, France on March 12,
2003
(AFP/File, Pierre Andrieu)
|
PARIS —
Blind mice have been able to see once more in a laboratory exploit that marks a
further boost for the fast-moving field of retinal therapy, according to a
study published on Sunday.
Scientists
in Britain used stem cells -- early-stage, highly versatile cells -- taken from
mice embryos, and cultured them in a lab dish so that they differentiated into
immature photoreceptors, the light-catching cells in the retina.
Around
200,000 of these cells were then injected into the mice's retinas, some of
which integrated smoothly with local cells to restore sight.
The rodents
were put through their paces in a water maze and examined by optometry to
confirm that they responded to light.
Embryonic
stem cells "could in future provide a potentially unlimited supply of
health photoreceptors for retinal transplantations to treat blindness in
humans," Britain's Medical Research Council (MRC) said in a press release.
Photoreceptor
loss lies behind degenerative eye diseases such as retinitis pigmentosa and
age-related macular degeneration, also called AMD.
Stem cells
have triggered a huge interest and investment on the back of hopes that they
can become replacement tissue, grown in a lab dish, for cells damaged by
disease or accident.
But the
exciting field has to overcome big obstacles.
One is the
ability to coax these immature cells into safely becoming the specialised cells
that are needed, rather than turn cancerous.
This is
where the new work marks a gain, according to lead researcher Robin Ali at the
University College London Institute of Ophthalmology and Moorfields Eye Hospital.
His team
previously found that sight could be restored in blind mice by transplanting
immature photoreceptors called rod cells that were taken from the retinas of
healthy rodents.
The latest
research takes things further because the transplanted material comprises all
the different nerve cells needed for sight -- and they were not taken from
other animals.
Instead,
they were grown in a lab and differentiated into the right cells thanks to a
new technique, pioneered in Japan, that replicates the shape of the retina.
"Over
recent years, scientists have become pretty good at working with stem cells and
coaxing them to develop into different types of adult cells and tissues,"
said Ali.
"But
until recently, the complex structure of the retina has proved difficult to
reproduce in the lab. This is probably because the type of cell culture we were
using was not able to recreate the developmental process that would happen in a
normal embryo."
Ali added:
"The next step will be to refine this technique using human cells to
enable us to start clinical trials."
The study
appears in the journal Nature Biotechnology.
Last month,
Japanese authorities approved proposals for the world's first clinical trials
using stem cells harvested from a patient's own body.
The goal is
to test therapy for AMD using so-called induced pluripotent stem cells, or iPS.
These are
adult cells that have been reprogrammed to return to their infant, versatile
state. Provided that they are proven safe, they can provide a non-controversial
alternative to stem cells culled from early-stage embryos.
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