Paris (AFP)
- Two people with severe vision loss due to a degenerative eye disease are able
to read after embryonic stem cell treatment, researchers said Monday.
The pair
suffer from "wet" age-related macular degeneration, which can blur
vision or cause a blind spot when abnormal blood vessels leak fluids into the
eye, causing damage to a layer of cells called the retinal pigment epithelium
(RPE).
This damage
to the retina kills light-sensing cells.
For the
study, a British-American research team used human embryonic stem cells (hESC)
to grow RPE cells on a thin plastic scaffold.
They then
transplanted this "engineered tissue" into the eyes of two
volunteers.
Before
surgery, neither was able to read any more, the team reported in the journal
Nature Biotechnology.
But a year
after the procedure, both could read "with normal reading glasses, though
slowly," said a Nature press summary.
Further
research must be done before the procedure can be approved as a treatment, said
the team.
Extraordinarily
versatile, embryonic stem cells can become any tissue of the body -- an ability
that has thrown up tantalising hopes of using them to replace limbs or organs
lost to disease, accident, or war.
But donated
stem cells can provoke an immune response, be rejected by the body, or even
cause cancer.
Stem cell
expert Dusko Ilic of King's College London described the study findings as
"encouraging", and said they reduced safety concerns around stem
cell-based therapies.
"They
represent another step forward in materialising our hopes of clinical
implementation of hESC-based treatment of age-related macular degeneration in
the not-so-distant future," he said.
The eye is
thought to be a promising site for stem cell transplants, as it is behind a
shield called the blood-ocular barrier where there is a weaker immune response.
Four years
ago, researchers used embryonic stem cells to restore some vision in patients
with a more common and less severe form of macular degeneration -- the
"dry" type.
Other teams
are testing so-called induced pluripotent stem cells -- adult human cells that
have been reprogrammed to a youthful, versatile state.
These can
be derived from the patient, making them less likely to be rejected, while also
sidestepping ethical qualms about taking cells from embryos.
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