Embryonic stem cells clear key hurdle in eye trial
PARIS (AFP) - Embryonic stem cells transplanted into 18 patients with deteriorating eyesight restored some vision in more than half the volunteers, the longest study into the fledgling technology reported Tuesday.
Stem cells derived from embryos "could provide a potentially safe new source of cells for the treatment of various unmet medical disorders requiring tissue repair or replacement," its authors said.
The study marks a new chapter in the long story of embryonic stem cells, which after their discovery in the 1990s were hailed as a miracle cure but then ran into problems.
Published in The Lancet, the paper looked at a US trial of stem cells among 18 patients suffering from two tragic, degenerative diseases of the retina.
Nine had a condition called Stargardt's macular dystrophy, a leading cause of juvenile blindness, and nine had dry atrophic age-related macular degeneration,hich occurs among the middle-aged and elderly.
There is no conventional treatment for either condition, which eventually leads to complete blindness as the retina's light-receiving cells die out.
The participants were injected with one of three different doses of retinal cells derived from early-stage embryos -- 50,000, 100,000 or 150,000 cells.
The transplants were placed in a space under the retina of the worst-affected eye.
The patients were monitored for up to 37 months, for an average of 22 months.
Out of the 18 treated eyes, 10 showed substantial improvements in vision, as measured by the ability to read letters on a board. Of these, eight patients were able to read 15 additional letters in the first year after transplant.
In seven other patients, vision in the treated eye remained stable or improved.
But in one patient, vision decreased, falling back by more than 10 letters --though the study did not clarify whether this was the expected degeneration associated with the disease's progression.
Untreated eyes did not show any improvement, thus pointing to the apparent benefit of the transplant, the researchers said.
And there were no side-effects or evidence of rejection.
The investigation is the first to give a longer-term validation to embryonicstem cells.
Extraordinarily versatile, embryonic stem cells can differentiate into any tissue of the body -- an ability that has thrown up tantalising hopes of using them to replace tissue lost through disease, accident or war.
