Cell transplant hope for eye diseases

Two new studies show that cell transplants could be used to treat people with vision problems. US scientists have managed to restore the sight of a woman affected by retinitis pigmentosa, an inherited eye disease. However, the research has sparked controversy, since the team used a sheet of retinal cells taken from an aborted fetus. In the second study, researchers in Canada isolated human eye stem cells, and showed that they could grow into all the different types of cell that make up the retina.

Researchers at the University of Louisville in Kentucky removed retinal cells from a 13-week-old aborted fetus, and transplanted them into the left eye of 64-year-old Elisabeth Bryan. From being virtually blind, Elisabeth can now see 'well enough to read, play computer games and check emails', according to New Scientist magazine. Her vision has apparently improved from 20:800 to 20:84 in the two and a half years since her operation. A further five patients affected by either retinitis pigmentosa, or another condition called macular degeneration, have now received similar transplants.

The team has received approval from the US Food and Drug Administration (FDA) to try out the treatment in patients with less advanced eye disease, which should be even more effective, according to team leader Robert Armant. However, the group are worried that critics will claim that their research is promoting abortion, and so are also looking at the possibility of using retinal sheets from genetically-engineered pigs. Other researchers trying to develop treatments for eye diseases are focussing on stem cells, but Armant does not think that this approach will be as successful. He thinks the retinal sheet transplants work because the 'circuitry' of the light-sensing cells remains intact, as does its supporting network of nourishing cells.

Despite Armant's reservations, many scientists are working on stem cell treatments for sight problems, including a team based at the University of Toronto. The researchers have found that the human eye contains a small number of retinal stem cells, which have the ability to replace themselves, and also to produce more specialised cell types. They isolated the cells from the eyes of deceased patients, and grew them into different retina cells in the laboratory. They also transplanted the cells into the eyes of mice and chicks, where they developed correctly into light-sensitive cells. UK stem cell scientist Stephen Minger, of King's College London, said that 'as a first step, I think this paper is superb'. The scientists, who published their findings in the Proceedings of the National Academy of Sciences, now want to see if the cells will do the same in eyes affected by disease.