RETINAL cells that could save people’s sight have been generated for the first time from human embryonic stem cells. Transplanted into eyes, the cells could be used to treat the commonest cause of blindness, age-related macular degeneration.
Researchers at the biotech firm Advanced Cell Technology, based in Worcester, Massachusetts, managed to produce retinal pigment epithelial cells. These nourish nearby photoreceptor cells – the rods and cones in the retina that respond to light. When epithelial cells start to wear out, in conditions such as age-related macular degeneration, the photoreceptors deteriorate too.
Some of ACT’s retinal cells spontaneously changed into rods and cones, suggesting it may be possible to replace damaged photoreceptors too (Cloning and Stem Cells, vol 6, p 217). “If they are growing rods and cones as well, that’s impressive,” says Norman Radtke of the Retina Vitreous Resource Center in Louisville, Kentucky, who is pioneering transplants of retinal pigment epithelial cells derived from miscarried fetuses.
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Another key step for ACT is that the embryonic stem cells were cultured without using mouse embryonic skin cells to nourish and support them. Most other embryonic stem cell lines have been made using mouse cells, and so could not be turned into therapies as they could pass on animal viruses.
ACT points out that to make the retinal cells it had to use cell lines that are banned for use in federally funded research in the US. Three years ago President Bush restricted federal researchers to using the 70 human embryonic stem cell lines that existed at the time. Only 11 of these are now viable.
When ACT researchers tried to produce the retinal cells using three of the “official” lines they all failed. “We would not have made this discovery if we had stuck to the lines approved by Bush,” says Bob Lanza, head of medical and scientific development at ACT.
