Stem cells findings raise hopes for blind treatment
Human embryonic stem cells can help slow sight loss in rats, US researchers reported today.
The findings raise hopes that a leading cause of blindness could eventually be treatable with stem cell therapy.
Scientists at Advanced Cell Technology discovered that tissue implants injected into rats with a degenerative eye disease similar to macular degeneration reduced the deterioration of their vision.
Macular degeneration is the most common cause of blindness in over 55s, although the experiments do not prove that the cells would work in people.
The Massachusetts-based company first developed a way of turning embryonic stem cells into retinal pigment epithelium cells, the tissue which nourishes the light-sensitive “photoreceptor” cells in the eye.
Then they injected the cells into the retinas of 14 rats with the rodent version of macular degeneration. There were eight control rats who got injections without any cells.
The animals that were treated had a visual acuity of around 70% of the normal rate, which the team said was a 100% improvement over the untreated controls.
The rats were tested for retinal electrical activity 40 days after treatment team, when the treated ones were twice as responsive as the untreated ones in response to flashes of light.
When their retinas were examined the treated eyes had healthy photoreceptor layers five to seven cells thick, while those that had not been treated had an average thickness of just one cell.
“Embryonic stem cells promise to provide a well-characterised and reproducible source of replacement cells for clinical studies,” senior author Robert Lanza said.
“All 18 human embryonic stem cell lines we studied reliably produced retinal cells that could potentially be used to treat retinal degenerative diseases, such as macular degeneration.
“We showed that these cells have the capacity to rescue visual function in animals that otherwise would have gone blind. Importantly, the cells did not appear to cause any unwanted pathological responses in the animals following transplantation.”
“We are encouraged by this data related to our retinal programme and are focused on driving therapies to the clinic,” Advanced Cell Technology’s chief executive William Caldwell added.
The research is published in the journal Cloning and Stem Cells.
