Canadian research gives blind a glimpse of hope

By David Stonehouse

Researchers may be on the cusp of a cure for some forms of blindness -- transplants of lab-grown cells and tissue to repair the eye and restore sight.

Scientists in Toronto are harvesting stem cells from the eye, using them to grow new cells transplanting the new cells in an attempt to coax back function.

A recent stem cell conference in Australia was told the work in Toronto could lead to a cure for blindness within five years.

"It is an exciting development for me and for blind people," University of Toronto researcher Derek van der Kooy told The Age newspaper in Melbourne, where he was attending a recent meeting of stem cell scientists.

The work by his team focusing on the retina, and strides made by researchers in Ottawa on using cells to repair or even replace the cornea, are breeding hope within the blind community.

"This is the first time we have ever been talking about therapies and actually bringing treatments to the patient. That is what is really exciting," says Sharon Colle, national executive director of the Foundation Fighting Blindness, which is funding the research.

"Up until now, we have been looking at the causes of the disease and we have been identifying genes. This is the first time, with stem cell research, that we are looking at a form of therapy for patients."

So promising is this research that the foundation is planning on spending up to $3 million over the next five years to fund it.

There are still hurdles to overcome. Researchers have shown that it is possible to generate new retinal and corneal cells in the lab and successfully transplant them -- a huge, encouraging step -- but they still have to find out whether these newly transplanted cells will actually work well enough in the eye to restore sight.

The trials in Toronto have demonstrated that retinal cells grown in the lab will take in the eyes of mice injected with them. The scientists have succeeded in removing stem cells from human eyes donated to the Eye Bank of Canada and using them to grow all different kinds of cells found in the retina.

Once injected, they seem to have settled into their proper places in the eye and remain active.

"You can see them in the right location and they look just like the host photoreceptors and so this is the first indication that says, 'Hey, this might work,' " says Vince Tropepe, an assistant professor of zoology at the University of Toronto, who was involved in some of the lab's earlier work in finding stem cells in the human retina, where it was previously believed there were none.

One of the first diseases the technique could be aimed at is retinitis pigmentosa, a chronic and hereditary condition that slowly causes degeneration of the retina. It could also be used against macular degeneration and glaucoma.

The uncertainties surrounding the research hasn't seemed to matter much to people who can't see.

"When I give talks where there are blind people in the audience, they want to do the procedure right away," Mr. van der Kooy told the Age." They say their eyes are no good to them now anyway -- so they want to give it a try."

Mr. van der Kooy did not return messages left at his Toronto office.

At the University of Ottawa Eye Institute, stem cell researchers are growing new corneal cells to help reverse or repair disease caused when cells in this part of the eye stop functioning as they should.

The institute made headlines around the world four years ago for successfully creating artificial corneas in the lab by adding viral genes to cells taken from corneas to grow new cells. Those cells were then used to carefully build new corneas layer by layer and then incubated for a couple of weeks to give them final form.

The concept was born when cell biologist May Griffith sought corneas for research into how corneas heal in response to laser surgery. Corneas donated to the Eye Bank did not have enough tissue for her research, so she set out to create her own.

And now, within weeks, the results of the latest round of testing on the artificial corneas are to be published in a U.S. medical journal -- another step toward the possible use of the bioengineered corneas in humans. But because the results are under embargo until they appear in the journal, she cannot talk about them publicly.

Still, the senior institute scientist talks optimistically about the potential for stem cell and artificial cornea replacements.

"It will basically allow us to replace, hopefully at some point, the entire cornea," she said.

© 2004 David Stonehouse. For permissions to reprint, please e-mail info@davidstonehouse.com