Jul 2016

Dr. Valerie Wallace (UHN Photo)

Cure for macular degeneration may be years away but scientist sees exciting advances on the horizon

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Dr. Valerie Wallace is realistic about finding cell-based cures for blindness.

“It’s a long road,” says the Dr. Wallace, Chair of the Vision Science Research Program at University Health Network’s Krembil Research Institute in Toronto. “Cell transplantation is tremendously complicated, difficult, and painstaking.”

But she is also optimistic about what the future holds for gaining a better understanding of the underlying causes of macular degeneration, which is triggered by deterioration of the cone photoreceptors (cones) in the centre of the eye that mediate reading and seeing fine detail. (In contrast, rod photoreceptors are concentrated along the edges of the retina to facilitate peripheral vision.)

“We are learning a lot about the biology that underpins photo cones, says Dr. Wallace. “They are a rare cell type and understanding their development has been difficult. Now we have tools to do that. That’s what I’m excited about.”

Her lab has developed a new mouse strain with fluorescently tagged cones to allow the researchers to track the progress of the cells to see if they can rescue visual function when transplanted into blind mice.

“We’re looking directly at this. Can cone cells transplant? Can they rescue vision? And if they can, what stage of cone development is the best for transplantation?”

The work she is doing feeds into a larger team effort dedicated to optimizing how to make photo receptors from human stem cells. What she learns from trying to engraft mouse cells will be applied to people. It also has implications for finding therapies for other neural degenerative diseases, such as Parkinson’s disease, Alzheimer’s and stroke.

“The eye has always been thought of as very different from the brain,” she says, “but it is part of the brain.  Our work on identifying novel approaches to promote the survival of these cells could extend to  promote neuron survival in other parts of the central nervous system.”

And the eye, aside from being the window to the soul, can also be a window into a person’s health. Says Dr. Wallace: “People are now using non-invasive imaging of the eye to look at markers of disease. There is a large study in Alzheimer’s that is imaging the eye to identify people at early stages of the disease. That’s happening more and more. People are appreciating that some aspects of eye health might inform the progression or even the diagnosis of other diseases.”

Dr. Wallace, who calls herself “a developmental biologist at heart,” doesn’t forget who she’s working for: people struggling with vision loss. Her past work with the Foundation Fighting Blindness, which helps fund her research, guarantees that. “I hear a lot about what’s important to patients.”

While progress is taking time, the science is steadily moving forward. “A lot of the things we’re doing now were not even being talked about 10 years ago.”

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