All the parts of the retina are very important but the part that concerns a lot of people with retinal disease are the photoreceptors.

Discovering how to restore eyesight through cell transplantation

About 500,000 Canadians live with some kind of visual impairment. Many of these visual impairments involve diseases of the retina – the thin, delicate tissue lining the back of the eyeball – such as age-related macular degeneration and retinitis pigmentosa.

“All the parts of the retina are very important but the part that concerns a lot of people with retinal disease are the photoreceptors,” says Dr. Valerie Wallace, Co-Director of the Donald K. Johnson Eye Institute at Toronto Western Hospital and the Donald K. Johnson Chair in Vision Research. Photoreceptors are light responsive neurons. “Without them, you are completely blind,” says Dr. Wallace.

Through basic research in the lab, Dr. Wallace and her team are investigating whether transplanting healthy photoreceptors into a diseased retina can restore vision.

Transplanted cells growing connections

For this to work, cells have to grow connections and connect to what’s left of the patient’s retina. “Then they have to be able to respond to light and, through those new connections, re-establish the flow of information from those new neurons to the parts of the brain that interpret light as vision,” says Dr. Wallace. “It’s a very tall order.”

Remarkably, Dr. Wallace and her team are finding that transplanted cells do survive and exchange some of their contents to the recipient retina. “This is a new way of thinking about how cell transplantation works.”

The implications for this discovery are exciting. “By understanding this exchange, we hope to not only discover better ways to treat retinal diseases but even prevent them from progressing in the first place,” says Dr. Wallace.

Research innovations like these — which depend on philanthropic support — are critical to ensuring that Canadians with degenerative eye diseases face a brighter future. “Discovery research is the only way that we are going to change the outcomes in the long term for patients with devastating eye diseases,” says Dr. Wallace.