Seeing the Possibilities in Stem Cells

By David McLaughlin

Losing vision can be one of the most profound health impacts of aging. The thought of never again seeing the faces of loved ones or another sunrise can be frightening.

But Professor Derek van der Kooy has shown it is possible to restore lost sight, and that it may be possible — one day — to cure blindness.

van der Kooy is a Professor in the Departments of Molecular Genetics and Medical Biophysics at the University of Toronto. He is also a researcher in the Terrence Donnelly Centre for Cellular and Biomolecular Research. In 2010, his lab captured global attention in scientific journals and mainstream media when they partially restored vision in blind mice.

Until the start of this century, scientists thought that humans and other mammals could not produce replacement cells in the retina to reverse damage. But in 2000, van der Kooy's group published a landmark paper that proved stem cells exist in the retinas of adult mice. Indeed, human eyes may hold as many as 10,000 retinal stem cells, regardless of age.

van der Kooy’s lab also has shown that, from a single retinal stem cell, it’s possible to generate several million cells. These can give rise to the seven cell types in the retina, including photoreceptors.

In 2010, van der Kooy’s lab salvaged stem cells from the retinas of cadavers and cultured them in a lab dish. They then engineered the cells to be photoreceptors, and inserted them into the retinas of young blind mice. The process partially restored vision in young mice, and transplantation of stem cell produced photoreceptors has worked similarly in adult mice.

This work could help people with two conditions in particular: retinitis pigmentosa, which destroys light-sensing cells in the retina so vision eventually fades to black, and age-related macular degeneration (AMD), which attacks central vision. One million Canadians have AMD, which is the leading cause of blindness in people over 60 years of age.

van der Kooy’s breakthrough has fostered real hope that stem cells will cure blindness. His team also is exploring of the potential of adult pancreatic stem cells to improve treatments for diabetes, and brain stem cells to treat neurodegenerative diseases.