Scientists look to human stem cells to enable the retina to repair itself.
Several new treatments that may help prevent vision loss in people with age-related macular degeneration are under investigation. Besides continuing development of treatments to prevent new blood vessel growth as well as leakage from blood vessels in the eye, researchers are also studying drugs known as angiostatic corticosteroids (such as anecortave acetate, tramcinolone, and flucinolone), sometimes in conjunction with other treatments such as photodynamic therapy.
What’s on the horizon? Human retinas damaged by diseases, such as age-related macular degeneration and diabetic retinopathy, are unable to repair themselves. But now in a report from the National Academy of Sciences (Volume 103, page 12769 ), researchers at the University of Washington and elsewhere suggest that the regeneration of damaged cells in the retina may someday be possible. Their optimism is based on successful treatment of diseased retinas in mice using human stem cells.
The University of Washington scientists first grew human embryonic stem cells (from a cell line approved in the United States) in a lab, then added growth factors -- proteins that enable cell growth -- central to the development of both human and mouse heads as well as a growth factor essential to a frog’s sprouting of large eyes. Within two weeks -- twice as fast as human cell development -- the embryonic cells became progenitor (forerunner) cells for retinal cells. The scientists injected these into a damaged mouse retina, where they developed into cones (the retinal cells responsible for color), rods (the cells that allow night vision), and other cells.
The scientists' next step will be to measure the nerve reactions within the repaired mouse retinas to see if vision has improved. If the research proceeds well, the researchers speculate that human tests might begin in two to three years.
