Progressive blindness has been reversed in two patients with age-related macular degeneration, also known as AMD. AMD is a leading cause of blindness in people over 50. AMD damages the central portion of the retina, called the macula, which decreases vision over time, and can lead to blind spot formation.
Phase 1 clinical trial results highlighting the effectiveness of a stem cell-based therapy were published two weeks ago in Nature Biotechnology . This therapy involves surgically placing a tiny patch of retinal cells, derived from human embryonic stem cells, in a patient’s retina. To create the single layer patch, the retinal cells are put into a synthetic membrane to keep them together in the eye.
This treatment effectively provides the eye with healthy new cells to replace damaged ones. While other treatments for some forms of AMD already exist, they involve frequent eye injections, and can only prevent the disease from further progressing. After 12 months post-surgery, both patients reported improved vision, which has lasted for an entire year.
Unfortunately, small areas of the patch were missing, indicating a potential immune response from the patient. To prevent rejection of the patch, the patients were given a local immunosuppressant long-term. Because stem cells grow so rapidly, there are also concerns that the patch may become cancerous. Thus far, there is no evidence indicating such effects.
It is also important to remember that this is a Phase 1 trial with only two patients. “While the two patients reported quite stark improvements, only testing in more patients can solidify its potential as a future treatment,”said Garrett Dunlap, a Biological and Biomedical Sciences Ph.D. student at Harvard University. “Further, a year simply isn’t enough time to ensure the long-term safety of these implants. Some side effects may take awhile to arise, so researchers must continue to monitor these patients.”
Advances in stem cell research “have enabled this group to improve vision to a greater degree than previous therapies, though with only two patients there is much that remains to be seen,” adds Nivanthika Wimalasena, a Neuroscience Ph.D. candidate at Harvard University.
With these initial promising results, 8 more patients will be enrolled into this clinical trial.
The lead researcher of this study, Dr. Pete Coffey, from the University College London’s Institute of Ophthalmology, told BBC, “We hope this will lead to an affordable ‘off-the-shelf’ therapy that could be made available to NHS patients within the next five years.”
Acknowledgements: Thank you to Garrett Dunlap and Nivanthika Wimalasena for their commentary on the implications of this work.
Managing Correspondent: Chelsea Weidman
Press Article: Doctors Have Restored The Sight of Two People in a Monumental World First. ScienceAlert.
Original Journal Article: Phase 1 clinical study of an embryonic stem cell-derived retinal pigment epithelium patch in age-related macular degeneration. Nature Biotechnology.
Image Credit: Wikipedia