Stem cells injected into the eyes of blind patients have cured them for the first time with no side effects.
The breakthrough has proved safe three years after patients were injected with stem cells derived from human embryos.
More than half of the patients with macular degeneration – where the eye’s light-sensitive cells are progressively destroyed – experienced a significant improvement in their eyesight, but none showed any adverse effects directly due to the transplant of the embryonic cells.
Follow-up testing showed that 10 out of 18 treated eyes had substantial improvements in how well they could see, with 8 patients reading over 15 additional letters in the first year after transplant.
Untreated eyes did not show similar visual improvements.
This is the first evidence of the medium-term to long-term safety and tolerability of transplanting human embryonic stem cells (hESCs) in humans.
