Study demonstrates stem cell safety

New research has for the first time demonstrated the medium- to long-term safety, tolerability and possible efficacy of transplanting human embryonic cells in humans.

Published in The Lancet, the paper looks at a US trial of stem cells among 18 patients suffering from different forms of macular degeneration.

Nine had Stargardt's macular dystrophy, a leading cause of juvenile blindness, while the other nine suffered from dry atrophic age-related macular degeneration.

Participants were injected with one of three different doses of retinal cells derived from early-stage embryos - 50,000, 100,000 or