London: Doctors here will carry out Europe's first clinical trial using human embryonic stem cells, BBC reported. Surgeons at Moorfields Eye hospital in London have been given the go-ahead to carry out the trial. They will inject retinal cells into the eyes of 12 patients with an incurable disease, Stargardt's macular dystrophy, which causes progressive sight loss.

The disease develops in childhood and affects around one in 10,000 people. It causes the gradual loss of central vision leaving only peripheral sight, BBC said.

The trial will test the safety of using replacement retinal cells known as retinal pigment epithelial cells, derived from human embryonic stem cells.

The trial is a partnership with an American bio-tech company Advanced Cell Technology (ACT) which has already begun treating patients in California.

Stem cells are the body's master cells - those from human embryos have the potential to turn into any of the 200 or so tissue types in the body. Supporters say embryonic stem cell therapy has the potential to treat not only blindness but a huge range of disorders, from heart disease to cancer.

Opponents object to the procedure because it began with the destruction of a human embryo.