A US company has been granted beneficial 'orphan drug' status by the US Food and Drug Administration (FDA), for an embryonic stem cell therapy it's developing to treat a rare form of blindness.

Advanced Cell Technology (ACT) of Worcester, Massachusetts, USA, will get advantages from the status through the Orphan Drug Act, including tax breaks, access to grant funding for clinical trials, accelerated FDA approval and up to seven years of market exclusivity. The Act helps to speed therapies for diseases afflicting fewer than 200,000 Americans, making developing drugs for them unattractive to pharmaceutical firms.

The company are developing a therapy for Stargardt's Macular Dystrophy - a blindness syndrome which destroys retinal cells in the eyes of young adults and children, and affects under 30,000 people in the US. Their treatment uses human embryonic stem cells to recreate retinal pigment epithelium cells, which support the photoreceptors needed for vision. It has shown promise when tested on rats and mice.

The embryonic stem cells used in the therapy are derived from pre-blastocyst human embryos. A change to regulations proposed by the US National Institutes of Health, and reported in BioNews last month, means work on these cells should become eligible for federal funding.

Mr William Caldwell, Chief Executive of ACT said, as well as creating a therapy for Stargardt's, the company also aims to use the work to develop similar treatments for blindness-related ailments such as macular degeneration, increasingly a problem because of the aging populations in many developed countries.