As one of the leading causes of vision loss, age-related macular degeneration (AMD) occurs due to the destruction of the part of the eye responsible for sharp, central vision. In a pioneering surgical procedure, doctors in the U.K. have used human embryonic stem cells in an attempt to cure a patient of the most severe form of AMD.
The surgery, which takes between one and two hours, is part of a trial looking into the safety of transplanting healthy eye cells derived from embryonic stem cells into patients who have lost vision due to AMD. The surgeons use a specially engineered patch of retinal pigment epithelial cells (RPE) and implant it in a region of the eye called the macula, the area responsible for central, high-resolution vision, where the patient’s original cells have been damaged.
There are two types of AMD, a “dry” form and a “wet” one. Dry AMD is caused by a breakdown or thinning of the layer of RPE cells in the macula and is characterized by the build-up of yellow deposits called drusen. This is the most common and least serious form of AMD, and it’s estimated that around one in four people over the age of 60 will develop it. It can, however, lead to the development of wet AMD, which is when the blood vessels behind the macula become abnormal and leak fluid or blood. This form of AMD is very serious, and can cause vision loss in a matter of days.
The surgery carried out is part of a trial run by the London Project to Cure Blindness, which over the next 18 months plans to carry out a further nine operations to investigate the safety and efficacy of the procedure. “There is real potential that people with wet age-related macular degeneration will benefit in the future from transplantation of these cells,” explained retinal surgeon Lyndon Da Cruz from Moorfields Eye Hospital, where the operation was carried out.
“This is truly a regenerative project,” Da Cruz told BBC News. “In the past it's been impossible to replace lost neural cells. If we can deliver the very layer of cells that is missing and give them their function back this would be of enormous benefit to people with the sight-threatening condition.”