Blind people around the world could have their vision actually restored using stem cells taken from the eyes of non-living donors, according to new research from Scotland.
Thanks to the pioneering tissue transplant, eight patients with a common condition that destroys vision have had the affected area repaired—and two were able to read again after having severe macular degeneration.
The revolutionary treatment may lead to a cure for blindness caused by damage to the cornea, the protective surface of the eye. It often becomes clouded in older people through injury or infection. In more underdeveloped countries, children and younger people are also increasingly prone.
“The findings from this small study are very promising and show the potential for safe stem cell eye surgery as well as improvements in eye repair,” said study leader Baljean Dhillon, professor of clinical ophthalmology at the University of Edinburgh’s Centre for Clinical Brain Sciences.
Describing the breakthrough as a “world first,” Dhillon and colleagues said that it sheds light on the causes of sight disorders and shows how eye damage can be fixed with organ donor stem cells.
The study published in STEM CELLS Translational Medicine focused on limbal stem cells, which are typically lacking in patients suffering from corneal blindness. The cells lie in the top layer of the cornea, the epithelium, and act as a barrier against dust and germs.
Without this tissue the cornea becomes irregular, destroying vision and leaving the eye prone to infection. It can result from damage caused by chemicals or heat, or a disease called aniridia, which can lead to scarring and severe vision loss in both eyes as well as chronic pain and redness.
Normal healthy corneas are transparent, but when these specialized cells are lost, the cornea becomes scarred and blurred.
As a means of repairing the cornea, the team used samples from people who had donated their eyes after death in order to grow the stem cells.
The researchers then divided 16 patients between the ages of 20 and 74 into two groups, one of which was randomly selected to receive the transplanted tissue. They were also given standard eye drops and immune system suppressing drugs in order to reduce the risk of rejection.
Those given the stem cells showed significant improvement in the ocular surface of their eyes, the outermost layer, over the course of 18 months. These results were not seen in the control group that received eye drops.
It is the first time that stem cells have been used for this purpose in a clinical trial, the gold standard scientific method for testing a new treatment.
The researchers hailed the step as a landmark for cell-based surgery and claimed that it shows promise for repairing the eye’s surface and paving the way for similar donor trials to be planned.
They believe the immune system could play a vital role in some forms of limbal stem cell deficiency (LSCD), but say more research is needed.
“Limbal stem cell deficiency (LSCD is an irreversible disease resulting from the loss or dysfunction of these epithelial stem cells. The corneal epithelium becomes deficient and is replaced by the surrounding conjunctival epithelium, resulting in a thickened, irregular, unstable epithelium, often with inflammation,” said Dhillion.
Dhillon hopes it could lead to new ways to tackle other forms of blindness. In the UK alone, there are almost 2 million people living with sight loss with around 360,000 registered as blind or partially sighted.
“Our next steps are to better understand how stem cells could promote tissue repair for diseases that are extremely hard to treat and if, and how, they could help to restore vision.”
Both the stem cell and control groups showed improvements in vision which the researchers said warrants further investigation in a larger trial.
Marc Turner, medical director of the Scottish National Blood Transfusion Service and Professor of Cellular Therapy at Edinburgh University, said: “Clinical studies such as these help us to understand how complex new cellular therapies may be able to complement existing medical approaches in restoring function to damaged tissues and organs.”
Last year, two patients had their sight restored after stem cells were used to regrow the cells responsible for detailed vision in their eyes.
The man in his 80s and woman in her 60s were able to read again after the procedure. They had severe visual impairment caused by age-related macular degeneration (AMD) which affects around 600,000 people in the UK alone.
The University College London team said the treatment could be effective in other blindness causing diseases.
