Stem Cell for Sight
Pioneering stem-cell surgery has restored one mother's sight, says Barbara Lantin
"The nurses told me I should keep the bandages on until the day after the operation, but I peeped through," says Deborah, 35, a civil servant from
"The older ones had changed so much and grown so tall in the two and a half years since I lost my sight, but Miracle touched me most because I hadn't seen her at all. People used to stop me in the street when she was tiny and tell me how pretty she was. I couldn't understand what the fuss was about until I lined up the photos of her when I got home. Then I started to cry."
Deborah, blinded when a woman threw acid in her face at a nightclub in 2002, is one of about 20 patients who have benefited from ground-breaking stem-cell transplantation surgery, performed by Sheraz Daya and his team at the Centre for Sight at
Mr Daya's technique involves taking stem cells from dead donors, living relatives or even the patients themselves. The cells are grown in the laboratory for two to three weeks until they form sheets, which are laid on the surface of the eye to help it heal. All the patients had lost vision because they had few or no limbal stem cells as a result of burns, chemical accidents or disease.
These cells, made just under the surface of the eye, are constantly regenerating: they keep the outermost epithelial layer of the eye clear so that it can act as an barrier against germs and dust. Without sufficient limbal cells, the cornea becomes overgrown, and vision becomes impaired.
"Before we transplant, we scrape off the material that has grown over the eye," says Mr Daya, who this month presented the results of a clinical trial of his technique to an international conference of eye specialists in
Most patients' vision improves quickly but some - like Deborah - require a corneal transplant later. This will fail if it is done before the surface of the eye is fully restored, which is why Deborah had to wait 18 months for her second operation. Mr Daya estimates that the procedure might be suitable for up to 1,000 patients in the
Seeking an explanation for this success, Mr Daya's team made a remarkable discovery. Analysis of patients' limbal stem cells following surgery revealed no donor DNA. "There are new stem cells there and they can only be coming from one place: the patient's own bone marrow. The donor cells we have put on the eye surface have somehow triggered the body into producing its own limbal cells."
This finding means patients no longer need strong immunosuppressant drugs designed to stop the body rejecting donor cells. It may also have major implications for other organs. "If we can figure out what the trigger signal is, we may be able to get heart muscle or even brain tissue to regenerate," says Mr Daya.
Leading transplant surgeon Prof Nadey Hakim of St Mary's Hospital, Paddington, has welcomed Mr Daya's findings. "Should we succeed in generating entire new organs using the patient's own genetic material, this would overcome the likelihood of the patient rejecting the transplanted organ and cancel the need for immunosuppressive drugs," he says. "The work of Mr Daya has undoubtedly brought us closer to realising this dream."
For Deborah, a dream has already come true. After eight operations - some of them excruciatingly painful - and two and a half years of blindness, she had despaired of regaining her sight. "Sometimes, I would just sit and cry," she recalls. "I couldn't cook for my children, plait their hair, sort their socks. When one of my sons was sick, I could not see what was wrong or pour his medicine. Miracle swallowed a coin and I had no idea until she vomited it up."
Bonding with her new baby took longer than usual. "I was not interested in her when I was pregnant or until she had her first injections and I heard her scream. Now she goes everywhere with me. I call her my handbag - I never put her down."
Deborah can now perform all the tasks she could do before her accident, including driving, but is considering having surgery on her left eye, which was damaged not only by the acid, but also by a childhood accident with a swing. She hopes to return to work shortly. "I don't have to ask anybody to do anything for me now," she says. "I feel like a human being again."
· The Centre for Sight: 01342 321201