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By Anne Harding
NEW YORK, Mar 13 (Reuters Health) - A new technique for harvesting eye stem cells for transplantation could speed up a surgery in which the cells are used to restore vision.
The mechanical device removes stem cell-containing tissue from cadaver eyes, a type of tissue known as the limbus. It is an adaptation of a machine called a microkeratome, and shaves a thin layer of tissue from the eye surface, according to Dr. Roy S. Chuck, an assistant professor of ophthalmology at the University of California at Irvine, and colleagues.
In the American Journal of Ophthalmology, Chuck reports on using the device on four cadaver eyes. While harvesting the tissue by hand with a scalpel takes 15 to 20 minutes, the device removed the limbus in 5 to 10 seconds, he reports.
The transplantation of stem cells into the eye is a relatively new procedure that offers hope to people whose eyes are damaged by burns, chemicals, or disease and cannot be helped by any other treatment.
Such patients are at risk for blindness because their cornea's epithelium, a thin layer of cells on the surface of the eye, is destroyed.
When the epithelium is damaged by disease or injury, it is replaced with opaque scar tissue, impairing vision. Thousands of people in the United States lose their vision each year for this reason.
If a person only has damage in one eye, stem cells--which have the ability to regenerate epithelium--can be harvested from the other eye. For those with damage in both eyes, donor cells can come from a relative or from a cadaver. Leaving the donor with at least half of his or her stem cells will allow the epithelium to regrow.
The success of the surgery depends on the severity of the damage to the epithelium, and the success rate is about 25% for those with the most severe damage.
The next step, Chuck said, will be to use the device for human transplants. "These trials should take place later this year," he told Reuters Health. "We would also like to make the device portable, especially for use in third world nations where corneal scarring from trachoma is a big problem. We are currently trying to raise grant support for this effort." Trachoma is a bacterial infection that blinds millions of people worldwide, mainly in Africa and Asia but also in the southeastern United States.
While the device could indeed speed up the operating time for performing the surgery, Dr. Edward Holland told Reuters Health, it will not make the surgery more effective.
"This study just simply looked at another way of cutting cells out of cadaver eyes," noted Holland, director of corneal services at the Cincinnati Eye Institute. "The real story," said Holland, who has been performing the surgery for 14 years, "is limbal cell transplantation."
SOURCE: American Journal of Ophthalmology 2001;131.
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