Thomas H. Maugh II
Los Angeles Times
August 26, 2010
An experimental synthetic cornea implanted in 10 patients may be a potential alternative to cadaver corneas for curing vision loss due to corneal inflammation and scarring, researchers said Wednesday.
Eye surgeons currently use primarily cadaver corneas for transplants, but that requires the use of anti-rejection drugs and presents a risk of infection. Plastic corneas can also be used, but they present other problems and are generally tried only when tissue transplants have failed.
The new artificial corneas use collagen produced in yeast as a scaffolding that allows cells from the recipient to grow into the graft so that it mimics the original tissue. The two-year preliminary test showed that the biosynthetic corneas restored vision as effectively as cadaver corneas, did not require anti-rejection drugs and allowed normal tears to form.
"This is a huge breakthrough," said Dr. Francis W. Price Jr., founder and president of the board of the Cornea Research Foundation, who was not involved in the research. "It still has to go through additional studies … but it shows a lot of promise."
An estimated 5 million people worldwide suffer corneal damage from trachoma, an eye infection caused by the bacterium Chlamydia trachomatis, and another 1.5 million to 2 million people develop it as a result of ulceration and trauma. In the United States, about 42,000 cadaver cornea transplants are performed each year and another 10,000 corneas are exported to other countries, according to Marianne O'Connor Price, executive director of the Cornea Research Foundation.
"The U.S. is very fortunate that everybody who needs a transplant here is able to get one, but there is definitely a big shortage around the world," she said. "Even people here could benefit if there was a synthetic cornea that eliminated the chance of rejection."
The new study, reported Wednesday in the journal Science Translational Medicine, used biosynthetic collagen produced by FibroGen Inc. of San Francisco. A team headed by Dr. May Griffith of the Ottawa Hospital Research Institute in Canada molded the collagen into an artificial cornea and demonstrated that it worked in animals.
Dr. Per Fagerholm of Linkoping University in Sweden then implanted the corneas in one eye of each of 10 Swedish patients with central corneal scarring. The researchers found that, after two years, no complications developed and, with the use of contact lenses, vision was as good as with cadaver transplants. Contact lenses are normally used with the latter as well.
The study is the first to show that an artificially fabricated cornea "can integrate into the human eye and stimulate regeneration," Griffith said.
Griffith said her team was now building a clean room to manufacture more of the corneas and that she hoped to begin larger clinical trials after the first of the year with about 20 to 25 patients.