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Transplanting human fetal retina to RP patients shows promise
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HYDERABAD, India — After 12 years of animal experimentation, a researcher here has successfully performed retinal transplantation using human fetal neural retina on three patients with advanced retinitis pigmentosa (RP).
According to Manuel del Cerro, MD, professor of ophthalmology at the University of Rochester School of Medicine and Dentistry, this is the first time there has been a human application of such a transplantation.
No complications
Del Cerro and a team of Rochester researchers were invited to collaborate with ocular surgeons at the L.V. Prasad Eye Institute here. The three male patients, age 24 to 32, were all long-time patients of the institute and had a history of retinitis pigmentosa that rendered them legally blind, having only light perception in each eye. The patients were grafted with the fetal retina in February 1995.
The gestational age of the elective aborted fetuses ranged between 14 and 16 weeks. "Donor tissue was mechanically dissociated into small cell clusters and single cells," explained del Cerro. "Using an anterior approach, this suspension was then injected into the subretinal space, temporal to the macula." One eye in each patient received the healthy cells.
Del Cerro and his colleagues presented 9-month postoperative observations of the extremely limited study at the Association of Research in Vision and Ophthalmology annual meeting in Ft. Lauderdale, Fla. "There were no clinical signs of rejection, despite the lack of immunosuppression," he said, citing that possible complications could have been inflammation, retinal detachment and hemorrhaging.
Both donors and hosts tested negative for transmissible pathogens. No immunosuppressive drugs were administered.
In addition to being complication-free, the procedure resulted in a visual-acuity improvement in one of the three patients. At 9-month follow up, that patient improved to 20/200; however, it was limited to the central island.
Del Cerro speculated that the reason a change in visual acuity took close to a year is because fetal tissue is only partially developed at 14 to 16 weeks. "This tissue needs to mature," he said.
The other two patients showed no noticeable change in visual acuity.
Del Cerro, who later this year will present the results of an additional seven patients, said surgeons should not be intimidated by the logistics of the procedure. "The surgery is no more difficult than any other form of retinal surgery," he said.
Future developments
The researcher also said that transplantation in the future could involve a more developed fetus, as well as harvesting of perinatal retinas. "Unfortunately, there are a number of children who die about the time of birth," he said. "This is something to be explored. We don't know at this time if it would work."
Although it is too early to promote the procedure as a cure for RP, said del Cerro, "this is perhaps a viable treatment for some forms of the disease. It shows significant promise."
While the immediate expectation of these transplants is not a reversal in the patients' blindness, "the transplantation was performed with the hope and expectation that the transplanted cells — replacing the damaged photoreceptor cells caused by RP — would make a connection," he said. "If the transplanted healthy cells can truly take hold, this procedure could revolutionize medicine's approach to RP and other ocular diseases that are considered untreatable by medical or surgical means."
For Your Information:
- Manuel del Cerro, MD, is director of the Retinal Transplantation Group and professor of ophthalmology, neurobiology and anatomy, University of Rochester. He can be reached at 601 Elmwood Ave., Box 659, Rochester, NY 14642; (716) 275-4027, fax:(716) 244-5667, e-mail: mdelcerro@medinfo.rochester.edu.