Retina Transplants Show Promise in Patients with Retinal Degeneration

An experimental transplant of cells into the eyes of patients with failing sight improved vision in most cases, US researchers say.

Following a successful experimental implant of retinal cells in visually impaired patients, researchers have reported promising results. Preliminary research shows encouraging results with transplantation of retinal cells in patients with blindness caused by retinal pigmentosa (RP) and age-related macular degeneration (AMD).

These findings, published in the American Journal of Ophthalmology, offers hope to the millions of Americans who suffer from such debilitating diseases.

In the FDA-monitored study, lead author Dr. Norman D. Radtke of the University of Louisville, KY, and colleagues performed the experimental transplant procedure in ten patients with vision loss resulting from retinal degeneration: six patients with RP and four with the dry form of AMD. Although they have different causes, both RP and AMD lead to destruction of the light-receiving (photoreceptor) cells of the retina. There is currently no effective treatment for recovery of visual loss from either condition.

RP and AMD are the most common causes of gradual and irreversible destruction of retinal cells, leading to blindness in old age.

AMD is the leading cause of vision loss among Americans age 60 and over. The macula is the central part of the retina, a layer of light-sensitive tissue at the back of the eye. When cells in the macula deteriorate, the result is a gradual or sometimes rapid loss of central vision. Both the wet and dry forms of AMD make reading, recognizing faces and driving increasingly difficult, if not impossible.

All ten RP and AMD patients underwent transplantation of fetal retina cells. The cells were implanted along with the attached retinal pigment epithelium, which plays a key role in nourishing the photoreceptor cells. The concept behind the experimental procedure was that the new cells would grow to replace the damaged photoreceptor cells, connecting to the patient’s remaining retina.

The technique required the researchers to implant the fetal retinal cells alongside cells, which have the job of nourishing them; this facilitated new cells to join forces with the existing cells for improving overall vision.

Hope for Better Sight
Follow-up testing showed visual improvements in seven of the ten patients: three patients with RP and all four patients with AMD. Although vision remained in the “legally blind” range for all patients, the gains in vision were measurable and significant. Additionally, one subject showed improvement six years after the operation.

The findings showed no rejection despite the lack of perfect immunological match between the transplant donors and recipients. University of Louisville scientists concluded that there is a special immunologic protection in the tissue which influences the patient’s immune system. There were some unexpected positive results in two patients who showed improved vision in untreated eyes; the cause is not known yet, but may have something to do with the transplantation effect on the immune system.

“This clinical evidence shows the promise of our method to alter progressive vision loss due to incurable degenerative disease of the retina,” said Dr. Radtke. “What we have learned will help us to refine this method and obtain further evidence that retinal transplants may be a viable therapy for retinal degenerative disease.”

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