by Dan Roberts
(Updated September, 2004)
Scientists are researching a new method of retinal transplantation in the continuing effort to restore sight to the blind. Drs. Robert Aramant and Magdalene Seiler (Doheny Eye Institute, Los Angeles) have had preliminary success transplanting double layers of cells from the retinas of aborted fetuses.
The two layers consist of 2mm squares of both the photoreceptor cells (the rods and cones) and the underlying epithelial cells. These sheets are inserted in tandem behind the degenerating retina, with expectations being that the epithelial cells will continue to nourish the new photoreceptors as they take the place of the old cells. Keeping the layers intact is vital to maintaining the circuitry between the photoreceptors. The use of fetal cells reduces the chance of rejection by the host, thereby eliminating the need for immunosuppressive drugs.
Results have been promising. In rodent models, the cells survived successfully and also formed connections with the remaining retinal cells. In human patients with retinitis pigmentosa, reports of improved vision have been observed through subjective reports. According to the researchers, this improvement could be a result of a “rescue effect.” This is a short-term reaction to surgery caused by the body’s release of growth factors that save damaged or diseased cells.
Dr. Norman Radtke (University of Louisville in Kentucky), who performed the surgery, hopes that this vision improvement is from connections between the old and new cells, rather than a rescue effect. Further study will provide more insight.
Dr. Radtke and his colleagues reported in the August 2004 issue of the Archives of Ophthalmology (Arch Ophthalmol 2004;122:1159-1165) that they had successfully and without complications performed a fetal cell transplant on a 64-year-old woman with retinitis pigmentosa.
The subject’s visual acuity in the treated eye was 20/800 before surgery. Six months after surgery, her acuity had improved to 20/400, and at twelve months, it had reached 20/160. After two years, she could read large-print with the operated eye.
The research team concluded that “Diseases that affect the retinal pigment epithelium and photoreceptor cells of the retina (eg. RP, age-related macular degeneration, rod-cone dystrophy, and Stargardt disease) might conceivably benefit from this type of transplantation in the future.”
by Dan Roberts