Modified Human Embryonic Stem Cells Can Preserve Visual Function in
Diseased Rat Retina
By Gail M. Seigel*
 
Age-related macular degeneration (AMD) is a blinding disease of the retina affecting 1.75 million Americans. ¹  Vision loss in AMD occurs due to the death of light-sensing cells in the central part of
the retina, the area of highest visual sensitivity.  In order to test new treatments before trying them in humans, an "RCS rat" was developed by the Royal College of Surgeons (RCS) that undergoes retinal cell death and visual loss that, in some ways, resembles retinal diseases seen in humans.
 
In a study led by Dr. Raymond Lund's group at the Moran Eye Center in Utah,² human embryonic stem cells were modified to become specialized retinal pigment epithelial (RPE) cells.   These RPE cells were injected into the eyes of RCS rats at an early age, prior to the onset of  disease, to see if they could prevent the death of retinal cells over time.  For comparison, a control group of RCS rats received an injection of liquid that did not contain RPE cells.
 
Two weeks after the injections, all groups of animals were tested for their ability to react to light and generate the electrical signals that indicate processing of visual information. RCS rats receiving RPE
injections were better able to detect and process light signals in the retina than were control RCS rats. The cellular structure of the rats' eyes was examined under a microscope. Animals that received RPE
injections had fewer retinal cells die over the course of the experiment than control RCS rats.   Further analysis showed that the injected human RPE cells partially prevented the death of the rats' own retinal cells.
 
In summary, it appears that human embryonic stem cells may hold promise for new treatment strategies that target blinding retinal diseases such as macular degeneration.
 
Notes
1. Prevalence of Age-Related Macular Degeneration in the United States. The Eye Diseases Prevalence Research Group, National Institutes of Health. Archives of Ophthalmology 2004; 122:564-572

2. Human Embryonic Stem Cell-Derived Cells Rescue Visual Function in Dystrophic RCS Rats.
RD. Lund, S. Wang, I. Klimanskaya, T. Holmes, R Ramos-Kelsey, B. Lu, S. Girman, N. Bischoff, Y. Sauve, and R. Lanza, Cloning and Stem Cells, 2006; 8 (3): 189-199.

 
*Author affiliation:
Gail M. Seigel, Ph.D.
Department of Ophthalmology, Ross Eye Institute University at Buffalo,
SUNY
Buffalo, NY USA

Posted September 29, 2006