September 15, 2004.
By Gabe Romain,
Transplanted adult stem cells have been found to preserve visual function in mice genetically engineered to model a degenerative eye disease.
Researcher Martin Friedlander and colleagues of The Scripps Research Institute in La Jolla, California used a combination of mouse and human bone marrow stem cells to regenerate the cellular structure of retinas damaged by retinitis pigmentosa—a degenerative eye disease that leads to vision loss and blindness.
"The surprising findings by Dr. Friedlander and colleagues establish a dramatically new paradigm for understanding and potentially treating retinal degenerative diseases using a cell-based approach," says Paul Sieving, director of the US National Eye Institute in Bethesda, Maryland.
Retinitis pigmentosa is a disease characterized by a progressive degeneration of the retina—a thin layer of cells at the back of the eyeball that convert light into neural signals.
The retina contains a number of specialized cells, including rods and cones, which capture light and send electrical signals to the brain. It also has an extensive vasculature—a layer of blood vessels formed by endothelial cells, the major cell type lining blood vessels.
As retinitis pigmentosa progresses, the outer layer of the retina containing the rods and cones, as well as other neuronal layers, degenerates. The disease causes a progressive deterioration of vision, and can lead to partial or complete blindness.
Transplanting bone marrow-derived stem cells into the retina is seen as a possible treatment, as they have the potential to develop into a number of different cell types, such as red blood cells, platelets, white blood cells and endothelial cells, and are well-known for their regenerative capabilities.
Friedlander and colleagues have now found that the stem cells, injected into the eyes of mice with a model of retinitis pigmentosa, lead to the development of blood vessels. Some stem cells were found to incorporate into the vasculature of the retina while others took up residence very close to blood vessels.
This provided a protective effect, rescuing and stabilizing the retinal vessels when they would otherwise degenerate. In addition, the stem cells protected the retinal neurons from death. The protection seemed to be directed at the cone cells—photoreceptors found in the center of the retina that function in relatively bright light.
"These cells are truly remarkable and provide a rationale basis for using vascular reconstructive approaches in the treatment of diseases in which the endogenous vasculature is subject to degeneration or malfunction," says Friedlander. "Since most diseases that cause profound visual loss have abnormalities in the vasculature, the potential clinical application of this approach is quite broad."
Friedlander and colleagues will next perform more preclinical studies aimed at taking the approach into clinical trials.
The research is reported in the Journal of Clinical Investigation (read abstract).
Copyright © 2002-2004 Betterhumans
End of article.
Any further reproduction or distribution of this article in a format other than a specialized format is an infringement of copyright.
Go to ...
Top of Page.
List of Categories.
Blind World Website
Designed and Maintained by:
All Rights Reserved.