Embryonic stem cells can serve as a renewable source of replacement tissue to rescue visual function in rats with degenerative eye disease similar to age-related macular degeneration, a leading cause of blindness in humans, according to a report to be published in the Fall 2006 (Volume 8, Number 3) issue of Cloning and Stem Cells, a peer-reviewed journal published by Mary Ann Liebert, Inc. The paper is available online ahead of print at www.liebertpub.com/clo
Robert Lanza, M.D. and Irina Klimanskaya, Ph.D. at Advanced Cell Technology (Worcester, MA), and Raymond Lund, Ph.D. and colleagues at the University of Utah Health Science Center (Salt Lake City) generated retinal pigment epithelium (RPE)--the cells that support photoreceptor function in the eye--from human embryonic stem cell lines grown in culture in the laboratory. They transplanted the engineered tissue into the eyes of rats that had a defect in their RPE. This defect results in the loss of photoreceptors and visual function.
The authors reported 100% improvement in visual performance (spatial acuity) in treated animals compared to an untreated control group, and the transplanted RPE cells did not cause any pathology. In the treated rats, spatial acuity, or the ability to see fine detail, was approximately 70% that of normal rats (that had no RPE defect).
"These observations are very exciting as they show that one day it will be possible to treat diseases of human eyes with cells," says Ian Wilmut, Ph.D., Editor-In-Chief of Cloning and Stem Cells and director of the Centre for Regenerative Medicine, in Edinburgh, Scotland. "They also emphasize the great potential benefit of research with human embryo stem cells, in this case for cell therapy."
Macular degeneration is the leading cause of blindness in persons over age 60 in the United States and affects more than 30 million people worldwide. Embryonic stem cells would offer a readily available, safe, and reproducible source of replacement tissue to restore photoreceptors damaged or destroyed by disease and to restore a range of visual functions.
"One important advantage offered by hES-derived cells over other cells developed to mimic or replace lost retinal pigment epithelium is that they more closely resemble primary human RPEs," stated Raymond D. Lund, Ph.D., Professor at the Moran Eye Center, University of Utah Health Science Center, Salt Lake City and the study's lead author. "Another significant advantage of using these cells is that a range of lines can be derived allowing the opportunity to 'tissue match' donor cells with recipient, a real advantage given that RPE cells are highly immunogenic and susceptible to rejection without some form of immunosuppression."
"Embryonic stem cells promise to provide a well-characterized and reproducible source of replacement cells for clinical studies," stated Robert Lanza, M.D., Vice President of Research & Scientific Development at ACTC and senior author of the paper. "All 18 human embryonic stem cell lines we studied reliably produced retinal cells that could potentially be used to treat retinal degenerative diseases, such as macular degeneration. We showed that these cells have the capacity to rescue visual function in animals that otherwise would have gone blind. Importantly, the cells did not appear to cause any unwanted pathological responses in the animals following transplantation."
Once useful human therapies are available which have been created using hESC the people making ethical arguments against the use of hESC are going to face much more opposition than they do today. The hypothetical future promise of hESC doesn't today motivate people to support hESC research as much as the availability of real treatments will.
The opponents of the use of hESC really ought to push harder to increase funding to develop other methods to create flexible and youthful stem cells. If they fail to do that they will find they are fighitng for a losing cause.
|Share |||Randall Parker, 2006 September 24 09:04 PM Biotech Stem Cells|