Washington Post, September 21, 2006
By Maggie Fox, Health and Science Correspondent
WASHINGTON (Reuters) – Human embryonic stem cells can partly restore vision in blinded rats, and may offer a source of transplants for people with certain eye diseases, researchers at a U.S. company reported on Thursday.
The finding, published in the journal Cloning and Stem Cells, might offer a way to use stem cells that now exist in laboratories, the researchers said.
“We have developed a technology that we hope can be used to treat degenerative eye diseases such as macular degeneration,” said Dr. Robert Lanza of Advanced Cell Technology in Worcester, Massachusetts, who led the study.
“We have demonstrated that these human embryonic-stem-cell-derived cells can rescue visual function in animals that otherwise would have gone blind,” Lanza said in an e-mail.
Stem cells are a kind of template cell for the body, producing the various tissue and cell types. Those taken from days-old embryos are especially malleable, and can produce any cell or tissue found in the body.
Their use and production is controversial, however, with opponents saying it is unethical to use human embryos in this way. They say there are plenty of good experiments to be done using so-called adult stem cells, and scientists are racing to find potential therapies using both kinds of cells.
President George W. Bush restricted federal funding of human embryonic stem cell research to a few lines, or batches, of cells that existed as of August 2001.
Private companies such as Advanced Cell Technology can do as they like, and Lanza’s team used some of those batches from 2001 as well as other batches produced using private funds.
They transplanted the cells into rats genetically engineered to have defective eyes. The rats usually go completely blind.
Lanza’s team was trying to get the stem cells to morph into retinal pigment epithelium cells, which support the photoreceptors in the eye.
Right now there is no ready source of these cells, and the company team thought this may be a good place to test out embryonic stem cells.
“First, the eye is an immune-privileged site—which means transplanted cells won’t be rejected as aggressively as the rest of the body,” Lanza said.
“And second, many of these diseases are quite serious. For instance, macular degeneration alone affects more than 30 million people worldwide and is the leading cause of blindness in patients over 60 in the United States.”
At the start of the experiment, the researchers had to get the stem cells to generate the desired tissue.
“In this study, we reliably generated retinal cells … from all 18 human embryonic stem cell lines that were studied. In fact, we generated 67 different retinal stem cell lines,” Lanza said.
Then they transplanted them into the rats. The cells grew normally and did not—as is a risk with embryonic cells—form tumors, Lanza said.
Soon the rats were able to follow lights with their eyes. They had about 70 percent of the spatial acuity of a normal, healthy rat, Lanza’s team said. When the rats were killed and their eyes examined, they had grown layers of the retinal cells.
“These observations are very exciting as they show that one day it will be possible to treat diseases of human eyes with cells,” said Ian Wilmut, editor-in-chief of the magazine and one of the researchers who cloned the first sheep, Dolly.
Lanza’s company has said it might be possible to create banks of human embryonic stem cells that would provide close tissue matches for a variety of patients.
“A bank of about 100 human embryonic stem cell lines could match half of the U.S. population,” the researchers wrote.