Eyes and Stem Cells
Two and a half years ago, Edward Bailey had a stem cell transplant to his left eye, which had been blinded in an industrial accident in 1993. His vision in the left eye is blurry, but he is able to see colors and shapes. Mr. Bailey told his story earlier this year on CNN
. The operation that Edward Bailey had was one of several in Britain that involved taking naturally occurring limbal stem cells from donors’ eyes, growing them in culture, and then transplanting them into the patient. According to The Times
, the doctors were “astonished at how the cells appeared to trigger the eye’s natural regeneration of its damaged surface.” There was no rejection issue, either. In these cases, the patients had all lost sight due to corneal injury, not to retinal damage. Similar work has been done at the Medical College of Wisconsin
since at least 2001.
How common is this story? We hear about stem cells being used in trials for heart conditions and leukemia, and earlier this month I reported that they are being used in deafness. What’s the standing with stem cells and vision?
Over a year ago, Dr. Robert Lanza’s team at Advanced Cell Technology in Massachusetts was able to make embryonic stem cells differentiate into retinal cells. Lanza was quoted in the MSNBC story
on this as saying, “They looked like little eyeballs. These things seem to be trying to assemble into primitive eyes.” Although the researchers were only clearly able to identify retinal cells, some of the cells resembled those that generate rods and cones. Lanza worked from cells which were not federally approved, and so was able to avoid the issue of contaminated lines; potentially, his cells could be transplanted into a human. He said that using cloning technology would ensure a genetic match and avoid rejection issues. The study was also reported by Wired News, and Lanza was quoted in that article as saying, “Embryonic stem cells like to do what they want to do, and one of the things they like to do is make neurons. They tend to be much easier to derive.” Retinal cells are actually a type of neuron. The Wired News article concluded,
Previous research has shown limited success in transplanting retinal cells derived from fetal or adult stem cells. Lanza and his colleagues are confident that their embryo-derived cells will work even better, because the cells are even more similar to natural retinal cells than those that were tested previously.
I checked the Advanced Cell Technology website and there are no press releases or published papers with any follow-up to this research, so I can’t tell you the current status of Lanza’s work in this area. In another study that was published in the journal Stem Cells on August 25, 2005, researchers from the University of Missouri demonstrated that embryonic stem cells transplanted into mice helped prevent retinal degeneration.
In 2004, researchers at Harvard's Schepens Eye Research Institute transplanted retinal stem cells from the eyes of healthy mice into mice who had retinal disease. After several weeks the transplanted cells had migrated into the damaged areas of the eyes and appeared to have become normal cells. (This study is reported on EurekAlert.)
The International Society for Stem Cell Research has a page devoted to the status of stem cell research on eyes.
It appears that for people with corneal injury, the potential for regaining sight through a limbal stem cell transplant is increasing. Stem cell treatment for retinal degeneration, disease, or injury is still a long way from actuality.