DURHAM -- One of the places that researchers are hoping people can benefit from stem cells' restorative properties is degenerative diseases of the eye.
Glaucoma, macular degeneration and the effects of diabetes destroy photoreceptors and other neurons in the retina, the inner lining of the back of the eyeball. Unlike other cells in our bodies, neurons don't naturally regenerate. Once they're damaged, they -- and the eyesight of people with those diseases -- are gone for good.
Early findings by Duke University ophthalmology researcher Dennis Rickman and others indicate that stem cells indeed restore damaged retinas.
"The cells migrate to the area of injury, and in many cases appear to integrate into the tissue and differentiate into those cells," Rickman said.
But it will take a lot more research before those findings can yield therapies.
"We don't know the full potential of these cells," he said.
Rickman's studies have demonstrated the effect in mice and rats, using stem cells from the rodents. But it's not yet clear whether it restores their vision. Finding out will require studies using electrodes that measure their retinal response to flashes of light, producing what's called an electroretinagram.
Despite the promise of stem cells, which are undifferentiated cells that can take on the properties of different kinds of cells and replicate themselves, research funding is limited, mostly because of federal restrictions on research with stem cells from human embryos, where they are most versatile. Stem cells also are found in postnatal people and animals, and it is these that Rickman has used so far, not embryonic cells.
Even so, he believes in keeping the option open to what he calls the ethical use of both adult and embryonic cells to treat degenerative eye diseases. To develop alternative sources of funding, Rickman has established and chairs SCIfEyes, a nonprofit organization with an advisory board including his wife and fellow Duke eye researcher, Catherine Bowes Rickman.
SCIfEyes received $10,000 last November from "Saturday Night Live" comedian Will Forte, who is its national spokesman, during Forte's visit to Duke.
Dennis Rickman is himself a former comic who, as a member of the Groundlings Theater in Los Angeles in the early 1980s, did improvisational comedy. His day job at the time was as a research technician in ophthalmology, in which he holds a doctorate. Forte also is a former Groundling, as are a number of other SNL alumni. Other entertainment celebrities also have contributed to the stem cell research funding cause, as in their backing of California's $3 billion bond issue for stem cell research that voters there approved in 2004.
Dennis Rickman's interest in stem cells, however, came from a serious turn in his own life.
In 1995, five days before his wife gave birth to their daughter, he was diagnosed with leukemia. After two rounds of chemotherapy, he relapsed a second time, as a search for a compatible bone marrow donor had proved fruitless. Finally, after a year, doctors found a close match with a German woman. In the summer of 1996, in Los Angeles, he received the transplant, which is a form of stem cell therapy. He's been free of the disease for 10 years now.
"This year is a milestone," he said.
Dennis Rickman urges people to join the National Marrow Donor Program. They must give a few drops of blood and be willing to give marrow if asked. Racial minorities, particularly, are underrepresented in the donor registry, he said.
In 2000, the Rickmans moved to Duke from the University of Iowa, where they had been for three years after working at St. Louis University.
"It wasn't until I came here that all these pieces fit together," Dennis Rickman said, although he had been thinking about stem cells for treating eye diseases since his marrow transplant.
One of those pieces is Duke's strength as a biomedical research center, the Rickmans said. Duke's Stem Cell Research Program is part of its Comprehensive Cancer Center, and extends to about 30 labs within Duke. Researchers are studying a number of possible applications.
"This is the cutting-edge place," Catherine Bowes Rickman said.
Another factor is Duke Medical School's program that allows third-year medical students to do research full-time, they said. One such student, Emily Davies, is working in Dennis Rickman's lab. Forte's gift will fund a research fellowship.
Building a base for the long term and for the next generation of researchers, is another priority for SCIfEyes, said Dennis Rickman, 54.
"Because I'm not naïve enough to think that it will be done in the next few years," he said. "When I'm not able to do this work anymore, there will be someone else carrying it on."