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Ophthalmologists Susanna Park and David Telander plan to begin clinical trials next year using adult stem cells to treat vision problems in patients suffering from blockage of blood flow to the retina

A 'light at the end of the tunnel' could be more than just an expression in the coming years. It could be a reality for people suffering from vision loss due to retinal vein occlusion. UC Davis researchers are poised to begin pioneering the use of adult stem cells to treat vision problems in patients with blockage of blood flow to the retina-the condition known as retinal vein occlusion or "RVO."

This will be the first time stem cell therapy has been tried with humans suffering from retinal vein occlusion. UC Davis scientists also are working on stem cell-based therapies that might delay progression of macular degeneration, which is the number one cause of age-related blindness in the nation. Such projects are all part of the research activities now underway through the new UC Davis Stem Cell Program in Sacramento.

Susanna Park, associate professor of ophthalmology and vision science, is the lead investigator for research to treat the retinal vein problem, a condition that is second only to diabetic retinopathy in causing vascular-related vision loss. Patients with the condition experience a sudden loss of sight due to blockage of circulation of the retinal vein resulting in hemorrhaging and impairment of the function of the retina, which is the light- sensing tissue that lines the back half of the eye.

"Animal studies have shown that in eyes where the retinal blood vessels have been damaged by diabetes or high eye pressure, adult bone marrow stem cells injected in the eye resulted in dramatic healing of the retinal blood vessels," says Park. "Whether this effect results in improved recovery of retinal function is not known, but we have great hope for success."

Clinical trial

She and David Telander, assistant professor of ophthalmology and vision science, plan to begin a Phase I clinical trial in 2008, pending approval by the Food and Drug Administration.

"We want to see if repairing damaged blood vessels using stem cells can improve vision for people with new vision loss from this condition," Park explained.

Park and Telander's therapy involves removing bone marrow from patients with new retinal vein occlusion, purifying the stem cells from their bone marrow and then injecting those cells directly into the eye. UC Davis hematologists Douglas Taylor and Carol Richman will be conducting the bone marrow procedures to obtain the cells Park and Telander need for their clinical trial. Purifying those adult stem cells will then take place in the specially-designed Good Manufacturing Practice (GMP) laboratory now being built as part of the new UC Davis Stem Cell Center. The center is under construction and set to open in 2008.

Currently, Park is working with Jan Nolta, director of the Stem Cell Program to gather the required, FDA long-term safety data from animal models. Once the animal studies have been completed, the team hopes to start its clinical trials.

Stem cells

Telander is also working with Larry Hjelmeland, an ophthalmology and molecular and cellular biology professor at UC Davis, to learn how either embryonic or adult stem cells might be used to delay macular degeneration.

"We're approaching the problem from both sides," says Telander. "Macular degeneration usually results in the slow loss of central vision as the cells in the macula area of the retina slowly die. The macula is the area of the eye responsible for sharp, central vision needed to read and drive. Our goal is to replace damaged cells and prevent healthy cells from dying."

As physicians, Park and Telander see patients who are suffering from retinal vein occlusion and other vision loss problems on an almost daily basis. As researchers, finding answers to such problems is the reason why they view their upcoming stem cell efforts as so important and promising for those currently living with blindness.