<b>September 17 2003</b> – Building on earlier successes reported last year, University of Florida scientists have scored another first in a string of advances using adult stem cells. Edward Scott of UF's Shands Cancer Center and colleagues report in the current online edition of the journal Blood that they can inject mice with adult stem cells from human blood and spur human blood vessels to grow in their eyes.
Ultimately the approach will help researchers develop safer, faster ways of testing stem cell-based therapies for many diseases in people, including sight-robbing retinal disorders and cancer, said Scott, who directs the program in stem cell biology at UF's College of Medicine.
"With our initial work, we showed that adult mouse stem cells can make new blood vessels in a model for diabetic retinopathy," he said.
Those findings were reported in May of last year.
"But mice are not people, so the question was, does it hold true for humans?" he asked.
Scott said the latest study took a similar approach, but used human cells to grow new blood vessels in a mouse's eye. UF researchers transplanted human blood stem cells derived from umbilical cord blood into dozens of mice lacking an immune system, all models for the human eye condition known as retinopathy.
Retinopathy, a diabetes-related condition, is the leading cause of adult blindness in the United States.
In diabetics who develop retinopathy, small blood vessels inside the retina of the eye weaken and rupture, leaking blood.
In response, new capillaries form as the body struggles to repair the light-sensing retina. These new blood vessels can also weaken and leak, compounding the problem.
The result is blurred vision that gradually worsens. About 3 percent of diabetics develop retinopathy so severe they eventually experience profound vision loss, even blindness.
In the current study, human blood vessels grew in the animals' eyes within four to six weeks.
"We were able to do that, and now know that the work we were doing on the mouse system should translate into a human therapy," Scott said.
UF researchers will next use their findings to test ways of preventing retinopathy in mice, and also to block blood vessel formation in solid tumors, using human pancreatic and human breast cancer cells.
"Once again we'll be using the mouse-human system to confirm that what works in a mouse works on human cells before trying to take it to a clinical trial," Scott said. "We're excited about having both systems to work with, so at every step along the way we can confirm that things we find in mice hold true for humans."
"What this study is demonstrating is the remarkable ability of stem cells that are derived from blood to reconstitute tissues in other organs," said Dr. John R. Wingard, a UF professor of medicine and associate director of clinical and translational research at the UF Shands Cancer Center.
"We are gaining increasing information about the potential of these cells to restore function in brain, heart, liver and other tissues," he added. "The more we learn about this, the more horizons are expanding as to clinical applications."
