Scientists have completed a study using mice which showed that bone marrow stem cells can switch roles and produce keratocan, a natural protein involved in the growth of the cornea, the transparent, outer layer of the eyeball. This ability of marrow cells to "differentiate" into keratocan-producing cells might provide a means for treating abnormal corneal cell growth in people.

Winston Whei-Yang Kao, PhD, professor of ophthalmology, and Hongshan Liu, PhD, research scientist in the department of ophthalmology, will present their findings at the annual meeting of the Association for Research in Vision and Ophthalmology being held in Ft. Lauderdale, Fla., May 9 and10.

In the laboratory, the researchers induced corneal abnormalities that mimicked genetic eye mutations and then injected bone marrow stem cells into the corneas to see if they altered the mutations.

The study showed that after only one week, the abnormal corneas of animal models injected with bone marrow stem cells began to change shape and heal.

"We found that bone marrow stem cells can contribute to the formation of connective tissues," Kao said. "If we can change the function of non-corneal bone marrow stem cells by introducing them into human corneas, we can possibly repair the loss of visual sharpness caused by mutations."

Kao and his coworkers are now planning a clinical trial. If the trial succeeds, Kao said, the procedure could help prevent blindness in future generations who suffer from genetic corneal diseases.

He added that cornea transplants have been successful to some degree but do not always eliminate the problem.

"When the donor cells disappear after a few years, the corneal disease often reoccurs," he said. "However, if we can place the stem cells inside the cornea, they will repair the lost function of the mutated gene, and stem cells can presumably renew themselves and maintain effective treatment longer, if not forever."

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The work was supported by HD advocacy organizations. "We are very excited about this significant discovery," said Allan Tobin, PhD, Senior Scientific Advisor to the High Q Foundation and CHDI, Inc. "This work helps define and refine possible therapeutic targets for a disease that lacks thorough understanding." Tobin added, "We are pleased this study is being published in an open-access journal, which makes it easier for scientists at other organizations to get to work on following up on this landmark discovery." Traditional peer-reviewed journals usually require scientists to pay a fee to access study results.

Tobin added that the need for further scientific inquiry is urgent. There is currently no effective treatment or cure for HD, which is typically characterized by involuntary movements and dementia. The disease slowly diminishes a person's ability to move, think and communicate. Those affected eventually become totally dependent on others for their care and usually die from complications such as choking, heart failure or infection. The disease is hereditary; each child of a person with HD has a 50/50 chance of inheriting the fatal gene. Approximately 200,000 Americans are believed to be at risk of developing HD, a disease that affects as many people as hemophilia, cystic fibrosis or muscular dystrophy. The symptoms of HD typically begin to appear in mid-life, although the progression of the disease varies among individuals and within the same family.

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