Article published May 23, 2007 May 23, 2007 Gene therapy at UF helps blind mice see
By DIANE CHUN Sun staff writer The three blind mice of nursery rhyme fame could have had their sight restored with a new gene therapy treatment developed at the University of Florida. And researchers in UF's Genetics Institute are banking that the approach could lead to treatments for human vision problems. The scientists used a harmless virus to deliver corrective genes to mice with a form of hereditary blindness. The discovery shows that it is possible to target and rescue cone cells - the most important cells for visual sharpness and color vision in people. "Cone vision defines whether someone is blind or not," said William W. Hauswirth, professor of ophthalmic molecular genetics in UF's College of Medicine. "If you can usefully deliver a gene specifically to cone photoreceptor cells, there are implications for all blinding diseases, not just inherited ones." Hauswirth explained that the findings in mice, reported in the current issue of Nature Medicine, suggest that it may be possible to rescue the vision of people afflicted with two very common types of blindness, age-related macular degeneration and diabetic retinopathy. The mice in the experiment had a form of hereditary blindness called achromatopsia, which affects about 1 in 30,000 Americans by disabling cone photoreceptors in the retina. The disease results in nearly complete color blindness and extremely poor central vision. The virus that carries the corrective genes to the cone cells, adeno-associated virus, causes no disease. In fact, most people have been infected with AAV at some point in their lives. Hauswirth sees the viral vector as a very effective form of "molecular scalpel." "We take (the virus') own DNA out and put in the DNA encoding the gene we are interested in," he said Tuesday. Injected into the the eyes of mice, the virus enters the cone cells and deposits its payload of corrective genes. Within two months of the gene therapy injection into the subretinal space of the mouse eyes, scientists measured the electrical activity in the retinas, finding that 19 of the 21 treated eyes positively responded to therapy, and 17 of those 19 had electrical readings from their retinas on par with those taken in normal mice. Part of the group of mice in the study were even given a test akin to the eye chart patients are asked to read in an ophthalmologist's office. In experiments overseen by Robert B. Barlow, a professor of ophthalmology at State University of New York Upstate Medical University, the mice were surrounded by four computer monitors that simulated the appearance of being inside a moving drum with vertical stripes on the walls. An animal with normal vision will naturally move its head in the same direction as the moving stripes. By making the stripes increasingly narrow, researchers could assess how well the mice could see. It's much the same as being asked to read the last few lines of an eye chart. As a group, all of the mice displayed normal visual acuity in their treated eyes. "People can talk and tell us what they see," said lead researcher John J. Alexander, a postdoctoral fellow in the department of ophthalmology at UF. "Animals are much more difficult. What makes this test so fantastic is that it involves an animal's natural response, and the results tell us that the animals' brains are involved in the process, that they are actually seeing something." Hauswirth said he's excited by the prospect of applying similar gene therapy in people with eye disease, after a series of animal studies demonstrate that the approach is both safe and effective. "The immediate impact could affect a few thousand patients," he said, "but there is the possibility of a longer-term impact that could affect millions of patients with other forms of blindness." Diane Chun can be reached at 352-374-5041 or [EMAIL PROTECTED] -------------------------------------------------------------------------------- University of Florida scientists William W. Hauswirth, left, and John J. Alexander used gene therapy to restore sight in mice with a form of hereditary blindness, a finding that has bearing on many of the most common causes of human blindness. (SARAH KIEWEL/UF Health Science Center) (Sweety Bhalla) IFA Dept. Planning & Research Floor 11th IFCI Tower, 61, Nehru Place New Delhi--110019 Office # +91-011-41792800 Ext. # 2068 Direct # +91-011-41732068 Fax # +91-011-26488471, 26230201 Mobile # 9868300466, 9818132488 Res. # +91-011-25250988 E-Mail [EMAIL PROTECTED] To unsubscribe send a message to [EMAIL PROTECTED] with the subject unsubscribe. To change your subscription to digest mode or make any other changes, please visit the list home page at http://accessindia.org.in/mailman/listinfo/accessindia_accessindia.org.in
