Dr. Jean Bennett, a gene therapist at the University of Pennsylvania, and her colleagues, began treating people who are blind with injections of a harmless virus that inserts good copies of genes that are defective in the patient. The genes were inserted into the cells of the retina. The retina is a light sensitive tissue at the back of the inner eyeball. Its job is to receive light and convert that light into neural signals to which the brain uses for visual recognition.
In 2007, researchers began conducting gene therapy clinical trials on ten patients with Leber’s congenital amaurosis Type 2. Leber’s congenital amaurosis Type 2 causes a degeneration of retinas thus limiting vision at birth and progressive blindness by mid life. The ten patients, ages ranging from 20-45, underwent gene therapy only in one of their eyes, the one which had the worst vision. After gene therapy for two or three years, researchers used an MRI to scan deep into the patients’ brains. The MRI showed the visual pathways in each patient was nearly as strong and healthy as a normal persons vision at that age. The MRI scan also showed the untreated eyes had much weaker visual pathways. This observation suggested that regaining sight also helped to rebuild the visual pathways in the brain. This revision is called brain plasticity.
The data collected from this study hinted that the patients’ visual pathways were in better condition after more and more time had elapsed since undergoing gene therapy. Because the pathways improve as more signals get sent through, Bennett and her colleagues are working on larger phase trials to determine whether their gene therapy can be used more widely as treatment.
This article and the research behind it were truly remarkable. The patients undergoing gene therapy are in their 20’s, and one patient was 45. This age range demonstrated visual pathways and brain plasticity could be improved at any age, not just young children. I found this article to be extremely uplifting and encouraging in the field of gene therapy. The ability to use gene therapy in repairing a person’s sight that had been nearly blind is just so moving.