New Virus Delivery Method Could Help Treat Blinding Diseases

Researchers have developed an easier method to insert viruses carrying special genes into the eye. Their eventual goal is restoring sight destroyed by blinding diseases.

The technique, developed by University of California, Berkeley scientists, could increase opportunities for gene therapy using viruses to treat serious vision disorders, according to Medical News Today. Prior research teams have treated patients with Leber's congenital amaurosis by injecting a virus engineered to carry a normal gene directly into the section of the eye with a defective gene.

Genetics Home Reference describes Leber's congenital amaurosis as a rare congenital illness that mainly affects the retina, the area at the back of the eye with specialized tissue for detecting color and light. Experts recognize at least 13 types of the disorder that vary according to patterns of vision loss, genetic cause, and other eye abnormalities. Leber's is one of the most common reasons for childhood blindness, even though it strikes just two to three children out of every 100,000 newborns.

Unfortunately, when earlier scientists injected Leber's patients with an engineered virus, the virus could not reach all retinal cells with defective genes. The California team considered the retinal injection a risky surgical procedure that could cause retinal detachment and sought a safer, more effective method.

They consider their procedure, which takes only about 15 minutes, safe and surgically non-invasive. It treats even difficult-to-reach retinal cells by injecting the virus into the vitreous humor, the liquid inside the eye.

The Berkeley scientists say their development could expand gene therapy and help restore sight to individuals who suffer from diseases such as retinitis pigmentosa. They also see the potential to treat degenerative disorders associated with aging, like age-related macular degeneration.

According to PubMed Health, age-related macular degeneration (AMD) develops after damage to blood vessels that feed the macula, a region of the retina linked to sharp, detailed vision. Around 90 percent of AMD patients have the dry form, in which small deposits of drusen form and distort central vision. The rest have wet AMD, in which new, abnormal blood vessels develop. Most vision loss is linked to the wet form.

Lead Berkeley researcher David Schaffer created 100 million variants of the virus needed to deliver healthy genes, then chose five that effectively penetrated the retina. His team further selected the best to carry genes to cells affected with two kinds of heredity blindness that have mouse models: X-linked retinoschisis and Leber's.

After injection into the vitreous humor, the virus delivered the new gene to all parts of the retina and made cells there almost normal. Tests showed it was able to penetrate the photoreceptor cells of monkeys, similar to those in human beings.

The researchers are currently working to identify patients likely to be helped by the new virus-delivery method. They anticipate clinical trials soon.

Vonda J. Sines has published thousands of print and online health and medical articles. She specializes in diseases and other conditions that affect the quality of life.

Source: http://news.yahoo.com/virus-delivery-method-could-help-treat-blinding-diseases-145700720.html

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