Viral Vector Holds Key in Treating Genetic Blindness Disorder

Published: 11 November 2011
By Wai Lang Chu

Scientists at Ohio State University Medical Center and Nationwide Children's Hospital in the US have created a viral vector engineered to transport a gene into the eyes of a patient born with a genetic, progressive form of blindness that affects mostly males.

Research carried out by a team based at the University of Oxford in the UK, focused on the administration of gene therapy to treat or even cure choroideremia, a condition that affects approximately 100,000 people across the globe.

The viral vector is primarily the work of Matthew During, PhD, Professor of Molecular Virology, Immunology and Medical Genetics and of Neuroscience and Neurological Surgery at Ohio State.

During also collaborated with Robert MacLaren, Professor of Ophthalmology at the University of Oxford, who also led the trial. Researcher K Reed Clark, Director of the Clinical Manufacturing Facility at the Center for Gene Therapy, Nationwide Children's Hospital, and his team produced the clinical-grade vector that was administered to patients in the trial.

During, who is also a Visiting Professor of Translational Neuroscience at University of Oxford, said of this pioneering surgery: “I and my colleagues are excited about contributing to this significant medical breakthrough. We have worked for many years to engineer and optimize viruses to safely deliver genes to humans, and the eye is an ideal target in many ways.”

“The clinical vector manufacturing facility at Nationwide Children's Hospital is outstanding, and Dr Clark and his team deserve congratulations for providing a clinical vector that for the first time offers these patients the possibility of an effective therapy.”

During and his team created the viral vector to invade and infect the light-sensitive photoreceptor cells that line the back of the eye and make up the retina. Choroideremia is responsible for the degeneration of these photosensitive retinal cells and resultant blindness. Diagnosis is usually determined in childhood and blindness occurs at around 45 years of age.

"This trial represents the first attempt to treat this disease and the first time that gene therapy has been directed towards the photoreceptor cells of the human retina," During said. "We believe it holds great promise for the treatment of other genetic causes of blindness such as retinitis pigmentosa."

The trial's participants were treated in one eye and the researchers said it would be 24 months until they could determine whether the gene-therapy treatment had stopped the degeneration. The research builds on gene-therapy trials conducted in collaboration with Professor Miguel Seabra at Imperial College London, along with During and Clark at Ohio State.

"This disease has been recognized as an incurable form of blindness for over a hundred years," MacLaren commented. "I cannot describe the excitement in thinking that we have designed a genetic treatment that could potentially stop it in its tracks with one single injection."