Irish and US scientists are working together to develop a novel treatment for blindness caused by diabetes.

Diabetic retinopathy is caused by high blood sugar levels damaging the blood vessels in the retina - the light-sensitive tissue lining the back of the eye. This disease is one of the five main causes of vision loss in Ireland and is the leading cause of blindness among people of working age.

Existing treatments, include monthly injections into the eye and laser treatment, however these do not work for everybody and can lead to serious side-effects.

Researchers at Queen's University Belfast and Dublin City University (DCU) are working with a team from the US to try to overcome these issues. They are using a gene therapy approach based on the use of adeno-associated viruses (AAV). These insert genetic material at a specific site.

The aim is to enable the long-term delivery of a protein known as COMP-Ang1 to the retina.

The researchers have previously discovered that COMP-Ang1 can protect the retina from diabetes-related damage. However, how it does this is unclear.

They plan to investigate how this protein protects and improves the function of the retina. They also plan to investigate whether the protein can enhance a stem cell therapy which the team at Queen's has been developing in recent years.

It is hoped that the protein will ultimately facilitate the reversal and repair of any damage to the retina as a result of diabetes.

"During diabetes, blood flow to the retina is impaired and this is believed to trigger the development of diabetic retinopathy. Our aim is to examine whether COMP-Ang1 treatment is capable of preventing or reversing diabetic retinopathy by improving blood flow and vascular repair in the retina," explained Dr Tim Curtis of Queen's Centre for Experimental Medicine.

Meanwhile, researchers at the University of Utah will try to discover how the drug prevents inflammation, using the smallest dose possible to achieve optimal long-term effects while minimising side-effects. The team at DCU will be working on increasing knowledge of therapeutic viruses to ensure their efficiency for delivery into the eye.

The five-year research programme begins this month.