Veterinary ophthalmologists at Pennsylvania’s Veterinarian School of Medicine found that LCA in humans mimics the same type of disease in dogs. According to a recent article in Science Daily, vision scientists William Beltran and Gustavo Aguirre have studied a broad range of retinal blinding disorders. They discovered that a mutation in dogs, naturally occurring NPHP5 that leads to LCA, parallels the human retinopathy where the retina is damaged by disease.

About LCA

LCA represents a broad range of vision disorders that are inherited. They appear early in a child’s life. The type of LCA that is associated with NPHP5 mutations is considered rare. Only about five thousand people worldwide are known to be affected. The disease is called “ciliopathy”. It affects the cilia cells in the retina that respond to light. The cilia are structures found on photoreceptor cells that convert light to visual signals.

Doctors Beltran, Aguirre, and colleagues submitted a paper to the journal Molecular Therapy in which they demonstrated that canine gene therapy is able to restore function and normal structure to the cone photoreceptor cells in the retina. These cells do not develop normally in LCA patients. Dogs that received the human or the canine form of the NPHP5 gene had their vision restored.

About the Canine Therapy

The doctors and their team used adeno-associated viral vectors (AAV) to transport retinal injections of normal forms of the NPHP5 gene. Viral vectors are tools often used to deliver genetic materials into cells.

The NPHP5 gene was delivered to nine dogs with LCA-like vision impairment. The five-week-old dogs received the NPHP5 in one eye only. The therapy, called gene augmentation, supplies healthy genes in situations where a mutation has led to an absent or defective protein.

About Photoreceptor Cells

Photoreceptor cells in the retina respond to light. Rod photoreceptor cells are responsible for vision in low light while cone photoreceptor cells are responsible for color vision and fine detail.

The NPHP5 disorder causes the death of rod photoreceptor cells while cone cells survive but cannot function.

The team proved that AAV-mediated NPHP5 augmentation of canine retinas restores photoreceptor vision, function, and structure using human or canine NPHP5 transgenes.

Testing the Therapy

Electroretinography, a method that measures the response of photoreceptor cells to light stimulus was used to test the effectiveness of the therapy. Optical coherence tomography was also used. This type of test is noninvasive and captures detailed cross-section images of the retina. The results were encouraging as the outer segment of the cones grew in the treated eyes.

Looking Forward

Doctors Aguirre and Beltran commented that they found it amazing that they were able to restore function and structure to partially completed cone cells. The doctors now have hope that they can apply their therapy to humans.