The retinal pigment epithelium (RPE) is the outermost layer of the retina. The RPE cells play a key role in normal retinal functioning, including several actions that assist, support and maintain the photoreceptors. Genetic mutations and malfunctions in the RPE cells are the cause of many ocular diseases including retinal degenerations, retinitis pigmentosa, Leber’s congenital amaurosis (LCA) and inherited macular degeneration.
The main goal of this project is to develop a technology that can activate a normal and functional gene specifically in the retinal pigment epithelium (RPE) cells of the eye. To achieve this, the researchers are creating a special segment of DNA called a “gene control fragment.” This control fragment has the ability to regulate the expression of the gene, making sure it is only active in the RPE cells.
Project Results and Impact
The project involved creating new gene therapy viruses that contain a special DNA segment called a control fragment. We made two types of viruses: one with a marker gene that glows green and helps us track the location and expression of the therapy viruses, and another with a normal copy of the RPE65 gene, which is important for the retina and can prevent a disease called Leber’s congenital amaurosis (LCA) in children.
We used a mouse model with a similar disease to LCA to test the effectiveness of the therapy viruses. We went through two stages: first, we genetically engineered the viruses to insert our control fragment, and then we produced the complete viruses in the lab using special cells. After that, we spent time testing and examining the viruses to see if they expressed the marker gene or the RPE65 gene and if they did so only in the retinal pigment epithelium (RPE) cells. We also performed safety tests to ensure the viruses were not harmful and couldn’t reproduce outside the lab.
Now, we are scaling up the production of the gene therapy viruses and hope to secure more funding to test them in live animals in the lab. The results from this project will be published in a scientific paper and will be used for future funding applications. We are grateful to Retina Australia for supporting this important research.
Professor Elizabeth Rakoczy
Lions Eye Institute / Centre for Ophthalmology and Visual Science