More than 126 million photoreceptors form part of the complex layers of cells that make up the retina at the back of our eye.
The tiny light-sensing cells are an essential part of the vision process – picking up light and sending it from the retina to the brain via the optic nerve, enabling us to see.
Photoreceptors rely on a series of complex genetic signals to function properly. But when these signals misfire, or the cell is damaged, irreversible vision loss and blindness can occur.
Globally, more than 190 million people have retinal diseases where the death of photoreceptor cells leads to a loss of sight.
Retinal diseases and gene therapy
These include rare inherited retinal diseases (IRDs) like retinitis pigmentosa or Stargardt’s disease and more common conditions, with a more complex genetic profile, such as age-related macular degeneration (AMD).
“Currently there is no cure for blindness once the photoreceptors are lost, ‘’ says Principal Investigator Dr Raymond Wong, who leads Cellular Reprogramming research at CERA.
“Our team is working on developing a new gene therapy that could help regenerate photoreceptors and treat a wide variety of degenerative retinal diseases.’’
In recent years, there have been rapid advances in gene therapy research that has led to hope of many new treatments for IRDs, which for decades were considered untreatable.
Conventional gene therapy for retinal diseases aims to halt photoreceptor loss by using safe viral vectors to introduce genes into the eye – either replacing faulty genes with healthy copies, or to introduce a protective gene to prevent cell damage.
These potential treatments are highly targeted towards the genetic profile they are treating – patients will need to be individually matched to the right therapy.
Dr Wong and his team are taking a different approach.
Armed with expertise in several innovative technologies, including cell reprogramming, transcriptomics and CRISPR gene activation, Dr Wong’s team are investigating ways to develop a gene therapy which could regenerate photoreceptor in a broad range of retinal diseases.
All cells within the retina have a precise genetic profile, and the genes they express, to function normally.
Professor Wong and his team are looking to take the profile that makes photoreceptors function successfully – and use it to ‘reprogram’ another group of cells in the retina known as Müller glia.
In humans, many millions of Müller glial cells help maintain the structural and functional stability in other cells of the retina.
They are of particular interest to researchers because they have stem-cell like qualities – and in other species – like zebra fish and chicken they have the natural ability to regenerate the retina.
“We use transcriptomics – a read out of the gene expression in the cell – to determine the important sets of genes in the human retina, in particular the photoreceptors,” says Dr Wong.
“We then grow Müller glial cells in the lab, and use CRISPR gene activation technology to switch on different sets of genes in the cells to turn them into photoreceptors’’.
Currently, the research is in pre-clinical stage, being tested on cells in the lab and animal models – with early progress backed by the National Health and Medical Research Council and generous philanthropic support from Retina Australia and the Kel and Rosie Day Foundation.
On Hope in Sight Giving Day on 14 October, backed by matched funds from the National Stem Cell Foundation of Australia and the Centre for Eye Research Australia Foundation, CERA is raising funds to further accelerate the pace of Dr Wong’s research.
“Funds raised from our generous supporters have been critical to getting our research to this point,’’ says Dr Wong.
“Every dollar we receive on Giving Day will further accelerate the pace of our investigations and move us closer to our goal of developing a treatment which could potentially restore sight.”
Donate at charidy.com/HopeinSight
This article first appeared in CERA’s Visionary.