Shining a new light on retinal degeneration
Underlying many of the best-known diseases, from cancer to retinal degeneration, is the “breakdown” of DNA. The source code of human life, DNA contains the blueprints for the proteins and structures within our body upon which we rely for a healthy life. As DNA breaks down or mutates, this code becomes corrupted and the resulting proteins and structures are built incorrectly, leading to tumours and degenerative diseases. The causes of DNA breakdown and mutation are countless; they include ageing, UV exposure, and toxic chemicals, such as those found in plastics. These various stressors can increase wear and tear on DNA through the buildup of reactive oxygen compounds within the body, ultimately causing irreparable damage to the DNA code. The mutations within the code have long been understood to lead to carcinomas and degenerative diseases.
One of the major difficulties in studying the physiology of degenerative diseases is they are progressive – once the cells die, it is no longer possible to observe them and establish the precise pathways of the disease. One such example is retinal degeneration – responsible for 90% of new cases of blindness and currently affecting about two million people in Canada. The retina – the part of the eye that detects light – progressively thins as cells die, leading to vision loss; once the cells of the retina die, it is no longer possible to study the disease pathway and the rapid degeneration of retinal cells means catching them at the right time is challenging. Capturing the precise moment of the disease’s existence in the affected cells of the retina will allow researchers to diagnose and predict the degradation of DNA and develop novel therapeutic techniques to slow, or even stop, the progression of the disease.
Kathleen Hill and her research group in the Department of Biology at Western University have studied a mouse model of retinal degeneration to establish a precise pathway and rate of retinal degeneration. They now know the brief timeframe in which therapeutics can be applied to cells while they have begun to deteriorate, but before they die.
Having now established when and where to treat retinal degeneration, the Hill group is now focussing on drug delivery so that the affected cells can be treated without harming sensitive nearby cells of the retina.
As Canada’s population ages, retinal degeneration will increase in prevalence – it is particularly pervasive amongst seniors and currently costs Canadians about $700 million for pharmaceuticals each year. Moreover, the model of DNA damage leading to cell death is applicable to other significant degenerative diseases like cerebellar degeneration - the deterioration of nerve cells in the part of the brain responsible for coordination. Having a model to track the progression of degeneration gives researchers the ability to time and target novel therapeutic techniques.