Research is the key to understanding more about all forms of sight loss. In each edition of Visionaries, we want you to meet the people behind the science and learn how their research is contributing to the development of better treatments for these varied conditions.
Dr Breandán Kennedy of the Conway Institute at University College Dublin (UCD), pictured left, recently showed us his lab and told us about the work his team are undertaking in eye research.
He said, “Our overall goal is to develop pharmacological and genetic treatments for human blindness; especially in retinal degenerations, some of our current efforts are focused on developing new drugs that can block the formation of new leaky blood vessels.”
The growth of new blood vessels is a hallmark of human eye disorders, such as the wet form of age-related macular degeneration (AMD) and proliferative diabetic retinopathy. At the moment current medication involves monthly injections into the eye, and while these treatments are effective, they can be inconvenient. Breandán explains to us the current burden and cost of this treatment method to both the patient and the doctor.
“At the minute there is a huge clinical burden and cost for eye therapies in Ireland,” he said. “Patients attend clinics up to once a month for diseases like AMD, and consultants administer thousands upon thousands of injections a year.”
The approach Breandán’s team take to find new therapies is known as phenotype-based drug discovery; this means that large numbers of drugs (over 5000) are screened to find one that gives the desired effect – one that inhibits blood vessel formation.
A number of compounds have so far been found in Breandán’s lab that have this potential and these are currently being evaluated in pre-clinical models of disease. He explained how these new drug findings could potentially be administered to patients and solve current frustrations with treatments:
“Two delivery systems are being explored; one via eye drops (similar to glaucoma medications) the other via a sustained release, biodegradable implant placed into the eye. The idea is that the drug would be encased in a biodegradable ‘shell’ and implanted into the eye. Over a period of time the drug slowly releases until one would need to have it replaced with a fresh implant. Having two approaches to drug delivery ensures the best chance of success.”
Slowing degeneration of cone photoreceptor cells, cells used for everyday tasks such as reading, writing and driving, is another basis of Breandán’s research. Preservation of these cells for a patient with an inherited retinal disease would have the potential to extend quality of vision for many years.
“We use zebrafish in our research, as they have predominant colour-based vision, having lots of cone photoreceptors, including red, green and blue sensitive cones like humans,” he explained. “While our focus is on cones, if this work is successful, this would have huge implications for rod based conditions, e.g. retinitis pigmentosa (RP). With RP you lose your rods first and then cones later, if we find a therapy to preserve cone vision we essentially preserve good vision for that patient also.”
Breandán also mentioned that, from a stem cell project funded by Fighting Blindness some time ago, a class of drug known as HDAC inhibitors were found to rescue the vision of fish with retinal degeneration. His group hope to test other HDAC inhibitors and other models of inherited blindness to determine the most appropriate drugs and patients that will respond positively.
Finally Breandán explained what he feels are the benefits of working with Fighting Blindness: “Working with a patient group empowers us as a lab and makes it very real – you learn a lot about what the real concerns of today’s patients are. For example, at the patient day during the Retina 2013 conference, we learned so much from the patients’ perspective, in terms of what they are looking for in a therapy and what their frustrations are. From this we gain even more insight, along with motivation and encouragement, to continue our task in finding new drug therapies.”
Best of luck to Breandan and his team as they continue their important work.