Emerging Technologies and Therapies Promise a Bright Future for Age-Related Macular Degeneration
Age-related macular degeneration (AMD) is still a common condition amongst adults over 50 years in Australia, however the latest developments in medical research are offering a more reassuring future for patients. One of the most promising future therapies is stem cell therapy for AMD. This treatment may one day be an option for patients where the retinal pigment epithelium (RPE) and outer retinal cells have already been lost. RPE transplantation surgery was first developed over thirty years ago. However, as it has not proven efficient to use RPE from a patient’s own eye, the use of stem cells to grow new RPE cells has been of great interest.
A stem cell is an unspecialised cell with the ability to develop or differentiate into various specialised cell types in the body. They can divide indefinitely to produce new cells. There are three types of stem cells; adult stem cells, embryonic stem cells, and induced pluripotent stem cells.
A concern in all cell-based therapies is the potential for neoplastic changes. Hence, stem cell-derived RPE and photoreceptor cells require in vivo tumorigenicity testing before transplantation. Unfortunately, there have been case reports of serious adverse events when patients have sought unapproved treatment at unregistered and unlicensed clinics. Many of these clinics inject adipose-derived stem cells intravitreally, with the cells being harvested through liposuction.
Overall, there have been significant advances in the field of cell therapy in the past few years. Once cell survival and integration of cells is improved, and better anti-rejection agents developed, stem cell treatment may become applicable for AMD.
Major advances in medical research have also helped to reveal the role of genetics in the development of AMD. These advances have aided the development of gene therapy for AMD. Gene therapy is a series of techniques that can treat a genetic disorder by inserting new genetic information into the patient’s cells. This can either replace a mutated gene (known to cause disease) with a healthy copy, inactivate a mutated gene that is not working (“gene-silencing”), or introduce a new gene to help fight the disease. The eye is an excellent target for gene therapy as it is easily accessible and has immune privilege due to compartmentalisation (i.e., the blood-retinal barrier).
Another new technology that has wide-ranging implications in healthcare, including for AMD, is the development of CRISPR/Cas9 gene editing technology in 2012. CRISPR/Cas9 technology is a powerful genome-editing tool developed by scientists from the immune system of bacteria to alter DNA sequences and modify gene function. CRISPR stands for “clusters of regularly interspaced short palindromic repeats” and is a specialised section of the DNA strand.
Figure 1 Schematic demonstrating CRISPR/Cas9 technology for gene editing.
Gene therapy is a very promising avenue of potential future treatment for both types of late-stage AMD (neovascular and atrophic). There has been significant research, over many years, to improve the safety and efficacy of viral vectors and improve the specificity of treatment and the surgical delivery approach. At present, a number of Phase I and II gene therapy clinical trials are in progress.
The University of Melbourne and The Centre for Eye Research Australia have recently created an online course to help update primary eyecare practitioners, including optometrists, orthoptists and ophthalmologists, with the latest research findings regarding AMD. The course details disease pathogenesis, imaging biomarkers, risk prediction, current management strategies and emerging treatments and technologies.
Age-Related Macular Degeneration for Primary Eyecare Practitioners is an e-Learning course, written by world-leading experts, which can be completed online at the learner’s own pace (anticipated approximately 10 hours of learning). The course is CPD-accredited with 20 points from the Optometry Board of Australia.
To find out more about this course, please visit our website below