1. MicroRNA as diagnostics and therapeutics for retinal degenerations

MicroRNA (miRNA) are small, endogenous, non-coding molecules that are powerful regulators of genetic information. Despite only being discovered as recently as the turn of this century, miRNAs are already used in clinical trials as therapeutic candidates for complex diseases such as cancer. This rapid bench-to-bedside transition demonstrates the therapeutic potential of miRNAs, particularly for multi-faceted diseases. In fact, miRNAs have already been implicated in the pathogenesis of complex neurodegenerative disorders such as Parkinson’s, Alzheimer’s, and Age-related Macular Degeneration (AMD). At the Clear Vision Research Lab, we believe that we can use miRNAs for two key areas currently lacking in the clinical landscape for AMD:

Diagnostic biomarkers

The Clear Vision Research Lab is currently undertaking a project in which we are investigating the use of miRNA as biomarkers for retinal degenerations. MiRNA demonstrate relatively high stability and abundance in biofluids such as tears, saliva, urine and blood, making them a promising target for prognostic research. Current investigations exploiting biofluid miRNAs for AMD diagnosis has yielded inconsistent results due to the multifaceted nature of disease progression and existing co-morbidities. Our research aims to identify specific miRNAs indicative for different stages in retinal disease and develop a method of disease grading based on their expression in biofluids. We further aim to determine if this panel of miRNAs can also be used as an indicator of therapeutic efficacy.

Therapeutic candidates

We currently have a number of ongoing projects where we are attempting to harness the regulatory capabilities of miRNAs to use as therapeutics for AMD. A single miRNA has the ability to control multiple different mRNA, often within the same molecular pathway (e.g. inflammation). This ability makes miRNAs promising therapeutic molecules to target multiple players in a single pathway. Due to the complex nature of AMD, we believe that this approach may prove fruitful in ameliorating key pathways known to lead to retinal degeneration, such as inflammation and oxidative stress. Ourresearch aims to characterise key miRNAs in the retina and, by understanding their dynamic activity under retinal stress, exploit those as therapeutic molecules in the retina.

2. Exosomes in retinal degenerations

Exosomes are small membrane-enclosed delivery vehicles (40-150nm in diameter), which selectively package and transport molecules from host to target cells. Exosome-packaged molecules can be proteins, RNAs and non-coding RNAs such as microRNAs (miRNAs). MiRNAs are endogenous ‘master-regulators’ of gene expression and a single miRNA can control multiple different mRNAs, often found within similar biological pathways. The exosomal transfer of these molecules, particularly miRNAs, can therefore functionally alter the environment of target cells. Exosomes are paramount to the pathogenesis of a plethora of neurodegenerative diseases but their role in retinal degenerations remains largely unknown. At the Clear Vision Research Lab we study exosomes using several miRNA-centered approaches:

1. We are characterising the molecular cargo of retinal exosomes, in particular their miRNA signature, to understand the relevance of these in the establishment and development of retinal degenerations.
2. Exosomes are known to be efficient at delivering their molecular contents, including miRNA, to recipient cells. To utilize this high delivery efficiency, we are developing ways to enrich retinal exosomes with specific miRNAs of therapeutic potential in an effort to deliver these directly into the degenerating retina.
3. Exosome-packaged molecules have high diagnostic potential. Exosomes also have the capacity to travel from their organ of origin, such as the retina, via biofluids such as blood. We are working towards uncovering the signature imprinted on blood-derived exosomes with the goal of establishing a panel of exosome-based biomarkers of retinal degenerations. This will aid the development of an objective and precise diagnostic kit for retinal degenerations.

3. The benefits of exercise for retinal health and reducing retinal degenerations

The benefits of exercise to the human body have long been known. Particularly in the central nervous system (CNS), regular exercise has been shown to improve memory, reduce inflammation and stimulate growth factors in the brain, and even prevent neuronal death. Exercise has also been shown to be an effective non-invasive therapy against neurodegenerative diseases such as Alzheimer’s and Parkinson’s. However, little is known if such benefits extend to another part of the CNS – the retina. At the Clear Vision Research Lab, we investigate the neuro-protective benefits of different forms of exercise to retinal health and aim to understand what molecular processes mediate this. Our ongoing projects aim to determine whether or not these benefits can be translated into therapeutic approaches for retinal diseases such as AMD.

4. Development of new animal models for retinal degenerations

The Clear Vision Research Lab has developed and incorporated a range of rodent models of retinal degenerations. While there is no perfect model to simulate all the pathologies associated with human AMD, we use a growing number of approaches to better understand the progression of AMD and retinal degenerations in general. These models also serve to test the efficacy of novel AMD therapeutic and diagnostic pipelines, with a view towards commercialisation and R&D avenues.

Light Damage

The Clear Vision Research Lab light-damage model, otherwise known as photo-oxidative damage (PD), was developed in-house (Natoli et al. 2016) as a means to induce AMD-like disease in pigmented rodents. In this model rodents are exposed to a high intensity of light with the key benefits that both the oxidative stress and inflammation arms of AMD progression are targeted. The light-damage model has been recognised for its uniqueness and has fostered industry collaborations that have led to the model’s commercialisation and distribution around the world.

Transgenic Mouse Models

The Clear Vision Research Lab has access to the Australian Phenomics Facility (APF), which is a nationally funded facility dedicated to the development, characterisation and archiving of mouse models of human disease. This facility has experts in place to identify genetic traits that lead to a particular disease. Through the APF, we have the capacity to import and generate transgenic mouse lines to mimic various retinal degenerations in vivo. We currently have transgenic mouse lines that mimic retinal pigment epithelium (RPE) dystrophy, which leads to photoreceptor loss in the retina. The benefit of transgenic mouse models is that retinal degeneration often progresses slowly, which parallels the progression of human AMD. The protracted nature of retinal degeneration provides a unique view toward early diagnostic markers of AMD and long-term efficacy of novel treatment strategies.

Sodium Iodate

The sodium iodate model of retinal degeneration is widely used in the research space and one that we have recently begun to use. In this model, mice receive a single dose of sodium iodate which selectively induces RPE cell death, in turn leading to AMD-like pathologies. The simplicity of this model makes it a useful tool for initial screens of novel therapeutics agents that may promote photoreceptor survival.

Choroidal Neovascularisation

The Phoenix MICRON IV™ system (Phoenix Technology Group) is a specialized rodent optical coherence tomography (OCT) and fundus imager that can deliver laser-mediated photocoagulation. This process results in a localized choroidal neovascularisation (CNV) response in rodent retinas that mimics pathologies associated with wet AMD. The MICRON IV™ allows the us to monitor the development of a CNV response in vivo and in real time and directly observe the efficacy of potential therapeutic agents.

Oxygen-Induced Retinopathy

The oxygen-induced retinopathy (ROP) model is a useful model to study the effects of neovascular diseases of the eye, such as retinopathy of prematurity (ROP) and wet AMD. Neonatal animals present with normal retinal vascularisation ex utero, rather than the abnormal retinal vascular development observed in premature infants. The ROP model takes advantage of the fact that by simply manipulating the environmental oxygen concentration, neovascularisation resembling that of premature infants can be induced and tightly controlled. This model provides us with a crucial tool to better understand ROP and test potential therapeutics together with the development of new medical devices.

5. Novel therapeutics to reduce the progression of retinal degenerations

In recent years, ophthalmic drugs have enjoyed a relatively high probability of success in progressing from Phase I clinical trials to market, estimated in 2015 at ~30%. This clinical success is driven by good preclinical models, especially for wet AMD. In 2016 we developed a mouse model for mimicking the oxidative stress, inflammation and cell death characteristics of the more prevalent form of AMD – dry AMD. This model has opened up both fundamental science and commercial opportunities to better understand and develop new strategies for combating dry AMD. In the Clear Vision Research Lab we are exploring a number of therapeutic options, developed at ANU and by commercial partners, which include gene-based therapies, non-invasive therapeutics (including the use of low-level laser therapy using red light) and novel compounds. We are actively engaging with commercial partners to help develop strategies to slow the progression of retinal degenerations, by targeting inflammation and oxidative stress processes.

Groups

• Leader, The Natoli Group - Clear Vision Research Lab

Projects

• Principal investigator, MicroRNA as diagnostics and therapeutics for retinal degenerations
• Principal investigator, The benefits of exercise for retinal health and reducing retinal degenerations
• Principal investigator, Development of new animal models for retinal degenerations
• Principal investigator, Exosomes in retinal degenerations
• Principal investigator, Novel therapeutics to reduce the progression of retinal degenerations
• Researcher, Integration of single-cell and spatial transcriptomics underlies the molecular disparity in age-related macular degeneration mice eye
• Supervisor, 670nm Red Light as a treatment for Retinopathy of Prematurity (Phase 1 Clinical Trial)
• Supervisor, Optimising the dose of 670nm light therapy for treatment of retinal degenerations
• Supervisor, Role of miRNA in retinal degeneration
• Supervisor, The role of oxidative stress in the progression of retinal degenerations
• Supervisor, The use of miRNA as potential therapeutic targets in diseases causing retinal degenerations