On the front lines of Parkinson’s research

Charles River and The Michael J. Fox Foundation team up to fight Parkinson’s disease

It starts simply. A slight tremor in a hand or a change in posture. However, as Parkinson’s disease (PD) progresses, patients have increasing mobility problems and neurological changes. PD is the second most common neurodegenerative disease in the world, with around 60,000 new cases each year in the United States alone. According to a 2018 CDC report, complications from PD are the 14th most likely cause of death in the US.

In PD research, there are several key targets researchers consider when looking for ways to treat the disease. The first is the aggregation of alpha-synuclein in Lewy bodies. The second is a mutation in LRRK2 (Leucine-rich repeat Kinase 2), a gene that encodes enzymes. Common consensus among researchers is that developing compounds that target alpha-synuclein and its aggregation, or compounds that inhibit LRRK2 could offer huge potential to treat PD.

In collaboration with The Michael J. Fox Foundation for Parkinson’s Research, Charles River has worked across multiple sites to better understand the pathophysiology of PD and to develop imaging agents to use as biomarkers in clinical studies. Many compounds from different chemical classes have been synthesized and tested in cell-based models as potential agents to interact with aggregated alpha-synuclein. Promising compounds are then radio-labelled and evaluated in PD animal models. These tracers could potentially be used as imaging agents in patients to help visualize the development alpha-synuclein enriched Lewy bodies.

Cell-based models are a useful tool to test the efficacy of disease-modifying therapies, since they develop the pathological hallmarks of PD quickly, do not require approval, and are cost-effective. Robust cell-based models are useful to rapidly screen compounds, which can then be further validated in research models of PD. Cell-based models are also used to identify and optimize compounds that inhibit LRRK2. Before any compound can go into research models, researchers need to see clear target engagement, and the right drug-like characteristics to be effective in PD patients.

In a project commissioned by The Michael J. Fox Foundation, scientists at Charles River have developed a high content analysis-based assay to measure alpha-synuclein aggregation in a terminally differentiated neuron cell-based model. This neuronal cell model effectively overexpresses alpha-synuclein, which then forms the standard protein aggregates. The aggregates are then detected using a conformation-specific antibody that binds with very high affinity to alpha-synuclein.

This model can facilitate high throughput, fully automated testing of therapeutic agents that reduce alpha-synuclein aggregation. Similarly, cell-based assays can be used to optimize compounds focused on inhibiting LRRK2. In collaboration with The Michael J. Fox Foundation and other organizations, Charles River has worked to understand how the LRRK2 inhibitors, identified from cell-based assays, influence function in models of PD. With the support of their partners, Charles River has used both normal healthy mice and mice with the human LRRK2-mutation to assess clinically relevant measures of PD.

Using these models, Charles River was able to demonstrate dose-related inhibition of LRRK2 activity in the brain. Models then received an infusion that led to an overproduction of alpha-synuclein. Models receiving the infusion displayed some of the classic signs of PD, including loss of dopaminergic function, reduction in dopamine cells, and clear motor impairment. Using the technique of push-pull microdialysis, researchers were also able to measure extracellular alpha-synuclein levels. These assays are now being used to identify novel compounds that could be progressed to the clinic.

A number of promising compounds have been identified that inhibit LRRK2 or alpha-synuclein aggregation in cell-based assays, which lead to meaningful effects in research models. Charles River developed a procedure called fine motor kinematic analysis that uses detailed video monitoring and proprietary analysis software to look at very subtle changes in motor function. Kinematic analysis allows researchers to see how compounds affect dopaminergic function at the very early stages, hopefully leading to the development of compounds that not only treat the symptoms of PD, but also slow or prevent the progression of the disease.

The examples above highlight the value of collaboration between contract research organizations like Charles River, industry and foundations to develop novel therapies focused on promising targets, with the ultimate goal of developing a cure for patients.