The Michael J. Fox Foundation for Parkinson's Research (MJFF), Thomas Jefferson University (Jefferson) and Taconic have collaborated to create, validate and distribute a valuable pre-clinical research tool: a genetically engineered rat with fluorescent dopamine-producing neurons—neurons that are affected in Parkinson's disease.
This unique nonprofit, academic and industry partnership provides easy and open access to this genetically engineered rat model, making it available to all interested researchers at low cost.
"The model of The Michael J. Fox Foundation is to encourage collaboration and support initiatives to help us find a cure for Parkinson's disease," said MJFF CEO Todd Sherer, PhD. "We are grateful for and invigorated by the willingness of Thomas Jefferson University and Taconic to work with us to break down one of the barriers to accelerating research: the availability of critical research tools."
"Research tools are the building blocks of discovery and, as our capabilities to mimic disease in models grows, we can improve our resources and get closer to finding a cure," said Lorraine Iacovitti, PhD, Professor in the Department of Neuroscience at Jefferson's Farber Institute for Neurosciences. "The way MJFF is encouraging collaboration and access in this area of need is commendable."
Visualizing Dopamine-Producing Neurons Using a Green Glow
A hallmark of Parkinson's disease is the loss of dopamine-producing neurons, and methods to visualize (and measure) changes in this neuronal population are needed. Previously, antibody-based technologies were used to quantify dopamine neuron loss. However, these methods are time-consuming and do not permit analysis of living neurons. Iacovitti and her group overcame these limitations by using genetic engineering methods to "mark" dopamine-producing neurons.
DNA sequences called "promoters" regulate when, where and how much of a protein is produced. In nature, the tyrosine hydroxylase (TH) gene promoter drives the production of TH—an enzyme catalyst involved in the production of dopamine. Iacovitti and her group engineered a DNA construct that fused the TH gene promoter with the DNA sequence encoding green fluorescent protein ("the hTH-GFP construct"). GFP is isolated from jellyfish and is what makes the marine creature glow. Iacovitti and her group had originally introduced this hTH-GFP construct into mice. Shining blue light on the brain makes the GFP-expressing neurons glow, enabling researchers to visualize dopamine producing neurons.
Removing Barriers to Progress with Research Tools
Since 2010 the MJFF Tools Program has created, validated and distributed research tools—such as pre-clinical models, viral vectors and cell lines—to free researchers from these tasks so they may focus on the discovery and testing that will find a Parkinson's cure. Often tool development is project-driven, a costly and time-consuming practice where scientists create and validate tools for specific experiments. Problems with reproducibility arise from tests done with self-produced tools, too. Complicated and lengthy material transfer agreements and intellectual property issues slow the sharing of established tools.
MJFF works with partners, including the recently established Parkinson's Disease Research Tools Consortium, to identify needs in this area and then develop and characterize research tools and distribute them to academic and industry researchers at low or no cost through an expedited process.
Putting Self-Interest Aside to Move Research Ahead
In 2011, MJFF approached Iacovitti with the idea of using a similar strategy to create a genetically engineered rat model. Why rats? The rat brain is bigger, and therefore easier to study smaller brain structures. Additionally, rats have behavioral and physiological features that are similar to humans as compared to mice, and are ideally suited to study diseases with complex physiological and behavioral symptoms. For example, researchers can mimic Parkinson's in rats by eliminating dopamine neurons selectively with a certain toxin.
To create this rat model, MJFF, Jefferson and Taconic entered into an unprecedented agreement. Though it owns the intellectual property on the hTH-GFP recombinant DNA construct, Jefferson provided this construct to MJFF for creating the hTH-GFP rat. Using this construct, Taconic generated five founder lines of the model and shipped rats to Iacovitti for characterization to determine which of these lines produced GFP in the correct location in the brain. Taconic will breed and distribute the model at the same cost to academic and industry researchers, without an upfront license fee and at a reasonable price set by MJFF.
Visualization of fluorescent dopamine-producing neurons provides data on anatomical localization, making it possible to isolate PD-vulnerable dopamine neurons from neighboring PD-resistant dopamine neurons. In addition, scientists can now identify and separate live (GFP-expressing) dopamine-producing neurons for laboratory culture studies. This was impossible using previous methods and is invaluable for understanding the function of dopamine-producing cells and how they may be affected in Parkinson's disease.
"Taconic has a long history of providing scientists with easy access to research models. Given that tradition, we are proud to work with The Michael J. Fox Foundation and Thomas Jefferson University to help speed laboratory discoveries that could lead to better treatment for Parkinson's disease," said Gretchen Kusek, PhD, Scientific Program Manager at Taconic.