Completed Projects

Hongjun Song, PhD

Johns Hopkins School of Medicine
Model ALS Using Human Pluripotent Stem Cells
   

Funding for this project was made possible by the Muscular Dystrophy Association

Much has been made about using neural stem cells – those in the adult central nervous system of humans and other mammals – as possible repair agents once ALS is slowed or cured. But not many people realize adult neural stem cells also provide a powerful way to study cell behavior. And with Packard scientists recently showing that interactions between motor neurons and their surrounding cells are crucial to the course of the disease, the time is ripe for a good way to study them.

New Packard researcher, Hongjun Song, is preparing laboratory cultures of stem cells to model normal cell interactions and contrast them with what occurs in ALS. He chooses these specific stem cells because they're endowed with nervous system characteristics but, unlike adult nerve cells taken from the body, they reproduce and survive in lab dishes. Also, as stem cells, they can morph into the various types of cells in the nervous system.
Song will work with both normal stem cells and those carrying the mutant SOD1 genes that can trigger ALS characteristics. He'll also use both mice and human cells in his cultures. His system should let him follow the course of disease at a cell level. It should also show how crucial each type of nervous system cell is to the process.

Thomas Brushart, MD

Johns Hopkins School of Medicine
The Role of Pathway-Derived Growth Factors in Motor Axon Regeneration

Regenerating motor neurons can distinguish between nerve pathways that lead to skin and those that lead to muscle. We have recently shown that these pathways differ in the types or patterns of release of the growth factors that they produce. However, we don't yet understand how that plays a part in motor neuron growth toward muscle targets.

My work for the Packard Center aims to shed light on the process, largely by creating a small, controlled system to study. Our cultures will consist of sections of spinal cord containing motor neurons placed close enough to living nerve to enable the motor neurons to regenerate into the nerve.
In this situation, we can explore the role of different growth factors and even cell structure that affects motor neuron outgrowth. We hope to apply this knowledge to patients, ultimately, to develop ways to overcome the effects of injury or disease in the nervous system.

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Albert Ludolph, MD & Philip Wong, PhD

University of Ulm / Johns Hopkins School of Medicine
Development of transgenic mice carrying dynactin mutations associated with sporadic ALS
   

Partial funding for this project was made possible by the Muscular Dystrophy Association

Mutations in the protein dynactin, part of a neuron's internal transport system, are suspect as a cause of amyotrophic lateral sclerosis. However, since the genetic findings in more than 2,000 patients and controls cannot reveal a cause-effect relationship for each of the mutations, we propose to investigate the detected sequence changes in transgenic mice.

Ahmet Hoke, MD, PhD

Johns Hopkins School of Medicine
Pleiotrophin in Motor Neuron Disease

Partial funding for this project was made possible by the Muscular Dystrophy Association

In ALS, current attempts at treating the illness are directed at promoting the growth of motor neurons without addressing the issue of changes that occur in the distal portions of the peripheral nerves. Local factors within the distal portions of the nerve may play an important role in degree of success during regeneration of motor neurons into the target tissue. Glial cell-line Derived Neurotrophic Factor (GDNF) is very important in motor neuron regeneration and survival. This project has two goals: (1) To transplant C17.2 stem cells in a model of regeneration after prolonged denervation in order to improve degree of motor regeneration; (2) To develop robust and reliable measures of motor regeneration that we can measure at the target tissue using electrophysiological and histological methods.

Jean-Pierre Julien, PhD

Laval University, Quebec
Development of Passive Immunization Approaches for ALS Caused by SOD1 Mutations

Our previous studies demonstrated therapeutic effects of vaccination against mutant SOD1 in mice models of ALS. In the past year, we tested a passive immunization based on intracerebroventricular (ICV) infusion in G93A-SOD1 mice of monoclonal antibodies specific to misfolded forms of SOD1. One antibody succeeded in prolonging the lifespan on G93A-SOD1 mice in proportion to the duration of treatment. Interestingly, the variable Fab fragment of this anti-SOD1 antibody was sufficient to confer protection in G93A-SOD1 mice. The dispensability of Fc region open new avenues for the use of single-chain variable fragments (scFv) or intrabodies of smaller size and with less immunogenicity. Here, we propose to use three different strategies for the testing of anti-SOD1 scFv antibodies for treatment of ALS caused by SOD1 mutations. First, we will test the therapeutic effects of anti-SOD1 scFv antibodies when infused ICV in G93A-SOD1 mice. Second, we will test a gene therapy approach based on adeno-associated virus (AAV) encoding scFv antibodies. Third, we will generate transgenic mice bearing Thy1-scFv constructs to test the therapeutic efficacy of scFv antibodies with or without signal peptide (intrabodies) for cellular secretion.

Thomas Lloyd, MD, PhD & Alex Kolodkin, PhD

Johns Hopkins School of Medicine
A Drosophila Model of Motor Neuron Disease Using Mutations in p150 Dynactin

Partial funding for this project was made possible by the Muscular Dystrophy Association

The fruit fly, Drosophila melanogaster, provides one of the most powerful gene-based systems for studying development and biology of the neuromuscular system. Because of the ability to express mutant human genes in Drosophila, the flies have recently been used as models of many neurodegenerative illnesses such as Alzheimer's, Parkinson's and Huntington's diseases. Such models allow rapid screening of all other genes, to search for those that modify the disease process in some way. They also reveal potential drug targets.

We're exploring mutations in genes involved in internal transport of materials within a motor neuron's axons, specifically those associated with motor neuron degeneration in humans. Since these genes are highly conserved from flies to humans, we expect that similar mutations in the fly will reproduce characteristics of the human disease. Our goal is to create a genetic model of motor neuron disease in Drosophila and then use this model to search for new drug targets for ALS.

John Gerdes, PhD & Richard Bridges, PhD (Renewal)

University of Montana
Cerebral Positron Emission Tomography (PET) Imaging Agents for Monitoring ALS Therapy

Dr. Gerdes is the Packard Center's Boye Foundation Researcher for 2006 and 2008

The EAAT2 molecule is a cell membrane protein that removes excesses of the neurotransmitter glutamate. Abnormalities in EAAT2 quantity or in its behavior have long been tied to ALS. That could make the molecule a good indicator, or biomarker, of nervous system health. At some point, it could provide a way to measure if treatment is effective.
In our supported research, we hope to create a radioligand (tracer) molecule targeted to the EAAT2 protein. The tracer will enable us to detect the EAAT2 biomarker noninvasively within the brain and spinal cord, using positron emission tomography (PET) imaging. Our challenge comes in designing a tracer with a unique chemical structure ? a molecule with a high affinity for the EAAT2 target protein, one that can penetrate the brain?s natural barriers and that reaches specific central nervous system tissues. Ultimately, data from our studies may lead to a noninvasive way to monitor ALS in the clinic.

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Weichun Lin, PhD (Renewal)

UT Southwestern
Neuromuscular Synaptic Degeneration in Motoneuron Diseases

Weichun Lin’s team has created a novel transgenic mouse—based, in part, on a fairly newly-discovered, inheritable ALS mutation—that develops motor neuron disease with key features of the human disease. The mice become paralyzed at 5 months of age, and the paralysis progresses to the rest of the body within ten months. The specific cell error the model mice show should shed light on poorly-explored aspects of the ALS process, namely, events at the motor neuron synapse and those involving the cell’s system for removing damaged proteins. Lin’s grant supports his month by month study of motor neurons and synapses in this new model. He hopes to see how synaptic and conduction changes relate to outward signs of the disease.

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Maiken Nedergaard, MD, PhD (Renewal)

University of Rochester
Identification of early changes in astrocytic gene expression in a mouse model of ALS using FACS-Array analysis

Astrocytes are the most abundant central nervous system cell, yet their having a role in the progression of ALS has been discovered only recently. The star-shaped cells configure themselves into a close network, creating micro-environments where they contact neurons. These areas are critical for proper activity of neurons at synapses.
We plan to analyze the physical changes that astrocytes undergo throughout the progression of ALS, to determine how changes in this highly structured network, or syncytium, as it's called, influence motor neurons' susceptibility to cell death.
We also plan to study astrocytic genes that are misregulated in very early phases of the disease - before symptoms - in an attempt to identify early markers and the earliest-disrupted chemical pathways. This, we believe, could shed light on ways that astrocytes affect motor neuron cell death.

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John W. Griffin, MD & Mohamed Farah, PhD

Johns Hopkins School of Medicine
New Tools for Assessment of the Pathology of Experimental Motor Neuron Diseases

Funding for this project was made possible by the Muscular Dystrophy Association

We have developed new techniques to investigate pathology of the peripheral nervous system with greater accuracy and efficiency. Now we're using them successfully to study growth factor and other types of cell signaling, nerve regeneration, and the effects of nerve demyelination. Applying these approaches to ALS models is especially timely; we simply don't know the extent and pace of neuronal changes in these disorders. A secondary but important goal is to find a simple, rapid indicator of the state of health of the peripheral nervous system, one that can be used by any investigator to any rodent model of motor neuron or peripheral nerve disease.

Ron Oppenheim, PhD & Carol Milligan, PhD

Wake Forest University
Early Changes in ALS: Motoneuron Cell Body and Synaptic Stripping

In ALS, the presumed cause of muscle movement loss has always been the death of motor neurons. New research is showing, however, that while motor neuron death does occur, it's the pulling away of neuron from muscle that appears to precipitate disease symptoms. Our work will study early changes in biology that occur at the motor neuron/muscle junction and relate them to earlier or subsequent changes in the motor neuron proper. We use a multidisciplinary approach to discover which portion of the nervous system shows ALS's earliest changes. Our intent is to find a biomarker for the disease - one that will report on the usefulness of new therapies.

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Philip C. Wong, PhD

Generation and Characterization of Wildtype and ALS-linked TDP-43 Mice (Renewal)
   

How disease arises in sporadic ALS remains elusive. The recent discovery of mutations in a gene called TDP-43 (TAR DNA-binding protein), linked to both sporadic and familial ALS, provides the opportunity to elucidate the underlying cause of sporadic ALS. In this project, we investigate whether an ALS-associated mutant TDP-43 protein can cause motor neuron disease in mice. If so, a mouse model will be available to clarify how disease arises in sporadic ALS and for design of therapeutic strategies to attenuate this devastating disease.

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Giovanni Manfredi, MD, PhD

Weill Medical College, Cornell
Mitochondrial Axonal Transport Defects in ALS Motorneurons
   

Partial funding for this project was made possible by the New York Community Trust

Giovanni Manfredi and others studying motor neurons in mouse models of ALS have noticed that the animals' mitochondria – the minute organs that produce most of a cell's energy – are damaged. The same is true in ALS patients, who also appear to have abnormal mitochondria.

Using mice carrying a mutated form of the cell enzyme SOD1 that's responsible for some types of inherited ALS, Manfredi has begun clarifying the damage process. His hypothesis is that their mitochondrial injury results in a loss of energy that trips motor neuron decline. Additionally, mitochondrial damage in SOD1 mouse models also appears to trigger apoptosis, cells' hard-wired program for death.

For now, Manfredi's focus rests on the activities of SOD1. The enzyme, he's discovered, can reside in mitochondria as well as in cell cytoplasm. But he says only mitochondria containing mutant SOD1 display features typical of injury.

Since joining the Center, Manfredi's begun looking at various different SOD1 mutations, to determine whether mitochondrial damage is a common denominator in all of them. By understanding SOD1's role in affecting mitochondrial health, he hopes to explain the overall effect on motor neurons in cell and animal models created in his laboratory.

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J. Paul Taylor, MD, PhD

St. Jude Children's Research Hospital
A Drosophila model to investigate the role of TDP-43 in ALS

Motor neurons of ALS patients typically contain abnormal deposits of the protein TDP-43. Some researchers have suggested such deposits are important in tripping ALS or in its progress. There is, however, no concrete proof of this. We have developed a model of ALS in the fruit fly, Drosophila by introducing the human TDP-43 gene. We hope to use this model to understand the protein's role in the disease.

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