Translational Science Unit (TSU)
The ALS Translational Research Group is composed of principle investigators, students, postdoctoral fellows and experienced research technicians. These individuals conduct experiments on a daily basis. It is through their work that we can better understand underlying events in ALS and ultimately identify targets for therapeutic approaches.
Carol Milligan, PhD heads the ALS Center’s TSU coordinating a series of institutional and national grants that fund research for treatments and potential causes of ALS. Dr. Milligan is Professor in the Department of Neurobiology and Anatomy, and an Associate in the Department of Neurology. The overall focus of the research in Dr. Milligan’s lab is to understand the intra- and intercellular mechanisms that mediate motor neuron survival and death during normal development and in ALS and other motor neuron diseases.
Current research projects include:
- Examining the role of signal transduction pathways in mediating motor neuron survival and death during CNS development
- Determining the motor neuron stress response and the role of astrocytes and muscle in disease
- Identification of CSF antibodies as potential biomarkers for ALS
- Identifying early changes in spinal cord and neuromuscular junctions in ALS
Despite the importance of muscle strength in preventing physical disability, the cellular and molecular mechanisms responsible for the age-dependent decline in the neuromuscular system are only partially understood. The main focus of our research is to determine the molecular and cellular mechanisms underlying the age-dependent alterations in structure and function of motor neurons and skeletal muscle fibers.
Particularly, we are interested in the reciprocal interaction between muscle cells and spinal cord motor neurons, the role of trophic factors and ion channels in tissue function, and interventions aimed at ameliorating and/or delaying the age-dependent impairment in the neuromuscular system.
Left to Right: Marlena Kuhn (1st year MD/PhD student), Carol Mansfield (lab tech), Matthew Martin (2nd year Med student), Jane Strupe (lab tech), Mac Robinson, PhD (Instructor-Mac will be leading the production of Hsp70), Kristen Sanders (Graduate student, Neuroscience Program), Carol Milligan, PhD (Professor Department of Neurobiology and Anatomy, Director ALS Center Translational Science Unit, Director of the Neuroscience Graduate Program), Sharon Vinsant (Research Associate). Ron Oppenheim, PhD, Professor Department of Neurobiology and Anatomy was not pictured.
[See a video explaining Wake Forest Baptist Health basic research efforts in ALS.]
One of our current projects is examining the very early events in ALS disease process, specifically those associated with muscle weakness. Muscle weakness occurs because the motor neurons, the cells that no longer function and die in ALS, lose contact with their target muscle. Motor neurons are complicated cells because their cell bodies are in the spinal cord, and they extend processes through the nerves to contact target muscles.
In ALS it is not known if the disease starts in the central nervous system (spinal cord and brain) or in the peripheral nervous system (motor neuron axon and nerve terminal that contacts muscle). Numerous ALS clinical trials have been unsuccessful, perhaps because the treatments are initiated too late in the course of the disease or because the targeted mechanism are too far down the cascade of events that leads to motor neuron death.
Understanding early events may provide new insight into motor neuron biology that may translate to human disease pathogenesis. After identifying the location of early nervous system changes in ALS we will use this information to propel further studies into disease biomarkers and the development of therapeutic interventions.
We are using the mutant SOD1G93A mouse model of ALS for this study. This mouse develops muscle weakness, a symptom of ALS, at approximately 90 days of age. We have found that motor neurons lose contact with their target muscles as early as day 25-30 of age, long before overt symptoms are noticed.
This tells us that the disease process begins before clinical signs are noticeable. Furthermore, we now know that the motor neuron appears to be sick before it loses contact with its muscle. We hope that by understanding why the cells are sick, and what can be done to help them, we can prolong the time that the motor neuron maintains contact with muscle and therefore slow, and possibly halt disease progression.
We have started to study the tibialis anterior (TA) muscle in the ALS mouse. This muscle in both human and mouse is responsible for raising the foot. In the mouse we find that the motor neurons lose contact with the muscle between day 14 and 30 of age, as shown in the graph below.
When we examine the area where the nerve comes in contact with the muscle (the neuromuscular junction) at day 14, we can see that even before the denervation occurs, there are abnormalities in the nerve. Below is a picture from the electron microscope. We can see the neuromuscular junction at 10,000 times magnification. The nerve terminal is shaded gold, and the muscle region is green.
The mitochondria in the mutant motor neuron are abnormal and appear to be swollen (arrows). Mitochondria are essential for the cell to have sufficient energy levels.
We are also trying to determine what the motor neurons look like in the spinal cord when they lose contact with the muscle. We have developed a technique that allows us to distinguish which motor neurons have lost contact with the muscle and those that remain in contact. To do this we make two injections into the TA muscle with a tracer that is taken up by the nerve terminal and transported back to the cell body in the spinal cord.
The first injection is at day 14 when all the motor neurons are in contact with the muscle. These cells appear green in the photo below. The second injection is at day 28 where 40% of the motor neurons have lost contact with the muscle. Only those cells in contact will take up the tracer and will appear red. Cells that contain both green and red are in contact with the muscle, while those that are only green have lost contact (white arrows).
With this type of approach, we can begin to determine specific differences between the motor neurons, helping us to understand why they lose contact with the muscle.
To learn more about ALS research and how you can help, select a link below.
Our research is funded in part by The Robert Packard Center for ALS Research at Hopkins, National Institutes of Health: National Institute of Neurological Disorders and Stroke, the Blazeman Foundation and the WFSM Translational Science Institute.