2004 Second Cycle Research Grant Recipients
$2,342,973
Researchers, please note that these grants were awarded for the second cycle of 2004 (application deadline June 2004).
Barros, Claudia, Ph.D., The Scripps Research Institute, La Jolla, CA
$120,000.00, 2-year Grant
ErbB signaling in glial development and myelination in the CNS
Research Category: Stem Cells
Glial cells are the supporting cast of the brain and spinal cord. Glia serve as stem cells, regulate the growth and function of neurons, and produce the myelin insulation that enables axons to transmit messages from neuron to neuron. However, researchers know little about how these important cells arise and assume their roles. One growth factor called neuregulin-1 (NRG-1) is thought to influence glial development. NRG-1 binds to a family of receptors on the surface of glial cells that are known as ErbB receptors, and this coupling switches on the signal pathways that deliver marching orders to the cell. Until recently, research on this signaling mechanism has been hindered by the lack of suitable animal models as well as the existence of several erbB receptors that may have both unique and overlapping roles. Dr. Barros has developed a mouse model in which NRG-1 signaling no longer works, and that model enables her to pinpoint what the various erbB receptors do. Her preliminary data already indicate that one erbB receptors – erbB2 – is required for myelination to occur. In this study, she expects to clarify how the erbB signaling sequence operates during both the development of glial cells and during formation and maintenance of myelin.
Bonni, Azad, M.D., Ph.D., Harvard Medical School, Boston, MA
$150,000.00, 2-year Grant
Cell-intrinsic regulation of axonal growth by Cdh1-anpahase promoting complex
Research Category: Axon Guidance, Synapse Formation and Neurotransmission
Researchers know very little about the changes that occur inside neurons after an injury and prevent them from sending out new axons to replace the ones that were lost or damaged. Dr. Bonni's team has discovered one such intrinsic mechanism that is activated by the proteins of myelin, the fatty coating that enwraps healthy axons. Following a spinal cord or brain injury, damaged myelin releases these proteins, and they flood the area surrounding the lesion, polluting the extracellular environment. A large protein complex termed Cdh1-anaphase promoting complex, or Cdh1-APC, appears to set off the myelin-induced reaction within the cell that then inhibits growth. Cancer researchers have long been interested in this protein complex because it performs an important role in cell division in proliferating cells. Neuroscientists have known that Cdh1-APC was present in neurons – even though they do not undergo cell division – but its function has remained mysterious. In this study, Dr. Bonni will build on his previous work to investigate the role Cdh1-APC plays in controlling axonal growth in the brain and spinal cord. In particular, he wants to clarify just how Cdh1-APC contributes to the inability of neurons to regrow their axons when myelin proteins are present. This strategy is promising because a therapy that would block Cdh1-APC might be enable neurons to regenerate injured axons.
Bregman, Barbara S., Ph.D., Georgetown University School of Medicine, Washington, DC
$150,000.00, 2-year Grant
The synergistic effect of rolipram administration and increased post-injury activity after spinal cord injury
Research Category: Promotion of Axon Growth and Remyelination
Successful treatments for spinal cord injuries will require not only medications that promote regeneration but also rehabilitation. Yet remarkably little research has focused on how the two approaches complement each other, and Dr. Bregman hopes to begin filling that gap. In this study, she will combine a drug that improves the capacity of neurons to regenerate with a rehabilitation routine that increases activity. She will test whether this tandem approach yields more rewiring of spinal circuitry and more recovery of function than either therapy does alone. She also will build on her previous findings that recovery of function in animal models that received treatments to promote the growth of new axons was due both to the new axons as well as to the reshaping of surviving nerve pathways above the spinal cord injury. Using animal models, she will administer rolipram, an FDA-approved antidepressant and anti-inflammatory agent that crosses the blood-brain barrier and increases the concentrations of a growth promoting substance called cAMP. In earlier experiments, Dr. Bregman confirmed that rolipram promotes axon regeneration, lessens scarring, and improves functional recovery after spinal cord injury. She will also use rehabilitation strategies – including an enriched environment for the animal models – that her team has found to encourage the rewiring of the nervous system and the recovery of function. Dr. Bregman will evaluate the combined effects of these interventions by quantifying changes in the spinal circuits and the behavior of the animals. She will use traditional measures as well state-of-the-art imaging techniques that will enable her to follow any reorganization of spinal circuits as well as functional improvements after injury.
Brownstone, Robert M, M.D., Ph.D., Dalhousie University, Halifax, NS, Canada
$149,490.00, 2-year Grant
Functional characterization of spinal cord interneurons expressing the homeodomain protein Hb9.
Research Category: Rehabilitation
In 1911, T. Graham Brown demonstrated that the mammalian spinal cord contains all the circuitry needed to activate the muscles involved in walking – even in the absence of input from both the brain and the limbs. In the last decade, this fascinating mechanism has opened the door to new rehabilitation routines as clinicians have begun to tap its potential to restore some function after a spinal cord injury. Yet no one has pinpointed the network of neurons, or central pattern generators, in the spinal cord that produces the rhythm muscle firings that enable us to place one foot in front of the other, again and again. Recent scientific and technological advances are likely to change that, however. For example, Dr. Brownstone's laboratory was able to identify in mice a population of interneurons that may be important in the generation of locomotor rhythms. Interneurons are the connector nerve cells in the spinal cord that transmit messages from sensory neurons to motor neurons. Under this grant, Dr. Brownstone will continue exploring these interneurons. He hopes to determine how they affect the production of locomotor activity and identify which neurotransmitters and neuromodulators determine the properties of the interneurons and how they do that. The results could provide new insight into the control of locomotion and eventually could help clinicians to develop better rehabilitation regimens that would help people with injured spinal cords to walk again.
Eftekharpour, Eftekhar, Ph.D., The Toronto Western Hospital Research Institute, Toronto, ON, Canada
$115,655.92, 2-year Grant
Repair of the chronically injured spinal cord: Use of neural stem cell transplantation to promote spinal cord remyelination.
Research Category: Stem Cells
Often many axons along the perimeter of the spinal cord survive an injury but no longer can conduct signals properly. Dr. Eftekharpour wants to understand better exactly what happens to these surviving axons so that the damage might be reversed. He has shown that a spinal cord injury actually alters the molecular structure of the surviving axons, interfering with their performance and worsening the loss of function. He and other scientists attribute these molecular abnormalities to the disintegration of the myelin layer that normally enwraps axons. In this study, he will try to reverse those changes by transplanting neural stem cells into mouse model of spinal cord. Based on preliminary results, he predicts the primitive cells will evolve into oligodendrocytes, which in turn will replace the missing myelin. Dr. Eftekharpour hypothesizes that remyelination will inhibit or reverse the molecular changes in the axons. If successful, this study could lead to treatments that would improve neurological function and the quality of life, both for the newly injured and people who have lived with spinal cord injuries for years.
Gu, Chenghua, Ph.D., Johns Hopkins University School of Medicine, Baltimore, MD
$120,000.00, 2-year Grant
Semaphorin/neuropilin signaling during development and adult CNS regeneration
Research Category: Axon Guidance, Synapse Formation, and Neurotransmission
Guertin, Pierre A., Ph.D., Laval University Research Hospital, Quebec, PQ, Canada
$145,200.00, 2-year Grant
Differential role of 5-HT2A and 5-HT2C receptor subtypes in acute induction of hindlimb movements in early chronic paraplegic mice
Research Category: Rehabilitation
In addition to robbing people of motor and sensory functions, spinal cord injuries often lead to severe health conditions related to both their paralysis and their inability to engage in regular physical activity. These complications include cardiovascular problems, osteoporosis, life-threatening infections, and muscle wasting. Dr. Guertin is trying to perfect a protocol that would make it easier for people with spinal cord injuries to exercise on treadmills and preserve their physical fitness. The approach hinges on the use of medication that he believes can safely trigger so-called automatic walking, in which the feet move involuntarily. In this project, he will try to decipher the molecular events that cause the lower spinal cord to generate the rhythmic nerve impulses that control locomotion. Dr. Guertin will administer the experimental drug quipazine to mouse models of spinal cord injury. A single injection of quipazine activates hindlimb stepping in paralyzed rodents for up to an hour. The drug acts through two receptors for the neurotransmitter serotonin, and Dr. Guertin will use a multi-disciplinary analysis to identify which of the two actually induces the stepping motions and which has other effects. If the results from the animal models apply to humans, then these experiments might lead to affordable, relatively simple ways to enable people with spinal cord injuries to exercise – even at home. These findings also might help clinicians to amplify the effects of rehabilitation routines that involve treadmill stepping.
Jessell, Thomas M., Ph.D., Columbia University, New York, NY
$150,000.00, 2-year Grant
Axonal Receptors and the control of motor axon guidance
Research Category: Axon Guidance, Synapse Formation, and Neurotransmission
Motor neurons are nerve cells in the spinal cord and hindbrain whose long axons connect the central nervous system to the muscles and control all motor activity. Linkages between specific sets of motor neurons and specific muscles form during embryonic development and do not regenerate later on if a spinal cord injury or neurodegenerative diseases disconnect them. Dr. Jessell focuses on just how embryonic motor neurons reach their final destinations. In this project, he will explore the function of three axon guidance receptors that appear to direct embryonic motor axons on their journey to target muscles. These receptors are proteins on the leading edge of growing axons that enable them to detect positional cues in their environment and figure out which direction to go. Dr. Jessell postulates that these three receptors are part of a motor neuron zip code that determines which motor neurons connect to which target muscle. One of the receptors, Cxcr4, and the molecule that binds to it, Cxcl12, control the early decision of motor axons to exit the embryonic spinal cord. This key maneuver distinguishes motor neurons from all other neurons.
The Jessell laboratory has found evidence that Cxcr4 desensitizes motor neurons to three types of cues that otherwise would lead the neurons astray. All three are chemorepellents, which turn away approaching axons. Dr. Jessell predicts that Cxcr4 might also suppress other molecular stop signs, in particular the one from the Nogo-66 receptor, which prevents nerve regeneration in the adult spinal cord. Using the most advanced tools of mouse genetics and developmental biology, he will test this theory on motor neurons that he derives from embryonic stem cells. If Cxcr4 does block the Nogo-66 receptor, then replacement motor neurons from embryonic stem cells could be genetically engineered to produce Cxcr4 and then implanted into injured spinal cord. This approach would enable the new axons to exit the adult spinal cord, clearing a major roadblock on the path to reconnecting a lost circuit. Dr. Jessell will also study how the two other axon guidance receptors influence the route that motor axons choose outside the spinal cord. The results of this study could enable doctors one day to transplant replacement motor neurons equipped with built-in "positioning devices" that would enable them to rewire the damaged motor control system and restore muscle function.
Neuhuber, Birgit, Ph.D., Drexel University College of Medicine, Philadelphia, PA
$117,858.00, 2-year Grant
Temporal and spatial regulation of transgene expression to promote axonal regeneration and recovery of function in spinal cord injury
Research Category: Promotion of Axon Growth and Remyelination
Treatment of spinal cord injury poses immense challenges because of the complexity and the duration of the body's reaction to the initial damage. Any successful treatment to protect surviving cells and rebuild the lost spinal circuitry will have to be multi-pronged and carefully staged to arrive at a precise place in the spinal cord at just the right time. This approach might, for example, include transplanted cells as well as the regulated delivery of various substances to promote axon growth, digest scars, and neutralize the toxic environment surrounding the lesion. Dr. Neuhuber and colleagues have developed a novel way to control the delivery of any number of therapies that would help repair the spinal cord. This system relies on small, harmless molecules that easily can be distributed throughout the body via the blood stream. These so-called inducers would work with transplanted cells that are genetically engineered to express a variety of therapeutic substances and can be turned on and off independently of each other. The inducers would throw the on switch, which would remain on only as long as they are being administered. This approach would prevent possible adverse side effects from long-term, unregulated gene activation.
In this proposal, Dr. Neuhuber will test this novel system with the growth promoter BDNF. In previous studies, BDNF delivered by transplanted cells has spurred the growth of new axons, but they remained within the cell grafts and failed to re-enter the more hostile environment of the damaged spinal cord. Dr. Neuhuber hypothesizes that the inducers will enable axons to overcome that obstacle. She plans to transplant bone marrow stromal cells, a type of stem cell, that will be genetically modified to express BDNF when inducers are present. She will place the cells at the injury site and a location distant from it and then use a different inducer for each location. She first will activate BDNF expression at the injury and then discontinue those inducers; then she will start giving the second inducers, which will produce BDNF at the farther location. The concentration of BDNF at the injury site then would decrease, while the axons would have a high level of BDNF to grow towards. Dr. Neuhuber expects that this well orchestrated approach will enable axons to extend through the cell transplant and into the host tissue, which could lead to the recovery of lost function. If successful, this flexible delivery system could enable doctors to administer a therapeutic cocktail to the injured spinal cord and use the inducers to activate each ingredient when and where it could do the most good.
Pearse, Damien Daniel, Ph.D., University of Miami School of Medicine, Miami, FL
$150,000.00, 2-year Grant
Sensory plasticity and pain associated with regenerative therapies for spinal cord injury
Research Category: Concomitant Function
Much of the experimental work on therapies for spinal cord injuries focuses on the recovery of motor function; little effort has been devoted to the changes – or plasticity – in the sensory system and the pain that results, after the injury or after trial treatments. Dr. Pearse believes that this three-stage project will be the first to analyze the development of pain following one of the most promising experimental treatments for spinal cord injuries: the transplantation of olfactory ensheathing glia (OEG) into the lesion. In animal experiments, these cells from above the nasal cavity have promoted regeneration of injured axons and improved functional recovery after spinal cord injury. He first will establish a testing regimen so he can identify changes in the sensory system and behavior of an animal models of spinal cord injury. Once he has characterized sensory plasticity and the development of pain, he then can see whether the grafting of the olfactory cells alters them. Finally, he will try to explain the mechanisms that cause sensory plasticity and pain after the transplantation of OEG by tracing the growth of new axons, looking for nerve cells that seem to be misfiring, and analyzing changes in neurotransmitters – all of which could contribute to pain. A better understanding of the processes that lead to chronic pain in people with spinal cord injuries will enable researchers to insure that new therapies do not inadvertently increase or create pain.
Roskams, Angela-Jane Irene, Ph.D., The University of British Columbia, Vancouver, BC, Canada
$150,000.00, 2-year Grant
Can Human Lamina Propria Ensheathing Cells Stimulate Repair in Contused Spinal Cord
Research Category: Stem Cells
Olfactory ensheathing cells (OECs) are a fascinating type of glial, or helper, cells found in the olfactory bulb. The bulb lies at the base of the brain, just above the nasal passages and receives sensory information from the nose. In the adult olfactory system, the cells retain some qualities of fetal cells and create a fertile environment for new nerve cells to replace old or damaged ones. In recent experiments, ensheathing cells that have been extracted from the olfactory bulb have shown exciting potential to promote repair and functional recovery in animals with spinal cord injuries. Dr. Roskams's laboratory has been studying these cells, using samples from the lamina propria (LP-OECs), a cell layer just below the surface of the roof of each nostril. These ensheathing cells are far easier to retrieve, both from rodents and humans, than cells from the more remote olfactory bulb. In the olfactory system, Dr. Roskams team has shown that ensheathing cells stimulate neuronal survival and regulate endogenous stem cells. In transplant experiments with rat models of spinal cord injuries, the researchers found that cells from the lamina propia performed like a multi-purpose repair kit. They activated surviving glial cells, created a permissive environment for growth, stimulated the emergence of new blood vessels, limited scarring and cavitation, and promoted axonal sprouting. In this three-part project, Dr. Roskams and her colleagues will continue to explore the properties of these unusual cells. These researchers first will try to perfect a technique to multiply human cells from the lamina propria. They then will assess how well these cells promoting regeneration in laboratory experiments. Finally, researchers will transplant the cells into both acute and chronic rat models of spinal cord injuries. These animal experiments are a crucial step toward long-awaited human trials of olfactory ensheathing cells.
Shields, Richard Kemp, Ph.D., The University of Iowa, Iowa City, IA
$150,000.00, 2-year Grant
Neuromusculoskeletal recovery after spinal cord injury
Research Category: Rehabilitation
Dr. Shields is developing an exercise routine that enables people with spinal cord injuries to put vital weight-bearing stresses on their leg muscles and bones. His approach relies on neuromuscular electrical stimulation (NMES), in which electrical current induces muscle contractions. This therapy has been shown to improve muscle endurance and bone strength and to promote useful adaptations in the nerve circuitry that survives the injury. However, NMES remains expensive, labor intensive, and available only in special research or rehabilitation centers. Moreover, although many studies indicate that NMES-assisted exercise may help people with spinal cord injuries, no one knows precisely now much is needed. Dr. Shields and his colleagues predict that their version of NMES will be easy to do at home, not disrupt people's lives, and require minimal supervision from a health care provider. In this study, they will test their protocol, trying to quantify both the effects of NMES-assisted standing on the neuromusculoskeletal system and the relationship between the dose of exercise and its benefits.
Subjects will use a commercially-available standing wheelchair and a customized electrical device to deliver the NMES. When subjects stimulate the quadriceps muscles of both legs simultaneously, they will stand up from a partial squat and support their own weight. They will repeat this maneuver for 30-40 minutes; the precise dose of exercise will vary based on how much they weigh. An apparatus mounted behind their knees will record how much exercise is completed. A visual monitor will tell subjects whether they have reached their target dose for each session, and this data will be stored in a built-in log. Participants will regularly download their logs onto home computers and transmit their statistics to the researchers via the internet. Subjects will return to the laboratory only for periodic follow-up and testing. If successful, this approach could enable most people with spinal cord injuries to get a high dose of closely monitored exercise and to preserve the health of their legs until treatments are developed to reverse their paralysis.
Simard, J. Marc, M.D., Ph.D., University of Maryland, Baltimore, Baltimore, MD
$150,000.00, 2-year Grant
The NC(Ca-ATP) channel - a new player in spinal cord contusion
Research Category: Neuroprotection
In earlier work on brain injuries and strokes, this physician-scientist discovered a destructive chain of events that kills a type of astrocyte in the vulnerable tissue surrounding a brain lesion, a zone called the penumbra. Normally, astrocytes nourish and provide structural support for neurons. Following an injury, a subset of these cells known as reactive astrocytes start to enlarge, proliferate, and form scars. When a stroke or other brain injury deprives tissue of oxygen, new pores (ion channels) appear on the cell membranes of reactive astrocytes in the penumbra. Sodium molecules rush through these channels into the cells, disrupting their normal electrical charge. Water then floods the cells, and they die. Dr. Simard found that this astrocyte death promoted edema and inflammation of the tissue around the injury, but astrocyte survival actually reduced these conditions. In rodent models, he prevented these new ion channels – NCCa-ATP channels – from opening by administering glibenclamide, a diabetes drug. Dr. Simard has early indications that the same mechanism that causes astrocyte death in the brain may occur in the spinal cord following an injury. In this three-part study, he first will confirm that NCCa-ATP channels appear in the reactive astrocytes in the penumbra and then document their role in the destruction of tissue. Finally, he will test whether glibenclamide can interrupt this damaging cycle in animal models of spinal cord injury. If successful, this study could lead to treatments to protect tissue and preserve function after a spinal cord injury.
Snider, William D., M.D., University of North Carolina at Chapel Hill, Chapel Hill, NC
$150,000.00, 2-year Grant
Roles of GSK-3 and ILK in Regenerative Axon Growth
Research Category: Promotion of Axon Growth and Remyelination
Neuroscientists know surprisingly little about the localized signaling cascade that launches axon regeneration in peripheral nerves. The importance of this mechanism was underscored recently when investigators in several laboratories improved spinal cord regeneration in animal models by trying to mimic what occurs naturally in the peripheral nervous system. Those studies used a variation of a wide-spectrum signaling protein called cAMP to initiate intracellular signaling pathways in the spinal cord that somewhat resembled the ones in the peripheral nervous system. Dr. Snider and his laboratory have been focusing on a more specific signaling pathway in the peripheral nervous system that controls a key step in axon growth: the assembly of microtubules in the growth cone, or leading edge, of an axon. Microtubules are tiny rigid tubes of protein molecules that alternate between phases of elongation and shrinkage. The tubes serve as scaffolding inside neurons and help axons extend toward their target connections.
In recently published work on cultured peripheral neurons, the Snider group identified how an important signaling pathway initiates axon growth. The signaling begins when nerve growth factor, a vital extracellular protein that promotes axon growth, deactivates glycogen synthase kinase 3ß (GSK-3ß) inside the growth cone. GSK-3ß mediates many events in the nervous system. Turning it off stimulates another protein, adenomatous polyposiscoli (APC) to bind to microtubules, helping them to assemble and promote efficient axon growth. Under this grant, Dr. Snider and his colleagues will continue exploring this pathway. They will use mice bred either without the gene that codes for GSK-3ß or for another protein that regulates GSK-3ß activity called integrin-linked kinase (ILK). These animals will enable the researchers to test whether GSK-3ß or ILK – or both – are required for peripheral nerve regeneration. If GSK-3ß does influence the assembly of microtubules during axon regeneration in living animals, and if ILK is confirmed as a key upstream regulator, then these experiments would suggest new targets for future drugs to improve axon regeneration in the spinal cord.
Wrathall, Jean R., Ph.D., Georgetown University School of Medicine, Washington, DC
$150,000.00, 2-year Grant
Endogenous precursor cells in chronic SCI
Research Category: Stem Cells
Glial cells control the chemical environment of neurons and insulate their axons with myelin. Even if some nerve cells and connections survive a spinal cord injury, people still lose function if glial cells are lost. Experimental treatments that protected or replaced glial cells have improved the outcome in animal models of spinal cord injury, but these approaches are difficult to use with humans. Dr. Wrathall and her colleagues are pursuing what promises to be a more practical way to replace glia. These researchers have detected a reservoir of glial precursor cells in rat models six weeks after they underwent experimental spinal cord injury. Dr. Wrathall believes that these primitive cells can be stimulated to divide and create more glial cells that would limit the loss of function from an injury.
In this project, she first will prepare tissue cultures of cells harvested from the injury site of rat models six weeks after the injury. She then will test a number of growth factors to see which best prod the precursor cells to proliferate and mature into viable glial cells. She also will examine cells from rats' spinal cords three and six months after an injury to see if the precursor cell reservoir still is present. The persistence of these cells for six months in rats would suggest that they might survive in humans for many years after injury. With the information gleaned in the first parts of the project, she then will design treatment protocols to test in the chronically injured rat spinal cord during the second year. She will assess whether the experimental treatments encourage glial cells at the injury site to proliferate and become mature glial cells. If they do, she will evaluate how they affect the test animals' ability to walk, swim, stand on an incline, and perform reflex tests. If successful, this study could help develop treatments for spinal cord injuries even years after they occur.
Zheng, Binhai, Ph.D., University of California, San Diego, La Jolla, CA
$150,000.00, 2-year Grant
Assessing the role of Nogo in spinal cord regeneration failure by acute deletion of the Nogo gene in adult mice
Research Category: Growth Inhibition
Myelin, the fatty insulation that enables axons to function properly, contains proteins that actively block the regeneration of axons after an injury. One powerful inhibitory protein in myelin is called Nogo, and it appears to be a major contributor to regeneration failure. However, recent experiments on spinal-cord injured mice that were bred without the gene for Nogo yielded decidedly mixed results. Outcomes varied from no axon regeneration to extensive regrowth. To explain this discrepancy, Dr. Zheng hypothesizes that the Nogo-deficient mice are a poor model for spinal cord research because they may undergo compensatory changes during embryonic development that mask the effect of deleting the Nogo gene. In this project, he proposes a new approach to evaluating how Nogo affects regeneration. He plans to develop a regulated way to delete the Nogo gene in adult mice, thus eliminating the chance for any developmental compensation. These mice then will be examined for their ability to regenerate spinal axons following spinal cord injury. Dr. Zheng notes that this new model also would reflect more accurately the clinical challenges posed by human spinal cord injuries, which occur following normal development in the presence of Nogo. Successful regeneration in the spinal cord of the new mouse model would indicate that Nogo indeed plays a significant role in preventing the growth of new axons. If no regrowth occurs, then researchers would have to explore the action of other inhibitory substances, either alone or in combination with growth-promoting factors. Dr. Zheng's approach, using his so called acute-deletion model, could provide a better way to study Nogo and other factors that might influence axon regeneration. The technique also might one day give doctors a way to inactivate other growth inhibitors immediately after a spinal cord injury.
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