2004 First Cycle Research Grant Recipients
$2,026,780
Dr Frédérique Jeanne Courtois, Ph.D., Université du Québec à Montréal, Montreal, QC; Canada
$138,668.00, 2-year Grant
Self-induced ejaculation and orgasmic potential in spinal cord injured men
Research category: Concomitant function
Men comprise at least 80 percent of the spinal cord injured population, and most are hurt in the prime of their reproductive and sexual lives. Unfortunately, doctors have had few options to offer men with spinal cord injuries who wished to improve their sexual function and sometimes to father children. Although doctor-assisted ejaculation was possible, traditionally the practice was limited to reproductive purposes. This meant the treatment was available only to patients who were of reproductive age, were involved in a stable relationship, and wished to have children. To retrieve semen for fertility tests or artificial insemination, doctors induced ejaculation with a rectal probe and sometimes drugs, which are no longer available because of their adverse side effects. Men who still had sensation below the waist often required anesthesia for the procedure. These intrusive techniques, and the de facto restrictions on their availability, generally became unnecessary with the advent of vibrator stimulation. The device enables spinal-cord injured men to achieve ejaculation in private, either for reproductive purposes or for sexual activity. For many men, this approach offers consistent ejaculation and the perception of sexual or orgasmic sensations. Ejaculation also reduces the common problem of spasticity, and this bonus effect can last from a few hours to several days.
In collaboration with one French and two Canadian rehabilitation centers, Dr. Courtois has developed a program to teach men with spinal cord injuries to induce ejaculation. Clinicians specifically mention to all male patients that ejaculation tests are available so that the men can assess their ejaculation potential independent of any reproductive issues. In this project, she and her colleagues will test the approach on four groups of men, categorized by the level of their injuries. Groups vary from quadriplegics with high-level injuries to men with injuries to the conus terminalus, the lowest portion of the spinal cord. Patients will engage in progressive exposure to various sources of self-stimulation, ranging from natural stimulation, to vibrator stimulation, to vibrator stimulation combined with oral doses of the drug Midodrin. The drug is usually used to treat abnormally low blood pressure and has fewer side effects than the agents that previously were used to help paralyzed men ejaculate. Researchers will monitor the subjects' heart rate and blood pressure and assess spasticity in their legs and lower abdomen. Using interviews and patient-completed questionnaires, Dr. Courtois and her colleagues also will collect data on the sensations that men perceive during ejaculation. (Even in complete spinal cord injuries, men still experience some sensations related to changes in blood pressure, heart rate, and shivering.) If successful, this protocol could greatly improve the quality of life for men with spinal cord injuries, offering them control over their sexual and reproductive functions. Moreover, it would reduce the costs and side effects of fertility tests and provide an alternate to drug therapy for the relief of spasticity.
Dr. Steven A. Crone, Ph.D., University of Chicago, Chicago, IL
$120,000.00, 2-year Grant
Identification of spinal interneurons required for locomotor function
Research category: Rehabilitation
Injury to the spinal cord often interrupts the flow of information from the brain to the spinal cord circuits that control muscle function. In this study, Dr. Crone plans to identify and characterize interneurons, the nerve cells in the spinal cord that receive input from the brain and transmit it to the muscles involved in locomotion. He already has identified one type of interneuron that potentially controls motor function. Interestingly, these neurons express a gene named Chx10, which will enable Dr. Crone to home in on these cells. Using laboratory mice, he will systematically inactivate those interneurons in a reversible fashion and then pinpoint their exact function by comparing their ability to walk on a treadmill to the performance of untreated control animals. Dr. Crone predicts that the methodology he will develop could be readily applied to test the function of any type of neuron in the spinal cord. Knowing which neurons are critical to the control of motor functions will help researchers design therapies that target those cells following spinal cord injury.
Dr. Eric Daniel Crown, Ph.D., University of Texas Medical Branch, Galveston, TX
$118,427.00, 2-year Grant
Cellular memory: A mechanism for pain after spinal cord injury
Research category: Concomitant function
Although researchers have achieved some advances in treating the persistent pain that afflicts many people with spinal cord injuries, its precise causes remain unknown. The trauma seems to trigger a series of molecular events that lead to permanent changes in the behavior of the sensory neurons ¾ the nerve cells that transmit pain messages from the periphery to the part of the spinal cord known as the dorsal horn. Dr. Crown theorizes that these changes resemble the cellular mechanisms that are at work when people are learning and memorizing. He suspects that a spinal cord injury activates genes in region of the dorsal horn closest to the injury site, and these genes make the pain transmitting neurons permanently more excitable. In this study, he will use a microarray technology to quickly to analyze thousands of genes at a time in tissue samples taken from the dorsal horns of rodent models of spinal cord injury. He will compare the activity of genes related to cellular excitability in the dorsal tissue of animals that experience chronic pain to the gene activity in samples from animals that are pain free. Dr. Crown expects his analysis to identify the gene changes that cause chronic pain and could help scientists design novel therapies to alleviate it.
Dr. Mike Fainzilber, Ph.D., Weizmann Institute, Rehovot, Israel
$149,600.00, 2-year Grant
A mechanistic approach to the conditioning lesioning paradigm in injured nerve
Research category: Promotion of axon growth and remyelination
When an axon of a peripheral neuron is damaged, it sends out a distress call to the cell body. The neuron responds by booting a self-repair program that calls for long-range, elongating growth. Dr. Fainzilber is interested in how the axon, which may be up to a meter from the cell body, manages to send this long-distance SOS message and how the cell's genetic machinery then responds. He and his colleagues have recently discovered that the mechanism for this transmission is based on the synthesis of nuclear import proteins at the point where the axon is injured. These proteins operate like taxis, carrying the your-axon-is-injured messages into the nucleus. Scientists had though import proteins existed only inside the cell body near the nucleus, so Dr. Fainzilber did not expect to find them elsewhere, including inside axons. The other surprise was that the outlying import proteins need their own chauffeur for part of their journey. They latch onto motor proteins in the axon that drive them along the length of the axon and into the cell body. Once they arrive, the import proteins detach from their driver and then deliver their own passengers ¾ the signaling molecules ¾ into the nucleus. These messengers in turn induce changes in the regenerative properties of the nerve.
Dr. Fainzilber and his team also demonstrated that they could block this reprogramming in the cell body by introducing synthetic peptides at the lesion that behave like the endogenous signaling molecules. These imposters muscle in, binding to receptor sites on the import proteins and making it impossible for the genuine signaling molecules to find an empty taxi. For this study, Dr. Fainzilber will use the peptides to try to identify which genes are activated very early in the regenerative process. With the help of microarray technology, he also will compare the gene activity in injured cell bodies when the peptides are present to the gene activity in cells without the peptides. Identification of the injury signals and their target genes could enable scientists to harness the mechanism to start a self-repair process in the injured spinal cord.
Dr. Bernhard H.J. Juurlink, Ph.D., University of Saskatchewan, Saskatoon, SK
$150,000.00, 2-year Grant
Glutamine and Quercetin as therapeutic interventions following spinal cord injury
Research category: Neuroprotection
Dr. Juurlink has long been investigating whether antioxidants can lessen the effects of degenerative diseases and aging on the neuromuscular system. Recently, he turned his attention to whether these substances can combat the inflammation and second wave of cell death that follows an acute spinal cord injury. In this study, he will explore the ability of the flavonoid quercetin to protect neurons and other cells after a spinal cord injury. Quercetin is a powerful antioxidant found in fruits and vegetables, including onions, red grapes, and apples. It is one of the 1000's of chemical compounds in foods called flavanoids that protect cells throughout the body from oxidative stress, a condition in which unstable molecules known as free radicals damage cells. In preliminary experiments on rat models, the animals that received quercetin ¾ even two weeks after an injury ¾ recovered significantly more function than the untreated controls. Under this grant, he will continue these studies, hoping to determine exactly how quercetin acts in the spinal cord and how to optimize any benefits. One possible explanation is that it inhibits a signaling pathway that is activated by a spinal cord injury and leads to delayed cell death. More specifically, he hypothesizes that blocking this pathway protects axons and oligodendrocytes, the cells that enwrap axons in protective myelin. Dr. Juurlink also will study the independent actions of several substances that occur naturally in the body and also combat oxidative stress, including glutamine. He already has shown that a combination of glutamine and the amino acid procysteine, which boosts the action of antioxidants, enhanced recovery of function. Finally, he will test for a synergistic interaction between quercetin and glutamine. Positive findings in these experiments would be particularly exciting because quercetin and the other agents appear to be safe for human therapy.
Dr. Scott T. Magness, Ph.D., University of North Carolina at Chapel Hill, Chapel Hill, NC
$120,000.00, 2-year Grant
Characterizing SOX2 function in neural stem cell induction, maintenance and regeneration capacity following spinal cord injury
Research category: Stem cells
Dr. Magness hopes to determine how a protein called SOX2 might be involved in turning on growth-permissive programs in the DNA of cells in peripheral nerves and in the spinal cord. SOX2 is part of a family of proteins that play a key role in determining the fate of primitive cells during development, including those in the brain and spinal cord. The programs that SOX2 turns on are essential for defining and maintaining adult neural stem cells and appear to contribute to neural regeneration following an injury. In preliminary studies, Dr. Magness found that an injury activates SOX2 in both the spinal cord and peripheral nerves. Yet it is unclear what role SOX2 plays after the injury. In this study, Dr. Magness will try first to pinpoint precisely which cell types express SOX2 as well as when SOX2 is turned on when an injury occurs. Next he will investigate how SOX2 functions in neural regeneration by evaluating mouse models that were bred without the SOX2 gene. Finally, he will try to identify all the genes that SOX2 turns on in the spinal cord and peripheral nerve tissue. Once researchers understand the DNA programs that SOX2 regulates after a nerve injury, they might design drugs to stimulate nerve regrowth, extend the life of endogenous adult neural stem cells, and enhance the ability of those stem cells to multiply within the spinal cord.
Professor Stephen Brendan McMahon, FMedSci, Ph.D., King's College London, London, England
$148,548.00, 2-year Grant
Use of retinoic acid receptor beta2 to promote functional recovery after spinal cord injury
Research category: Promotion of axon growth and remyelination
When retinoic acid is applied to cultured neurons, it stimulates the growth of both axons and dendrites, the extensions of neurons that transmit and receive nerve impulses. Retinoic acid is a byproduct of Vitamin A and is vital to the normal development of the bones, skin, brain and spinal cord; it is also used to treat skin disorders and leukemia. However, simply administering retinoic acid might have a range of effects in the spinal cord, including harmful ones such as the unwanted proliferation of some cells. So Dr. McMahon and his colleagues looked for a more targeted, controlled way to increase the amount of retonic acid precisely where it could do the most good. They previously had found that the molecule known as retinoic acid receptor beta2 (RARbeta2) induces axonal growth in nerve cultures. They discovered further evidence in animal models that this molecule prods damaged peripheral nerves to regrow and promotes the recovery of sensation. Dr. McMahon hypothesized that perhaps too few of these receptors for retinoic acid were present following a spinal cord injury. This scarcity would limit the amount retinoic acid and perhaps account for the failure of spinal axons to regenerate. In an earlier study, researchers tested a novel form of gene therapy that produced more RARbeta2 molecules in the treated animals. The approach relies on a viral vector, a safe form of a virus that can no longer cause illness, to deliver into the spinal cord the genes that express the receptor.
In this project, Dr. McMahon will use animal models to test whether this receptor can improve the recovery of function and sensation following a spinal cord injury. He also will assess whether the viral vector works as well in the spinal cord as it does in the peripheral nervous system and will determine how best to administer it. Finally, he will test whether this experimental treatment works better in combination with other growth-promoting substances known as neurotrophins. If successful, this project could lead to new treatments as well as better ways to administer them to patients.
Dr. Steve I. Perlmutter, Ph.D., University of Washington, Seattle, WA
$150,000.00, 2-year Grant
Function of reflex circuits in the spinal cord of behaving primates
Research category: Rehabilitation
When we decide to pick up a fork, a complicated set of spinal circuits integrate commands that start in the brain, travel through the spinal cord, and go out to the muscles in the arm and hand. At the same time, sensory nerves transmit ongoing feedback to the spinal cord about, for example, where our hand is in space. Although the sequence of these events is firmly established, little is known about precisely what goes on in the nervous system, including how the sensory information that enters the spinal cord gets modified, regulated, or combined with outgoing signals. Nor do scientists understand which intermediate nerve cells ¾ or interneurons ¾ are involved nor which reflex pathways control the various parts of arm movements. The lack of answers makes it far more difficult to understand both deficits in motor function following spinal cord injury as well as the therapeutic potential of interventions. Because spinal cord injuries leave spinal pathways mostly intact ¾ though modified ¾ they are candidates for pharmacological and rehabilitative treatments. But scientists must know precisely how any treatment would affect spinal circuitry to promote functional recovery.
This project is designed to characterize the role of spinal neurons in normal movement. Dr. Perlmutter, an expert in the field of movement science, uses a multidisciplinary approach that includes neurophysiology, electrophysiology, and anatomical and behavioral analyses. He and his team will conduct a series of experiments on monkeys to explain how spinal pathways contribute to a wide range of arm movements, performed with varying loads and from different postures. The researchers will also look at how sensory feedback affects the responses of interneurons to various perturbations, such as ____________[SF1]. This project will lay the groundwork for the development of a primate model of spinal cord injury, which will enable Dr. Perlmutter and his colleagues to study spinal reorganization and mechanisms of functional recovery.
Dr. Elisabeth Schultke, M.D., University of Saskatchewan, Saskatoon, SK
$120,000.00, 2-year Grant
Does administration of the flavonoid quercetin modulate glial scar formation after spinal cord injury?
Research category: Promotion of axon growth and remyelination
Dr. Schultke, a neurosurgeon, is currently a postdoctoral fellow in the laboratory of Bernard Juurlink. Taken together, their individual CRF-funded studies should determine how well the flavonoid quercetin protects neurons and leads to the recovery of function in rat models of spinal cord injury. [See Dr. Juurlink's abstract in Neuroprotection.] In earlier experiments, Dr. Schultke found that quercetin did improve nerve cell survival in a rat model of brain trauma and in a rat model of spinal cord injury. In the spinal cord experiments, quercetin also improved the animals' ability to use their hind limbs. Quercetin helped to detoxify the zone around the lesion by clearing away excess iron, fighting a harmful condition called oxidative stress, and reducing inflammation. Quercetin also limited apoptosis, a process in which aging or damaged cells destroy themselves but one that occurs prematurely in healthy cells near the site of a spinal cord injury.
Under this grant, Dr. Schultke and her colleagues will investigate how quercetin affects the scar that forms after a spinal cord injury, which normally inhibits the regrowth of axons. She hypothesizes that quercetin will make the scar tissue more permissive for axon regeneration. If it does, then the researchers will assess whether this alteration actually leads to more replacement axons. Among other analyses, they will look at whether quercetin decreases levels of chondroitin sulphate proteoglycan (CSPG), an extracellular component of scar tissue that blocks axon regeneration; lowering the concentration of CSPG has been shown to improve regeneration. Dr. Schultke will first will study scar formation in animals treated with quercetin as early as one hour after injury. Next she will assess scarring in animals treated two weeks after injury. Based on her earlier experiments, Dr. Schulte expects to see recovery of motor function in a high percentage of animals in both groups. If she does, then this compound found in many fruits and vegetables could soon be tested in human trials.
Dr. Harold David Shine, Ph.D., Baylor College of Medicine, Houston, TX
$140,679.00, 2-year Grant
Mechanisms of induced neuroplasticity in the lesioned spinal cord
Research category: Promotion of axon growth and remyelination
Two-thirds of spinal cord injuries are incomplete. Dr. Shine want to exploit the inherent ability of those spared nerve circuits to reshape themselves after an injury, a mechanism known as plasticity. These adaptations might restore limited but significant function to people with spinal cord injuries. In this study, Dr. Shine will continue his investigation of how surviving axons respond to the injury and whether a growth-promoting protein called Neurotrophin-3 (NT-3) might be used to encourage them to sprout toward the source of the NT-3. In recent experiments, Dr. Shine and his team used gene therapy to induce a local, sustained release of NT-3 in spinal neurons. Axons responded by extending towards them, but only when NT-3 was released and the spinal cord was injured. This observation suggests that at least two types of signals are required to induce regrowth after injury: NT-3 molecules and others released in the wake of spinal trauma. In this project, Dr. Shine and his colleagues will test to see if byproducts of the injured spinal cord induce the surviving axons to grow when NT-3 is present. If an injury does release co-inducing signals, then the researchers would try to pinpoint their source and the molecular nature of their pro-growth signals. Successful results could suggest ways to use gene therapy to exploit the innate plasticity of the nervous system to compensate for an injury.
William D. Snider, M.D., University of North Carolina, Chapel Hill, NC
$150,000.00, two-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 ¾ or both ¾ 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.
Dr. Richard Bernard Stein, Ph.D., University of Alberta, Edmonton, Alberta
$150,000.00, 2-year Grant
Strengthening connections by functional electrical stimulation after human spinal cord injury
Research category: Rehabilitation
Mild electrical current usually can stimulate contractions in muscles that have been paralyzed by a spinal cord injury. When used regularly, this modality can improve muscle strength and endurance as well as reversing the severe bone loss that often accompanies paralysis. If the current is applied during a normal movement such as stepping, then it appears to revitalize compromised nerve circuits and reduce abnormal activity such as spasticity. This approach is called functional electrical stimulation (FES). Dr. Stein, who comes from a physical therapy background, is well known for his work combining physiology, neuroscience, and biomechanics. In this project, he will investigate whether FES can alleviate foot drop, a common problem in people with incomplete spinal cord injuries who no longer can flex their ankles. When they try to swing a foot forward during stepping, it drops and may even drag on the ground. Dr. Stein and his colleagues have developed two novel systems to stimulate the nerve that normally bends the ankle. The first uses electrodes mounted on the skin and the other uses tiny implanted stimulators that can be injected with a hypodermic needle. Subjects will try both systems to see which they prefer. Researchers will measure changes in spacticity as well as speed, endurance, and efficiency during walking. In addition, they will assess how each system affects the quality of life of the subjects. Finally, Dr. Stein's team will use the latest non-invasive measurement techniques to pinpoint changes in subjects' muscles, spinal circuits, and connections from the brain that would account for any improvements in function and spacticity. Based on preliminary results, this project promises to enhance significantly the ability of some people to walk after spinal cord injuries.
Dr. Charles Haskell Tator, Ph.D. M.D., The Toronto Western Hospital Research Institute, Toronto, ON
$147,033.00, 2-year Grant
Transplantation of adult human spinal cord stem/progenitor cells to the injured adult rat spinal cord
Research category: Stem cells
Although many researchers believe that stem cells hold great promise for treating spinal cord injuries, major hurdles remain. Researchers still do not know the source for most effective stem cells or the right doses and combinations of supporting factors needed to multiply them in culture and ensure that they become the right kind of replacement cells. Dr. Tator, a neurosurgeon as well as a scientist, believes that the center of the spinal cord, in a region called the ependyma, contains stem cells that will give rise to new neurons and their supporting glial cells. In theory, these ependymal cells could be transplanted into people to treat spinal cord injuries. However, stem cells from the adult human spinal cord have never been harvested or transplanted, so no one knows how these cells behave in culture or after transplantation. In this project, Dr. Tator will obtain these ependymal cells from deceased human organ donors after the other organs have been taken for transplantation. He then will attempt to multiply the cells and examine how they behave in culture, including how they respond to various substances that help neurons to grow and survive. He then plans to transplant these stem cells into animal models of spinal cord injury to see if they promote regeneration and repair. The cells will be transplanted three days after injury to simulate the acute phase in humans and 28 days after injury in other animals to simulate humans with chronic injuries.
Dr. Ina Beate Wanner, Ph.D, University of Miami School of Medicine, Miami, FL
$150,000.00, 2-year Grant
Novel use of Schwann cell precursors to promote axonal regeneration across reactive astrocytes
Research category: Axon guidance, synapse formation and neurotransmission
Schwann cells enwrap axons in the peripheral nervous system with protective myelin just as oligodendrocytes do in the brain and spinal cord. When transplanted into the injured spinal cord, Schwann cells promote axon regeneration, but, unfortunately, the regrowing fibers do not extend beyond the injury area to repair damaged spinal circuitry. Dr. Wanner has been studying a more primitive form of Schwann cells and has found them to be a highly supportive framework for axon growth, both in vitro and in vivo. She attributes this to the presence of a cell adhesion molecule called N-cadherin. During embryonic development, when peripheral nerve fibers travel through the limbs towards their target connections, their tips are entirely cloaked in sheets of Schwann cell precursors. These precursors emit growth permissive cues and shield the axons tips from contact with other tissues. After fibers reached their targets, the N-cadherin disappears. Dr. Wanner wants to know what regulates N-cadherin expression and whether this agent might extend the time that Schwann precursor cells promote axon regrowth. In this project, she first will try to grow cultured sensory neurons on a field of reactive astrocytes, the cells that form scars after brain or spinal cord injuries and interfere with axon regeneration. Dr. Wanner then will add Schwann cell precursors in hopes that they will enable sensory neurons to regenerate axons across an inhibitory environment. Second, she will transplant Schwann cell precursors and related cells into animal models of spinal cord injury. Dr. Wanner hypothesizes that the transplanted cells will protect the tips of regenerating axons so they can extend through the hostile zone around the injury and rebuild the damaged circuits.
Dr. Sung Ok Yoon, Ph.D., The Ohio State University, Columbus, OH
$149,575.00, 2-year Grant
Role of p75 as the receptor regulating pro-apoptotic JNK3 and Rho activity after spinal cord injury
Research category: Promotion of axon growth and remyelination
Dr. Yoon has been studying the molecular signals that are activated after a spinal cord injury and either help neurons to survive or widen the cellular destruction. In this project she will focus on two molecules that she has found to have detrimental effects and explore what happens if they are thwarted. The first is a death-promoting molecule called JNK3 and the second is a molecule known as Rho, which inhibits the growth of neurons. JNK3 launches the destroy-your-self mechanism called apoptosis in oligodendrocytes, which are the cells that encircle axons with protective myelin. Using mice bred without the gene for JNK3, Dr. Yoon will test whether more oligodendrocytes survive after a spinal cord injury than they do in the normal controls. She also will assess the effect of blocking Rho by introducing into mice a mutant gene that can inhibit Rho after a spinal cord injury. If blocking JNK3 and Rho yields beneficial results, then Dr. Yoon will explore a possible two-for-one therapeutic target, a molecular signal called p75 that activates both JNK3 and Rho in experiments with cells. She theorizes that by repressing this one molecule, she might block both these unwanted signaling pathways. Developing this approach is one of her long-term goals.
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