Roman Reed Research Grants 2002-2003

Allan Basbaum, Ph.D.
University of California, San Francisco 		Anatomical and functional recovery after spinal cord injury: Contribution of cyclic nucleotides ** $77,428
Armin Blesch, Ph.D.Laura Taylor, B.S.
University of California, San Diego 		Regulated lentiviral gene therapy for spinal cord injury $46,000
Corinna Darian-Smith, Ph.D.
Stanford University 		Cervical dorsal root lesions in monkeys: neuronal consequences and impairment of voluntary hand function $96,539
Ray de Leon, Ph.D.
Cal State University, Los Angeles 		Combining pharmacological and robotic training approaches for improving locomotor recovery after a spinal transection $74,589
Candace Floyd, Ph.D.
University of California, Davis 		Transplantation of olfactory ensheathing cells modified by non-viral gene therapy to secrete NT-3 following spinal cord injury in the rat $68,676
Alan Garfinkel, Ph.D.
University of California, Los Angeles 		Computer simulation of a neuro-musculo-skeletal model of human locomotion $33,878
Susan Harkema, Ph.D.
University of California, Los Angeles 		Activity-dependent plasticity after human spinal cord injury $131,452
Hans Keirstead, Ph.D.
University of California, Irvine 		The remyelinating potential of humane embryonic stem cell-derived oligodendrocytes $92,484
Harley Kornblum, M.D., Ph.D.
University of California, Los Angeles 		Stem cell implantation in a chronic cauda equina / conus medullaris injury model $91,000
Thomas Lane, Ph.D.
University of California, Irvine 		Mechanisms of remyelination following spinal cord damage and demyelination $56,200
Linda Noble, Ph.D.
University of California, San Francisco 		Matrix metalloproteinases and demyelination after spinal cord injury $139,951
Paul Patterson, Ph.D.
California Institute of Technology 		Using leukemia inhibitory factor to promote repair mechanisms after spinal cord injury $58,750
Roland Roy, Ph.D.
University of California, Los Angeles 		Use of a minimally invasive stimulation device (BIONtm System) to induce stepping in completely spinal rats $59,237
Michael Sofroniew, M.D., Ph.D.
University of California, Los Angeles 		Genetically targeted astrocyte scar ablation and biopolymer tissue support after spinal cord injury $100,650
Robert Stern, M.D.
University of California, San Francisco 		The first human chondroitinase: Isolation and characterization of an enzyme that promotes recovery from severe nerve and spinal cord injuries ** $127,320
Mark Tuszynski, M.D., Ph.D. Shula Stokols, B.S.
University of California, San Diego 		Polymer guidance channels for spinal cord injury $46,500
Mark Tuszynski, M.D., Ph.D.
University of California, San Diego 		University of California consortium to study axonal plasticity and regeneration in the primate spinal cord $200,000
James Waschek, Ph.D.
University of California, Los Angeles 		The role of PACAP in remyelination after experimental SCI ** $100,000

** Project will be carried out in the Roman Reed Core Laboratory
TOTAL $1,532,883

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Research Abstracts

An injury to the spinal cord is one of the most devastating assaults the body can sustain, and for centuries spinal cord trauma was considered utterly untreatable. Yet the last twenty years, researchers have made remarkable progress toward understanding the havoc that a spinal cord injury wrecks and identifying potential ways to halt and reverse the damage. We now know that no single drug or surgical advance will ever cure a spinal cord injury. Instead, victims will need a precisely timed series of medications and procedures, starting immediately after the injury and continuing through rehabilitation or longer. Some of these interventions promise to help people living with older injuries as well. Assembling the parts of this treatment package requires a multi-disciplinary effort. Toward that end, the Roman Reed Spinal Cord Injury Research Program has awarded 18 Roman Reed Awards to researchers from a wide range of specialties. What follows are brief descriptions of some major areas of spinal cord research and the Roman Reed projects in each one.

Preventing Secondary Damage

A spinal cord injury unleashes a biological tempest that continues to damage and destroy cells for weeks and perhaps months. This so-called secondary cascade is fueled by an invasion of inflammatory cells, rising pressure inside the spinal cord, dying cells spewing toxins, and healthy cells that self-destruct when they "sense" that something is awry. The Roman Reed Spinal Cord Injury Research Program has awarded Roman Reed Awards to the following scientists who tested ways to prevent or limit the terrible wake of a spinal cord injury:

Matrix metalloproteinases and demyelination after spinal cord injury
Linda J. Noble, Ph.D.
University of California at San Francisco

Dr. Noble has been studying a family of enzymes called matrix metalloproteinases (MMPs). They play a role in cell migration throughout the body, especially in the invasion of immune cells and destruction of tissue that follows injuries and that occurs in some neurological diseases like multiple sclerosis. In a previous study, she found that rats with spinal cord injuries recovered significant function, including walking ability, when she blocked the action of MMPs, starting 3 hours after the injury and continuing the treatment for the next three days. Those promising results led to this project, in which Dr. Noble fully described how the recovery unfolded and tested whether her rat models would fare even better if she extended the duration of the blocking therapy.

In the first part of her project, Dr. Noble learned that the recovery she had observed occurred because her impeding of MMPs promptly after an injury had protected the myelin sheath that surrounded key nerve fiber tracts in the spinal cord. Without myelin, nerve cells are unable to transmit signals. In the second part of this study, she discovered that when she continued her experimental therapy in the animals for seven days, she actually hindered their recovery. She hypothesized that lengthening the therapy must have interfered with a subset of MMPs that promote wound healing and motor recovery. Dr. Nobel and her team then focused on one particular MMP, MMP-2, because it is not expressed in the acutely injured cord but makes an appearance only as healing begins. To test this theory, the researchers evaluated recovery in spinal cord injured mice that were bred without MMP-2. These mutant mice fared significantly worse than the normal controls. Furthermore, Dr. Noble found that other MMPs also seem to emerge on cue and play distinct roles. For example, MMP-9, which peaks one day after an injury, disturbed the integrity of blood vessels and promoted early inflammation in the injured cord. Findings from this project and Dr. Noble's earlier work, provide tantalizing evidence that doctors might use medications to control the various MMPs, suppressing the harmful actors and boosting the performance of helpful ones.

Using leukemia inhibitory factor to promote repair mechanisms after spinal cord injury
Bradley Kerr, Ph.D. and Paul Patterson, Ph.D.
California Institute of Technology

The inflammatory response to a spinal cord injury is a decidedly mixed blessing. When immune cells flock to the injury site, they help to isolate damaged tissue, clean up cellular debris, and promote healing. But immune cells also cause harmful inflammation which, among other things, contributes to the death of healthy neighboring cells. The inflammatory response may also indirectly prevent axons from regrowing through the damaged area of the spinal cord. These researchers looked at the role of cytokines, proteins that orchestrate the body's immune response. Cytokines summon immune cells to the injury site and enable them to interact with blood cells, neurons, and glia, the cells that support neurons. In this project, Drs. Kerr and Patterson focused on a particular cytokine family called leukemia inhibitory factor (LIF), which they suspected was vital to co-ordinating the immune response. In this study, they explored the action of LIF to see if they could harness it to enhance the positive actions of immune cells. If, for example, LIFs could accelerate the activity of scavenger cells so that they would clear away the toxic molecules that hinder axon regrowth, then more cells might survive the initial injury and more regeneration might occur. Promoting Axon Regeneration Axons are the snaky arms of the nerve cell bodies that transmit electrical impulses from one neuron, or nerve cell, to another. Unlike neurons in the body's extremities, neurons in the brain and spinal cord cannot regrow their axons after an injury. But scientists are closing in on the reasons for this difference and are devising strategies to make axon regeneration in the central nervous system more likely. We know, for example, that spinal cord injuries churn up naturally occurring substances that transform the area around the wound into hostile territory for new axons. The body also manufactures growth boosters known as neurotrophins, or growth factors, that both spur neurons to replace their lost axons and enable those new axons to flourish. A two-step approach is needed that would both stymie growth inhibitors and amplify the effects of neurotrophins. The following scientists have received Roman Reed Awards to focus on how axons can be helped to regenerate:

Anatomical and functional recovery after spinal cord injury: Contribution of cyclic nucleotides
Allan I. Basbaum, Ph.D. and Simona Neumann, Ph.D.
Department of Anatomy, W.M. Keck Foundation Center for Integrative Neuroscience UC San Francisco

Drs. Basbaum and Neumann approached the problem of axon regeneration from two directions. First, they focused on the latent ability of certain nerve cells to regrow their injured axons in hopes that a therapy might be developed that would reawaken that mechanism. In earlier experiments, Drs. Basbaum and Neumann had discovered that they could prime nerve cells in the spinal cord to regenerate their axons by exposing them to a molecule known as cAMP prior to an injury. In this study, they tried to spur the same regrowth by infusing cAMP into the spinal cord at the time of injury and soon afterward. Unfortunately, these approaches failed. Drs. Basbaum and Neumann concluded that their original technique must have affected the genetic machinery of the nerve cells, enabling them to produce new axons. While it is clear that nerve cells possess this intrinsic ability, more work is needed to learn how rouse it.

In a second series of experiments, Dr. Basbaum's team examined how new axons formed a leading edge, or growth cone. This elaborate structure contains the navigational "equipment" that enables each axon to reach its intended destination in the nervous system. The assembling of a growth cone is an essential step if regeneration of injured axons is to occur. In this project, Drs. Basbaum and Neumann evaluated how a family of proteases, or enzymes, named calpains contributes to the development of growth cones. In laboratory tests, calpains significantly affected the development of sensory neurons. Drs. Basbaum and Neumann plan to continue exploring what calpains do and how they might aid in the repair of the spinal cord.

Regulated lentiviral gene therapy for spinal cord injury
Laura Taylor and Armin Blesch, Ph.D.
Department of Biology, University of California at Los Angeles

Genetically engineered cells may one day deliver the instructions that enable the body to produce it own "medicine" at the precise spot it is needed. In theory, such treatments would reverse the toll of injury and disease and, perhaps, even aging. Neuroscientists already are injecting these altered cells into animal models to produce more growth factors, or neurotrophins, which are vital to nerve cell growth and survival. Many studies have shown that increasing the concentration of neurotrophins promoted regeneration in rats with spinal cord injuries. In this project, Taylor and Blesch wanted to improve their ability to control the effects of future gene therapy. They used viral vectors, genetically altered viruses that no longer can cause illness, to stimulate the production of neurotrophin-3 (NT- 3) after spinal cord injury. When used in combination with transplanted cells that fill the cavity that forms at the injury site, the NT-3 caused axons to grow across a spinal cord injury in a rat model. In addition, these researchers created vectors that could be turned on and off simply by adding an antibiotic to the animals' drinking water. In future studies, Taylor and Blesch will try to control the growth responses and the way new axons then span a spinal cord injury. Finding a reliable way to administer and direct therapeutic genes is vital to making gene therapy safe.

The first vertebrate chondroitinase: A new therapeutic for promoting functional recovery from spinal cord injury
Robert Stern, M.D.
Department of Pathology, UC San Francisco

In 1998, scientists began reporting that an enzyme derived from bacteria could, quite literally, cut through the scar tissue that poses both physical and chemical barriers to axon regeneration after a spinal cord injury. Researchers learned that if they used this enzyme called chondroitinase to treat mice with spinal cord injuries, new axons would emerge and grow through the spinal lesion to reconnect damaged circuitry. The treated animals regained their ability to walk while the controls remained paralyzed. Thanks to the newly decoded human genome and a decade of experience studying other enzymes, Dr. Stern and his colleagues, unexpectedly discovered genes for the first chondroitinase to be found in vertebrates. Because large quantities of the enzyme were needed to continue testing it in spinal cord experiments, Dr. Stern's laboratory tried in this project to produce chondroitinase through genetic engineering. This involved the insertion of the genetic code for making the enzyme into cultured cells, but this approach failed to yield enough of the enzyme. Dr. Stern is now collaborating with a former graduate student from his laboratory who has developed a tissue-culture system for making an enzyme involved in human fertilization that resembles chondroitinase. Dr. Stern is hopeful that this new process will yield the industrial amounts of chondroitinase that scientists need. He and others believe that human chondroitinase is less likely than the bacteria-derived form to trigger an immune response in the recipients and holds great promise as a treatment for spinal cord injuries

Genetically targeted astrocyte scar ablation and biopolymer tissue support after spinal cord injury
Michael V. Sofroniew, M.D., Ph.D., Ben Wu, Ph.D., Jill Faulkner (nee. Lomonaco), Julia Herrmann, B.S., Chananit Sintuu
Neurobiology & Biomedical Engineering, University of California, Los Angeles

This group is working on a combination of three experimental therapies in their ongoing project to promote axon regeneration and recovery of function after spinal cord injury. The approach involves eliminating or reducing scarring, stimulating axon regrowth, and providing "scaffolding" to support axons as they elongate. In this project, these researchers continued to test two techniques for preventing the formation of scar tissue, which stops regenerating axons in their tracks. First, they tried to eliminate the cells that comprise scar tissue; second, they tried to keep those scar-producing cells from responding to an injury. At the same time, this group is perfecting the composition of biodegradable microbeads that can be injected into the spinal cord and gradually release growth factors to prompt nerve cell bodies to produce new axons. The beads are coated with sticky molecules that give axons a footing as they grow through the spinal lesion. Once the technical problems have been resolved, this research team plans to test their anti-scarring therapies along with their new micro beads. If these tests are successful, the next step would be to evaluate whether the axon regeneration restores function.

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Remyelinating Axons

Some axons survive a spinal cord injury but lose their protective sheath of myelin, the fatty substance that insulates and protects them. Stripped of myelin, axons no longer can transmit electrical impulses, and nerve circuits go silent. How to induce remyelination is one of the challenges in treating both spinal cord injuries and neurological diseases like multiple sclerosis that rob people of movement, bowel and bladder control, and other functions. The following researchers have Roman Reed Awards to test approaches to remyelination:

Anatomical and functional recovery after spinal cord injury: The remyelinating potential of human embryonic stem cell-derived oligodendrocytes
Hans S. Keirstead, Ph.D.
Reeve-Irvine Research Center, University of California at Irvine

Stem cells give rise to the more specialized types of cells that become skin, bones, and all the organs. Scientists have been searching for laboratory techniques that would enable them to "order" those master cells to spin off the particular types of cells needed to repair the injured spinal cord. Using federally approved human embryonic stem cells, Dr. Keirstead and his research team have pioneered a technique that causes the stem cells to produce oligodendrocytes, the cells that produce myelin in the brain and spinal cord. The researchers then transplanted those cultured oligodendrocytes into animal models of spinal cord injury. The cells survived after transplantation, spread throughout the injured portion of the spinal cord, and successfully produced myelin. Dr. Keirstead is also testing the cells in animal models that mimic other types of conditions that destroy myelin. These studies are a crucial step in testing the potential of stem cells to treat humans.

Mechanisms of remyelination following spinal cord damage and demyelination
Thomas E. Lane, Ph.D. and Michelle Hickey
University of California, Irvine

These researchers have found a therapy to reverse nerve damage in mice infected with a virus that strips axons of myelin through an inflammatory process. Lane and Hickey focused on one member of a family of proteins known as chemokines that beckon the immune cells that cause inflammation. They learned that a particular chemokine known as IP-10, or CXCL10, was especially prominent in the infected animals. Moreover, blocking the action of IP-10 led to remyelination. In this project, Lane and Hickey conducted sophisticated tests of the genetic activity in the mice that received the experimental treatment and compared it to genetic activity in the untreated mice. Their analysis showed that more genes involved in myelin production and fewer genes related to chemokines were active in the mice treated with the anti-CXCl10 agent than in the control mice. The researchers also noted a difference in the prevalence of certain genes that promote the development of oligodendrocytes, the cells that make myelin in the brain and spinal cord. Lane and Hickey are continuing to investigate whether the anti-CXCL10 treatment directly affects the production of oligodendrocytes. This work could help scientists identify new targets for gene therapy that could prevent axons from losing their myelin to disease or injury.

The role of PACAP in remyelination after experimental SCI
James A. Waschek, Ph .D.
University of California at Los Angeles

Dr. Wascheck began last year to examine a new treatment strategy that one day could both limit the severity of spinal cord injuries and promote recovery. This project is based on the recent discovery that a neuropeptide called PACAP, a protein-like molecule that helps nerve cells communicate with each other, appears in the brain and spinal cord after injury. PACAP can regulate myelination, a critical process for recovery. Moreover, it does so, in part, by influencing oligodendrocytes, the cells that produce myelin in the central nervous system. Because the normal response to spinal cord injury is so complex, a primary goal of this project is to determine precisely how and when PACAP takes part in the many steps of remyelination after spinal cord injury. A secondary goal is to determine how best to utilize PACAP to program stem cells in vitro to evolve into oligodendrocytes so that these primitive cells can be transplanted into an injury to remyelinate axons. If successful, the two-part project would lay the groundwork for new approaches to the treatment of spinal cord injuries.

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Replacing Cells

One strategy for repairing the damaged spinal cord and restoring function is to replace the lost neurons and the glial cells that support, protect, and nourish them. Some scientists work on transplanting primitive stem cells that spawn the cells needed to repair the spinal cord. Other researchers concentrate on how best to pretreat those master cells so that they become neurons or glia. Still others believe the body has the potential to repair itself, and they focus on the mechanisms that first created the brain and the spinal cord and how they might be revived to make new cells following a stroke or spinal cord injury. The following researchers who study cellular replacement have received Roman Reed Awards:



Transplantation of olfactory ensheathing cells modified by non-viral gene therapy to secrete NT-3 following spinal cord injury in the rat
Candace L. Floyd, Ph.D.
University of California, Davis

Dr. Floyd has combined two promising approaches to repairing the injured spinal cord: cell transplantation and gene therapy. She focused on the therapeutic potential of olfactory ensheathing cells, fascinating support cells found in the nasal passages and the part of brain that processes smell. Nerve cells in this olfactory system turn over frequently throughout life, a process that does not occur in other parts of the central nervous system. When transplanted into animals with spinal cord injuries, scientists have found that the ensheathing cells prime the area for nerve cell regeneration and also wraps the new axons that do emerge with a vital layer of the fatty insulation known as myelin. Moreover, patients own olfactory ensheathing cells might be harvested and then reintroduced into their injured spinal cord. This technique would reduce the chances that the transplanted cells would trigger the imune system to reject them. In this project, Dr. Floyd wants these ensheathing cells to do double duty: remyelinate axons and produce growth factors, or neurotrophins, that act like nerve fertilizer to encourage and support the growth of new axons. She has perfected techniques for transplanting the ensheathing cells, monitoring their progress in the injured spinal cord, and assessing any recovery of function that occurs following the transplant. She also is working out the technical challenges of genetically engineering them to produce a growth factor known as NT3. Dr.Floyd has already determined that the way the ensheathing cells are multiplied in the lab affects the techniques used to insert the gene for NT3 production. Her next step is to transplant the NT3-secreting cells into the rat. If successful, this study could have far-reaching consequences.

Anatomical and functional recovery after spinal cord injury: The remyelinating potential of human embryonic stem cell-derived oligodendrocytes
Hans S. Keirstead, Ph.D.
Reeve-Irvine Research Center, University of California at Irvine
(see Remyelinating Axons)

Stem cell implantation in a chronic cauda equina / conus medullaris injury model
Harley I. Kornblum, Theresa Kelly, Thao X. Hoang, Andres Paucar, Jaime H. Nieto, Brett T. Franchini, Elizabeth A. Warner, Leif A. Havton
Departments of Pharmacology and Pediatrics, UCLA School of Medicine

This team hopes one day to use some form of stem cells to repair a rat model of injuries to the lowest part of the spinal cord and the nerve roots that emerge just below it. In humans, such injuries can result from accidents and ruptured discs and cause bowel and bladder dysfunction and some degree of lost sensation and movement in the legs and hips. During this project, the UCLA team determined the safest, most effective way to transplant and monitor stem cells and began to assess the therapeutic protential of different types of primitive cells derived from mice and rats. The group learned that using tiny glass pipettes to deliver embryonic stem cells to the rat spinal cord caused less damage to the host animal's spinal cord than using needles. But because the transplanted cells did not survive, researchers began the arduous process of finding cells that would. This task involved confirming that candidate cells can be multiplied in the laboratory and coaxed to evolve into spinal neurons. The UCLA team evaluated embryonic stem cells that give rise to multiple cells types as well as the more specialized primitive nerve cells called neural progenitors that give birth only to cells destined only for the nervous system. The neural progenitors were derived from embryonic spinal cords at different stages of development. Preliminary results showed that progenitor cells harvested from younger embryos spun off more neurons than those harvested from both older embryos and newborn animals. Researchers also compared the properties of progenitor cells taken from embryonic brains with those found in embryonic spinal cords of the same age. This work will continue and should further scientists' understanding of neural progenitors and which types of cells show the greatest promise for replacing spinal neurons that are damaged or destroyed.

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Implanting Artificial Substrates

In animal experiments, scientists have learned to overcome the natural barriers to nerve cell regeneration in the central nervous system and now can trigger a vigorous outgrowth of new axons to replace those damaged or destroyed by a spinal cord injury. However, the growth is disorganized, and the new axons rarely find their way through the lesion to healthy tissue. The next challenge, then, is to control and guide those new axons so that they can extend over long distances, make the proper connections, and reconstruct working nerve circuits. With that goal in mind, more and more scientists are combining experimental therapies that promote axon regeneration with devices that fill the gap in the injured spinal cord and keep growing axons on track. Researchers are testing tiny bridges, tunnels, and scaffolding or substrates that would be inserted between the two stumps of the injured spinal cord to support and guide regenerating axons as they travel toward their final destinations. The following researchers received a Roman Reed Award to explore this approach:

Polymer guidance channels for spinal cord injury
Shula Stokols and Mark Tuszynski, M.D., Ph.D.
University of California, San Diego

Drs. Stokols and Tuszynski have been testing a scaffold composed of precisely positioned channels designed to guide axons across the site of a spinal cord injury. In theory, this device would deliver molecules that stimulate regeneration, provide a physical bridge across the lesion, and contain substances that enable axons to latch onto as they elongate. In this study, the researchers found that agarose, a gel extracted from seaweed, could be fashioned into a biocompatible and inert set of vertical channels, each roughly the diameter of a human hair. Furthermore, when implanted into rat models, axons entered the channels and grew straight across the back from the head to the tail. By packing these channels with neurotrophins that promote axon growth, Drs. Stokols and Tuszynski increased the amount of axon regeneration that occurred in their experiments. Additional work is underway to identify the material that could fill the channels and provide the best "footing" for axons. The researchers also are evaluating other ways to deliver growth-promoting substances, including increasing their concentration in the surviving ends of the spinal cord.

Genetically targeted astrocyte scar ablation and biopolymer tissue support after spinal cord injury
Michael V. Sofroniew, M.D., Ph.D., Ben Wu, Ph.D., Jill Faulkner, Julia Herrman, Chananit Sintuu
Neurobiology & Biomedical Engineering, University of California, Los Angeles
(See Promoting Axon Regeneration)

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Retraining and Rewiring the Spinal Cord

Certain forms of rehabilitation appear to do more than maintain muscle strength and cardio-vascular fitness in someone with a spinal cord injury. Recent research has shown that some training protocols including progressive weight bearing and repetitive stepping routines may restore function by reshaping nerve circuitry, a process known as plasticity. These routines seem to condition the spinal cord below the level of an injury to activate the muscles in the legs and feet even without input from the brain. Vigorous exercise also appears to promote axon regeneration and lead to overall improvements in health and quality of life. With Roman Reed Awards, the following researchers will continue to explore these promising techniques:

Combining pharmacological and robotic training approaches for improving locomotor recovery after a spinal cord transection
Ray de Leon, Ph.D.
Department of Kinesiology and Nutritional Science, California State University, Los Angeles

With their body weight supported in harnesses, people with spinal cord injuries can be helped to move their legs in stepping motions over a treadmill. This so-called supported treadmill training, when repeated regularly for several months, can improve walking following a spinal cord injury. However, this training requires the active support of several therapists, who often find it difficult to assist people in moving their legs, particularly those with full paralysis. In this project, Dr. de Leon tested two approaches to make this training both easier and more effective. With a rat model of complete spinal cord injury, he used a robot-training system to guide animals' hind limbs in a walking pattern over a moving treadmill. In addition, he administered the drug quipazine before training sessions to boost the activity of the spinal neurons that generate stepping. He found that the robotic device generated sensory signals that are necessary to improve hindlimb walking in the rats. In addition, quipazine did improve the results of the training. These findings could forward the development of the human version of the robot, which could help to standardize this form of training and make it more widely available. When used in conjunction with drug therapy, this regimen could enable people with spinal cord injuries to recover at least some ability to walk.

Activity dependent plasticity after human spinal cord injury
Susan Harkema, Ph.D.
Department of Neurology, University of California at Los Angeles

Under this grant, Dr. Harkema continued her work on training people with spinal cord injuries to regain some ability to stand or walk. Building on previous results from animal studies, she tested whether training techniques tailored to each participant to emphasize muscle activation during standing would help people with complete spinal cord injuries to stand. In addition, she looked at whether the training would build up the bone density in their legs. Leg and hip bones quickly begin to lose their mineral content following spinal cord injury, increasing the chances that people with these injuries will suffer fractures. These breaks often require hospitalization and sometimes surgery, making them a serious and costly complication of spinal cord injuries. Traditional rehabilitation therapy that involved some form of standing has been relatively unsuccessful at reversing the loss of bone density. In most of the older studies that have looked at bone density and standing, subjects stood with the help of a frame or similar device that bore most of their weight; little or no leg muscle force was used. Dr. Harkema's preliminary results showed that when subjects with severe spinal cord injuries completed her form of weight-bearing training, they could stand with a walker for several minutes to over an hour, and their bone density got better. Dr. Harkema also observed that the blood pressure readings of participants with higher level injuries improved following training. Her results are important because if people with spinal cord injuries could stand, even for short periods of time, it would greatly increase their independence during routine tasks such as cooking or washing, improve their general health, and reduce the likelihood that they will suffer debilitating fractures.

Use of a minimally invasive stimulation device (BIONtm System) to induce stepping in completely spinal rats
Ronaldo Ichiyama, Ph.D. and Roland Roy, Ph.D.
Department of Physiological Science, University of California at Los Angeles

In this project, Drs. Ichiyama and Roy explored a novel approach the help rats with spinal cord injuries to walk again. The two researchers demonstrated that paralyzed rats would produce weight-bearing steps when electrical stimulation was delivered to their spinal cords via tiny electrodes implanted on the back surface of their cords. Drs. Ichiyama and Roy developed a way to insert the devices without causing further damage, and the implants, known as the BION™ System, proved effective and long-lasting. In a series of experiments, Drs. Ichiyam and Roy homed in on the points on the spinal cord where electrical stimulation produced the best and greatest number of steps. Next, they varied the frequency, intensity, and duration of the stimulation to see which combination worked best. Having succeed with their original aims, Drs. Ichiyam and Roy went on to test whether they could obtain even better results by combining electrical stimulation with the administration of the drug quipazine to boost the activity of nerve cells. The dual approach produced very effective weight bearing steps that that closely resembled those of normal rats. These dramatic results with rats could soon lead to human clinical trials.

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Restoring Concomitant Function and Eliminating Complications

In addition to having various degrees of paralysis, people living with spinal cord injuries often deal with a host of other problems that limit their independence and have a major impact on their quality of life. These conditions include loss of bowel, bladder, and sexual function; spasticity; intractable pain; and broken bones. Some complications like infections and irregularities in temperature and blood pressure are potentially life-threatening A Roman-Reed award will support the following researcher who is trying to find a way to preserve bone mass in the legs and prevent fractures.

Activity dependent plasticity after human spinal cord injury
Susan Harkema, Ph.D.
Department of Neurology, University of California at Los Angeles
(See Retraining and Rewiring the Spinal Cord)

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Creating New Models For Spinal Cord Research

Before promising therapies can be tested on humans, scientists need to learn as much as possible about precisely what happens following a spinal cord injury and how well potential treatments work in animals. Other scientists are working to create computer simulations or types of programs that will help to devise and evaluate treatments and rehabilitation strategies to restore lost function. These researchers have won Roman Reed Awars to develop new models of spinal cord injuries:

Cervical dorsal root lesions in monkeys: Neuronal consequences and impairment of voluntary hand function
Corinna Darian-Smith, Ph.D.
Stanford University

Neck and shoulder injuries that damage the key junctures, or dorsal roots, between the spinal cord and the sensory nerves leading to the arm and hand often cause a permanent, severe loss of manual dexterity. Dr. Darian-Smith has developed a primate model that enables her to measure very precisely the effects of injuries limited to very specific nerve roots. She observes how these injuries disrupt sensory input from the skin and deeper tissues of the index finger and thumb and affect grasping and fine motor skills. She also studies how the peripheral nervous system then reorganizes following the injury and eventually restores function to the affected hand. In an earlier project, she found that primary sensory nerve cells played a key role in dramatic changes in the nerve circuits that occurred two to four months after a disabling injury. In this investigation she found that cells in the spinal cord and brain stem continued to change 15-25 weeks after the cervical roots were cut. She also looked at whether these changes correlated with behavioral recovery. Indeed, she found that the animals' ability to reach, grasp, and retrieve objects improved. This recovery occurred in both limited and more severe injuries, although the recovery was delayed for several months in the animals with more extensive damage. These results will help scientists to understand better how the nervous system can adapt following an injury. Dr. Darian-Smith's work also raises the possibility that this intrinsic ability to reorganize nerve circuitry might be enhanced to help people recover from neck and shoulder injuries.

Computer simulation of a neuro-musculo-skeletal model of human locomotion
Uday Patel and Alan Garfinkel, Ph.D.
Department of Physiological Sciences, University of California at Los Angeles

Walking requires a perfectly orchestrated pattern of nerve impulses to activate and then inhibit the muscles that move the trunk, hips, knees, and ankles. Normally, the nerve circuits in the lower spinal cord receive and process walking orders from the brain and sensory information from the leg, such as the slope of a path. These circuits then coordinate the complex muscle activity that enables someone to place one foot in front of the other, again and again, to walk without falling. When a spinal cord injury reduces or cuts off the input from the brain, the lower spinal cord retains the ability to generate the elaborate patterns for stepping and standing and can be "trained" to operate on its own. Patel and Garfinkel are interested in how this adaptation occurs so they can maximize its effects to restore the ability to walk after spinal cord injury. In this project, they have been working on a computer simulation of how the nerve network in the lower spinal cord stimulates the various muscles of the legs in walking patterns. Their model also illustrates the wave of inhibition that enables the left and right legs to alternate. It demonstrates that coordination of the muscles within a leg and coordination between legs could be accomplished by generating wave after wave of activation and inhibition. Patel and Garfinkel now are trying to identify the mechanism that initiates each step. They then plan to develop a second simulation that will show how the neuronal network in the lower spinal cord actually drives bones and muscles.

University of California Consortium to Study Axonal Plasticity and Regeneration in the Primate Spinal Cord
1M Tuszynski, 2T Bernot, 1A Blesch, 3R Edgerton, 3L Havton, 3J Hodgson, 2H McKay, 2J Roberts, 3R Roy, 4O Steward, 1L Vahlsing, 1H Yang, 3H Zhong
1UCSD, 2UC Davis, 3UCLA, 4UC Irvine

In this multi-laboratory collaboration, University of California scientists have developed a humane and practical primate model of common type of human spinal cord injury: an incomplete injury to the the 5th and 6th vertebrae in the neck. This type of injury robs people of varying degrees of movement and function below the level of the lesion. The primate models have measurable losses of hand and leg function, but retain voluntary bowel and bladder control and can move freely about in their cages. This model enables the UC Primate Consortium to test in larger animals the therapies that have led to some recovery of function in mice and rats.

With this primate model, the consortium has begun long-range studies on the how spinal cord injuries damage and destroy axons following an injury and how that toll might be lessened and nerve circuitry rebuilt. Scientists have already observed surprising spontaneous recovery of function in the primates and are trying to explain precisely how that occurred. This work could lead to therapies that would strengthen those self-repair mechanisms. Researchers also are testing a form of gene therapy in which they transplant replacement cells into the animals that secrete substances that promote axon regeneration. The transplanted cells have survived as long as a year and are being carefully monitored to see how well they are growing into and through the spinal cord lesion. Primate models may be a key step in validating some promising experimental treatments so that they can be moved into human clinical trials.