Monday, May 05, 2008

Advances Offer Hope for Spinal Cord Injury Patients

Cell transplantation, physical therapy show promise in restoring function

There is no cure for a spinal cord injury, but much headway has been made in clinical research that could lead to one. Other therapies have helped to restore some function in spinal cord injured patients. A look at some efforts…

The latest in cell transplantation

Cell-based therapies hold the potential for replacing cells and restoring function lost to disease or injury. Among those being developed to help treat spinal cord injuries:

Stem cells are building blocks capable of turning into various cells and tissues found in the body. Embryonic stem cells, in particular, are able to transform into any tissue, given the right biochemical instructions, and could be used to replace spinal cord cells lost during injury. However, human embryonic stem cell research is politically controversial, because culling the cells destroys embryos. Still in the research phase, stem cells have helped paralyzed rodents move again in several ways, including helping to regrow destroyed nerve cells in the spinal cord and successfully restoring myelin, a nerve fiber insulation that helps maintain the electrical conduction required to move.

Olfactory tissue, which covers about one-inch of the upper nasal cavity, contains many cells with regenerative potential, including olfactory ensheathing cells (OECs). Several experiments have found that OECs promote nerve regeneration and may restore function when implanted into an injured spinal cord. These OECs produce insulating myelin sheaths around the damaged nerve cells, encouraging regrowth. While research continues, some scientists, including Portugal's Dr. Carlos Lima, have transplanted olfactory tissue into patients with spinal cord injuries. Preliminary results were published in 2006 in the Journal of Spinal Cord Medicine.

Schwann cells: Another type of "ensheathing" cell, Schwann cells may also help stimulate nerve regeneration of an injured spinal cord. According to Dr. Wise Young, founding director of the W.M. Keck Center for Collaborative Neuroscience at Rutgers University, many laboratories have shown that Schwann cells alone will improve function after spinal cord injury in animals and even more so when they are combined with other therapies, such as OECs.

New advances in physical rehabilitation

Functional electrical stimulation: When connections between the brain and spinal cord are diminished by trauma, the ability to control movement can be eroded or lost. Functional electrical stimulation, or FES, systems can act as a substitute for those lost signals. FES systems apply a small electrical current that stimulates muscle contractions via electrodes that are either taped to the skin or surgically embedded. The contractions help maintain muscle mass, initiate movement in hands or legs or even stimulate the bladder or diaphragm. Dr. John McDonald of Baltimore's Kennedy Krieger Institute uses special exercise bicycles hooked up to FES systems to help paralyzed patients pedal, believing the repetitive activity helps restore function and also may stimulate regrowth of the damaged neural connections. McDonald also used FES in working with the late actor Christopher Reeve.

McDonald says: "We're focused on incremental improvements. What we ... say is this: No one can tell you whether you can walk or not walk. All I can say is doing an activity-based program in today's world is your best chance at meeting the cure halfway.''

Treadmill training uses repetitive motion to try to teach the legs how to walk again. A paralyzed person is suspended in a harness above a treadmill, reducing weight the legs have to bear. As the treadmill starts, therapists move the person's legs in a walking pattern. The theory driving the work is that paralysis causes "learned nonuse" of muscles, but the injured nervous system may be capable of recovery when certain conditions are optimized, including the patterned neural activity that accompanies treadmill walking. (Source: The Christopher and Dana ReeveFoundation Paralysis Resource Center.)

Activity-based, exercise or aggressive physical rehabilitation: Based on the same activity-triggering premise, several centers across the nation are using aggressive exercise, or activity-based therapy, to help restore function in some spinal cord injured patients. Results vary, depending on the patient's level of injury and how much time has passed since the injury.

But researchers like Young, of Rutgers, voice encouragement: "Many of the people who are currently not walking, if trained properly, would be able to walk. What is really necessary is more evidence-based medicine to indicate that these things really work and then to show to the insurance companies that this is an effective therapy so that they will cover it. Hundreds of thousands of peoples' lives would be affected.''

Centers include: Project Walk in Carlsbad, Calif.; BeyondTherapy, at the Shepherd Center in Atlanta; The Center for SCIRecovery at the Rehabilitation Institute of Michigan.

Pharmaceutical

Methylprednisolone, a steroid drug, became a standard treatment for acute spinal cord injury in 1990 when a large-scale clinical trial showed significantly better recovery in patients who were given the drug within the first eight hours after their injury. It appears to reduce the damage to nerve cells and decrease inflammation near the injury site by suppressing activities of immune cells. (Source: National Institute of Neurological Disorders and Stroke.)

Other drug-related research now under way includes: Studies to determine whether Riluzole, now used to treat Lou Gehrig's disease, may protect nerve cells and promote motor recovery when administered after spinal cord injury; and a trial involving the drug Cethrin, which has been found in animal studies to lessen post-traumatic neural cell death.

Gene therapy

Gene therapy carries the potential to provide the injured spinal cord with the specific gene products, or proteins, that it needs to promote functional recovery. Gene therapy is not a current treatment for spinal cord injuries but is being studied with animal models of spinal cord injury. The concept is to transfer into the spinal cord a gene encoding a therapeutic protein, such as a growth factor or an axon guidance molecule, or to transplant cells modified to incorporate the gene. When the gene is expressed, the cell makes the desired protein. (Source: "Spinal Cord Injury: Progress, Promise and Priorities,"' a publication of The Institute of Medicine, an arm of The National Academies.)

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